Evidence-Based Nutrient Recommendations

Vitamin D: Basics


by Jack Norris, RD


Healthy Vitamin D Levels

Vitamin D is important for bones because it can increase calcium absorption when the body signals that it needs calcium. Research has shown that in populations whose calcium intakes are similar to omnivores in the United States, vitamin D is more important than calcium for preventing osteoporosis.

In recent years, vitamin D levels have been associated with many other diseases and some researchers have suggested that the recommended vitamin D levels are too low and many laboratories adjusted their recommended levels upward. The Institute of Medicine has reviewed the research and concluded that the recommended levels shouldn’t be adjusted upward. The controversy has resulted in many people thinking they are deficient in vitamin D when they are not.

Make sure that you’re not trying to raise your levels beyond what the Institute of Medicine says is adequate (50 nmol/l or 20 ng/ml) as there’s no sense in worrying if you cannot seem to get your vitamin D levels twice as high as necessary!

Sources of Vitamin D

Most people get a significant amount of their vitamin D from the action of UV rays on their skin. While the body can store vitamin D made in the sunnier months for use during less sunny months, this does not work for everyone. In fact, some people, even those living in sunny climates, develop extremely low levels of vitamin D. This can manifest itself through fatigue and bone pain.

The only significant, natural, dietary sources of vitamin D are fatty fish, eggs (if chickens have been fed vitamin D), and mushrooms (if treated with UV rays). Most Americans get their dietary vitamin D through fortified milk and fortified margarine.

The vegan diet contains little, if any, vitamin D without fortified foods or supplements. On average, vegans’ vitamin D levels are adequate, but somewhat lower than non-vegans.

There are two forms of supplemental vitamin D: ergocalciferol (D2) and cholecalciferol (D3). Vitamin D2 is always vegan, made from exposing fungi to UV rays. Vitamin D3 normally comes from fish oil or sheep’s wool, but there is a vegan version made by Vitashine.

A great deal of research has compared vitamin D2 to D3. Vitamin D2 is effective at increasing bone mineral density (when given to people who are deficient). Vitamin D2 can also increase vitamin D levels temporarily but is not as effective as vitamin D3 at keeping vitamin D levels raised when taken only weekly.

Thus, if you take vitamin D on a daily basis, D2 should be fine, whereas if you’re only going to take it sporadically, without getting sun in the interim, or find that your vitamin D levels will not increase on D2, then you should opt for D3.


Please see our list of Daily Needs for how to obtain adequate vitamin D.

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  • If you have a question about whether it's okay to cut supplements in half or combine supplements to achieve the dose we recommend, the answer is “Yes.” Be aware that nutrient recommendations are only estimates—it's not necessary to consume the exact amount we recommend every single day.
  • We aren't able to respond to questions about which brands of supplements to take.
  • We cannot provide personal nutrition advice for specific health conditions. If you need private counseling, here's a list of plant-based dietitians and we especially recommend VeganHealth contributor Taylor Wolfram, MS, RDN, LDN.
  • We urge you to consult with a qualified health professional for answers to your personal questions.

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