What is Vitamer?

A vitamer of a particular vitamin is any of a number of chemical compounds, generally having a similar molecular structure, each of which shows vitamin-activity in a vitamin-deficient biological system.

For instance, Vitamin A has at least six vitamer chemicals that all qualify as "vitamin A", each with slightly different properties. In such a system, "vitamin A" is termed the "generic descriptor" of the vitamin, which is defined by its biological properties in a vitamin deficient organism, not by its chemical structure. In the "vitamin A" system, four of the chemicals naturally found in foods are chemically carotenoids (three carotenes and one xanthophyll), found in certain plant foods like carrots. However, the retinol and retinal forms, which occur in animal-based foods, are several times as effective in humans, per microgram, as the carotenoid forms. In some cases these differences are extreme: for example the carotenoid forms of vitamin A cannot be absorbed by cats or ferrets at all, and therefore do not have vitamin A activity in these species.

Typically, the vitamin activity of multiple vitamers is due to the body's (limited) ability to convert one vitamer to another, or many vitamers to the same enzymatic cofactor(s), which is active in the body as the important form of the vitamin.

As part of the definition of vitamin, the body cannot completely synthesize an optimal amount of vitamin activity from simple foodstuffs, without some minimal amount of a vitamer molecule as a basis.

Typically not all vitamers possess exactly the same vitamin potency, per mass. This is due to differences in absorption and interconversion of the various vitamers of a vitamin. Often for the same reason, the toxicity of vitamers varies by molecule, as is the case with vitamin E.

A set of chemicals may be (but is not always) grouped under an alphabetized vitamin "generic descriptor" title, such as "vitamin A". Other examples of vitamers include cyanocobalamin, hydroxocobalamin, methylcobalamin, and 5-deoxyadenosylcobalamin (adenosylcobalamin—AdoB-12), which are all vitamers of B12, and thus all possess "B12 activity". Another example is that both niacinamide and nicotinic acid (niacin) have vitamin B3 activity.

Questions and answers on "Vitamer"

Why my family doctor prescribed me Remylin D and what is the use of this tablet and side effects of this...

doctor1 MD


Thanks of the query

REMYLIN-D contains alpha lipoic acid 100 mg, pyridoxine hydrochloride 3 mg, methylcobalamin 1500 mcg, folic acid 1.5 mg,...

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I recently got Vitamin D Tested and its 32 the reference says its insuficient.
The Reason i went for the tests was the recommendation of my...

doctor1 MD

Hi Sachin,

Thank you for your query.

Unfortunately I do not see your medical history or lab reports in the query that you have raised. If you have...

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I am seeing purple spots out of the corner of my eye after coming back from a dentist appointment and having the right side of my face numbed. The...

doctor1 MD


The numbness of the face after visit from dentist is probably due to the local anesthesia dentist might have given you. If it is a big purple...

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