What is the most important vitamin for your body?

This question is about Nutrition

Elle Penner, MPH, RD

Although all vitamins are essential and serve unique and important functions in the body, many health experts agree that vitamin D is the most important vitamin because it plays a profound role in our overall health and vitamin D deficiency is very prevalent. It has been estimated that vitamin D insufficiency affects roughly 50 percent of the population worldwide


. At Elo approximately 90 percent of our members have low vitamin D upon joining.

What is vitamin D and what does it do? 

Vitamin D

is a fat-soluble vitamin that is obtained through diet and sun exposure. Vitamin D plays an important role in bone health, calcium absorption, blood sugar regulation, cell proliferation and turnover, and immune function. Optimizing vitamin D levels may even help protect against severe COVID-19, type 2 diabetes, depression, as well as some autoimmune diseases, neurodegenerative diseases, and cancers [










]. Vitamin D is so important that its receptor is found in nearly all (if not all) cells in the body



Several factors contribute to low vitamin D levels: 

  • Limited sun exposure: Sun exposure is the best way to get vitamin D but today people are spending more time indoors and avoiding the sun to minimize sun damage and skin cancer risk. 

  • It’s difficult to obtain through food: Few foods contain vitamin D, which makes it difficult to consume enough from food alone. It’s found mostly in fatty fish and fortified dairy products.

  • Older age: Vitamin D synthesis in skin declines gradually with older age.

  • Dark complexion: Melanin in dark skin reduces the skin’s ability to absorb UV radiation needed to synthesize vitamin D.

  • Living in cold or northern climates: People who live above 37°N latitude typically don’t get enough sun to synthesize vitamin D year-round.

  • Pregnancy and breastfeeding: Pregnant or breastfeeding women have increased vitamin D needs.

  • Obesity: Subcutaneous fat appears to sequester more of the vitamin, often resulting in low vitamin D levels.

  • Certain health conditions: Some conditions including cystic fibrosis, Crohn's disease, celiac disease, kidney or liver diseases, can interfere with vitamin D absorption and/or synthesis. People who have had gastric bypass surgery are also at greater risk for deficiency due to decreased absorption. 

How to get enough vitamin D

  • Increase consumption of vitamin D-rich foods like salmon, herring, canned tuna, eggs (with the yolk), and fortified foods like milk, yogurt, and breakfast cereals.

  • Get 10–30 minutes of unprotected midday sunlight most days.

  • Take a vitamin D supplement. Dosage will depend on your vitamin D level. For very low levels (<20 ng/mL) you may need to take 5,000 IU daily for several months to significantly improve your vitamin D status. For those in the 20-40 ng/mL range, a daily dose of around 2,0000 IU may be adequate, however it’s best to work with a health professional.

vitamin d capsules


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  2. Demir, M., Demir, F., & Aygun, H. (2021). Vitamin D deficiency is associated with COVID-19 positivity and severity of the disease. Journal of medical virology, 93(5), 2992–2999.


  3. Kayaniyil, S., Vieth, R., Retnakaran, R., Knight, J. A., Qi, Y., Gerstein, H. C., Perkins, B. A., Harris, S. B., Zinman, B., & Hanley, A. J. (2010). Association of vitamin D with insulin resistance and beta-cell dysfunction in subjects at risk for type 2 diabetes. Diabetes care, 33(6), 1379–1381.


  4. Examine.com. (2019, April). A D-fence against cancer?


  5. Yang, C. Y., Leung, P. S., Adamopoulos, I. E., & Gershwin, M. E. (2013). The implication of vitamin D and autoimmunity: a comprehensive review. Clinical reviews in allergy & immunology, 45(2), 217–226.


  6. Groves, N. J., McGrath, J. J., & Burne, T. H. (2014). Vitamin D as a neurosteroid affecting the developing and adult brain. Annual review of nutrition, 34, 117–141.


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  8. National Institutes of Health. (2021, March 26). Office of Dietary Supplements - Vitamin D. National Institutes of Health – Office of Dietary Supplements.