Approximately 50% of . citizens are Vitamin D deficient. The numbers are higher among hispanic and black populations. The melanin in darker-skinned people interferes with the synthesis of the vitamin D that starts at the level of the skin when the sun comes into contact with it. Therefore, darker-skinned people tend to be more deficient. Vitamin D is crucial for good health , and may be one of the simplest solutions to a wide range of health problems, from diseases of the eyes to the bowels, and conditions rooted in chronic inflammation and immune dysfunction in particular. It is a common deficiency worldwide, even in sundrenched areas, yet many people, including physicians, are unaware they may be lacking this important nutrient.