Too much vitamin A can lead to fractures: study
Last Updated Thu, 23 Jan 2003 10:54:24
STOCKHOLM - Taking vitamin A supplements can weaken the bones, according to a new study.
A Swedish study conducted on men concluded that taking the supplements increased the risk of fractures by up to seven times.
The study is the first to measure levels of the vitamin in blood, rather than just interviewing the participants about their diet and supplement use. Previous research has indicated high intakes raised the risk of broken hips in women.
The study involved 2,322 men and was conducted over a 30-year period. It's published in the New England Journal of Medicine.
Researchers found one-fifth of the men were at risk because they had the highest levels of vitamin A. The men were about two-and-a-half times more likely to suffer any fracture than those with lower levels of the vitamin in their blood.
They concluded a daily vitamin A consumption of more than 1.5 mg can be dangerous and that supplements are not necessary.
The recommended daily allowance for women is 0.7 mg a day and for men, it's 0.9 mg.
"Unless there is a known medical reason, like certain diseases of the eye,...people should not be taking vitamin A supplements," says Dr. Donald Louria, a preventive medicine expert from New Jersey.
Louria says multi-vitamins containing 0.1 mg or less of vitamin A are fine for people eating a healthy diet.
Vitamin A can interfere with cells that produce new bone. It tends to stimulate cells that break down old bone and interferes with vitamin D, which helps the body maintain calcium levels.
Vitamin A is abundant in beef liver, fish liver oils, egg yolks, butter and cream. Milk and certain cereals are fortified with vitamin A.
Written by CBC News Online staff