Vitamin D

Today is the start of winter, the day with the fewest hours of daylight. It’s also the coldest time of year with the least amount of skin exposed. Consequently, skin production of vitamin D ceases in in cold climates. Many adults require vitamin D supplements, especially in the winter when stores can go to zero by spring. Vitamin D deficiency is associated with osteoporosis as well as the health of the immune and cardiovascular systems.

The prevalence of low vitamin D is increasing globally and is more common in South Asia and the Middle East. Black Americans have lower measured vitamin D levels, but have better bone density and fewer fractures. Ironically, almost all research on vitamin D supplements have been done on white patients but black women will increase levels after supplements at the same rate as white women.

Vitamin D supplements are inexpensive and widely available. For patients with normal vitamin D levels, as daily supplement of at least 800 IU is adequate. Higher doses are needed to treat deficiency. For high risk patients, prescription strength dosing of 50,000 IU once weekly may be needed followed by daily supplements.

All patients should maintain a daily total calcium intake (diet plus supplement) of 1000 mg (for ages 19 to 70 years) to 1200 mg (for women ages 51 through 70 years and all adults 71 years and older).