Why Vitamin D3 Supplements are Better Than Vitamin D2

Sunshine Jiaren Lau

Benefits of Vitamin D

Vitamin D is produced under the skin when it is exposed to sunlight. It provides many benefits for the body. It promotes calcium absorption from the gut and helps maintain proper levels of calcium in the blood stream for bone formation and cellular activity. Low vitamin D levels can trigger the body to breakdown bone in order to provide calcium that is needed elsewhere. This could result in weak bones and osteoporosis.

Vitamin D3 has been clinically shown to help prevent broken bones.1 Vitamin D also plays a role in cell growth, it strengthens the immune system, reduces inflammation, and is needed for prostate health.

Why Vitamin D3 Is Better Than Vitamin D2

Vitamin D supplements come in two different forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). They were considered equal for years, because they both provide all the same benefits as has been discussed for vitamin D. However, cholecalciferol (D3) just does it better.2 They both absorb from the GI tract equally well, but D3 is more effective.3

In fact, one study has demonstrated that vitamin D2 is less than one-third as potent as vitamin D3, and has a much shorter duration of action.4×

In spite of these facts, vitamin D2 continues to be more prevalent than vitamin D3 in North America. This is due to a lack of awareness. When buying a vitamin D supplement, check the label and make sure it says either D3 or cholecalciferol.

Vitamin D2 supplements should be avoided because it would take a lot more to get the same benefit as from a cholecalciferol supplement. A Vitamin D3 review is not needed because all you have to look for is cholecalciferol from a reputable company at a decent price.

Vitamin D and Heart Disease

Vitamin D deficiency can lead to other problems and diseases, and is often misdiagnosed as fibromyalgia.5 Low vitamin D levels can increase the risk for common types of cancers, type-1 diabetes, and cardiovascular disease.

In fact, an association between vitamin D deficiency and cardiovascular disease is well documented.6 This may be due to the fact that blood vessels and heart muscles have vitamin D receptors.

Dietary Sources

Vitamin D is naturally present in only a handful of foods, and since adequate sunlight is required to make vitamin D, residents in Northern climates or those who consistently wear sunscreen, may need a supplement during the winter months. Food sources of vitamin D are mostly limited to fish and egg yolks. Small amounts are also added to milk, yogurt, orange juice, and cereal in the U.S.

Dosage or Dietary Reference Intake (DRI)

The old RDA of vitamin D was 400 IU a day. The latest guidelines recommend 600 IU a day for people between the ages of 1 and 70. For those over 70, the recommended amount is 800 IU each day.

To determine a general guideline of how much sun exposure is needed to make an adequate amount of vitamin D is extremely difficult. Time of day, season, cloud cover, pollution, and skin pigment all affect exposure and vitamin D synthesis. Clouds and pollution can block up to 60% of the ultraviolet energy from the sun, and a sunscreen with a SPF of just 8 can completely block all vitamin D producing rays. Sunlight that comes through windows does not promote vitamin D synthesis because UVB rays cannot penetrate glass.
In spite of these limitations many researches have suggested that 5 to 30 minutes of sun exposure to adequate areas of the body twice a week can provide most people with enough UVB to make the necessary amount of vitamin D.

Also, keep in mind that since vitamin D is fat-soluble, your body can store it up during the sunny months and access it later in the Winter.

Side Effects

It is not possible to get too much vitamin D from sunlight, and it would be extremely difficult to get too much from food. It is possible, however, to get too much from supplements. The recommended upper limit that has been established is 2,000 IU a day. Exceeding that could result in weight loss, bone pain, muscle problems, tiredness, excessive thirst, and a metallic taste in the mouth.

Drug Interactions

Weight loss drugs that prevent some dietary fat from absorbing (Xenical, Alli) can also reduce the absorption of vitamin D because it is fat-soluable as well. By the same token, drugs that lower cholesterol by binding to it and preventing its absorption (cholestyramine, Questran) can have the same effect on vitamin D.

References

  1. Trivedi D, Doll R, and Khaw KT. (2003). “Effect of four monthly oral vitamin D3 (cholecalciferol) supplementation on fractures and mortality in men and women living in the community: randomised double blind controlled trial”. BMJ 326(7387): 469.
  2. Khazai N, Judd S, Jen L, et al. (2009). “Treatment and Prevention of Vitamin D Insufficiency in Cystic Fibrosis Patients: Comparative Efficacy of Ergocalciferol, Cholecalciferol, and UV Light”. The Journal of Clinical Endocrinology & Metabolism 94 (6): 2037-43.
  3. Houghton L, Vieth R. (2006). “The case against ergocalciferol (vitamin D2) as a vitamin supplement”. American Journal of Clinical Nutrition 84(4): 694-697.
  4. Armas L, Hollis B, Heaney R. (2004). “Vitamin D2 Is Much Less Effective than Vitamin D3 in Humans”. The Journal of Clinical Endocrinology & Metabolism 89 (11): 5387-91.
  5. Holick M. (2004). “Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis”. Am J Clin Nutr (79)3: 362-71.
  6. Wang T, Pencina M, Booth S, et al. (2008). “Vitamin D Deficiency and Risk of Cardiovascular Disease”. Circulation. 117: 503-11.

 

photo credit of sun/beach: Jiaren Lau

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