Lack of Vitamin D Could Have You Feeling Down
By Tope Pedro
What is Vitamin D and why is deficiency common?
Vitamin D is a fat-soluble vitamin naturally present in a few foods, fortified in others, and available as a dietary supplement. However, the most significant source of vitamin D for most people is sun exposure because it’s produced in our bodies when sunlight strikes our skin. Since few of us live in places where there is adequate sunlight year round, vitamin D deficiency can be quite common. Other risk factors also include darker skin tone, use of large amounts sunscreens or make up, older age, medications that alter vitamin D metabolism, and diseases of fat malabsorption (vitamin D requires fat for absorption).
Why is deficiency a big deal?
Vitamin D has many important functions in our bodies as well as many benefits. It aids in the absorption of calcium and phosphorus, which is needed for strong bones and teeth. It also helps with muscle, nerve, and immune function. Furthermore, it’s been shown to have a role in chronic disease prevention including cancer, diabetes, cardiovascular disease, and neurodegenerative diseases by regulating factors in the body that have an impact on those conditions. One of vitamin D’s biggest claims to fame is the positive effect it has on improving mood and helping with seasonal depressive disorder.
How much should we be getting?
The recommended dietary allowance (RDA) for vitamin D is 600 IU (15 mcg) per day. As with all macro- and micronutrients, natural sources, in this case food and sunlight, should be our primary source of Vitamin D. Supplements should only be taken if necessary and advised by a physician.
When UVB rays hit the skin conversions happen in the skin, liver, and kidneys leading to the synthesis of the active form of vitamin D in the body, calcitriol or 1-25 dihydroxyvitamin D3. Anything covering the body including clothes, makeup, and sunscreen (though important and necessary to minimize skin cancer risk) significantly reduces the body’s ability to synthesize the vitamin. Regardless of those factors, sunlight is still the most common and efficient source of vitamin D, and just 20 minutes of direct sun exposure per day can be sufficient to meet daily needs.
Unlike other vitamins and minerals, vitamin D is not abundant in foods, but there are some good sources including cod liver oil, shiitake mushrooms, egg yolks, and fatty fish like mackerel, salmon and tuna. Certain foods are also typically fortified with vitamin D like milk, cereals and orange juice.
Vitamin D comes in two major forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Commercially manufactured supplements contain either form and the term “Vitamin D” refers to both. If you get a blood test and your vitamin D is low, your physician may recommend a supplement that will likely contain more than the 600 IU RDA to correct the deficiency. Similarly to almost every other nutrient, moderation and correct dosage is key. Vitamin D is potentially the most toxic vitamin when too much is consumed. One of its properties is helping the body fully utilize calcium, and in excess quantities it can cause calcification of the soft tissues that make up our organs. It is nearly impossible to get a toxic amount of vitamin D through sunlight or food so this is only a precaution for the supplemental form.
Tope Pedro is a future dietitian currently completing her dietetic internship through San Francisco State University. She has bachelors degrees in both Biochemistry and Dietetics and a Master’s of Public Health. She is passionate about sports nutrition, which stems from her life-long experiences as an athlete, currently as a professional boxer. She also teaches cardio boxing class and enjoys working with clients to help them reach their health goals. As a registered dietitian, Tope hopes to work in the sports nutrition and fitness sectors, specifically with combat sport athletes and fitness enthusiasts.