What’s the Difference Between Vitamin D and D3?

Photo: Ryan Edwards-Crewe

A vitamin can be defined as a substance that is all of the following (a) soluble in either water or fat; (b) needed to maintain life but does not supply energy; and (c) a deficiency of which may result in various diseases.

An deficiency example would be scurvy, which results from a deficiency of vitamin C and was a common disease among sailors who had few fresh fruits and vegetables to eat.

There are five forms of vitamin D, of which two (D2 and D3) are especially important. In fact, the label “vitamin D” normally refers exclusively to them – unless otherwise specified – and it is those two that we will discuss.

Vitamin D2 and D3 are both fat soluble, chemically classified as secosteroids (that is, steroids with a “broken” ring in their molecules), and in both forms, the vitamin is essential for calcium and phosphorus metabolism. Vitamin D2 is derived from ergocalciferol (chemical formula C28H44O), whereas vitamin D3 from cholecalciferol (chemical formula C27H44O). Thus, they differ only in one carbon atom.

A deficiency of vitamin D (in general) causes rickets, in which the bones become so soft that they bend abnormally and often develop knobs on them. The victim, most commonly a child, develops unnatural poses such as knock knees or bow legs, which usually remain when the bones harden later in life. It has also been postulated that a deficiency of vitamin D can be a factor in the development of multiple sclerosis. Certainly, the results of recent research strongly indicate that victims of that disease whose diet is low in vitamin D are more likely to relapse into it.

Vitamin D2 can come only from plants. It aids in the production of insulin and helps the body fight tumors. Sunlight is the most direct source for this vitamin, so at least thirty hours of exposure should provide enough for the body to function. Foods high in vitamin D2 include egg yolks, boxed cereals, and fortified margarine.

Vitamin D3 aids in the absorption of calcium by the bones. It too comes from sunlight, but here only ten minutes at most, without a powerful sunscreen, should be enough to provide the body’s needs. Foods high in vitamin D3 include the oils of such fish as mackerel, cod, tuna, pink salmon, and catfish. Beef liver and cheese also contain small amounts of the vitamin.

Like all vitamins, D2 and D3 can be obtained in the form of pills. D3, however, is much more prevalent. Instructions on the label should be always be followed.

Biologists do not agree on which form of vitamin D is more powerful, or if they are both equally so. But it is now known that they are not equivalent, for four reasons:

(1) Vitamin D2 has a shorter shelf life.

(2) They are not equally effective at raising the levels of serum 25- hydroxyvitamin D.

(3) The metabolites of vitamin D2 do not easily bind to the plasma protein that binds vitamin D.

(4) The metabolism of vitamin D2 is non-physiological.

You can get a vitamin D test by going online to lifelinescreening.com, selecting the desired test, and bringing it to a local laboratory. The results should be in within 72 hours at most.

If you are not getting enough sunlight because either (a) you spend too much time indoors year-round, or (b) it’s winter, where the sun is at a lower angle and you are spending more time indoors because it is freezing outside…

Then you should supplement vitamin D. In fact, I believe everyone should supplement both vitamin D (unless you get adequate sun year-round) and omega 3. Multivitamins, on the other hand, are a waste of money (in my opinion) and are not necessary. If you are deficient in a particular vitamin or mineral, then, you should just supplement said vitamin/mineral.

The information on this website has not been evaluated by the FDA and is not intended to diagnose, treat, prevent, or cure any disease.

By accessing or using this website, you agree to abide by the Terms of Service, Full Disclaimer, Privacy Policy, and Affiliate Disclosure. Content may not be reproduced in any form.