Vitamins

Edited By Shivani Poonia | Updated on Jul 02, 2025 08:03 PM IST

Vitamins form a significant part in the context of our health. They take part in many functions of our bodies: starting with support to our immune system and ending with the production of energy. Principally, these organic compounds are classified into two main classes: fat-soluble and water-soluble vitamins. Though these are very essential, many people do not seem to know the types of vitamins, their supply through diet, and the after-effects of deficiency. This may result in an inadequate consumption of nutrients and could be the cause of many health-related problems

This Story also Contains

Understanding Vitamins
Classification of Vitamins based on their solubility
Classification and Food Sources of Vitamins
Real-Life Applications of Vitamins
Some Solved Examples
Summary

Vitamins

Today, more than ever before, such knowledge is necessary when fast foods and packet snacks dominate diets. Many people do not even think about including a range of fruits, vegetables, whole grains, and proteins in their diet, and it can lead to deficiencies. Here's an example: While vitamin D was considered a "sunshine vitamin" with a role in maintaining bone health, it's also important for having a good mood and healthy immunity. On the other hand, it has been shown that people are not consuming enough daily intake of vitamin C, yet it is best known as an antioxidant and performs collagen synthesis.

Understanding Vitamins

Vitamins are organic materials that the body requires for proper metabolism and which are only required in trace amounts. There are 13 known human vitamins that have been established to be essential for good health and another handful of substances recognized to have some vitamin-like activities. All the vitamins do have unique roles to play in maintaining a healthy body and supporting some physiological functions in the human body. The human body cannot make most vitamins, except for a few exceptions, thus the need for the vitamins to be part of the diet or taken as a dietary supplement.

It has been observed that certain organic compounds are required in small amounts in our diet but their deficiency causes specific diseases. These compounds are called vitamins.

They are the chemical substances that are needed in small amounts for the growth of human beings.
They can’t be synthesized in our bodies and therefore need to be taken from outsourced.
Their deficiency can cause one or other types of diseases.

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Type of Vitamins, their sources and functions:

Diseases caused due to deficiency of various vitamins:

Classification of Vitamins based on their solubility

1. Fat-soluble vitamins:

These are vitamins A, D, E, and K. They are stored in the body's fatty tissues and the liver. They require dietary fat for absorption, and when taken to excess, they will accumulate in the body and result in toxicity.

2. Water-soluble vitamins:

This group includes the B vitamins and vitamin C. Since they are, in fact, fat-soluble vitamins, they dissolve in water and are hence not stored inside the body; their intake should, therefore, be frequent enough to keep up the proper levels. Excess amounts, however, just get excreted via urine and hence rather are not prone to toxicity.

The various vitamins also perform some specified functions, such as giving support to immune functions, helping along the metabolism of energy, and facilitating healthy skin and vision. Their deficiency, therefore, may cause quite a number of health problems. Again, this very visibly states the fact that a balanced diet with a variety of food sources is so important.

Classification and Food Sources of Vitamins

Vitamins are primarily classified based on their sources and functions into two major groups. These are:

Fat-Soluble Vitamins

Vitamin A: Good for vision, immune function, and skin. Foods providing this vitamin include liver, carrots, and leafy green vegetables.
Vitamin D: Sometimes called the "sunshine vitamin," it helps your body absorb calcium for healthier bones. Your body can make it when your skin is exposed to sunlight, but you also get it from foods that have been fortified with it, like milk, cheese, and fatty fish.

Vitamin E: This is an antioxidant that protects the cells from damage. It is naturally found in nuts, seeds, and vegetable oils.

Vitamin K: Needed for blood clotting and for bones. It occurs naturally in green leafy vegetables and fermented foods.

Water-Soluble Vitamins

Vitamin B1 (Thiamin): Plays a Crucial Role in Energy Metabolism and Correct Nerve Functioning: Found naturally in whole grains, pork, and legumes.

Vitamin B2 (Riboflavin): Needed in the process of turning carbohydrates into energy and maintaining the health of the skin. It is acquired from milk, eggs, and green vegetables.

Vitamin B3 (Niacin): Aids digestion and gives good, healthy skin. It is obtained from meat, fish, and whole grains.

Vitamin C: The antioxidant, if taken in adequate amounts, promotes healthy skin through the production of collagen, apart from improving immune function. Its rich sources include citrus fruits, berries, and bell peppers.

Each of the vitamins has some crucial functions in the body, and their deficiency may potentially give rise to serious health issues. Lack of vitamin C can give rise to scurvy, and the lack of vitamin D causes rickets in children and osteomalacia in adults.

Real-Life Applications of Vitamins

Their relevance extends beyond nutrition into health promotion and public health. Knowing about vitamins will allow individuals to make informed dietary choices and improve health outcomes.

The learning institutions can review the health-related subjects or curriculums that dwell on nutrition. For instance, teaching the learners why vitamins are essential will help such students develop good eating habits for life. Moreover, schools through activities that put emphasis on the intake of fruits and vegetables can reiterate the importance of vitamins in growth and development.

The assessment of vitamin levels is part of routine health evaluations that occur often in clinical practice. For example, because of the low level of vitamin D in populations with low sun exposure, supplementation or dietary modification is recommended. This message also applies to public health campaigns targeted more at those with an increased risk of deficiency, by promoting the consumption of products fortified with these vitamins and minerals and encouraging a varied diet.

Case studies illustrate how supplementation of vitamins has, in some instances, altered the trajectory of populations. For instance, folic acid supplementation is universally recommended in pregnant women in order to prevent birth defects—neural tube defects—in neonates. Similarly, vitamin B12 supplementation may be necessary in older adults due to reduced absorption efficiency.

As such, vitamins are very key to sustaining health and well-being. They are critical not only to physical health but are also considered to play a very principal role in education and public health. Being able to know the kind of food, source, and activity of the vitamins may provide one with an educated choice on what diet best keeps one fit and healthy.

Some Solved Examples

Example 1 The RBC deficiency is a deficiency disease of which vitamin?

1) Vitamin B12
2) Vitamin B6
3) Vitamin B1
4) Vitamin B2

Solution:
RBC deficiency is caused by a deficiency of Vitamin B12.

Hence, the answer is option (1).

Example 2 Deficiency of which of the following vitamins causes a delay in blood clotting?

1) Vitamin K
2) Vitamin B
3) Vitamin C
4) Vitamin E

Solution:
Vitamin K is used by the body to help blood clot. A deficiency of Vitamin K increases the time required for the clotting of blood.

Hence, the answer is option (1).

Example 3
Question:
Match List - I with List - II:

Choose the most appropriate answer from the options given below:

1) (a) - (iv), (b) - (ii), (c) - (iii), (d) - (i)
2) (a) - (iv), (b) - (iii), (c) - (i), (d) - (ii)
3) (a) - (iv), (b) - (iii), (c) - (ii), (d) - (i)
4) (a) - (iii), (b) - (ii), (c) - (iv), (d) - (i)

Solution:
We know these facts:

- Chlorophyll is a coordination compound of magnesium.
- Vitamin B12 (cyanocobalamin) is a coordination compound of cobalt.
- Cisplatin, used as an anti-cancer drug, is a coordination compound of platinum.
- Grubbs catalyst contains ruthenium.

Hence, the answer is option (3).

Example 4
Question:
Deficiency of Vitamin K causes:

1) Increase in fragility of RBCs
2) Decrease in blood clotting time
3) Increase in blood clotting time
4) Cheilosis

Solution:
Deficiency of Vitamin K causes an increase in blood clotting time.

Hence, the answer is option (3).

Example 5
Question:
Which one of the following is a water-soluble vitamin that is not excreted easily?

1) Vitamin B2
2) Vitamin B1
3) Vitamin B6
4) Vitamin B12

Solution:
Vitamin B12 is a water-soluble vitamin that is not excreted easily.

Hence, the answer is option (4).

Summary

The paper has shed adequate light on the vitamins, ranging from their definition to their classification and applications in real life. We have seen how important the vitamins are in different functions of the body and how their deficiencies may lead to serious health problems. These two main groups of vitamins, fat-soluble and water-soluble, each have different sources and functions that greatly play their role in health maintenance.

Frequently Asked Questions (FAQs)

1. Why is vitamin E considered a powerful antioxidant?

Vitamin E is considered a powerful antioxidant because of its ability to protect cell membranes from oxidative damage. It is fat-soluble and can integrate into cell membranes, where it neutralizes free radicals that could otherwise damage the lipids in the membrane. This protection is particularly important for neurons and red blood cells. Vitamin E also works synergistically with other antioxidants like vitamin C, enhancing overall cellular protection.

2. What is the relationship between vitamin C and collagen synthesis?

Vitamin C is essential for collagen synthesis because it acts as a cofactor for enzymes involved in collagen production. Specifically, it helps in the hydroxylation of proline and lysine amino acids in procollagen, which is necessary for the formation of stable collagen molecules. Without adequate vitamin C, collagen production is impaired, leading to issues like poor wound healing and weakened blood vessels.

3. What is the role of vitamin A in vision?

Vitamin A is crucial for vision, particularly in low-light conditions. It is a component of rhodopsin, a light-sensitive protein in the retina's rod cells. When light hits rhodopsin, it triggers a series of chemical reactions that send signals to the brain, allowing us to see. Vitamin A also helps maintain the health of the cornea and other parts of the eye, supporting overall eye function and preventing night blindness.

4. How does folate (vitamin B9) contribute to DNA synthesis?

Folate, or vitamin B9, is essential for DNA synthesis because it plays a key role in the production of nucleic acids, the building blocks of DNA. It acts as a coenzyme in the synthesis of purines and pyrimidines, which are crucial components of DNA. Folate is also involved in the methylation of DNA, an important process for gene expression regulation. This is why folate is particularly important during periods of rapid cell division, such as fetal development.

5. How does vitamin B12 deficiency affect the nervous system?

Vitamin B12 deficiency can severely impact the nervous system because this vitamin is crucial for maintaining the myelin sheath that surrounds and protects nerve fibers. Without adequate B12, the myelin sheath can degrade, leading to nerve damage and neurological symptoms. This can result in numbness and tingling in extremities, balance problems, confusion, depression, and in severe cases, dementia-like symptoms. B12 is also necessary for the formation of red blood cells, so deficiency can lead to anemia, further impacting neurological function.

6. How do water-soluble and fat-soluble vitamins differ?

Water-soluble vitamins (like vitamin C and B-complex vitamins) dissolve in water and are not stored long-term in the body. They need to be consumed regularly as excess amounts are excreted in urine. Fat-soluble vitamins (A, D, E, and K) dissolve in fat and can be stored in the body's fatty tissues and liver for longer periods. They don't need to be consumed as frequently but can potentially accumulate to toxic levels if taken in excess.

7. What is hypervitaminosis and why is it more common with fat-soluble vitamins?

Hypervitaminosis is a condition caused by excessive intake of vitamins, leading to toxic effects. It's more common with fat-soluble vitamins (A, D, E, K) because these can accumulate in the body's fat tissues and liver over time. Unlike water-soluble vitamins, which are easily excreted if taken in excess, fat-soluble vitamins are stored and can build up to toxic levels if consumed in large amounts over extended periods. This is why it's important to be cautious with supplements of fat-soluble vitamins, especially in high doses.

8. Why are some vitamins better absorbed when taken with food?

Some vitamins, particularly fat-soluble vitamins (A, D, E, and K), are better absorbed when taken with food because they require dietary fat for optimal absorption. The presence of fat in the digestive tract stimulates the release of bile acids, which help emulsify fats and fat-soluble vitamins, making them more easily absorbed by the intestinal cells. Additionally, some water-soluble vitamins may be better absorbed with food because it slows down digestion, allowing more time for absorption, and can protect the vitamins from stomach acid.

9. How do cooking methods affect vitamin content in foods?

Cooking methods can significantly affect the vitamin content in foods. Heat, light, and oxygen exposure can degrade certain vitamins, particularly water-soluble ones like vitamin C and B vitamins. Boiling vegetables can lead to vitamin loss in the cooking water. However, some cooking methods can increase the bioavailability of certain vitamins. For example, cooking tomatoes increases the availability of lycopene, a carotenoid with vitamin A activity. Generally, methods that minimize heating time and water use, such as steaming or microwaving, tend to preserve more vitamins.

10. What is the connection between vitamin D and calcium absorption?

Vitamin D plays a crucial role in calcium absorption by increasing the efficiency of the intestines in absorbing dietary calcium. It does this by stimulating the production of calcium-binding proteins in the intestinal cells. Additionally, vitamin D helps maintain proper calcium levels in the blood by promoting calcium reabsorption in the kidneys and, when necessary, mobilizing calcium from bone. This intricate relationship between vitamin D and calcium is essential for maintaining strong bones and proper muscle and nerve function.

11. How do antioxidant vitamins protect our cells?

Antioxidant vitamins, such as vitamins C and E, protect our cells by neutralizing harmful free radicals. Free radicals are unstable molecules that can damage cell components, leading to oxidative stress. Antioxidant vitamins donate electrons to these free radicals, stabilizing them and preventing cellular damage that can contribute to aging and various diseases.

12. What is the connection between vitamin D and sunlight?

Vitamin D is unique because our bodies can synthesize it when our skin is exposed to sunlight, specifically UVB rays. When sunlight hits the skin, it triggers a chemical reaction that converts a form of cholesterol in the skin into vitamin D3. This is why vitamin D is often called the "sunshine vitamin." However, factors like skin pigmentation, sunscreen use, and geographic location can affect this process.

13. Why do some vitamins act as coenzymes?

Some vitamins, particularly B-complex vitamins, act as coenzymes because they assist enzymes in catalyzing biochemical reactions. These vitamins bind to enzymes, forming active enzyme complexes that are essential for various metabolic processes. Without these vitamin coenzymes, many crucial biochemical reactions in our bodies would occur too slowly to sustain life.

14. How does vitamin K contribute to blood clotting?

Vitamin K plays a crucial role in blood clotting by helping to produce several proteins involved in the coagulation process. It acts as a cofactor for an enzyme that carboxylates certain glutamic acid residues in these proteins, allowing them to bind calcium. This calcium binding is essential for the activation of the clotting factors, which then work together to form blood clots and prevent excessive bleeding.

15. Why can't humans synthesize most vitamins?

Humans lack the enzymes necessary to synthesize most vitamins. This is due to evolutionary adaptations where our bodies lost the ability to produce these compounds because they were readily available in our diets. As a result, we must obtain most vitamins from food sources or supplements to maintain proper health.

16. What are vitamins and why are they important?

Vitamins are essential organic compounds that our bodies need in small amounts for proper functioning. They are important because they play crucial roles in various metabolic processes, support the immune system, and help maintain overall health. Unlike carbohydrates, proteins, and fats, vitamins don't provide energy directly but are necessary for energy production and other vital functions.

17. What is the difference between vitamins and minerals?

Vitamins are organic compounds that can be broken down by heat, air, or acid. Minerals are inorganic elements that maintain their chemical structure. Vitamins are needed in small amounts and are involved in metabolic processes, while minerals are required for structural and functional roles in the body, such as bone formation or fluid balance.

18. How do vitamins contribute to energy metabolism?

Several vitamins, particularly B-complex vitamins, play crucial roles in energy metabolism. For example, thiamine (B1), riboflavin (B2), and niacin (B3) are involved in the conversion of carbohydrates into glucose, which cells use for energy. Pantothenic acid (B5) is part of coenzyme A, which is central to the metabolism of fats, proteins, and carbohydrates. These vitamins don't provide energy themselves but are essential for the biochemical processes that release energy from food.

19. How do vitamins interact with each other?

Vitamins can interact with each other in various ways, sometimes enhancing or inhibiting each other's functions. For example, vitamin C enhances the absorption of iron, while also regenerating vitamin E to its active form. Vitamin D works synergistically with vitamin K in bone metabolism. However, some vitamins can interfere with others: large doses of vitamin C can reduce vitamin B12 absorption, and excess vitamin A can interfere with vitamin K absorption. These interactions highlight the importance of a balanced intake of vitamins rather than excessive supplementation of individual vitamins.

20. How do vitamins contribute to the immune system?

Vitamins play crucial roles in supporting the immune system. Vitamin C enhances the production and function of white blood cells, particularly neutrophils, lymphocytes, and phagocytes. Vitamin D helps activate T cells, which are crucial for fighting off pathogens. Vitamin A is essential for maintaining the integrity of skin and mucous membranes, our body's first line of defense. Vitamin E acts as an antioxidant, protecting immune cells from damage. B vitamins support the production of antibodies. Together, these vitamins help maintain a robust and responsive immune system.

21. What is the role of vitamins in neurotransmitter synthesis?

Vitamins play crucial roles in the synthesis and function of neurotransmitters, the chemical messengers in our nervous system. Vitamin B6 is a cofactor in the production of several neurotransmitters, including serotonin, dopamine, and GABA. Vitamin C is needed for the synthesis of norepinephrine from dopamine. Folate and vitamin B12 are involved in the production of S-adenosylmethionine, which is necessary for the metabolism of neurotransmitters. Vitamin D receptors are present in areas of the brain involved in neurotransmitter synthesis, suggesting a role in this process. These vitamin-dependent processes are essential for proper brain function and mental health.

22. What is the role of vitamins in gene expression?

Vitamins play important roles in gene expression through various mechanisms. Some vitamins, like vitamin A and D, act as ligands for nuclear receptors that directly regulate gene transcription. Folate (vitamin B9) is crucial for DNA methylation, an epigenetic modification that can turn genes on or off. Vitamin C is involved in the demethylation of DNA and histones, affecting gene accessibility. B vitamins like B12 and B6 are involved in the production of S-adenosylmethionine, a universal methyl donor for many biochemical reactions including DNA methylation. These vitamin-dependent processes help regulate which genes are expressed, influencing cellular function and development.

23. How do vitamins contribute to skin health?

Vitamins are essential for maintaining healthy skin. Vitamin A (retinol) promotes cell turnover and collagen production, helping to keep skin smooth and reduce signs of aging. Vitamin C is crucial for collagen synthesis and acts as an antioxidant, protecting skin from UV damage. Vitamin E, another potent antioxidant, helps protect cell membranes and can reduce inflammation in the skin. Vitamin D is involved in skin cell growth, repair, and metabolism. B vitamins, particularly biotin and niacin, support healthy skin by promoting proper fat metabolism and reducing inflammation. Together, these vitamins help maintain skin elasticity, hydration, and overall health.

24. What is the connection between vitamin deficiency and anemia?

Several vitamins play crucial roles in preventing anemia, a condition characterized by a lack of healthy red blood cells. Vitamin B12 and folate (vitamin B9) are essential for the production of red blood cells. A deficiency in either can lead to megaloblastic anemia, where the body produces large, immature red blood cells that don't function properly. Vitamin C enhances iron absorption, and its deficiency can contribute to iron-deficiency anemia. Vitamin A is also involved in iron metabolism and red blood cell production. Vitamin E protects red blood cells from oxidative damage. Thus, deficiencies in these vitamins can contribute to various forms of anemia.

25. How do vitamins support bone health beyond just vitamin D?

While vitamin D is crucial for bone health, other vitamins also play important roles. Vitamin K is essential for the production of osteocalcin, a protein that helps bind calcium to bones. Vitamin C is necessary for collagen synthesis, which forms the matrix of bone. Vitamin A helps regulate bone cell growth and differentiation. B vitamins, particularly B12, B6, and folate, help lower homocysteine levels, high levels of which are associated with increased fracture risk. Vitamin E, as an antioxidant, may help protect bone cells from oxidative stress. This multi-vitamin approach to bone health highlights the complex interplay of nutrients in maintaining strong, healthy bones.

26. How do vitamins contribute to cardiovascular health?

Vitamins play various roles in maintaining cardiovascular health. Vitamin B complex, particularly B6, B12, and folate, help lower homocysteine levels, high levels of which are associated with increased risk of heart disease. Vitamin E acts as an antioxidant, protecting LDL cholesterol from oxidation, which is a key step in the development of atherosclerosis. Vitamin C helps maintain the health of blood vessels and acts as an antioxidant. Vitamin D may help regulate blood pressure and reduce inflammation. Vitamin K is crucial for blood clotting and may help prevent arterial calcification. Together, these vitamins support heart health through multiple mechanisms.

27. What is the relationship between vitamins and enzyme function?

Many vitamins serve as coenzymes or cofactors, which are essential for enzyme function. For example, thiamine (B1) is a cofactor for enzymes involved in carbohydrate metabolism. Riboflavin (B2) is part of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), which are crucial for many oxidation-reduction reactions. Niacin (B3) is part of NAD and NADP, important in energy metabolism. Vitamin K acts as a cofactor for enzymes involved in blood clotting. Without these vitamin-derived coenzymes, many enzymes would be unable to catalyze their specific biochemical reactions, severely impacting cellular metabolism and function.

28. How do vitamins interact with minerals in the body?

Vitamins and minerals often work together in the body. Vitamin C enhances iron absorption, particularly non-heme iron from plant sources. Vitamin D is crucial for calcium absorption and utilization. Vitamin K works with calcium in blood clotting and bone metabolism. B vitamins, especially B6, B12, and folate, interact with iron in the formation of hemoglobin. Vitamin A helps mobilize iron from storage sites. On the other hand, some minerals can interfere with vitamin absorption: high doses of zinc can impair copper absorption, which is necessary for some vitamin-dependent enzymes. These interactions highlight the importance of a balanced diet for optimal nutrient utilization.

29. What is the role of vitamins in energy production at the cellular level?

Vitamins play crucial roles in cellular energy production, particularly in the processes of glycolysis, the citric acid cycle, and the electron transport chain. Thiamine (B1) is essential for the conversion of pyruvate to acetyl-CoA, a key step in glucose metabolism. Riboflavin (B2) and niacin (B3) are components of FAD, FMN, NAD, and NADP, which are electron carriers in many metabolic reactions. Pantothenic acid (B5) is part of coenzyme A, central to the citric acid cycle. Biotin (B7) is a coenzyme in carboxylation reactions in fatty acid synthesis and gluconeogenesis. These vitamin-dependent processes are essential for the efficient conversion of nutrients into cellular energy (ATP).

30. How do vitamins support protein synthesis?

Vitamins play important roles in protein synthesis at various stages. Vitamin B6 is involved in amino acid metabolism and is necessary for the synthesis of amino acid precursors. Vitamin C is crucial for collagen synthesis, a major structural protein. Vitamin K is needed for the synthesis of several proteins involved in blood clotting. Vitamin A regulates gene expression, including genes coding for proteins. B-complex vitamins, particularly B12 and folate, are necessary for DNA synthesis, which is a prerequisite for protein synthesis. Additionally, many vitamins act as coenzymes in various metabolic pathways that indirectly support protein synthesis by providing necessary precursors and energy.