How much vitamin D do you need daily to prevent fractures?

A vitamin capsule. (iStockphoto/Thinkstock)
A vitamin capsule. (iStockphoto/Thinkstock)

Basking in the sun is one way to obtain vitamin D

Basking in the sun is one way to obtain vitamin D although the risk of skin cancer increases. Other sources of vitamin D are fortified dairy products, fatty fish and egg yolks.

Answer to this question appears in an article in the New England Journal of Medicine (NEJM) published in July, 2012. The authors examined the relationship between vitamin D supplementation and fracture reduction.

They looked at 11 double-blind, randomized, controlled trials of oral vitamin D supplementation (daily, weekly, or every 4 months), with or without calcium, in persons 65 years of age or older. The goal was to look for the incidence of hip and any nonspinal fractures.

The study included 31,022 persons (mean age, 76 years; 91 per cent women) with 1111 incident hip fractures and 3770 nonspinal fractures.

When they looked at a subgroup of participants by actual intake of vitamin D, they found reduction in the risk of fracture was shown only at the highest intake level (median, 800 IU daily; range, 792 to 2000), with a 30 per cent reduction in the risk of hip fracture and a 14 per cent reduction in the risk of any nonspinal fracture.

“Benefits at the highest level of vitamin D intake were fairly consistent across subgroups defined by age group, type of dwelling, baseline 25-hydroxyvitamin D level, and additional calcium intake,” says the NEJM paper.

The conclusion of the study was that high-dose vitamin D supplementation (≥800 IU daily) was somewhat favorable in the prevention of hip fracture and any nonspinal fracture in persons 65 years of age or older.

As we know, vitamin D is a nutrient that helps the body use calcium and phosphorous to build and maintain strong bones and teeth. Vitamin D is unique in that it can be synthesized by the body after exposure to ultraviolet rays from sunlight.

Too much vitamin D can cause too much calcium to be deposited in the body, which can lead to calcification of the kidney and other soft tissues including the heart, lungs and blood vessels. But it is hard to define what is too much. Some expert recommend daily intake of 1000 to 2000 IU of vitamin D to prevent certain types of cancers.

Health Canada’s recommendation for daily dietary intake of vitamin D in adults age 70 and over is 800 IU (20 mcg). This is based on the assumption that there is minimum of exposure to sunlight. The major sources of vitamin D are fortified foods. In Canada, cow’s milk and margarine must be fortified with vitamin D. The only natural sources of vitamin D in the Canadian food supply are fatty fish and egg yolks.

Many people meet at least some of their vitamin D needs through exposure to sunlight. Although there is some risk of skin cancer. But you never know how much vitamin D you are getting through sun exposure. It all depends on the season, time of day, cloud cover, smog, skin pigmentation, and sunscreen use.

Daily intake of vitamin D recommendation depends on a person’s age. Talk to your doctor or see Health Canada website for more details. But do not forget to drink your milk everyday.

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