Is it true everyone living in the north should take vitamin supplements? What if I am very healthy, very active, and participate in outdoor sports activities like golf, tennis, and hiking? How do I know what I really need?

Current studies have provided convincing evidence that most people (children and adults) in the United States are Vitamin D deficient. You wouldn’t think athletes with their strong bones and muscles would need any Vitamin D supplementation. But they do.

According to a group of researchers from Marshall University School of Medicine in West Virginia, there are sports health benefits to taking Vitamin D supplements. Some of those benefits actually come in the form of prevention. That is — preventing the musculoskeletal events that can occur when someone is Vitamin D deficient (e.g., bone fractures, musculoskeletal pain, frequent illness).

People living in certain (Northern) regions of the globe don’t receive enough of the essential sun rays. This is especially true if they compound the problem by using sunscreen. And obesity has also reduced the amount of Vitamin D available in the body because it is a fat-soluble vitamin. This means fat cells store the vitamin rather than allowing the body to use those essential substances.

Because very little Vitamin D comes from natural food sources, some products like cereals and milk are Vitamin D fortified. But even with these dietary sources, most everyone is still Vitamin D deficient and in need of supplementation. Athletes and sports participants (indoor and outdoor athletes) are no exception.

To clarify a bit more, indoor athletes do need more Vitamin D supplementation than outdoor sports participants. But outdoor athletes must be aware of seasonal differences in sun exposure and supplement accordingly. Outdoor athletes should have their blood tested in early autumn to adjust for seasonal differences in sun exposure.

There is no extra advantage of having a blood value of more than 50 ng/mL of vitamin stores in the body. Differences in skin pigmentation must be taken into consideration. African Americans (and other dark-skinned individuals) need up to ten times more sun exposure to reach the same levels of Vitamin D in the body compared with Caucasian or light-skinned athletes.

If your blood test shows you are Vitamin D deficient (less than 30 ng/mL of 25(OH)D — the measure used to assess blood levels), then you may be advised to take 50,000 IU of Vitamin D3 each week for eight weeks or until blood tests show a steady level of at least 25(OH)D.

It is clear that the effects of too-low levels of Vitamin D include severe muscle weakness, loss of muscle tone, generalized body pain, increased falls, and bone deformities. Athletes who have enough Vitamin D have fewer colds and flus. And they may have the added benefit of faster recovery from inflammation after bouts of overtraining.

Sunshine is still nature’s perfect solution to strong muscles, teeth, and bones. Adequate exposure to ultraviolet rays that stimulate production of Vitamin D in the body avoid any excess accumulation or toxicity in the body. That’s because the body has special feedback loop to prevent this negative effect. Although these are published guidelines for athletes and sports participants, it is still best to ask your primary care physician to guide you through this process.