Beta carotene supplements

Beta carotene supplements are available in various forms, including synthetic forms and those extracted from algae and palm oil. Some studies suggest that those extracted from palm oil are absorbed more efficiently. Natural beta carotene may have greater beneficial effects than synthetic forms.
Beta carotene Supplements

Therapeutic uses of supplements

Beta carotene supplements have been used in cancer and cardiovascular disease prevention trials, including the Finnish Alpha Tocopherol Beta Carotene Cancer (ATBC) Prevention Study, the US Carotene and Retinol Efficacy Trial (CARET) and the US Physicians Health Study. In 1996, these studies reported results which received wide publicity.

ATBC study

The ATBC Prevention group studied 29,000 men who smoked and drank alcohol. The results showed an 18 per cent increase in lung cancer deaths and an 11 per cent increase in ischemic heart disease deaths in men who took daily supplements of 20 mg beta carotene.

CARET study

The CARET study was stopped 21 months early. This study was examining the effect of beta carotene (30 mg daily) and retinol (7500 mcg RE daily) supplementation on the prevention of cancer and heart disease in over 18,000 smokers and people who had been exposed to asbestos. The trial was stopped when the results showed a 28 per cent increased risk of lung cancer, a 26 per cent increase in the risk of death from cardiovascular disease, and a 17 per cent increase in overall deaths in the group receiving the supplements.

Physicians Health Study

This study examined the effect on over 22,000 male doctors of 50 mg beta carotene taken every other day for 12 years. The results suggest that beta carotene has no effect, either positive or negative, on the risk of cardiovascular disease or cancer. Analysis of a subgroup of 333 men in the study with a prior history of heart disease suggested that beta carotene supplements reduced the risk of heart attacks and death by a small amount.

There are a number of possible explanations for the adverse effects of beta carotene supplements found in these studies and for the failure of supplements to show the protective effects suggested by epidemiological studies.

Beta carotene is susceptible to oxidative damage from alcohol and the gases in cigarette smoke which may lead to the formation of harmful by-products. Beta carotene may be dependent on other antioxidants, such as vitamins C and E to exert protective effects. An individual's total dietary intake of antioxidants may therefore need to be considered when assessing protection by beta carotene.

Further analyses of results from the ATBC trial support the suggestion that smoking and alcohol consumption may contribute to the adverse effects of beta carotene. The adverse effects appeared stronger in men who drank alcohol and in those who smoked 20 cigarettes a day than in those who smoked less. This is confirmed by the CARET results which showed greater risk in current smokers than former smokers and also in those who drank alcohol.

Another aspect to be considered is the fact that beta carotene exists in many possible forms and some research suggests that the specific form chosen for use in these clinical trials was not the most active. A mixture of various forms of beta carotene, similar to that which occurs naturally, may have the most beneficial effect. It is also possible that the large dose of the particular form of beta carotene used in the trials competed with other, possibly more beneficial forms at vital sites in the body.

The results of these trials point to the importance of considering total diet and a balanced mixture of nutrients when studying protection against cancer risk. High blood levels of carotene seem to predict lower risk and these high blood levels of beta carotene may be accompanied by high levels of other carotenoids, and even other nutrients, which may also play a vital part in cancer protection. Both the ATBC and CARET studies found that those with higher blood beta carotene levels on entering the trials had a lower risk of lung cancer.

Beta carotene supplementsLaboratory research suggests that vitamin C protects against the harmful effects of beta carotene in smokers. Smokers tend to have low levels of vitamin C and this may allow a build-up of a harmful form of beta carotene called the carotene free radical which is formed when beta carotene acts to regenerate vitamin E. These results suggest that in smokers, dietary vitamin C supplementation should accompany beta carotene supplementation.

Double-blind placebo-controlled studies may be more useful for evaluating a specific drug for one condition in one population group and less suitable for investigating multifactorial agents in complex, mixed population studies. These studies do not invalidate hundreds of other studies showing that diets high in fruits and vegetables protect against a variety of diseases.

Immune system support

In a 1997 double-blind, placebo-controlled study done in the UK, researchers tested the effects of daily doses of 15 mg of beta carotene in 25 healthy, adult male nonsmokers. Their findings showed improvement in function in various parts of the immune system, including white blood cells known as monocytes which are involved in surveillance of tumors.

Large doses of beta carotene may boost immune function in AIDS patients. In a Yale University study done in 1995, researchers found that daily supplements of 60 mg beta carotene given to seven AIDS patients for a period of four weeks increased CD4+ lymphocyte cell counts.

Other uses

In addition to exerting protective effects against a wide range of diseases, beta carotene may slow the rate of aging in the skin and other organs by protecting against free radical damage caused by smoking, pollution, ultraviolet light and other chemicals. Beta carotene is also used to treat oral leukoplakia, a pre- cancerous condition of mucous membranes.

Beta carotene may also be beneficial in pre-eclampsia. Other results from the CARET study suggest that beta carotene supplements can help to improve lung function in men that have been exposed to asbestos.

Beta carotene is used to decrease light sensitivity reactions in sufferers of the disease, erythropoietic protoporphyria. Beta carotene supplements have been shown to have beneficial effects in cystic fibrosis by decreasing harmful lipid peroxidation. Fibrocystic breast disease, a painful cystic swelling of the breast which affects 20 to 40 per cent of premenopausal women, may be helped by vitamin A and beta carotene.

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Other Vitamins:

Vitamin A
Beta carotene
Vitamin B6
Vitamin B12
Pantothenic acid
Vitamin C
Vitamin D
Vitamin E
Vitamin K