Many clinicians are unaware that ethnic populations in North America do not achieve optimal serum 25-hydroxyvitamin D (abbreviated 25[OH]D) because of the increased pigmentation in their skin, which reduces vitamin D production. Vitamin D insufficiency is more prevalent among individuals with darker skin, compared with those with lighter skin at any time of year, even during the winter months. Contributing to the deficiency, the dietary intake of vitamin D intake among African Americans in particular is often below the recommended intakes in every age group after puberty. However, data have shown vitamin D protects against Sjögren’s syndrome, psoriasis, type 1 and type 2 diabetes, multiple sclerosis, and rheumatoid arthritis.
Vitamin D also may protect against cardiovascular disease through its anti-inflammatory effects and may reduce the risk for colorectal cancer, breast cancer, and prostate cancer by promoting cell differentiation and down-regulating hyperproliferative cell growth. Most of these conditions have been shown to be as prevalent, if not more prevalent, among blacks than whites.
While vitamin D can be obtained from sun exposure, this is not always a viable option. UV exposure is linked to skin cancer, which leads clinicians to encourage sun avoidance, but they may disregard the need for vitamin D. In addition, darker pigmentation of the skin reduces vitamin D synthesis in the skin.
How can you help your skin of color patients get enough vitamin D, especially in the winter? Nutritional sources of vitamin D include salmon, sardines, and cows’ milk; however, many individuals do not achieve optimal vitamin D status from food intake alone.
Since UV exposure and diet are not sufficient sources of vitamin D, supplementation has become crucial to our patients, particularly those with darker skin. Dietary reference intakes for vitamin D have been under considerable scrutiny, and many experts now believe that intakes of 25 mcg/d (1,000 IU) or more may be needed for most people to achieve optimal blood levels of 25(OH)D. The two forms of vitamin D used in dietary supplements are ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Cholecalciferol, the D3 form of the vitamin, is the form of choice when supplementing with vitamin D. Types of D3supplements include gel caps, liquid, powders, and tablets. Vitamin D is often measured in International Units (IU) or mcg. One mcg of cholecalciferol is equal to 40 IU of vitamin D.
The debate continues over the most effective forms of vitamin D acquisition; however, many health professionals agree that vitamin D supplementation, particularly in winter months, should be an integral part of our armamentarium of therapeutics for ethnic patients, and especially those who suffer from psoriasis and other autoimmune and inflammatory skin conditions.