Does Vitamin A In Retinol Increase The Risk Of Bone Fractures?

New evidence suggests a connection between vitamin A and bone fractures, but the conclusions are far from clear.

Vitamin A is important in maintaining healthy skin, mucous membranes, night vision, red blood cells, bones, and the reproductive and immune systems. Deficiencies of vitamin A seldom occur in healthy adults living in the United States, where the diet is high in animal based proteins. Despite this, many people continue to take retinol supplements in the form of vitamin A.

Sources of vitamin A include beef and chicken livers, eggs, cod liver oil, and dairy products such as whole milk, and cheese. Vitamin A is also found in fortified foods such as cereals and skim milk. Vegetarians can obtain enough vitamin A from their diet by making sure they eat at least five servings a day of fruits and vegetables rich in beta-carotene such as sweet potatoes, carrots, kale, apricots, and squash. Beta-carotene is considered an indirect source of vitamin A because it is converted to vitamin A in the intestines.

Vitamin A is stored in the liver and used by the body when it is needed. Vitamin A is a fat-soluble vitamin, which means that it is not excreted in urine, but is stored in the body. Vitamin A that is not used by the body can build up to excessive levels. In large amounts, vitamin A is quite toxic, leading to liver damage, fetal abnormalities, and abnormal growth and development in the skeletal system.


The average well-balanced diet of healthy adults provides just over 2,500 I. U. of vitamin A. Studies in Sweden indicate that middle aged men consuming more than 5,000 I. U. of vitamin A per day are more likely to develop osteoporosis, which may lead to an increase in bone fractures""especially of the hips.

The current recommended daily allowance (RDA) for adults is 10,000 IU, or International Units. Based on this recent evidence, the scientific community is now suggesting the RDA should be lowered to less than 2,500 I. U.

There are two reasons why vitamin A may accumulate in the body. First, as people age, they do not metabolize nutrients, including vitamins, as efficiently. This in turn may lead to an excess of vitamin A in the body.

Second, taking vitamin A supplements, in addition to a well balanced diet, almost always results in excessive levels of vitamin A being accumulated in the body. Retinol supplements, in the form of capsules, liquid, or pills typically contain 5000 IU, 10,000 IU, 15,000 IU, or 25,000 IU of vitamin A.

Eating too many foods rich in beta-carotene, or taking beta-carotene supplements and multi-vitamins with beta-carotene will not affect the amount of vitamin A in the body because it is converted only when needed.

An excessive level of vitamin A may inhibit the absorption of calcium by interfering with vitamin D. Vitamin D is manufactured by the body when exposed to at least 15 minutes of sunlight per day. In northern climates during the winter season, many people may not have adequate levels of vitamin D, which interferes with calcium absorption and creating potential long-term effects such as osteoporosis and bone fractures.

It is not clear whether vitamin A is to blame for the increase in bone fractures in elderly populations and further research is needed. Until then, the best advice is to eat a balanced diet or take a supplement in the form of beta-carotene to avoid the potential for adverse side effects in the future.

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