vitamins

Vitamin D, sometimes referred to as the “sunshine vitamin”, is produced by the body when exposed to sunlight. Vitamin D is also available as an oral supplement. In certain places of the world where adequate sunlight exposure may not be feasible, such as those cold Canadian winters, taking a supplement may be beneficial – but what is the difference between vitamin D and vitamin D3?

The amount of Vitamin D in the body is often measured using an indicator molecule called 25 hydroxyvitamin D. The more vitamin D consumed, the higher the levels of 25 hydroxyvitamin D in the blood. Vitamin D is converted into 25 hydroxyvitamin D in the liver; it must pass through this step to be used by the body.1

Vitamin D exists as either vitamin D2 or vitamin D3. Vitamin D2 is the vitamin D obtained from plants. Vitamin D3 is produced from sunlight or obtained from an animal source. Foods that are high in vitamin D3 include fatty fish and liver. 

Both vitamin D2 and D3 are converted to 25 hydroxyvitamin D, so both contribute to the overall vitamin D level in the body. 

Why is it important?

Vitamin D plays a key role in maintaining bone strength and absorbing calcium.1 Consuming enough vitamin D is crucial to help prevent excessive bone fractures and osteoporosis. Vitamin D can also help support the immune system and reduce inflammation. 

According to the United States National Institutes of Health, adults aged 19-70 are recommended to consume 20mcg (800IU) per day.2 Seniors aged 70+ and children aged 1-18 should consume 15mcg (600IU) per day. 2 

Vitamin D vs. D3: which is more effective?

Studies have suggested that vitamin D3 is more effective than D2 at increasing 25 hydroxyvitamin D levels in the body. 

One study administered either vitamin D2 or D3 to females aged 66-97 who had a deficiency. Results showed that vitamin D3 increased 25 hydroxyvitamin D levels almost twice as efficiently compared to vitamin D2.3 A review study that analyzed 10 studies comparing 25 hydroxyvitamin D levels after vitamin D3 or D2 consumption found similar results.1

A 2015 study measured the sustainability of 25 hydroxyvitamin D levels after vitamin D3 or D2 was administered. Vitamin D3 was shown to sustain 25 hydroxyvitamin D levels for a longer duration than vitamin D2.4

Thus, taking vitamin D3 may be more beneficial than a D2 supplement. However, more studies need to be completed comparing the effectiveness of vitamin D2 versus D3 based on sex and age.1

Both vitamin D and D3 supplements can be purchased. If the supplement is called a “Vitamin D” supplement, it may contain both forms. “Vitamin D3” supplements contain only the D3 form. 

Consult your healthcare provider to determine which supplement is best for you.

References

  1. Tripkovic, L. et al. (2012). The American Journal of Clinical Nutrition; 95(6): 1357-1364. Doi:  10.3945/ajcn.111.031070
  2. Vitamin D. (n.d.). National Institutes of Health. Accessed on Feb. 3 2022. Retrieved from https://ods.od.nih.gov/factsheets/VitaminD-Consumer/. 
  3. Romagnoli, E. et al. (2008). Short and long-term variations in serum calciotropic hormones after a single very large dose of ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) in the elderly. The Journal of Clinical Endocrinology and Metabolism; 93(8): 3015-3020. Doi: 10.1210/jc.2008-0350.
  4. Oliveri, B. et al. (2015). Vitamin D3 seems more appropriate than D2 to sustain adequate levels of 25OHD: aa pharmacokinetic approach. European Journal of Clinical Nutrition; 69: 697-702. Doi: 10.1038/ejcn.2015.16.

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