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Beta-Carotene and Smokers Revisited

Friday, September 05, 2003

In the past month, the public has been exposed to several conflicting press Articles regarding the safety of beta-carotene supplements for smokers. It appears that the only impetus behind this new media frenzy is a postintervention follow-up on the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study (ATBC) completed in the mid 1990s. The conclusion of the postintervention trial is that the beneficial and adverse effects of supplemental beta-carotene disappeared during postintervention follow-up. Two important beta- carotene studies from the mid-1990s arguably raised as many questions as they answered.

The first questionable study was the 1994 ATBC study involving Finnish men who were heavy smokers and alcohol drinkers. The volunteers were either given 20 milligrams of synthetic beta-carotene, vitamin E, a combination of the two, or a placebo. The totally unexpected outcome suggested that there was an 18 percent increase in lung cancer rates in the beta carotene-only group. However, it is highly significant that other research showed that this damage could be prevented by combining beta-carotene with other antioxidants. To underline this point, there was no increase in cancer rates in the ATBC volunteers who used a combination of synthetic beta-carotene and vitamin E.

The second trial was the 1996 Carotenoid and Retinol Efficacy Trial (CARET), which was a lung cancer prevention study involving a combination of 30 mg of synthetic beta carotene and 25,000 IU of retinol, versus placebo. The volunteers were either smokers or asbestos workers. This study was stopped early due to the fact that preliminary findings suggested that there was a 28 percent increase in cancer rates in the beta carotene/vitamin A group, compared to placebo.

The CARET study data was very confusing. In spite of the statistical increase in cancer in the current smokers, former smokers in the beta-carotene group actually experienced a 20 percent reduction in lung cancer rates! And as was the case in the ATBC study, those with the highest blood levels of beta-carotene in the placebo group had the lowest rates of lung cancer. This finding was consistent with previous epidemiological studies. Although this is very serious statistical information, it is always helpful to put such statistics in perspective. For example, the 28 percent increase reported in the CARET study amounted to an increase from 5 cases of lung cancer per 1000 smokers to 6 cases per 1000.

Around the same time, the 12-year long Physicians' Health Study (PHS), involving more than 22,000 volunteers, showed no statistical increase in lung cancer rates with 50 mg of synthetic beta-carotene Â? even in the eleven percent of the volunteers who were smokers.
After the release of the ATBC results, the scientist who carried out the research said that any increase in cancer rates was almost certainly due to chance. The PHS trial, which included more than 2000 smokers, and on average used twice as much beta carotene for twice as long as the ATBC and CARET studies, was not the only trial to call into question the significance of the ATBC / CARET data.

It was observed in both these studies that high doses of synthetic beta-carotene seem to inhibit the uptake of other dietary carotenoids ( once again, this is important information for the AMD patient. Excessive beta-carotene, like the amount included in B&L's PreserVision and other copy-cat formulations, will most likely interfere with lutein carotenoid absorption). If this blocking of absorption was occurring over the several-year duration of these studies, this could help to explain a statistical increase in lung cancer rates (or as the PHS trial and others might suggest, this could help explain why the beta-carotene did not reduce lung cancer rates.) Nevertheless, it is prudent to recommend that high doses of synthetic beta-carotene, taken as a single nutrient, be absolutely avoided by smokers.
These studies underline the need to focus on the wide range of carotenoids rather than just relying on isolated ones as 'magic bullets'. These studies also show the limitations of applying the 'magic bullet' approach to nutritional medicine. Hopefully the limitations of synthetic beta- carotene in cancer research will encourage scientists to focus more research on the synergy of the vast array of phytonutrients found in nature.

Ellen Troyer, MT MA - Biosyntrx Chief Research Officer


After lengthly study of both the ATBC and CARET trials, the Biosyntrx Scientific advisors are confident that Syntrx Complete and Macula Complete are safe for smokers and former smokers. Our research and design team carefully studied the beta-carotene trials from the mid 1990s before including a very small amount of beta-carotene in our multiple formulations to address specific issues of singlet oxygen formation and diseases of the eye. Biosyntrx multiples include less than one (1) mg beta-carotene, which is appropriately balanced with a complete host of carotenoids and other phytonutrient antioxidants, including 400 IU of mixed tocopherol Vitamin E and 500 mg of vitamin C, which are both vital to healthy lungs for all who smoke or have smoke damaged lungs.


Clinical references available in the Biosyntrx office.