December 10, 2009 in Features

Woman ponders vitamin D dosage

Peter H. Gott, M.D., United Media
 

DEAR DR. GOTT: I am confused about vitamin D and how much I need. I’m an 83-year-old female and take a daily women’s vitamin, which has 800 IU of D, 450 mg of calcium and many more important vitamins. I also take an additional calcium tablet with 600 mg and a 1,000-mg fish-oil tablet. I eat fortified cereal and when the sun is shining, I spend one to two hours working out in it.

My doctor thinks I should take more vitamin D. I feel I am getting enough and have read articles that a person can get too much. Now I need to have my mind put at ease about the proper amount of D for a person my age to take.

DEAR READER: Unless you are deficient, I must agree with you and not your doctor. Vitamin D is required for the development of teeth and bones, as well as the absorption of calcium and phosphorous from the intestines. It is a fat-soluble vitamin that requires bile acids for absorption. Once absorbed, fat-soluble vitamins remain in storage until needed.

There is variation in recommended doses depending on age. Healthy people between the ages of 19 and 50 require 200 IU daily; those between 51 and 70 require 400 IU daily; those 71 years of age and older should consume 600 IU daily.

Let’s consider some additional food sources for dietary consumption of vitamin D. One tablespoon of cod-liver oil contains 1,360 IU, and 3-1/2 ounces of salmon contain 90 IU. Milk, including the nonfat variety, contains 98 IU per cup. Beyond foods, most people meet their needs through exposure to sunlight.

As people age, their skin cannot synthesize vitamin D as efficiently as it could in their younger years. Furthermore, the risk of osteoporosis is greater. Nonetheless, your supplement plus your sunlight exposure is adequate. You are on top of things and should continue on course.

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