Vitamin D Deficiency
This was my very first experience with Vitamin D deficiency and I have since learned that Vitamin D deficiency is becoming an epidemic worldwide, not only in geographic regions where sun exposure is limited. And my discussions with fellow dietitians working with college runners and professional athletes in generally sunny states (Texas and Florida) confirmed the alarming prevalence of Vitamin D deficiency across ethnicity and gender.
Athletes who live in northern latitudes (north of 35 degrees), or use sunscreen consistently, perform their sport indoors, or keep their skin covered are at the greatest risk. Melanin affects the production of Vitamin D. So those with more melanin, or darker skin, produce less Vitamin D.
Since Vitamin D is a fat-soluble vitamin, athletes with fat malabsorption problems such as cystic fibrosis, Crohn’s disease, and celiac disease are at risk for deficiency. Those who have normal levels typically (around 50 ng/ml) live in sub-equatorial Africa and work outdoors for most of the summer.
Once thought of as being primarily involved in bone development, activated Vitamin D (calcitriol), a steroid hormone, is responsible for regulating more than 1,000 human genes. Almost every cell in the human body has receptors for Vitamin D. Recent research shows that Vitamin D deficiency increases the risk of different types of cancer (such as breast cancer and prostate cancer), as well as heart disease, diabetes, depression, autoimmune diseases, hypertension, obesity, gum disease, chronic pain, muscle wasting, inflammation, birth defects, osteoporosis, influenza, colds, etc.