Nutrition is a key factor in our body. The correct amount and the essential kinds of nutrients are required to maintain a healthy life. Among the many important kinds of nutrients, vitamins required by the human body are in very little amounts, but the role it plays in maintaining the health of an individual is huge.
Vitamins are any group of organic compounds which are essential for the normal growth and nutrition of a living being and are required in small quantities from the diet due to their incapability of being synthesized by the body. Most of the vitamins required by a human being are obtained through water, which is advised to be consumed daily in an amount of 2-4 liters. The rest of it is acquired from a healthy diet.
Each organism has different vitamin requirements, for example, humans need to acquire vitamin C from their diets whereas dogs can produce all the vitamin C they need within their bodies. Vitamin D on the other hand gets synthesized in the human body itself as a sufficient amount of it is not found in the diet we consume. The major source of Vitamin D synthesis in our body is obtained from sunlight.
Types of Vitamins
Vitamins can be broadly classified as fat-soluble and water-soluble vitamins.
1. Fat-Soluble Vitamins
The body absorbs fat-soluble vitamins through the intestines with the help of fats that are lipids. People who follow a low-fat diet may not be able to absorb sufficient amounts of these vitamins. They are stored in the liver, fatty tissues, and muscles.
The four essential fat-soluble vitamins are vitamins A, D, E and K. These stored vitamins can stay in our body for days and sometimes even months. The lipids that help in these vitamin absorptions are called dietary fats, meaning those fats which we acquire through our eating habits.
a) Vitamin A
Vitamin A is referred to as retinol, retinal, and “the four carotenoids” chemically. It includes the major beta carotene. It is present in two major forms, vitamin A1 and A2. Carotenoids such as alpha, beta, and gamma along with cryptoxanthin act as a provitamin form of vitamin A. Among these the most potential provitamin form is beta.
Beta carotene is made up of eight 5-carbon isoprenoid units. They are linked together to form a long chain of 40 carbon atoms with an ionone ring at each end. Each hydrolysis of this compound yields two moles of the vitamin. The cleavage usually occurs at the midpoint of the carotene in the chain with the help of two ionone rings connected at each end.
The conversion of beta carotene into vitamin A can be observed in the liver of fishes and almost all mammals. Post the esterification with a fatty acid, vitamin A becomes complex primary alcohol called retinol.
Vitamin A contributes maximum to the growth and improvement of eyesight due to which it is also called an antixerophthalmic factor or the bright eyes vitamin. They are found in abundance in fish liver oil. Other important sources of vitamin A include butter, milk, egg, carrots, broccoli, sweet potatoes, spinach, pumpkin, apricots, and certain kinds of cheese.
Along with improved eyesight, vitamin A also forms and maintains healthy teeth, bones, soft tissues, mucous membrane, and skin. The deficiency of vitamin A can lead to night blindness and keratomalacia, which causes the clear front layer of the eye to grow dry and cloudy.
b) Vitamin D
Chemically vitamin D is referred to as ergocalciferol and cholecalciferol. These are the two different forms of vitamin D, namely D2 and D3 respectively. Ergosterol is converted to vitamin D2 through differential cleavage. 7-dihydroxycholecalciferol is a provitamin found in animals that are converted into cholecalciferol.
Due to its capability in the prevention of rickets, vitamin D is also called an antirachitic factor. Fish liver oil, fatty fish, eggs, beef liver, and mushrooms are rich in vitamin D. It is referred to as a sunshine vitamin since its provitamin form present in the human skin is converted to active vitamin D by irradiation with UV light.
c) Vitamin E
Also referred to as tocopherol chemically, vitamin E are derivatives of 6-hydroxychroman bearing an isoprenoid side chain at the second carbon atom. Breakdown of α-tocopherol involves both oxidative cleavages of the chroman ring to yield quinine or hydroquinone-like compounds and the degradation of the isoprenoid side chain.
Tocopherols are powerful antioxidants and prevent oxidative damage of other lipid molecules such as vitamin A and fats present in food. Due to this property, they are commercially added to foods to prevent their spoilage. The antioxidizing property of vitamin E is stimulated by vitamin C and phenols. They also protect the mitochondrial system from being inactivated by lipid peroxides. Additionally, vitamin E also helps the body to form red blood cells.
They are found abundantly in wheat germ, kiwis, almonds, eggs, nuts, leafy greens, and vegetable oils and they are found in little quantities in rice, corn, soybean, coconut, and peanut. Due to its antioxidant property, it helps prevent oxidative stress in our body which if not done can result in widespread inflammation and various diseases. Rarely deficiency of vitamin E can cause hemolytic anemia in newborns which destroys blood cells.
d) Vitamin K
It is a derivative of naphthoquinone. The two forms of vitamin K naturally occur, vitamin K1 and K2. The third carbon atom of the quinone ring has a phytol radical attached to vitamin K1. In vitamin K2, this position is acquired by four isoprene units followed by six isoprene units towards the side each of them possessing a double bond.
Vitamin K is also known as a coagulation vitamin or antihemorrhagic factor due to its role in blood clotting. Vitamin K1 is obtained from green leafy vegetables such as cabbage, spinach, etc. On the other hand, vitamin K2 is present in putrefied fish meat. Other than these two pumpkins, figs and parsley are rich sources of vitamin K. These vitamins also help in blood clotting and the electron transport system for oxidative phosphorylation.
2. Water-Soluble Vitamins
These should be consumed regularly as they are washed out quickly and are not stored for a longer period in our body. Any leftover or excess amounts of these vitamins, leave the body through urine. The nine essential water-soluble vitamins include vitamin C and all the B complex vitamins. B12 is the only water-soluble vitamin that can be stored in our body within the liver for more years.
Vitamin B complex consists of a group of vitamins which are, vitamin B1, B2, B3, B5, B6, B7, B9, and B12. They are related in their structures slightly but in features efficiently. All of them are water-soluble, act as coenzymes that take part in metabolic pathways, can be obtained from the same source being liver and yeast and most of them can be synthesized by intestinal bacteria.
a) Vitamin B1
Chemically vitamin B1 is the compound thiamine or 2,5-dimethyl-6-aminopyrimidine. It is bonded through a methylene linkage to form 4-methyl-5-hydroxyethyl thiazole. In the metabolic pathway, thiamine is phosphorylated with ATP to form thiamine pyrophosphate(TPP), in association with lipoic acid forms the prosthetic group for enzyme carboxylase.
Vitamin B1 is an essential factor for producing various enzymes that help in breaking down blood sugar. Deficiency of this can lead to diseases such as beriberi and Wernicke-Korsakoff syndrome. Foods such as yeast, pork, cereal grains, sunflower seeds, brown rice, whole grain rye, asparagus, kale, cauliflower, potatoes, oranges, liver, and eggs are rich in thiamine.
b) Vitamin B2
The water-soluble riboflavin is the only form of vitamin B2 and is essential for the growth and development of body cells and metabolism. Asparagus, bananas, okra, cottage cheese, milk, yogurt, meat, fish, eggs, and green beans are rich sources of riboflavin. The deficiency of vitamin B2 can cause inflammation of the lips and fissures in the mouth.
c) Vitamin B3
Comprising mainly of two variants: niacin and niacinamide, it is important in human health for the cells to grow and work correctly. Low levels of vitamin B3 could result in pellagra, which causes diarrhea, skin changes, and intestinal upset. Vitamin B3 is found in chicken, beef, tuna, salmon, milk, eggs, tomatoes, leafy vegetables, carrots, nuts, tofu, and lentils.
d) Vitamin B5
Vitamin B5, also known as pantothenic acid is necessary for the strong production of energy and hormones in the human body. It is obtained from meats, whole grains, broccoli, avocados, and yogurt. The deficiency of pantothenic acid can cause paresthesia. It is also important for a healthy metabolism.
e) Vitamin B6
It is also known as pyridoxine and helps in the formation of red blood cells and maintaining brain function. The more protein a person consumes, the more B6 is required by that body due to its co inherent function with the proteins. The deficiency of B6 can lead to anemia and peripheral neuropathy. It can be obtained from chickpeas, beef liver, bananas, and nuts.
f) Vitamin B7
Biotin or vitamin B7 enables the human body to metabolize proteins, fats, and carbohydrates. It also contributes to keratin, which is the most important structural protein required by the skin, hair, and nails. Low levels of biotin can result in dermatitis or inflammation of the intestines. Egg yolk, broccoli, spinach, and cheese are good sources of biotin.
g) Vitamin B9
Folic acid is one of the major vitamins required by the human body due to its function in the process of making DNA and RNA which holds the base of every life. Hence a deficiency of B9 especially during pregnancy can be dangerous to the fetus as it can affect its nervous system. Thus doctors recommend folic acid supplements during the pregnancy period. Healthy sources of folic acid include leafy vegetables, peas, legumes, liver, fortified grain products, and sunflower seeds.
h) Vitamin B12
B12 is also called cyanocobalamin, hydroxocobalamin, and methylcobalamin chemically. It plays a key role in the smooth functioning of the human nervous system. Good balamins are obtained from fish, fortified cereals, fortified soy products, and fortified nutritional yeast. People who follow a vegan diet are generally recommended by doctors to consume B12 supplements as veggies generally lack them.
i) Vitamin C
Also known as ascorbic acid, they are strong producers of collagen and help in the healing of the wound, bone formation, and strengthening of blood vessels. They also help in the growth of the immune system, ultimately meaning helps leucocytes, supporting the absorption of iron, and act as an antioxidant.
Hence deficiency of vitamin C could result in scurvy which causes bleeding gums, loss of teeth, and poor tissue growth and wound healing. All fruits and vegetables which are raw are great sources of Vitamin C, however, if cooked the vitamin is destroyed.
With the increase in an unhealthy lifestyle, supplements be it proteins or vitamins and their demand has significantly increased. However, according to multiple research sources, supplements are not required by our body as it does not provide the vitamin levels we require daily due to the difference in their structural integrity.
It is advised to be consumed only during certain cases such as, while in pregnancy or people with restricted diets and for people facing certain health issues. Unsure trials of supplements can result in varied health issues. Such as certain medications can influence these supplements and sometimes overdosage can lead to health issues too.
The best and healthiest way to consume vitamins is through a varied diet that contains plenty of fruits and vegetables, especially leafy vegetables.