Vitamins are essential micronutrients that are required by human body. These are organic molecules that are necessary for adequate growth and development. As vitamins cannot be synthesized by human body therefore they are obtained through various dietary sources.
Functions of vitamins
Vitamins have diverse functions that overall maintain our health:
- They regulate growth and differentiation of various cells, tissues and organs (Vitamin A)
- They are important for the proper growth and development of human body (B complex vitamins)
- They provide protection against diseases and infections (Vitamin D and E)
- They help to strengthen our bones by controlling the mineral metabolism. (Vitamin D)
- They act as antioxidants. (Vitamins C and E)
- They strengthen the digestive and nervous system (B complex vitamins)
- Vitamins are required in small quantities as they cannot be synthesized by our body
- Excess of water soluble vitamins is excreted through urine as they cannot be stored in the body.
- The main source of vitamins is a balanced diet. However, some vitamins are acquired through other means such as vitamin K and biotin are produced by the microorganisms in the gut flora. Vitamin D is synthesized on exposure of human’s skin to sunlight.
- The deficiency as well as the excess intake of vitamins is harmful for our health
Vitamins are mainly divided into two broad categories:
- Water-soluble: These vitamins can easily dissolve in water. It includes 9 vitamins (8 B vitamins and vitamin C).
- Fat-soluble. These vitamins can easily dissolve in fats. These vitamins can be stored in our body’s fat and if required can be used later. It includes 4 vitamins (A, D, E, and K)
Water-soluble versus Fat-soluble
|Absorption||Directly to blood||Absorbed through the intestinal tract via lipids|
|Transportation||Occurs Freely||Requires carrier|
|Storage||Circulates freely||Stored in cells with fat|
|Intake||More consistent intake (2-3 days)||Less consistent requirement ( every week)|
|Group of vitamins||vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine), vitamin B7 (biotin), vitamin B9 (folic acid or folate), vitamin B12 (cobalamins), vitamin C (ascorbic acid)||vitamin A (as all-trans–retinol), vitamin D (calciferols), vitamin E (tocopherols), and vitamin K (phylloquinone and menaquinones).|
Effect of key vitamins on COVID-19
Various research studies have shown that few vitamins help to boost our immunity and provide protection against coronavirus. These include Vitamin D and C.
- Vitamin D acts as a modulator of the immune system. It provides effective physical barrier and strengthens the immunity against upper respiratory tract infections. In a recent study, it was reported that prophylactic supplementation of vitamin D (in doses up to 2000 IU/d) helped to decrease the severity of COVID-19 infection mainly in elderly population. It has demonstrated antiviral and anti-inflammatory actions.
- Vitamin C acts as a powerful antioxidant. It provides protection against oxidative stress that results in the accumulation of free radicals. Free radicals are the reactive molecules that cause cell damage and affect the immune status. Vitamin C supplementation has shown significant improvements in symptoms of patients affected with viral infections and respiratory problems.