Vitamin D - More Better than Less

Until the past several years, doctors and dietitians were usually scared off by the thought of vitamin D supplementation. Evidence that’s now recognized as terribly archaic suggested that supplemental vitamin D could be toxic in amounts modestly above official “recommended” levels.

What has changed? Vitamin D is needed for both strong bones and strong skeletal muscles, which hold up those bones. A huge body of research has found that a minimum of 800 IU of vitamin D daily is required to reduce the risk of falls and fractures among the elderly. The latest research indicates that adequate vitamin D levels can reduce the risk of cancer, heart disease, diabetes, and many other diseases.

Some dosage recommendations go far higher, and even the ever-cautious researchers at Harvard University are now suggesting higher dosages. In a interview, Harvard‘s Walter C. Willett, MD, DrPH, told me that many people could benefit from supplements containing 2,000 to 5,000 IU of vitamin D daily.

Still other researchers, such as Reinhold Vieth, PhD, of the University of Toronto, recommend upwards of 10,000 IU daily. Simply spending 15 minutes in the summer sun, in walking shorts and a tee shirt, enables your body to make 10,000 IU. Contrast these numbers with the meager Reference Daily Intake (RDI) of 200 to 500 IU. Food sources of vitamin D are limited, and it‘s common for people to develop marginal vitamin D levels or outright deficiencies during the winter months when they are exposed to little sunlight.

Get out a map, and if you live north of Phoenix, Arizona – 35° north – you probably don't get enough winter sun exposure even if you spend lots of time outdoors. That means you should most likely supplement with vitamin D. If you spend most of the year indoors, regardless of your latitude, you may never adequately build up your vitamin D levels, meaning that you will probably benefit from year-round supplementation.