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By Megan Ng

Dietary supplement shelf

Image by Angel Sinigersky/Unsplash.

Even with longer days and more opportunities for sunshine, many of us still do not receive adequate amounts of the sunshine vitamin, Vitamin D. However sun exposure alone cannot support all of our Vitamin D needs, incorporating supplementation with a healthful and balanced diet can help. But, how do we navigate the overflowing and confusing supplement aisles?

Forms of Vitamin D

There are two forms of vitamin D: Vitamin D2 “ergocalciferol” and Vitamin D3 “cholecalciferol” (Harvard T.H. Chan School of Public Health, n.d.). Vitamin D2 is made from plants and found in fortified foods and some supplements. Vitamin D3 is naturally produced in the human body from sun exposure and is found in animal food sources. Both Vitamin D2 and D3 have been found to raise blood concentrations (Wilson et al., 2017). However, some research suggests that Vitamin D3 is preferable to D2. This is because D3 was found to raise blood concentrations of the vitamin more and sustained those levels longer than D2 (Tripkovic et al., 2012); (Wilson et al., 2017).

Additionally, Vitamin D supplements are available in a variety of forms. These supplements can be pills, liquids, and gummy chewables. Although all forms are effective, pills and liquids may be preferable since many gummy chewable vitamins contain an excess sugar coating (Wilson et al., 2017).

How Much Do I Need?

How much Vitamin D you need depends largely on your lifestyle, age, diet, skin color, and sun exposure. The National Institutes of Health (NIH) recommends at least 600 IU per day for adults up to 70 years of age and 800 IU for adults over 70 years of age (U.S. Department of Health and Human Services, n.d.). However, it is best to work with your healthcare provider to determine the correct dose for you.  Your provider may recommend a blood serum test to check your current Vitamin D status.

Supplement Search

After determining the type and dose of Vitamin D supplement that you need, there are some things to keep in mind as you shop for supplements. The supplement industry is loosely regulated by the U.S. Food and Drug Administration (FDA). Supplement companies are responsible for the safety and purity of supplements which can be difficult to judge.  Therefore, looking for third-party testing and certifications is important. These third-party organizations verify that the product quality meets the minimum standards and that the label accurately reflects what is in the bottle (Akabas et al., 2016).

These third parties include:

  • National Sanitation Foundation (NSF)
  • Informed Choice
  • United States Pharmacopeia (USP)


Vitamin D is crucial for many of the body’s functions and processes. Vitamin D needs to vary for each individual, and working with a health professional can inform you of your Vitamin D status. Sun exposure and dietary intake play a large role in Vitamin D levels, but supplements can help maximize Vitamin D absorption and status. Thus, being a savvy shopper when looking for supplements is key to reaching optimal health status.

  1. Akabas, S. R., Vannice, G., Atwater, J. B., Cooperman, T., Cotter, R., & Thomas, L. (2016). Quality certification programs for dietary supplements. Journal of the Academy of Nutrition and Dietetics, 116(9), 1370–1379.
  2. Harvard T.H. Chan School of Public Health. (n.d.). Vitamin D. The Nutrition Source. Retrieved March 29, 2023, from,is%20found%20in%20animal%20foods.
  3. Tripkovic, L., Lambert, H., Hart, K., Smith, C. P., Bucca, G., Penson, S., Chope, G., Hyppönen, E., Berry, J., Vieth, R., & Lanham-New, S. (2012). Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. The American journal of clinical nutrition, 95(6), 1357–1364.
  4. U.S. Department of Health and Human Services. (n.d.). Vitamin D. NIH Office of Dietary Supplements. Retrieved March 29, 2023, from
  5. Wilson, L. R., Tripkovic, L., Hart, K. H., & Lanham-New, S. A. (2017). Vitamin D deficiency as a public health issue: using vitamin D2 or vitamin D3 in future fortification strategies. The Proceedings of the Nutrition Society, 76(3), 392–399.

Megan Ng is a Graduate Student in Food Science and Human Nutrition at the University of Illinois at Urbana Champaign.