The Sunny Side of Health: Why Vitamin D Matters

What we know:

Vitamin D, nicknamed “The Sun Vitamin”, aids in the absorption and maintenance of calcium and phosphorous and is thereby essential for bone health. A lack of Vitamin D can lead to rickets in children and osteomalacia in adults.

Vitamin D comes in two different forms: Vitamin D2 and Vitamin D3. We know that Vitamin D3 is the form that we make naturally, so if you are taking a Vitamin D supplement, try to find one in the D3 form (also called cholecalciferol). Because Vitamin D3 comes mainly from animal sources, people following a strict vegetarian or vegan lifestyle are at a higher risk for deficiency.

From age 1 to 70, the Recommended Dietary Allowance for Vitamin D is 600 IU. If you are over the age of 70, your kidneys begin to lose their ability to convert Vitamin D to its active form and you are at a higher risk for Vitamin D deficiency. For individuals 70+, your RDA is 800 IU (supplementation may be wise). BEWARE, it is possible to have too much Vitamin D, the most you should consume through supplements is 4,000 IU/day.

There are very few food sources of Vitamin D, but it can be found in some fatty fish (salmon, tuna, and mackerel), fish liver, egg yolks, cheese, and fortified dairy products. For most people, the main source of Vitamin D is made in the skin when it is exposed to the sun (crazy right?).

What we are unsure of:

We are unsure if Vitamin D plays a role in the prevention of other health conditions. In some studies, Vitamin D deficiency has been associated with cardiovascular disease, some cancers, asthma in children, and cognitive decline. The fun thing about research, though, is that it is very difficult to establish causation (i.e. the lack of Vitamin D caused this person to have heart disease). While these studies have not established causation, they have raised enough concern to dramatically increase the number of Vitamin D lab tests ordered by physicians.

My advice to you:

For everyone with medium to dark skin complexion (think Halle Berry to Lupita Nyong’o), you are at risk for Vitamin D deficiency. While melanin protects the skin from sun damage #melaninrocks, it also blocks the UV rays from allowing the skin to make Vitamin D #melaninblocks. Consider a Vitamin D supplement for individuals with the darkest skin if you do not eat a lot of fish or fortified dairy (people from South Sudan and Senegal are the two that come to mind). For all others in this category, you may need close to 30 minutes in the sun twice a week without sunscreen, according to the National Institutes of Health. While I am not encouraging indecent exposure, the more skin you expose to the sun, the more Vitamin D you will make. Just saying…

For everyone with fair to medium skin (think Nicole Kidman to Eva Mendez), while you may not have a lot of melanin that blocks Vitamin D production, you are artificially blocking Vitamin D production with sunblock. Now, hear me out, I do NOT think that you stop wearing sunscreen. Some research suggests spending 10-15 minutes in the sun without it, twice a week (if you can without burning), and then applying as normal. Be advised, though, that there are no established requirements for sun exposure due to the public health concerns about skin cancer.

Last, but not least, not all sun exposure is equal. Exposure to the sun from November to February produces a very small amount of Vitamin D. For all other months, the general rule is if your shadow is smaller than you, you have enough sunlight and UV rays to produce Vitamin D.

That’s all for now! Feel free to add any discussion in the comments :-)

References:

Holick, MF. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. Am J Clin Nutr. 2004 Dec;80(6 Suppl):1678S-88S. Retrieved from http://ajcn.nutrition.org/content/80/6/1678S.long.

Vitamin D. National Institutes of Health. Retrieved from https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#en20.