Vitamin D
Believe it or not, 75% of Americans are deficient in vitamin D despite it being the only free vitamin that we can absorb by simply stepping into the sun! Although animal and plant sources can provide us with this vitamin, it is nearly impossible to get enough just from these sources. Thankfully, we have the ultraviolet rays from the sun to promote vitamin D synthesis in our skin. Of course, we still want to be cautious of sun overexposure, so sun exposure limited to 10-15 minutes at least 3 times per week without sunscreen may just do the trick. The vitamin D absorbed in our skin is first converted into a hormonally-active form known as 1,25 dihydroxycholecalciferol by the liver and kidney. While supplementation is often necessary to meet required amounts, vitamin D produced in the skin can last 2-3 times longer in our circulation when compared with ingesting it orally.
Vitamin D is most recognized for its involvement in mineral metabolism (especially calcium, phosphate, magnesium) and bone growth; however, vitamin D receptors are actually present in most of our cells, indicating that it plays a role in other areas outside of mineral homeostasis and bone function. For instance, studies have found vitamin D to fight against infection as it increases the expression of defense proteins to fight against the infectious agents!
Additional vitamin D Benefits
Aids in prevention of insulin resistance
Helps pancreas release insulin
Important for thyroid function
Anti-inflammatory function
Necessary for blood clotting
Support mental health
Food sources with Vitamin D
Canned sardines
Salmon
Tuna
Shrimp
Butter
Sunflower seeds
Liver
Eggs
Fortified milk
Mushrooms
Natural cheese
In addition to food sources and the sun, vitamin D supplements (preferred form is vitamin D3) can aid you to meet the necessary requirements. However, I recommend ordering a blood test (recommended values 55-80ng/mL) and consulting with your healthcare provider to determine your needed dosage of vitamin D. High doses of the vitamin can result in toxicity, especially given the some conditions (Crohn’s disease, cancer, hyperparathyroidism) can cause a person to be hypersensitive to this vitamin.
Now, go enjoy some sunshine!
References:
Aranow C. Vitamin D and the immune system. J Investig Med. 2011; 59:881–886.
Seppa, N. (2011). the power of D: Sunshine vitamin’s potential health benefits stir up, split scientists. Science News, 180(2), 22–26. http://www.jstor.org/stable/41332571.
Smith, P. W. (2020). What You Must Know About Vitamins Mineral Herbs and So Much More (2nd ed.). Square One Publishers.
