Fall 2004 - Patient Newsletter

Nutrient Notes

Vitamin A, Obesity, and Gastric Bypass Surgery

What is vitamin A?

Vitamin A is actually not a single nutrient, but a family of vitamins. Vitamin A is one of four vitamins that are carried into the body with fat, and are called fat-soluble for that reason. The preformed active form of vitamin A is found in animal foods such as eggs and liver, as well as in some fortified foods or supplements. Most fat free milk and dried nonfat milk solids sold in the US are fortified with vitamin A to replace the vitamin A lost when the fat is removed. Many breakfast cereals also have added vitamin A.

Other foods, however, contain several compounds that can be converted by the body to vitamin A. These forms are called "provitamin A carotenoids". You might recognize one of the better know provitamin A carotenoids, beta-carotene. These compounds are found mainly in dark green leafy vegetables, and in vegetables and fruits that are orange and yellow.

What is the function of vitamin A?

Vitamin A is important in many bodily functions, including immunity, vision, bone growth, and normal function in all of the body's cells. For reasons that are unclear, people who are obese tend to have lower blood levels of some of the vitamin A forms. Obese people also tend to be at higher risk for some of the diseases that vitamin A helps against, such as certain types of cancer and an age-related problem with vision called macular degeneration. The link between obesity, blood levels, and disease risk, however, is not fully understood.

Some digestive disorders may result in decreased absorption of vitamin A from the intestines. After gastric bypass, however, absorption of vitamin A and other provitamin A compounds appears to be unaffected.

So why should you be concerned about vitamin A?

Consuming a diet rich in vegetables and fruits can help protect against heart disease and cancer. If you've already had surgery to reduce your weight, you still need to do all you can to be healthy. Foods that contain vitamin A and its precursors the carotenoids are usually low in calories, rich in other vitamins or minerals, and high in dietary fiber, all of which are a plus for most people.

Can I consume too much vitamin A?

YES! There can be severe health consequences of consuming too much of preformed vitamin A. However, this situation usually results from ingestion of supplements containing vitamin A or from foods that are fortified with large amounts of vitamin A. In addition, taking supplements that contain carotenoids such as beta-carotene may worsen certain health conditions. People with kidney problems may be especially susceptible. When too much of the precursor forms are ingested, the body tends to decrease conversion of the precursors to the more active vitamin A form in an effort to protect against overload. That is why a diet that contains many fruits and vegetables rarely results in serious vitamin A toxicity.

After gastric bypass, no additional vitamin A supplementation is routinely recommended other than that found in a daily multivitamin. You should always consult with a health-care professional before taking supplements that contain vitamin A or carotenoids.

What is the take home message?

Vitamin A and its precursors in food, the carotenoids, have an important role in maintaining health. After surgery you will still need to keep up your intake, even though gastric bypass doesn't seem to diminish absorption. The best way to insure that you are receiving the health benefits of the vitamin A family is to eat a wide variety of vegetables and fruits.


If you have specific questions regarding your intake of vitamin A, it is recommended that you discuss this information with your physician or other trained health care practitioner to determine what's best for your personal health.

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