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Vitamins

Vitamins are nutrients with specific functions to perform in the body; such as helping with the production of certain enzymes, vision, functioning as anti-oxidants or hormones, etc. They do not contribute to the structure of the body as carbohydrate, proteins and fats does, nor do they provide significant energy upon assimilation.

Types of vitamins

Vitamins are generally classified into two:

• Fat soluble, and
• Water soluble vitamins.

Fat soluble vitamins are stored in the body: usually in the liver, muscles and fats, thus offering you a bit of flexibility in consuming these vitamins irregularly.

However water soluble vitamins aren't stored in the body and the surplus vitamins are excreted through urine (remember amber yellow urine post consumption of multi-vitamins?). Therefore, it is essential to consume water soluble vitamins through diet on a regular basis.

Vitamers and provitamins

Vitamins are a generic group name given to compounds called vitamers that has similar chemical structure and comparable functions in the body¹. In other words similar vitamers form particular vitamin groups.

For instance, retinol, retinal and retinoic acid are three compounds that are structurally similar and serve comparable functions in human vision. They are grouped as Vitamin A.

Provitamins are substances that can be converted to vitamins in the body by certain processes. You can call provitamins are precursors of vitamins.

For instance, β-carotene is a compound with 1/6th biological activity of retinol (Vitamin A). The body converts β-carotene to retinol using an enzyme. However, note that not all vitamins have provitamins.

Vitamers and provitamins are interesting entities to study further, but only as a science and medical student. There is no benefit to further covering them in this handbook since they aren't nutrients per se, but components of nutrients.

13 vitamins

There are 13 vitamins essential for human body¹. Their names, vitamers and provitamins are listed below. Since vitamins engage in multiple biological functions and most functions require multiple vitamins, it would be inaccurate to say that one vitamin is good for this and the other for that.

Requirements

All RDA requirements are taken from the ICMR report called Nutrient Requirements for Indians, 2020², while all RNI requirements are taken from WHO recommendations³.

For men

For women

Surplus of vitamins

Vitamins and mineral deficiency can cause long lasting damages to the human body. But so is their surplus in the body. You don't risk either of these dangers if you have a balanced meal, but the moment you stop consuming diverse food, or consume a particular food in questionable amounts, or consume multi-vitamin pills for no particular reason, you are in that danger zone.

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