This question is about Nutrition
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 [1]
Vitamin D 2 3 4 5 6 [7]
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.
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.
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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. https://doi.org/10.1002/jmv.26832
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Examine.com. (2019, April). A D-fence against cancer? https://examine.com/members/deep-dives/article/a-d-fence-against-cancer/
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Bikle D. D. (2016). Extraskeletal actions of vitamin D. Annals of the New York Academy of Sciences, 1376(1), 29–52. https://doi.org/10.1111/nyas.13219
National Institutes of Health. (2021, March 26). Office of Dietary Supplements - Vitamin D. National Institutes of Health – Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/