Synthetic beta-carotene increases cancer and heart disease risk

Beta-carotene increases cancer risk

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by Dr Norman Swan

A study shows that the antioxidant beta-carotene increases the risk of lung cancer and diminishes the anti-cancer effect of eating fruit and vegetables.

12 06 2003

Antioxidants are incredibly popular and, despite the controversy surrounding Pan Pharmaceuticals, people are still swallowing supplements as if there’s no tomorrow.
The assumption is they’re safe, but a salutary study has fired a shot across the bows of one supplement at least: beta-carotene - the raw material for vitamin A.
A few years ago there was a large trial of beta-carotene to see if it would prevent lung cancer in heavy smokers and people exposed to asbestos.
The trial was stopped early because those who received beta-carotene had an increased risk of lung cancer compared to those on placebo, not decreased as expected.
The results have been re-examined and even more disturbing findings made, this time on the effects of beta-carotene on the benefits of fruit and vegetables. You see, the original study showed that people eating fruit and vegetables had lower rates of cancer.
But the re-analysis found that those taking beta-carotene actually lost that protection. In other words, beta-carotene both increased the risk of malignancy and blocked the beneficial effects of plant-based foods.
It’s a warning that supplements are not necessarily harmless and a reminder there’s a lot more to whole foods than meet the eye.

Vitamin Overdose: The Beta Carotene Tests

A Finish study of high-risk lung cancer patients was one of the first to come back, and demonstrated how mistaken we were.

The study showed that not only had the beta carotene failed to prevent lung cancer, it had actually increased the subjects' chance of getting it by 28 percent (5)! The death rate from heart disease had also increased by 17 percent (6).

The study was called off when the scientists realized what was happening, and only much later did people come to understand what occurs when you flood the body with beta carotene in isolation.

The problem is that a pill is not a plant. Beta carotene is one of about 50 carotenoids found in plant foods. Normally, when the appropriate mixture of carotenoids enters a cell, they float around in the cytoplasm until they find a receptor site to attach to.

But when the body is flooded with a vitamin overdose of isolated beta carotene from a pill, there is an overwhelming competition for the receptor sites, and the 50 other needed carotenoids are displaced, creating deadly nutritional imbalances.

More Cancer

The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group. A total of 29,133 male smokers were assigned to one of four regimens: alpha-tocopherol (vitamin E) alone, beta-carotene alone, both alpha-tocopherol and beta-carotene, or placebo.⁷ Findings: 18 percent more lung cancer and 8 percent more deaths in those taking the preparations with beta-carotene.

The Beta Carotene and Retinol Efficacy Trial. A total of 18,314 smokers, former smokers, and workers exposed to asbestos assigned to take beta-carotene and retinol (vitamin A) or placebo.⁸ Findings: 17 percent more deaths, 46 percent more lung cancer, and 26 percent more cardiovascular disease for those taking the supplement.

More Heart Disease

Alpha-tocopherol Beta-carotene Cancer Prevention Study. A total of 1862 male smokers who had had a previous myocardial infarction were assigned to dietary supplements of alpha-tocopherol, beta-carotene, both, or placebo.¹⁷ Findings: There were 75% more deaths from fatal coronary artery disease in the beta-carotene groups and a slight increase in the alpha-tocopherol groups.