Vitamins are vital organic compounds that our body needs in small quantities. These micronutrients cannot be produced endogenously by the body. The human body can only acquire vitamins through the food we eat.
These vitamins requirement differs from one organism to another. Humans can only acquire vitamins through food sources, whereas dogs can produce them.
Vitamins are required in different quantities depending upon a person’s physique. Vitamin deficiency or abundance in vitamins can cause health issues. They should be taken in the recommended amount.
Vitamins are natural organic compounds. Organic compounds contain carbon, and the essential nutrient can be acquired through the food we eat.
Our body primarily requires vitamins and nutrients to combat the disease and other foreign bodies that invade our body and mitigate the effect of the disease.
The various types of vitamins, dietary sources, their importance to the human body and the diseases caused due to deficiency are briefed.
Scientific Name of Vitamins and their Sources
The below table represents the scientific names of vitamins and their major food sources.
Common Name | Scientific Name | Major Source |
Vitamin A | Retinol | Green leafy vegetables, sweet potato, pumpkin, etc. |
Vitamin B1 | Thiamine | Cauliflower, oranges, eggs, potatoes, etc. |
Vitamin B2 | Riboflavin | Mushrooms, fortified cereals, dairy products, etc. |
Vitamin B3 | Niacin | Red meat, fish, legumes, bananas, etc. |
Vitamin B5 | Pantothenic acid | Broccoli, brown rice, oats, chicken, etc. |
Vitamin B6 | Pyridoxine | Cantaloupe, papayas, chickpeas, etc. |
Vitamin B7 | Biotin | Almonds, spinach, oatmeal, whole wheat bread, etc. |
Vitamin B9 | Folic acid | Brussels sprouts, spring greens, organ meat, etc. |
Vitamin B12 | Cobalamin | Eggs, dairy foods, chicken, red meat, etc. |
Vitamin C | Ascorbic acid | Pepper, broccoli, potatoes, strawberry, etc. |
Vitamin D | Calciferol | Tuna fish, orange juice, sardines, etc. |
Vitamin E | Tocopherol | Sunflower oil and seeds, wheat germ oil, peanut, almond, etc. |
Vitamin K | Phytonadione | Vegetable oil, blueberries, figs, etc. |
Vitamin A
Vitamin A is a fat-soluble vitamin. Vitamin A is also called retinol, retinal, retinoic acid and beta-carotene. The provitamin A carotenoids are dietary precursors of retinol.
The recommended dietary allowance (RDA) of retinol is 900 and 700 μg for men and women, respectively.
The dietary sources of vitamin A are abundantly found in dark-coloured fruits and vegetables. These vitamins can also be acquired through certain animal sources.
Plant-based foods like green leafy vegetables, spinach, amaranth, carrots, yellow maize, mangoes, papayas, squash, kale, broccoli, sweet potato and pumpkin are rich in vitamin A.
Foods like tomato, red bell pepper, milk and fortified cereals are also rich in vitamin A. Animal-based foods include eggs, beef liver, fish oil, milk, sausage, mackerels, salmon and cod liver oil.
Retinoic acid is essential during embryonic development and maintenance of immune functions.
Vitamin A deficiency can lead to various health ailments. If vitamin A is not absorbed properly in the digestive system, it can lead to vitamin A malabsorption which causes Celiac disease, Crohn’s disease, cystic fibrosis and cirrhosis.
A mild vitamin A deficiency can cause fatigue and become susceptible to infections.
The other health ailments caused due to vitamin deficiency are
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- Night blindness or Nyctalopia,
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- Irregular patches on the white of the eyes,
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- Growth retardation,
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- Dry skin and
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- Xerophthalmia—A condition that causes severe dryness, which can lead to blindness.
However, intake of vitamin A above the recommended range can cause vitamin A intoxication. According to a paper published in the NCBI, vitamin A toxicity can lead to muscle and bone pain, anorexia, headache and risk of seizures.
Vitamin B1
Vitamin B1 is also called thiamine. Thiamine plays an essential role in glucose metabolism and nerve, heart and muscle functions.
Vitamin B1 is a water-soluble vitamin. The water-soluble vitamins are easy to carry in the bloodstream, and the unused vitamins are eliminated through urine because thiamine can only be stored for a shorter duration.
Thiamine intake also regulates the proper blood levels. The recommended daily intake (RDI) is 1.2 mg/day and 1.1 mg/day for men and women, respectively. For pregnant women, the RDI is 1.4 mg/day.
Foods like cauliflower, kale, oranges, eggs, asparagus and potatoes are rich in vitamin B1. Meat, fish and whole grain are the natural sources of thiamine. Other sources include pork, beans, lentils, green peas, enriched cereals, bread, rice, sunflower seeds, yoghurt and fortified cereals.
A thiamine deficiency can cause beriberi. Beriberi is the loss of muscles and numbness in your hands and feet. It also leads to fluid build-up in the heart as it impairs the reflexes and motor functions.
People with other conditions like AIDS (acquired immunodeficiency syndrome), alcohol dependency, old age, diabetes, post-bariatric surgery, gastrointestinal diseases, fasting, pregnancy, lactation and malignant disease are prone to vitamin B1 deficiency.
Symptoms of vitamin B1 deficiency include weight loss, anorexia, short-term amnesia, malaise, muscle weakness, confusion and cardiac symptoms.
If vitamin B1 deficiency is left untreated, it might lead to a condition called Wernicke-Korsakoff syndrome (WKS)
Vitamin B2
Vitamin B2 is also called riboflavin. Vitamin B2 is vital for breaking down the food components, absorbing the nutrients from the food and maintaining the tissues.
Vitamin B2 is a water-soluble vitamin, and the excess is excreted through urine. The riboflavin is actively absorbed in the small intestine.
Riboflavin actively breaks down nutrients like carbohydrates, fats and proteins, which helps maintain the body’s energy levels.
The recommended daily allowance (RDI) is 1.3 milligrams per day and 1.1 milligrams per day for men and women, respectively.
Foods rich in vitamin B2 are grains, plant-based foods and dairy products. Eggs, asparagus, artichokes, avocados, cayenne, kelp, fortified cereals, molasses, mushrooms, nuts, currants, pumpkin, parsley, navy beans, peas, sweet potatoes, sage, broccoli, brussels sprouts, spinach, watercress and dandelion greens can help with vitamin B2 deficiency.
Riboflavin acts as an antioxidant that regulates the immune system. It also helps to maintain your skin and hair. It is essential for normal development, lactation and reproduction.
If there is a deficiency in vitamin B2, nutrients like fat, proteins and carbohydrates cannot be digested, which results in malabsorption of vitamin B2.
Riboflavin absorption can be identified by the colour of the urine. Riboflavin contains a yellow-green fluorescent pigment which turns the urine yellow. This is an indication that the body absorbs the vitamins.
Inadequate dietary intake of riboflavin can result in endocrine abnormalities. The antioxidant riboflavin works as antioxidant glutathione. The glutathione is responsible for invading the free radicals and detoxing the liver.
Riboflavin deficiency can lead to diarrhoea, alcoholism, hemodialysis and liver disorder.
Vitamin B3
Vitamin B3 is also called niacin, and it is a water-soluble vitamin. Nicotinic acid and nicotinamide are the common forms of vitamin B3.
Like the other water-soluble vitamins, the excess vitamin is excreted through urine. Niacin is an essential coenzyme, and almost 400 enzymes depend on niacin.
Niacin is vital for functions like converting nutrients into energy, repairing DNA, aiding in DNA formation, and having antioxidant effects.
Red meat, fish, poultry, brown rice, nuts, fortified cereals, bananas, legumes and seeds are rich in niacin.
Niacin deficiency is rare as it is found in most foods, and the body can it absorb easily. A niacin deficiency can lead to pellagra. Pellagra causes dark, scaly rashes when exposed to sunlight, bright red tongue and constipation or diarrhoea.
Symptoms of niacin deficiency include depression, headache, memory loss, fatigue and hallucinations.
Vitamin B5
Vitamin B5 is called pantothenic acid, a vital vitamin for the body. It breaks the food we eat and converts them to energy.
Pantothenic acid is naturally present in various plants and animal-based foods. Vitamin B5 deficiency is rare since it is primarily found in all foods, and the body can absorb the nutrient.
Pantothenate deficiency plays a vital role in Ach deficiency, myelin loss, age-related dementia-like Huntington’s disease and neurodegeneration.
The recommended dietary intake (RDI) is 5 mg/day, for pregnant women 6 mg/day and lactating women 7 mg/day.
Foods like fortified cereals, chicken, mushrooms, avocado, nuts, seeds, brown rice, oats, broccoli, potatoes, dairy products and yoghurt are rich in vitamin B5.
Vitamin B5 deficiency is rare since it is found in all living organisms. Symptoms of vitamin deficiency include headache, irritability, restlessness, numbness, muscle cramps, nausea and vomiting.
Vitamin B6
Vitamin B6 is one of the water-soluble vitamins and is also called pyridoxine. Pyridoxal 5’ phosphate (PLP) is the common and active form of coenzyme in the body.
The coenzyme is required by 100 enzymes to break down proteins, fats and carbohydrates to maintain normal homocysteine. It also promotes brain health and aids immune functions.
The recommended dietary allowance (RDA) is 1.3 mg for men and women. The foods rich in vitamin B6 are red meat liver, fish like salmon and tuna, fortified cereals, poultry, chickpeas, dark green leafy vegetables and fruits like cantaloupe, papayas, bananas and oranges.
Vitamin B6 deficiency causes skin and scalp conditions, confusion, depression, lowered immunity and microcytic anaemia.
If the body does not absorb vitamin B6, it can lead to conditions like celiac disease, Crohn’s disease, ulcerative colitis and autoimmune disorders like rheumatoid arthritis.
Vitamin B7
Vitamin B7 is also called biotin and is a water-soluble vitamin. Biotin assists the enzymes in the breakdown of carbohydrates, fats and proteins from the food we eat.
Biotin plays a significant role in histone modification and cell signalling and regulates the genes. The biotin in the foods is bound to the protein. The enzymes in the stomach, like the protease, help break down the protein-bound biotin in the food.
The biotin broken down is then absorbed in the small intestine and stored in the liver. The adequate intake of biotin is 30 mcg for men and women.
Foods like eggs, meat, fish, seeds, nuts and sweet potatoes are rich in biotin. Other sources include almonds, spinach, broccoli, cheese, banana, oatmeal, apple and whole wheat bread.
Biotin deficiency causes hair loss, skin rashes and brittle nails. Other symptoms of biotin deficiency are depression, lethargy, hallucination, ataxia (loss of control in bodily movements), weakened immune system and seizures.
Vitamin B9
Vitamin B9 is also called folic acid and is a water-soluble vitamin. Folic acid aids in the formation of DNA and RNA. It is also involved in protein metabolism.
Folic acid helps break down homocysteine. Homocysteine is a harmful amino acid that can adversely affect our body if present in large quantities.
Folic acid is important for pregnant women as it is required for foetus development. Folic acid helps in the formation of healthy red blood cells.
The recommended dietary allowance (RDA) is 200 µg/day and 180 µg/day for men and women.
Folate deficiency causes folate deficiency megaloblastic anaemia. Folate deficiency can produce unhealthy red blood cells. Other symptoms of folic acid deficiency include dementia, cardiovascular diseases, infertility and depression.
Foods like broccoli, brussels sprouts, green leafy vegetables like kale, spring greens, spinach and cabbage, kidney beans, chickpeas, fortified cereals and organ meat are rich in folate.
Vitamin B12
Vitamin B12 is a water-soluble vitamin. Vitamin B12 is also called cobalamin and is mainly derived from animal foods.
Foods like red meat, eggs and dairy products are rich in cobalamin. The glycoprotein, called intrinsic factor, produced by the parietal cells in the stomach helps absorb cobalamin in the terminal ileum.
The absorbed cobalamin is used as an enzyme cofactor and aids in synthesising DNA, myelin and fatty acids.
The cobalamin is usually stored in the liver to avoid deficiency. However, deficiency can be caused due to malabsorption and dietary insufficiency.
The deficiency of vitamin B12 can lead to neurological and hematologic symptoms. Foods like organ meat, chicken, eggs and dairy are rich in vitamin B12. Vitamin B12 is significantly less in plant sources.
Vitamin C
Vitamin C is another water-soluble vitamin and is abundantly found in citrus fruits. Vitamin C is also called ascorbic acid. Vitamin C is a water-soluble vitamin, and the excess will be excreted through urine, so it should be consumed daily.
Vitamin C deficiency will cause scurvy. Scurvy leads to malnutrition, and your hair follicles become clogged with keratin. The wounds will not heal, and the old wounds will rupture again. The deficiency of vitamin C may lead to death if left untreated.
Vitamin C acts as an antioxidant and helps heal infections. It scavenges the free radicals and controls infections that invade our bodies.
Vitamin C helps in the formation of collagen. The recommended dietary allowance is 90 mg for men and 75 mg for women.
Foods like orange, pepper, broccoli, potatoes, strawberry and brussels sprouts.
Vitamin D
Vitamin D, also known as Calciferol, is one of the essential vitamins our body needs. It helps to maintain healthy teeth and bones. Vitamin D is also called the “sunshine vitamin”.
Our body synthesises vitamin D through exposure to sunlight. Vitamin D is also obtained from our dietary sources.
The deficiency of vitamin D in children leads to rickets. Vitamin D deficiency results in deformed bone formation in children.
In adults, it leads to osteomalacia, which results in abnormal mineralisation of collagen in the matrix of the bone. If the collagen is weak, it might lead to fracture risk. The collagen will not provide enough structural support.
Foods rich in vitamin D are cod liver oil, tuna fish, orange juice, sardines, organ meat, swordfish and dairy products. Vitamin D is a fat-soluble vitamin.
Vitamin E
Vitamin E is a fat-soluble vitamin. Vitamin E occurs in various forms, but our body can only use alpha-tocopherol.
The primary function of vitamin E is to scavenge the lost electrons called free radicals that damage the cells. These free radicals can cause cancer and lead to certain chronic conditions.
Vitamin E acts as an antioxidant that regulates immune function. Further, it prevents clot formation in the arteries.
The recommended dietary allowance is 15 mg for men and women. For lactating women, it is 19 mg.
Sunflower oil and seeds, wheat germ oil, peanut, almond, pumpkin, spinach, mango, asparagus and avocado are rich in vitamin E.
Vitamin E deficiency can lead to vision loss, muscle damage, loss of feeling in the arms and legs and body weakness.
Vitamin K
Vitamin K is a fat-soluble vitamin and is divided into two types called phylloquinone and menaquinones. Phylloquinone is found in green leafy vegetables, and animal and fermented foods contain menaquinones.
Vitamin K is primarily necessary for blood clotting. Prothrombin is a protein that is involved in the process of blood clotting and requires vitamin K.
A protein called osteocalcin also requires vitamin K for healthy bones. The recommended dietary allowance is 120 and 90 mcg for men and women, respectively.
Food sources include green leafy vegetables, vegetable oil, blueberries and figs. Other sources include cheese, eggs, meat and soybeans.
Classification Of Vitamins
The vitamins are classified into two types, water-soluble and fat-soluble vitamins.
Water-soluble vitamins
| Vitamin | Food source | Deficiency |
| Vitamin B1 (thiamine) | Peas, bananas, nuts, bread, fortified cereals, organ meat and oranges. | Beriberi |
| Vitamin B2 (Riboflavin) | Milk, yoghurt, egg, cheese, red meat, fish, almond and spinach. | Hair loss, skin rash, sore throat, anaemia and swollen tongue. |
| Vitamin B3 (niacin) | Red meat, poultry, fortified cereals, seeds, nuts, bananas, legumes, fish and brown rice. | Headache, fatigue, depression, memory loss and hallucination. |
| Vitamin B6 | Red meat, fish, peanut, oats, milk, banana and fortified cereals. | Anaemia, dermatitis, depression, weak immune system and swollen tongue. |
| Vitamin B7 (biotin) | Red meat, avocado, sweet potato, seeds and nuts, egg and fish. | Brittle nails, hair thinning and skin rashes. |
| Vitamin B9 (folic acid) | Broccoli, cabbage, kale, spinach, fortified cereals, peas and organ meat. | Fatigue, weakness, mouth sores and neurological problems. |
| Vitamin B12 (cobalamin) | Fish, egg, cheese, milk, meat and yoghurt. | Weakness, tiredness and lightheadedness. |
| Vitamin C | Citrus fruits, broccoli, potatoes, blackcurrants,strawberries, and pepper. | Anorexia, poor wound healing and hyperkeratosis. |
Fat-soluble vitamins
| Vitamin | Food source | Deficiency |
| Vitamin A | Cheese, egg, fortified cereals, carrot, milk, yoghurt, mango, papaya, apricots and oily fish. | Dry eyes, dry skin and night blindness |
| Vitamin D | Cod liver oil, fish, orange, organ meat and dairy products. | Cystic fibrosis, Crohn’s disease and Celiac disease. |
| Vitamin E | Sunflower oil and seeds, peanut, pumpkin, red bell pepper and spinach. | Nerve damage, muscle damage, loss of feeling in the legs and hands and vision loss. |
| Vitamin K | Turnip, spinach, broccoli, cabbage, lettuce and soybean. | Poor bone development, bleeding, osteoporosis and cardiovascular diseases. |
Benefits of Different vitamins in our body
Vitamins and minerals are essential for the proper functioning of our body. Vitamins play vital roles in our body, from breaking down the nutrients to proper immune function.
Vitamins help heal wounds and alert the immune system to fight further infection. They break down the foods we eat and convert them to energy so our bodies can use them for various functions.
Vitamins are also called micronutrients. These micronutrients play a major role in our bodies to make them stable.
Usage and Dosage of Vitamins
Before getting to know about the dosage of vitamins, there are specific terms to be familiar with.
RDA— is the recommended dietary allowance. The RDA is the range of vitamins and minerals needed for the body. It differs for various groups like men, women and children.
UL— Tolerable upper intake level is the maximum range of daily vitamins and minerals intake that can be consumed without the risk of overdosage or other intoxication.
Supplements are suggested when you don’t get enough nutrients from dietary sources. These supplements are designed in such a way that they give you the required nutrition in the recommended range.
However, there are risks of vitamin intoxication if there is an overdose of the supplement.
Conclusion
Vitamins are required for all organisms for growth and development. Vitamins should be taken in the recommended ranges. If the range exceeds, it can cause toxicity; if the range decreases, it can cause deficiency.
You cannot measure all the vitamins and consume them according to the recommended dietary allowance. Instead, consume all foods in the correct quantity. Consume a balanced diet to avoid any vitamin deficiency. Good food is always good health.
