Introduction to Vitamins, their Classification, Functions, Sources, Uses and Diseases caused by their deficiency ~ Study Notes, Exams Guide, and Carrier Paths

Vitamins are organic molecules that are essential for the proper functioning of the body. They are required in small amounts for the maintenance of good health, but they cannot be synthesized by the body (except Vitamin D, K, and some of the vitamins of B-Complex ), and therefore must be obtained from the diet or supplements.

Vitamins play a variety of roles in the body, including helping to build and maintain healthy tissues, supporting the immune system, and converting food into energy. A deficiency in certain vitamins can lead to specific deficiencies or health problems.

Vitamins, their classes, sources, and roles in our body.

Classification of Vitamins

There are two main types of vitamins: fat-soluble vitamins and water-soluble vitamins.

A. Fat-soluble vitamins: These vitamins are dissolved in fats and stored in the body's fatty tissue. Examples include vitamin A, vitamin D, vitamin E, and vitamin K.
B. Water-soluble vitamins: These vitamins dissolve in water and are not stored in the body to the same extent as fat-soluble vitamins. Examples include vitamin C and the B-complex (B1 to B12).

A. Fat Soluble Vitamins

They include vitamins A, D, E, and K.
Only Vitamin K has a coenzyme activity.
These vitamins are released, absorbed, and transported along with the diet's fat.
They are not readily excreted in the urine.
They are stored in significant amounts in the liver and adipose tissues.

Vitamin-A (Retinol)
Vitamin A is present in the diet in the following two forms

a. Preformed vitamin A (retinol): It is found in animal-derived foods such as liver, eggs, and dairy products, and

b. Provitamin A (beta-carotene): It is found in plant-derived foods such as fruits, vegetables, and whole grains

Functions of Vitamin-A

Before getting depth into the Functions of Vitamin-A, when have to first consider two forms of Vitamin-A i.e.

a. Retinal: It is the aldehyde form of Retinol that performs all Vitamin-A's functions.

b. Retinoic Acid: It is an oxidized form of retinol that performs the functions of growth and maintenance of epithelial tissues.

Now we are going to explore the functions/roles of Vitamin-A, given as under

1. Role of Vitamin-A in Visual Cycle

The visual cycle is the process by which the body converts light into electrical signals that can be interpreted by the brain.

In the visual cycle, vitamin A is converted into a retinal molecule, a key component of the protein rhodopsin.
Rhodopsin is found in the rods, which are light-sensitive cells in the retina that are responsible for detecting low levels of light (dim light).
When eyes are exposed to bright light all of the rhodopsin gets hydrolyzed and when the person comes back to the darkroom, he/she will be unable to see in the darkroom for a while.
In the darkroom or dim light, re-synthesis of rhodopsin takes place and after some time the person begins to see in the dim light.
If Vitamin-A is deficient, the synthesis of rhodopsin cannot take place and the person becomes unable to see in dim light, a condition known as Night Blindness.

2. Role of Vitamin-A in Reproduction

Vitamin A is also important for the proper functioning of the reproductive system.

In males, vitamin A is required for the production of testosterone, a male hormone that is important for the development and maintenance of male reproductive organs. Vitamin A is also involved in the production of sperm and may be important for fertility.
In females, vitamin A is required for the proper functioning of the ovaries and the development and maintenance of the female reproductive system. It is also involved in the production of estrogen and progesterone, two hormones that are important for reproductive health.
Vitamin A is essential for the proper functioning of the reproductive system, and a deficiency in vitamin A can lead to reproductive problems such as infertility.

3. Role of Vitamin-A in Bones growth

Vitamin A is also important for the proper growth and development of bones.

Vitamin A is involved in the synthesis of collagen, a protein that is important for the structure and strength of bones. It is also involved in the regulation of osteoclast activity, which are cells that break down bone tissue.
In addition, vitamin A plays a role in the development and maintenance of the chondrocytes, which are cells that produce and maintain cartilage. Cartilage is a type of connective tissue that cushions and supports bones and joints.
Vitamin A is essential for the proper growth and development of bones, and a deficiency in vitamin A can lead to bone problems such as osteoporosis.

4. Metabolic Role of Vitamin-A

Vitamin A is also involved in various metabolic processes.

One of the main metabolic roles of vitamin A is in the maintenance of the epithelial tissues, which are tissues that form the outer layers of the skin, the respiratory and digestive tracts, and other organs. Vitamin A is required for the proper differentiation and proliferation of these cells, and it helps to maintain their integrity and function.
Vitamin A has also involved in the metabolism of fats and the synthesis of certain hormones e.g. glucocorticoids.
It is required for the proper functioning of the liver, which plays a central role in metabolism, and it is involved in the synthesis of bile, which is necessary for the digestion and absorption of fats.
It also helps in the synthesis of glycogen from its precursor, such as lactate and glycerol (gluco-neo-genesis).
It is required for the normal activity of mitochondria. An excess or deficiency of Vitamin-A interferes with Oxidative Phosphorylation (ATP Production).

5. Role of Vitamin-A in the prevention of Chronic Diseases

Some studies have suggested that vitamin A may also have a role in the prevention of chronic diseases.

One area where vitamin A may have a protective effect is the development of cancer. Some studies have suggested that vitamin A may help to prevent the development of certain types of cancer, such as lung, breast, and prostate cancer. However, more research is needed to confirm these findings and to determine the optimal dosage and duration of vitamin A supplementation for cancer prevention.
Vitamin A may also have a protective effect against cardiovascular disease. Some studies have suggested that high levels of vitamin A may be associated with a lower risk of heart disease, although more research is needed to confirm these findings.

Absorption and Transport of Vitamin-A

The absorption of vitamin A from the small intestine is facilitated by bile acids, which help to solubilize the vitamin in the intestine. Once absorbed, vitamin A is transported to the liver via the hepatic portal vein, where it is stored in the liver and other fatty tissues. Upon requirement, it is transported from the liver to targeted cells. Thus absorption and transport of Vitamin-A occur in two steps i.e

I. From the intestine to the liver :

Retinol esters present in the diet are hydrolyzed to free fatty acid and retinol (Vitamin-A).
Carotenes in diet are cleaved and reduced to retinol.
In the intestinal mucosa, retinol is re-esterified to the long-chain fatty acid.
This esterified Vitamin-A is absorbed by the intestine and released into the lymphatics as a component of chylomicrons.
Retinol esters present in the chylomicrons are taken up and stored in the liver.

II. From the liver to the target cells :

When the body needs retinol, the liver release retinol.
Retinol attaches to the plasma's Retinol Binding Protein (RBP).
This retinol-RBP complex is transported to the extrahepatic tissues.
The retinol-RBP complex attaches to the specific receptors on the surface of the target cells.
The complex breaks up and retinol enters the cell.
Inside the cell, retinol binds with cellular RBP.
This cellular retinol-RBP complex is carried to the sites in the nucleus where the vitamin acts in a manner analogous to steroid hormones.

Sources of Vitamin-A

Animal Sources: Liver, Kidneys, cream, egg yolk, fish e.g. Halibut (richest source), Colostrum (a form of milk produced in late pregnancy and a few days after giving birth. It is thick, sticky, and yellowish) is also very rich in Vitamin-A.

Plant Sources: Carotenes

What is Carotene?

Carotene is a pigment that is found in plants, fruits, and vegetables, and is responsible for giving them their yellow, orange, and red colors.
It is a type of carotenoid, which is a class of plant pigments that are responsible for producing the bright colors of many fruits and vegetables.
Carotene is an antioxidant (anti-aging) that is believed to have a number of health benefits when consumed as part of a healthy diet.
Carotene (specifically Beta-Carotene) is used in the production of vitamin A, which is important for maintaining healthy vision and a strong immune system.
Since thyroxine (a hormone of the thyroid gland) is required for the conversion of carotenes to Vitamin-A, thus in thyroxine deficiency (known as Hypothyroidism), carotenes accumulate in the blood resulting in a condition known as Carotenemia.
Besides hypothyroidism, the conversion of carotenes to active Vitamin-A is also decreased in diabetes mellitus.

Vitamin-A deficiency | Clinical Notes

Many of the clinical disorders of Vitamin-A deficiency are because of the keratinization (accumulation of keratin protein) of the normal epithelium throughout the body. However, we can classify some of the disease caused by Vitamin-A deficiency as follow

1. Ophthalmic disorders

There are several ocular (eye) disorders that can be caused by vitamin A deficiency. These include:

Night blindness: This is the inability to see in low light or darkness, and it is one of the first signs of vitamin A deficiency.
Dry eyes: Vitamin A deficiency can cause dryness and inflammation of the eyes, leading to discomfort and an increased risk of eye infections.
Corneal ulcers: These are painful sores on the clear front surface of the eye that can be caused by vitamin A deficiency.
Bitot's spots: These are small, white, foamy patches that appear on the whites of the eyes. They are a sign of advanced vitamin A deficiency.
Xerophthalmia: This is a pathological dryness of the conjunctiva and cornea. This condition causes the eyes to become dry and inflamed, leading to a reduction in vision. It is a severe form of vitamin A deficiency, and if untreated it can result in corneal ulceration.
Keratomalacia: This is a condition in which the cornea (the clear front surface of the eye) becomes soft and damaged, leading to vision loss. It mostly occurs in the first year of life. It is a severe form of vitamin A deficiency.
Corneal scarring: Vitamin A deficiency can cause scarring of the cornea, which can lead to vision loss.

2. Genito-Urinary Disorders

Vitamin A deficiency can cause a number of genitourinary (reproductive and urinary) disorders, including:

Infertility: Vitamin A deficiency has been linked to infertility in both men and women.
Increased risk of sexually transmitted infections: Vitamin A deficiency can weaken the immune system, making individuals more susceptible to sexually transmitted infections.
Increased risk of cervical cancer: Some studies have suggested that vitamin A deficiency may increase the risk of cervical cancer in women.
Urinary tract infections: A deficiency of vitamin A can increase the risk of urinary tract infections.
Kidney damage: Vitamin A deficiency has been linked to kidney damage in some studies.

3. Pulmonary Disorders

Cilia of the respiratory tract are lost resulting in higher rates of chest infection, such as Pneumonia. This is because vitamin A is important for the proper functioning of the immune system, and a deficiency can weaken the body's ability to fight off infections.

However, it's important to note that the evidence linking vitamin A deficiency to respiratory infections is largely based on observational studies and more research is needed to confirm a causal relationship. Vitamin A deficiency is rare in developed countries and can usually be easily treated with supplements or a diet rich in vitamin A.

4. Dermatological Disorders

Since Vitamin-A is required for healthy epithelium, therefore Vitamin A deficiency can cause a number of dermatological (skin) disorders, including:

Acne and Psoriasis: Acne is a common skin condition that is characterized by the presence of pimples, blackheads, and whiteheads. It most often occurs on the face, neck, chest, and back. Psoriasis is a chronic skin condition that causes the rapid build-up of skin cells. This leads to thick, red, scaly patches on the skin. Psoriasis can occur anywhere on the body, but it most commonly affects the scalp, elbows, and knees. Both acne and psoriasis can be treated with a variety of medications and therapies, including topical creams, oral medications, and phototherapy. In severe cases, more aggressive treatments, such as immunosuppressants or biologics, may be necessary.
Dry skin: Vitamin A deficiency can cause dry, rough, and scaly skin.
Dry, thinning hair: A deficiency of vitamin A can cause hair to become dry, brittle, and prone to breaking.
Dermatitis: This is a general term for inflammation of the skin, which can be caused by vitamin A deficiency.
Follicular hyperkeratosis: This is a condition in which there is an excess of keratin (a protein found in the skin, hair, and nails) in the hair follicles. It can cause the skin to become rough and bumpy and is often associated with vitamin A deficiency.

5. Defective Dentine

Formation of the tooth enamel will be defective and this may lead to dental caries.

Symptoms of Vitamin A deficiency

Vitamin A deficiency can cause a wide range of symptoms, including:

Dry, itchy skin.
Dry eyes and vision problems, including night blindness.
Dry, rough, and scaly skin.
Slow growth in children.
Weakened immune system.
Loss of appetite.
Inflammation in the eyes can lead to infections.
Delayed sexual development in adolescents.

Vitamin-D (Cholecalciferol)

Introduction to Vitamin-D

Vitamin D is a fat-soluble vitamin that is essential for the proper absorption of calcium and phosphorus, which are important for the maintenance of healthy bones and teeth.
It is also important for the proper functioning of the immune system.
Vitamin D can be synthesized by the skin when it is exposed to sunlight, and it can also be obtained from certain foods, such as fatty fish, beef liver, and egg yolks.
Vitamin D deficiency can cause a number of health problems, including osteomalacia (softening of the bones) in adults and rickets in children.
Vitamin D deficiency is also associated with an increased risk of certain chronic diseases, such as osteoporosis, diabetes, and certain cancers.
Vitamin D deficiency is most commonly caused by a lack of sunlight exposure and a diet that is low in vitamin D.
It can be treated with vitamin D supplements and a diet that is rich in vitamin D.

Before discussing the functions/roles played by Vitamin D, we have to first know about the activation of Vitamin D.

Activation of Vitamin D

Vitamin D2 (from diet) and D3 (under the skin), are not physiologically active but are first converted to the active form by the following two sequential hydroxylation reactions.

First Hydroxylation occurs in the liver, whereby the action of the Hydroxylase enzyme, Vitamin D2, and D3 are converted into 25-Hydroxy Cholecalciferol (25-OH D3).
The product 25-OH D3 is also inactive but it is the predominant and major storage form in the plasma.
Second Hydroxylation occurs in the kidney, where again by the action of the same enzyme (Hydroxylase) 25-OH D3 is converted into 1,25-Dihyroxy Cholecalciferol (1,25-di OH D3).
1,25-di OH D3 is the active form of Vitamin D.

Mechanism of action of 1,25-di OH D3

1,25-di OH D3 binds to intracellular receptor proteins.
The 1,25-di OH D3-receptor complex interacts with DNA in the nucleus of target cells and either selectively stimulates gene expression, or specifically represses gene transcription resulting in protein synthesis.
The most prominent action of 1,25-di OH D3 is to regulate plasma Calcium levels.

Now we will discuss the functions/roles of Vitamin D, specifically its active form i.e. 1,25-di OH D3.

Functions of Vitamin-D

As stated above that the overall function of 1,25-di OH D3 is to maintain plasma Ca++ level. It does that in the following way.

i. Increase uptake of Ca++ by the intestine.
ii. Minimize loss of Ca++ by the kidney.
iii. Stimulates resorption of bone when necessary.

a. Effects of Vitamin D on the Intestine

1,25-di OH D3 stimulates the intestinal absorption of Ca++ and Pi (inorganic phosphate).
1,25-di OH D3 enters the intestinal cells and binds to cytosolic receptors.
1,25-di OH D3-receptor complex then moves to the nucleus where it selectively interacts with the cellular DNA and forms specific Ca++ binding proteins.
Ca++ binding protein causes the absorption of Ca++ from the intestines.
In this way, the mechanism of action of 1,25-di OH D3 is typical of steroid hormones.

b. Effects of Vitamin D on the Kidney

These are of minor importance, Vitamin D minimizes the loss of Ca++ from the kidney.

c. Effects of Vitamin D on the bones

1,25-di OH D3 stimulates the mobilization of Ca++ and phosphate from bones by a process that requires protein synthesis and the presence of the parathyroid hormone (Parathormone).

d. Role of Vitamin D in Supporting the immune system

Vitamin D helps to regulate the immune system and may play a role in preventing and treating certain types of infections.

e. Role of Vitamin D in Regulating blood pressure

Some research suggests that vitamin D may help to regulate blood pressure and improve hypertension.

f. Role of Vitamin D in Reducing inflammation

Vitamin D may have anti-inflammatory effects and may be useful in the management of certain conditions characterized by inflammation, such as asthma and rheumatoid arthritis.

g. Role of Vitamin D in Regulating insulin production

Vitamin D plays a role in regulating insulin production and may be beneficial for people with diabetes.

h. Role of Vitamin D in Enhancing muscle function

Vitamin D may help to improve muscle function and reduce the risk of falls in older adults

Absorption, Storage, and Excretion of Vitamin D

I. Absorbtion of Vitamin D

Vitamin D is a fat-soluble vitamin, which means that it is absorbed into the body along with fats in the diet.
Vitamin D is absorbed in the small intestine, where it is transported to the liver because bile salts present in the liver are required for the digestion and absorption of Vitamin D.
Then it moves to the kidneys, where it is converted into its active form.
There are several factors that can affect the absorption of vitamin D in the body, including:

The amount of vitamin D in the diet
The presence of other nutrients, such as calcium and phosphorus.
The presence of fat in the diet, presence of fat in the diet can affect its absorption.
The presence of certain medical conditions, such as Crohn's disease and celiac disease.
The use of certain medications, such as antacids and cholesterol-lowering drugs.

II. Storage of Vitamin D in our Body

Vitamin D is a fat-soluble vitamin, which means that it is stored in the body's fat tissue.
The body stores excess vitamin D in the liver and fatty tissue, and it can be released as needed.
Vitamin D is stored in the body for future use, so it is not necessary to consume it every day. However, it is important to get enough vitamin D on a regular basis to ensure that the body has a sufficient supply of it.
The amount of vitamin D that is stored in the body can vary depending on a number of factors, including age, sex, and life stage.

III. Excretion of Vitamin D outside our body

Vitamin D is not easily excreted from the body, so it is important to get enough of this important nutrient on a regular basis.
It is either reabsorbed into the bloodstream by the carrier proteins called Vitamin D carrier proteins or excreted in the bile, or eliminated in the urine.

Sources of Vitamin D

There are several sources of vitamin D, such as

Sunlight: The body can produce vitamin D when the skin is exposed to sunlight. However, the amount of vitamin D that is produced depends on a number of factors, including the latitude, the season, the time of day, and the amount of skin that is exposed. People who live in areas with low levels of sunlight may be at greater risk of vitamin D deficiency.
Diet:

Ergocalciferol (Vitamin D2) is found in plants.
Cholecalciferol (Vitamin D3) is found in animal tissues is the source of pre-formed Vitamin D.
It is found naturally in a few foods, including fatty fish (such as salmon, mackerel, and sardines), cod liver oil, and egg yolks. Some foods are also fortified with vitamin D, including certain types of milk, orange juice, and cereals.

Supplements: Vitamin D supplements are available in the form of pills, capsules, and liquids. They can be taken orally or given by injection. It is important to speak with a healthcare professional before starting any supplement regimen.
Endogenous Vitamin D Precursor:

Endogenous vitamin D refers to vitamin D that is produced within the body.
The main precursor of endogenous vitamin D is 7-dehydrocholesterol, which is a compound that is found in the skin.
When the skin is exposed to ultraviolet B (UVB) radiation from the sun, 7-dehydrocholesterol is converted into previtamin D3.
Previtamin D3 is then converted into vitamin D3 (also known as cholecalciferol) in the skin.
The production of endogenous vitamin D is dependent on the presence of UVB radiation, so people who live in areas with low levels of sunlight may be at greater risk of vitamin D deficiency.

Vitamin-D deficiency | Clinical Notes

A deficiency of Vitamin D causes two distinct medical conditions i.e. Rickets in children and Osteomalacia in adults.

1. Rickets

Rickets is a bone disease that is caused by a deficiency of vitamin D, calcium, or phosphate. It occurs most often in children and is characterized by the continued formation of the collagen matrix of bone but incomplete mineralization resulting in softening and weakening of the bones, which can lead to deformities.

Rickets can be treated with supplements of vitamin D, calcium, and phosphate. In severe cases, treatment may also involve the use of braces or other supportive devices to help correct deformities. It is important to get enough vitamin D and other nutrients to prevent the development of rickets and to support the health of the bones.

Rickets can be nutritional or renal i.e.

i. Nutritional Rickets

Nutritional rickets is a type of rickets that is caused by a deficiency of vitamin D, calcium, or phosphate in the diet.
It is most common in children and can occur when the diet does not provide enough of these essential nutrients or when the body is unable to absorb them properly.
Mechanism of development of nutritional rickets

Decrease 1,25-di OH D3.
Decreased absorption of Ca++ from the intestines.
Decreased Plasma Ca++ level.
Increased Parathormone secretion.
Increased mobilization of Ca++ from bones.

ii. Renal Rickets

Renal rickets is a type of rickets that is caused by a deficiency of vitamin D or a problem with the kidneys' ability to convert vitamin D into its active form.
Renal rickets can occur in people with kidney disease, such as chronic renal failure (in which kidneys are unable to form Vitamin D) or in people who have problems with the enzymes that are responsible for converting vitamin D into its active form. It can also occur in people who have a deficiency of vitamin D in their diet.
Occurs mostly in women who are economically poor and undergo repeated cycles of pregnancy and lactation. Lactation put relatively more burden than pregnancy.

Symptoms of Vitamin D deficiency

Vitamin D deficiency can cause a wide range of symptoms, including:

Weak bones and muscle weakness.
Increased risk of falls and fractures.
Delayed growth in children.
Bone deformities, such as rickets.
Tooth deformities.
Low blood levels of calcium and phosphorus.
A weakened immune system.
Chronic fatigue.
Depression.
Muscle aches and pain.
Hair loss.

Vitamin-E (Tocopherol)

Vitamin E is a fat-soluble nutrient that is important for good health. It is a powerful antioxidant (anti-aging) that helps to protect cells from damage caused by free radicals, which are unstable molecules that can cause harm to the body's tissues. Vitamin E is the least toxic of all the fat-soluble vitamins.
Functions of Vitamin E

Vitamin E is important for a number of functions in the body, including:

Role of Vitamin E in Antioxidant activity: Vitamin E is a powerful antioxidant that helps to protect cells from non-enzymatic oxidation (degradation) damage caused by destructive factors e.g. molecular Oxygen and Oxygen derived free radicals, which are unstable molecules that can cause harm to the body's tissues.
Role of Vitamin E in Skin health: Vitamin E is important for maintaining healthy skin and may be helpful in protecting the skin from the damaging effects of the sun.

It may help to reduce the risk of sunburn and skin cancer.
Vitamin E can help to keep the skin moisturized and may be helpful in reducing the appearance of dry, flaky skin.
Some research suggests that vitamin E may be helpful in reducing the appearance of scars and stretch marks.
Vitamin E may help to reduce the appearance of fine lines and wrinkles and may improve the overall appearance of aging skin.

Role of Vitamin E in Eye health: Vitamin E may help to prevent or delay the development of age-related eye disorders, such as cataracts and age-related macular degeneration.
Role of Vitamin E in Immune system support: Vitamin E may have a role in supporting the immune system and may be helpful in reducing the severity and duration of colds and other infections.
Role of Vitamin E in Blood clotting: Vitamin E is involved in the process of blood clotting and may be helpful in preventing blood clots.
Cardiovascular health: Some research suggests that vitamin E may be beneficial in reducing the risk of heart disease and stroke.

Absorption, Storage, and Excretion of Vitamin E from our body

Note: Absorption, Storage, and Excretion of Vitamin E from our body is in the same manner as that of other fat-soluble vitamins, and is discussed earlier in this article.

Sources of Vitamin-E

Diet: Vitamin E is found naturally in a variety of foods from animal sources and plants source. (Animal Sources) : Meat, liver, egg, fish, liver oil, milk (human milk is 2-4 times richer than cow's milk), and butter. (Plant Sources): Plant sources of Vitamin E are highly recommended, they include wheat, germ oil, cotton oil, peanut oil, and all green leafy vegetables.
Supplements: Vitamin E supplements are available in the form of pills, capsules, and liquids. They can be taken orally or applied to the skin.

Vitamin E deficiency | Clinical Notes

Vitamin E deficiency is rare in healthy individuals who consume a balanced diet. However, certain groups of people may be at greater risk of vitamin E deficiency, including:

Certain medical conditions, such as Crohn's disease and cystic fibrosis, can interfere with the absorption of vitamin E.
Vitamin E is a fat-soluble vitamin, so people with conditions that cause difficulty absorbing fats, such as celiac disease and cystic fibrosis, may be at risk of vitamin E deficiency.
People who receive nutrients intravenously (through a vein) over an extended period of time may be at risk of vitamin E deficiency because they do not consume fats in their diet.

Here are some abnormal conditions that arise from Vitamin E deficiency, such as

RBCs become more susceptible to the hemolyzing action of Hydrogen-per-oxide.
In-vivo red cell survival time is decreased and may lead to anemia.
In children, there will be muscular lesions, decreased muscular creatine, creatinuria, and raised serum creatinine phosphokinase levels.

Vitamins-E supplements reverse these conditions.

Symptoms of Vitamin E deficiency

Weakness.
Fatigue.
Muscle weakness.
Loss of muscle mass.
Impaired function of the immune system.
Loss of balance and coordination.
Difficulty walking.

Vitamin-K (Tocopherol)

Vitamin K (K for Koagulation - In German) is a fat-soluble vitamin that is important for good health. It plays a crucial role in the body's ability to form blood clots and helps to prevent excessive bleeding. It is also important for maintaining strong bones.

There are two main types of vitamin K:

Vitamin K1 (also known as phylloquinone). It is found in green, leafy vegetables, such as spinach and kale.
Vitamin K2 (also known as Menaquinone). It is found in fermented foods, such as cheese and natto (a type of fermented soybean).

Functions of Vitamin-K

1. Role of Vitamin-K in Gamma-Carboxyglutamate Formation

Vitamin K is required in the hepatic synthesis of prothrombin and the blood clotting factors II, VII, IX, X, and proteins C and S.
Vitamin K plays a crucial role in the formation of gamma carboxyglutamate (GLA). GLA is a modified amino acid that is found in certain proteins.
Vitamin K is involved in the process of Gla formation through a process called gamma-carboxylation.
During this process, vitamin K is converted into its active form, called vitamin K hydroquinone.
It is then used to convert certain amino acids into GLA. This process occurs in the liver and requires the presence of hydroquinone form of vitamin K, Carbon-di-Oxide, and oxygen.

2. Role of Vitamin K in the interaction of Prothrombin with Platelets

Vitamin K plays a crucial role in the interaction of prothrombin with platelets (Platelets are small cells in the blood that help to form blood clots).

Prothrombin is a protein that is involved in the blood clotting process.
Vitamin K is involved in the activation of prothrombin. When the body is injured and bleeding occurs, prothrombin is converted into an active form called thrombin.
Thrombin then plays a crucial role in the blood clotting process by converting fibrinogen, a protein found in the blood, into fibrin.
Fibrin is a protein that forms a mesh-like structure that helps to stop bleeding.
Platelets also play a crucial role in the blood clotting process. When the body is injured, platelets are activated and they adhere to the site of the injury. They release chemicals that help to stimulate the formation of a blood clot.

Absorption, Storage, and Excretion of Vitamin K from our body

Note: Absorption, Storage, and Excretion of Vitamin K from our body is in the same manner as that of other fat-soluble vitamins, and is discussed earlier in this article.

Sources of Vitamin K

There are several sources of vitamin K, including:

Diet: Vitamin K is found naturally in a variety of foods, including green, leafy vegetables, such as spinach, kale, spinach, egg yolk, liver, and broccoli, and fermented foods, such as cheese and natto (a type of fermented soybean). Other sources of vitamin K include avocados, kiwifruit, and prunes.
Supplements: Vitamin K supplements are available in the form of pills, capsules, and liquids.
Bacteria in the gut: The human body contains bacteria (specifically Gram +ive bacteria) that produce vitamin K. These bacteria can contribute to the body's vitamin K needs, but they are not a reliable source of this nutrient.

Vitamin K deficiency

Vitamin K deficiency is rare in healthy individuals who consume a balanced diet. However, people who are taking certain medications, such as anticoagulants, may be at risk of vitamin K deficiency because these medications can interfere with the body's ability to absorb vitamin K.
Vitamin K deficiency can interfere with the formation of Gla proteins and can lead to problems with blood clotting and bone health. Bleeding occurs mostly from the gastrointestinal tract, urinary tract, and uterus.
Vitamin K deficiency can interfere with the activation of prothrombin and the interaction of prothrombin with platelets. This can lead to problems with blood clotting and an increased risk of bleeding.

Symptoms of Vitamin K deficiency

Vitamin K deficiency can cause a wide range of symptoms, including:

Easy bruising.
Excessive bleeding, including bleeding from the gums, nosebleeds, and heavy periods.
Blood in the urine or stool.
Osteoporosis (weak bones).

B. Water Soluble Vitamins

Water-soluble vitamins are a group of nutrients that are soluble in water and are not stored in the body to any significant extent. This means that they must be consumed regularly to meet the body's needs.

There are several water-soluble vitamins, including:

I. Vitamin C: Vitamin C is an antioxidant that is important for the health of the skin, blood vessels, and bones. It is also important for the proper functioning of the immune system.

II. B Vitamins: There are several B vitamins, including thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9), and cobalamin (B12). B vitamins are important for energy metabolism, the proper functioning of the nervous system, and the synthesis of red blood cells.

Many water-soluble vitamins, specially B-Complex, are the precursors of coenzymes.
Water-soluble vitamins are non-toxic.
The number of water-soluble vitamins stored in the body is usually small, therefore must be continually supplied in the diet.
When ingested in excess, they are readily excreted in the urine.

Vitamin-C (Ascorbic Acid)

Vitamin C is a water-soluble vitamin.
It is a white crystalline, an odorless substance with a sour taste.
It is destroyed by heat, oxidation, and exposure to air, especially in the presence of iron and copper ions.
Alkalies also destroy it and therefore its absorption is reduced in achlorhydria (lack of HCl).

Functions of Vitamin C

1. Role of Vitamin C in Hydroxylation of Proline and Lysine (Role in Collagen synthesis)

Vitamin C is required for the activity of enzymes called prolyl hydroxylase and lysyl hydroxylase, which are responsible for the hydroxylation of proline and lysine, respectively. (Hydroxylation is a chemical reaction in which a hydroxyl group (-OH) is added to a molecule).
In the case of proline and lysine, hydroxylation refers to the process of adding a hydroxyl group to these amino acids.
Hydroxylation of proline and lysine is an important process that occurs during the synthesis of collagen, a protein that is important for the health of the skin, blood vessels, and bones.

2. Role of Vitamin C in the synthesis of intracellular ground substance

Vitamin C plays a crucial role in the synthesis of the intercellular ground substance, which is a gel-like substance that fills the space between cells.
The intercellular ground substance is composed of molecules called glycosaminoglycans (GAGs), which are long chains of sugars that are important for the health of the skin, blood vessels (vascular endothelium), and bones.

3. Role of Vitamin C in the Immune System

Vitamin C is important for the proper functioning of the immune system.
It helps to protect the body from infections and may help to reduce the severity and duration of colds.
It is also involved in the production of white blood cells, which are an important part of the immune system.

4. Role of Vitamin C as an antioxidant

Vitamin C is a powerful antioxidant that helps to protect cells from damage caused by free radicals. Free radicals are highly reactive molecules that can damage cells and contribute to the development of chronic diseases, such as cancer and heart disease. Antioxidants are substances that can neutralize free radicals and protect cells from damage.

5. Role of Vitamin C in Synthesis of Neurotransmitters

Vitamin C is also involved in the synthesis of catecholamines (a neurotransmitter that plays a role in the regulation of mood, behavior, and other functions).
Catecholamines are synthesized from the amino acid tyrosine, which requires the presence of vitamin C.

6. Role of Vitamin C in the metabolism of fats

It is also involved in the synthesis of carnitine, a molecule that is important for the metabolism of fat.

7. Role of Vitamin C in the absorption of iron

Vitamin C can help to increase the absorption of iron (important for the production of red blood cells and the transport of oxygen in the body) from the intestine. There are two forms of dietary iron: heme iron, which is found in animal-based foods, and non-heme iron, which is found in plant-based foods. Non-heme iron is less well absorbed than heme iron.

Vitamin C can increase the absorption of non-heme iron by reducing it from the Ferric form (Fe+++) to the Ferrous form (Fe++).

When vitamin C is consumed with a meal that contains non-heme iron, it can help to increase the absorption of this form of iron. This is why it is often recommended to consume vitamin C-rich foods, such as oranges and strawberries, with plant-based sources of iron, such as legumes and leafy green vegetables.

8. Role of Vitamin C in the maturation of RBCs

Vitamin C converts folic acid to Tetrahyroxy Folate (THF). This reaction is necessary for the utilization of Folic acid in the maturation of RBCs.

9. Role of Vitamin C in the synthesis of steroid hormones

A large amount of Vitamin C is present in glandular tissues, especially in the adrenal cortex and corpus leuteum, and here it takes part in redox (oxidation/reduction) reactions involved in the synthesis of steroid hormones.

Absorption, Transport, and Excretion of Vitamin C from our body

i. Absorption of Vitamin C

Vitamin C is absorbed in the small intestine through a process called facilitated diffusion.
This process involves the use of a specific transport protein, called Sodium-dependent Vitamin C Transporter 2 (SVCT2), which is responsible for the uptake of vitamin C into the cells of the small intestine.

ii. Transport of Vitamin C

Once inside the cells, vitamin C is transported into the bloodstream, where it is distributed to the body's tissues.

iii. Excretion of Vitamin C

Vitamin C is excreted from the body through the urine.
The kidneys are responsible for filtering the blood and removing excess substances, including vitamins, from the body.
Vitamin C is not stored in the body to any significant extent, so any excess vitamin C that is not used by the body is excreted through the urine.

Vitamin C deficiency | Clinical Notes

Vitamin C deficiency can lead to a number of health problems, including:

Scurvy (Scorbutus): This is a rare but potentially serious condition that can occur if a person does not consume enough vitamin C. Scurvy causes the gums to bleed, the skin to develop painful, bumpy rashes, and the joints to become stiff and painful. Infants nursed on cow's milk from the beginning may develop Moeller-Barlow disease, a severe Vitamin C deficiency, resulting in growth disorder of the bones.

Anemia: Vitamin C is required for the proper absorption of iron (a mineral that is essential for the production of red blood cells). A deficiency of vitamin C can lead to anemia (a condition characterized by a low number of red blood cells).

Wounds and Bruises: Vitamin C plays a role in the production of collagen. A deficiency of vitamin C can lead to poor wound healing and a higher risk of bruising.

Weakness and Fatigue: Vitamin C plays a role in the metabolism of fat and the production of catecholamines (neurotransmitters that play a role in the regulation of mood, behavior, and other functions). A deficiency of vitamin C can lead to weakness and fatigue.

Reduced Immune Function: A deficiency of vitamin C can lead to an increased susceptibility to infections, particularly infections of the respiratory tract.

Symptoms of Vitamin C deficiency

Some common symptoms of vitamin C deficiency include:

Fatigue.
Muscle weakness.
Bruising easily.
Swollen and bleeding gums.
Dry, scaly skin.
Anemia.
Slow wound healing.
Rough, dry, or bumpy skin.

Vitamin-B1 (Thiamine)

The biologically active form of thiamine is Thiamine Pyrophosphate (TPP), a coenzyme of Thiamine.
TPP is required in the decarboxylation of Alpha-Ketoacids and in the formation and degradation of Alpha-Ketos by Transketolase in the HMP (Hexose Monophosphate) Pathway.
Vitamin B1 is a water-soluble vitamin that is essential for human health.
It is one of the eight B vitamins and plays a crucial role in energy metabolism, nerve function, and cognitive function.
Vitamin B1 is necessary for the proper functioning of the nervous system, including the brain, and it also helps convert carbohydrates into glucose, which is used as energy by the body.

Functions of Vitamin-B1

Vitamin B1 plays several crucial roles in the body, including:

Role of Vitamin-B1 in Energy metabolism: Vitamin B1 helps convert carbohydrates into glucose. It is involved in the production of adenosine triphosphate (ATP)(the primary energy currency of the cell).
Role of Vitamin B1 in Nerve function: Vitamin B1 is essential for the proper functioning of the nervous system. It plays a role in maintaining the health of the myelin sheath (the protective covering that surrounds nerve fibers) and helps with the normal function of the nerve cells.
Role of Vitamin-B1 in Cognitive function: Vitamin B1 is important for cognitive function, including memory and concentration. Studies have shown that a deficiency of thiamine is linked to cognitive decline, cognitive impairment, and problems with memory.
Role of Vitamin B1 in Heart health: Vitamin B1 is necessary for the proper functioning of the heart and cardiovascular system.
Role of Vitamin-B1 in Muscles function: Vitamin B1 is necessary for the proper functioning of muscles.
Role of Vitamin-B1 in Fermentation of Glucose: The coenzyme (TPP) is used in the Oxidative Decarboxylation of Pyruvate by Pyruvate Decarboxylase for the fermentation of Glucose to yield Alcohol.

Absorption, Transport. Storage, and Excretion of Vitamin B1

Vitamin B1 (thiamine) is absorbed in the small intestine, with the help of a specific transport protein called Thiamine Transporters. These transporters are located on the surface of the cells that line the small intestine, and they are responsible for the active transport of thiamine across the intestinal cell membrane and into the bloodstream.
Once in the bloodstream, thiamine is transported to the liver where it is stored or used by various tissues and cells in the body.
The liver can store up to 30-40mg of Thiamine but the excess is excreted in urine.

Sources of Vitamin B1

The richest sources are whole grains and legumes.

Natural sources are found mainly in combination with starch i.e. husks of grains.
Therefore, there is a good reason for the belief that whole meal products and unmilled (brown) are particularly healthy foods.

Deficiency of Vitamin B1 | Clinical Notes

Severe cases result in Beri-Beri.

Beri-Beri (I Can Not - I Can Not): It is a neurological disorder, that was endemic in polished rice-eating countries. Beri-Beri is of the following three types

Dry Beri-Beri: It is a chronic disease of adults in which Polyneuritis is the principal feature. This type of Beri-Beri Calf muscle show tenderness. In the late stages, Muscular Atrophy results. Knee jerk will be diminished or absent.
Wet Beri-Beri. It is an acute disease characterized by cardiac failure of high output type and edema.
Infantile Beri-Beri. It occurs in the first year of life. Cardiovascular abnormalities are the principal feature of this type of Beri-Beri.

Wernicke-Korsakoff Syndrome: This is a neurological disorder that affects memory and cognitive function. Symptoms include confusion, memory loss, vision problems, and coordination difficulties. Actually, Wernicke-Korsakoff Syndrome refers to two different clinical conditions i.e.

Wernicke's Encephalopathy: It damages the lower part of the brain called the Thalamus and Hypothalamus.
Korsakoff Psychosis: It results from damage to areas in the brain involved with memory.

Neuropsychiatric symptoms: Symptoms such as irritability, restlessness, apathy, insomnia, and anorexia can also occur with deficiency.
Myelopathy: This is a condition affecting the spinal cord which can lead to muscle weakness, loss of reflexes, and difficulty with coordination.
Decreased ATP Production: In Thiamine deficiency, the activity of the two dehydrogenase reactions (i.e. Pyruvate Dehydrogenase and Alpha-Ketoglutarate Dehydrogenase) is decreased, resulting in decreased production of ATP that results in impaired cellular functions.
Cause of some Neurological Disorders: Defective function of the Pyruvate Dehydrogenase, due to the deficiency of TPP, is responsible for the accumulation of Pyruvate and Lactate in the brain leading to neurological disorders characterized by Polyneuritis or generalized malfunctioning of the motor nervous system.

Symptoms of Vitamin B1 Deficiency

A deficiency of vitamin B1 (thiamine) can cause a number of symptoms which can vary depending on the severity and duration of the deficiency. Some common symptoms of vitamin B1 deficiency include:

Fatigue and weakness.
Nervous system damage.
Appetite loss.
Cardiovascular symptoms.
Psychological and mental symptoms.
Gastrointestinal symptoms, such as nausea, vomiting, abdominal pain, etc.

Vitamin-B2 (Riboflavin)

Vitamin B2 is a water-soluble vitamin that is essential for human health.
It plays a key role in many of the body's metabolic processes, including energy production, cell growth and repair, and the conversion of food into energy.
One of the primary functions of riboflavin is to act as a cofactor for enzymes that are involved in energy metabolism, including the enzymes that oxidize food to produce energy in the form of ATP.
Riboflavin also plays an important role in the production of red blood cells.
This vitamin (B2) helps to maintain healthy skin, eyes, and nervous system.

Functions of Vitamin B2

Role of Vitamin B2 in Energy metabolism: Vitamin B2 acts as a cofactor for enzymes that are involved in energy metabolism. Riboflavin (Vit-B2) forms two biologically active coenzymes i.e.

Flavin Mononucleotide (FMN): It acts as a cofactor for several enzymes involved in cellular metabolism, including enzymes involved in energy metabolism, amino acid metabolism, and detoxification reactions.
Flavin Adenine Dinucleotide (FAD): It serves as an electron carrier, specifically in the electron transport chain within the mitochondria, where it is used to transfer electrons to molecular oxygen during the process of cellular respiration.

Role of Vitamin B2 in Red blood cell production: Vitamin B2 (riboflavin) plays a crucial role in the production of red blood cells (RBCs) by participating in the process of heme synthesis.

Heme is a crucial component of hemoglobin.
During the process of heme synthesis, vitamin B2 acts as a cofactor for an enzyme called delta-aminolevulinic acid dehydratase (ALAD), which is responsible for converting porphyrin precursors into heme.
Without sufficient levels of vitamin B2, the ALAD enzyme cannot function properly and the synthesis of heme is impaired, resulting in a decrease in the production of RBCs.

Role of Vitamin B2 in Vision: Vitamin B2 is essential for the maintenance of healthy eyes.

It helps in the production of a light-sensitive pigment called rhodopsin (found in the retina of the eyes), which is important for normal vision, especially in low-light conditions.
When light hits the retina, rhodopsin absorbs the light and sends a signal to the brain, allowing us to see.

Role of Vitamin B2 in Skin, nails, and hair:

In the skin, riboflavin helps to protect against UV damage and inflammation and plays a role in collagen production and tissue repair. It can help with skin disorders such as eczema and acne.
Riboflavin also helps to improve blood flow to the nails, leading to healthier growth.
It also helps in the production of keratin, the protein that makes up hair, which keeps hair strong and healthy.

Role of Vitamin B2 in the Nervous system: Riboflavin is important for the proper functioning of the nervous system

It participates in the production of neurotransmitters such as serotonin, which help to transmit nerve impulses throughout the body.
It also plays a role in the maintenance of healthy myelin sheaths, which are protective coverings that surround nerve fibers and help to ensure efficient nerve impulse conduction.
In addition, riboflavin is also an antioxidant and helps protect the nervous system which can damage cells and contribute to neurodegenerative disorders.

Role of Vitamin B2 in the Metabolism of other vitamins: Vitamin B2 is necessary for the metabolism of other vitamins such as vitamin B3 (niacin) and vitamin B6 (pyridoxine).

Absorption, Transport, and Excretion of Vitamin B2

Vitamin B2 is absorbed in the small intestine through active and passive transport mechanisms.
Active transport occurs at the brush border of the duodenum and jejunum, while passive transport occurs throughout the small intestine.
Once absorbed, Vitamin B2 is transported to the liver where it is stored or metabolized.
Then it is excreted primarily through urine, with small amounts excreted through feces and sweat.

Sources of Vitamin B2

Dairy products such as milk, yogurt, and cheese.
Eggs.
Meat, poultry, and fish.
Leafy green vegetables such as broccoli and spinach.
Fortified breakfast cereals and grains.
Nuts and legumes.
Organ meats, like liver.

Deficiency Symptoms of Vitamin B2 | Clinical Notes

A deficiency in vitamin B2 (not associated with major human disease)can cause a range of symptoms, such as

Sore throat.
Swollen, cracked, and red lips.
Tongue inflammation and cracking at the lips, angular stomatitis (angular scars), magenta tongue, and cheilosis (fissuring of the angles of the mouth).
Skin rashes and dry, itchy skin. Skin also has scaliness and greasiness, and there may be fissures in the folds of the nose and ear (dyssebacea).
Iron-deficiency anemia.
Fatigue or weakness.
Eye fatigue, sensitivity to light, and blurred vision.
Dermatitis of scrotum and vulva.

Vitamin-B3 (Niacin)

The other names of Niacin are Niacinamide, Nicotinic Acid, Nicotinamide, and Pellagra Preventing Factor.

Functions of Niacin in our body

Vitamin B3 plays important roles in many bodily functions, such as

Role of Vitamin B3 in Metabolism: Niacin produces two biologically active forms of coenzymes i.e. Nicotinamide Adenine Dinucleotide (NAD+), and Nicotinamide Adenine Dinucleotide Phosphate (NADP+).

NAD and NADP help in the redox reactions.
Reduced forms are NADH2 and NADPH2.
NAD and NADP act as coenzymes in the synthesis of ATPs through Oxidative Phosphorylation.
It also plays a role in the production of hormones, enzymes, and red blood cells.

Role of Vitamin B3 in Nervous system function: Niacin is involved in the functioning of the nervous system and helps to maintain healthy skin and nerves.
Role of Vitamin B3 in DNA synthesis and repair: NAD+ and NADP+ are involved in a process called DNA base excision repair (a mechanism that cells use to repair damage to their DNA). In this process, enzymes called DNA glycosylases recognize and remove damaged base pairs from the DNA molecule. NAD+ and NADP+ are then used by other enzymes to fill in the gap created by the removal of the damaged base pairs, thus repairing the DNA.
Role of Vitamin B3 in Lowering cholesterol and triglycerides: Niacin can increase the levels of high-density lipoprotein (HDL) or "good" cholesterol, and lower levels of low-density lipoprotein (LDL), or "bad" cholesterol and triglycerides, in the blood, which can lower the risk of heart disease.
Role of Vitamin B3 in Helping to maintain healthy skin: Niacin is important for maintaining healthy skin, tongue, and digestive system, and can help in preventing pellagra, a disease characterized by skin lesions, diarrhea, and dementia, that is caused by deficiency of niacin.
Role of Vitamin B3 in Clinical Use: It is used in the treatment of Hyperlipidemia. it strongly inhibits lipolysis in adipose tissues (the primary producers of circulating free fatty acids).

Absorption, Transport, and Excretion of Vitamin B3

Vitamin B3 is present in food in two forms: nicotinic acid and nicotinamide. Both forms are absorbed in the small intestine by active transport mechanisms.
Once absorbed, niacin is transported to the liver, where it is converted to its active form, NAD+ or NADP+. The absorption of nicotinic acid is much higher than nicotinamide.
It is not stored in the body to any significant extent, so any excess is rapidly excreted in the urine.

Sources of Vitamin B3

Meat, poultry, and fish (particularly organ meats like liver).
Whole grains, such as Whole wheat, barley, oats, and brown rice are rich sources of niacin (niacin present in these is bound to fibers and protein, making it less bioavailable).
Legumes, such as Peanuts, lentils, and soybeans.
Vegetables, such as Asparagus, avocados, and mushrooms.
Dairy products like Milk and cheese.
A limited amount of Niacin can also be obtained from the metabolism of Tryptophan. (60 mg of Tryptophan produces 1 mg of Niacin).

Deficiency of Vitamin B3 | Clinical Notes

A deficiency of Niacin causes Pellagra. It is a disease involving the skin, gastrointestinal tract, and Central Nervous System. Pellagra is characterized by a set of symptoms (3Ds) that include:

Diarrhea.
Dementia.
Dermatitis (skin inflammation and scaling), and death if untreated.

Symptoms of Vitamin B3 deficiency

Other symptoms of niacin deficiency may include:

Fatigue.
Loss of appetite.
Headaches.
Depression.
Irritability.
Memory loss.

Vitamin-B5 (Pantothenic Acid)

Function of Vitamin B5

This vitamin plays several important roles in the body i.e.

Role of Vitamin B5 in Metabolism: It is involved in the metabolism of by providing coenzyme-A (Co-A), which helps in the transfer of acyl group. Examples of such compounds are Succinyl Co-A, Fatty Acyl Co-A, and Acetyl Co-A.
Role of Vitamin B5 in Synthesis of lipids: It also plays a role in the synthesis of fatty acids and cholesterol, being a component of fatty acid Synthetase.
Role of Vitamin B5 in Hormone production: It is necessary for the production of hormones such as adrenal hormones, which are involved in the stress response.
Role of Vitamin B5 in the Synthesis of neurotransmitters: It also helps to synthesize neurotransmitters, such as Acetylcholine, Serotonin, Gamma-Aminobutyric acid (GABA), and Dopamine.
Role of Vitamin B5 in Red blood cell formation: It is involved in the formation of red blood cells.
Role of Vitamin B5 in Skin and hair health: It also contributes to healthy skin and hair, by helping to keep the hair and scalp moisturized.
Role of Vitamin B5 in Wound healing: It also plays role in wound healing by speeding up the process.

Absorption, Transport, and Excretion of Vitamin B5

The absorption, transport, and excretion of vitamin B5 occur through several pathways in the body:

Absorption of Vitamin B5: Pantothenic acid is generally well-absorbed in the small intestine, with the aid of bile and pancreatic enzymes. It is then transported to the liver, where it is either stored or transported to other parts of the body.
Transport of Vitamin B5: Pantothenic acid is transported in the blood by a protein called Transcobalamin II, which is responsible for delivering the vitamin to the cells that need it.
Excretion of Vitamin B5: Excess pantothenic acid is excreted in the urine. It is not toxic, which is a characteristic of water-soluble vitamins, The body can excrete what it doesn't need and also regulate it easily as needed.

Sources of Vitamin B5

Meats, such as liver and kidney, are particularly rich in pantothenic acid, as well as chicken, turkey, and lean cuts of beef.
Whole grains, such as oatmeal, barley, and quinoa.
Legumes, such as lentils, beans, and chickpeas.
Vegetables, such as sweet potatoes, mushrooms, and broccoli.
Dairy products, such as milk, cheese, and yogurt.
Eggs are also a good source of pantothenic acid, particularly yolks.
Fruits like avocado, cauliflower, raspberries, and sun-dried tomatoes.

Deficiency of Vitamin B5 | Clinical Notes

A deficiency of Vitamin B5 is relatively rare and not well characterized, but can occur in certain individuals who have a limited dietary intake or who have certain medical conditions that affect the absorption or metabolism of this vitamin.

Symptoms of Vitamin B5 deficiency

Fatigue.
Muscle cramps.
Irritability, insomnia, and depression.
Gastrointestinal problems.
Skin disorders.
Hypoglycemia.

Vitamin-B6 (Pyridoxine)

Vitamin B6 is a collective term for Pyridoxine, Pyridoxal, and Pyridoxamine, all are derivatives of Pyridine.

Functions of Vitamin B6

Role of Vitamin B6 in Metabolism:

Pyridoxine, Pyridoxal, and Pyridoxamine serve as precursors of the biologically active coenzyme Pyridoxal Phosphate.
Pyridoxal Phosphate is a coenzyme for a large number of enzymes, particularly those that catalyze reactions involving amino acids e.g. Transamination, deamination, decarboxylation, and condensation.
Vitamin B6 is involved in the metabolism of proteins, carbohydrates, and fats.
It helps in the production of neurotransmitters and hemoglobin and aids in the formation of red blood cells.

Role of Vitamin B6 in Hormone regulation: Vitamin B6 is important for the production of hormones, such as serotonin, norepinephrine, and melatonin. It helps to regulate mood, appetite, and sleep.
Role of Vitamin B6 in Brain development: Vitamin B6 is necessary for the proper development and function of the brain and nervous system and has been used in the treatment of conditions such as depression and anxiety.
Role of Vitamin B6 in the Immune system: Vitamin B6 helps to boost the immune system by increasing the production of white blood cells.
Role of Vitamin B6 in Cardiovascular health: It helps to keep homocysteine levels in check, a type of amino acid that can contribute to heart disease when levels are too high.
Role of Vitamin B6 in Pregnancy: Vitamin B6 is important for pregnant women as it helps in the development of the fetus's nervous system, and also helps to prevent morning sickness.
Role of Vitamin B6 in Skin and hair: Vitamin B6 can also contribute to healthy skin and hair by providing nutrients that are important for the health of these tissues.

Absorption, Transport, and Excretion of Vitamin B6

Absorption: Vitamin B6 is absorbed in the small intestine, with the aid of pancreatic enzymes and bile. It can be absorbed in both free forms and in a form bound to proteins.
Transport: Vitamin B6 is transported in the bloodstream bound to proteins called Transcobalamin and Albumin, which help to deliver the vitamin to cells and tissues throughout the body.
Excretion: Any excess vitamin B6 not used by the body is excreted in the urine. The half-life of Vitamin B6 in the body is about 25 days, which means that after 25 days half of the vitamin is eliminated through urine.

Sources of Vitamin B6

Wheat.
Corn.
Egg yolk.
Muscle meats.

Deficiency of Vitamin B6 | Clinical Notes

Some of the diseases that can be caused by a deficiency in vitamin B6 include:

Anemia: Vitamin B6 is necessary for the formation of red blood cells, and a deficiency can lead to anemia.
Skin disorders: A deficiency in vitamin B6 can cause skin disorders such as Eczema, Seborrheic Dermatitis, and cracks in the skin.
Nervous system disorders: Vitamin B6 is important for the proper function of the nervous system, and a deficiency can lead to neurological symptoms.
Immunodeficiency: A deficiency in vitamin B6 can lead to a weakened immune system, making the body more susceptible to infections.
Cardiovascular disease: Low levels of Vitamin B6 have been linked with high levels of Homocysteine, an amino acid associated with heart disease.
Seizures: In infants and children, a deficiency in Vitamin B6 can cause seizures.

Symptoms of Vitamin B6 deficiency

Deficiency symptoms appear after a prolonged deficiency and occur mainly in very young infants and pregnant women.
Anemia (Hypochromic, Microcytic type).
Dermatological problems especially on the face, nasolabial seborrhea.
Tongue shows inflammation (Glossitis).

Vitamin-B7 (Biotin) or Vitamin-H

Functions of Vitamin B7

Biotin is an important nutrient that helps to support various metabolic and physiological processes in the body i.e.

Role of Vitamin B7 in Metabolism: Biotin helps in the metabolism of carbohydrates, fats, and amino acids, by assisting in the transfer of carbon dioxide and breaking down certain fatty acids.
Role of Vitamin B7 in Skin, Hair, and Nail Health: Biotin plays a role in maintaining the health of skin, hair, and nails by supporting the metabolism of keratin, the protein that makes up hair and nails.
Role of Vitamin B7 in Glucose synthesis: Biotin also helps in the synthesis of glucose.
Role of Vitamin B7 in Nerve function: Biotin helps in the proper functioning of the nervous system and is involved in the production of certain neurotransmitters.
Role of Vitamin B7 in Gene regulation: Biotin also plays a role in gene regulation by assisting in the modification of histones, which are proteins that control gene expression.