Positive Health Online

Abstract

ALBANES, Cancer Prevention Studies branch, Division of Clinical Sciences, National Cancer Institute, Bethesda, MD, 20892-7058 USA. daa@nih.gov writes that the conflicting evidence of the relation between beta-carotene and lung cancer in humans serves as a poignant case study regarding what types of evidence are sufficient to support or change a nutrition recommendation . The author reviews (37 references) the available evidence of the relation between beta-carotene and lung cancer, including data regarding beta-carotene intake from diet and supplements, beta-carotene biochemical status and vegetable and fruit consumption, and discusses the role of this evidence to make nutrition recommendations.

Background

Methodology

Results

More than 30 case-control and cohort studies have been conducted over many years in various countries which have indicated that people who eat more vegetables and fruit, foods rich in carotenoids and carotenoids (beta-carotene in particular) as well as those with higher blood beta-carotene concentrations, have a reduced risk of lung cancer than those people eating fewer such foods or with lower beta-carotene concentrations. In contrast, the results from large, controlled trials of beta-carotene supplementation do not support the observed beneficial associations or a role for supplemental beta-carotene in lung cancer prevention; rather they provide evidence for adverse, i.e. excess lung cancer incidence and overall mortality in smokers.

Conclusion

These findings require that caution be exercised in recommending supplemental beta-carotene, particularly for smokers, and argue against changing the vegetable-fruit recommendations in the direction of greater nutrient specificity.

References

Albanes D. Beta-carotene and lung cancer: a case study. American Journal of Clinical Nutrition 69(6): 1345S-1350S. Jun 1999.

Comment

Perish the thought that anyone should suggest to people that they eat more fruit and vegetables, or that they take supplements. It is typical of reductionist clinical trials to test a particular isolated substance i.e. beta-carotene, rather than the real nutrient, which acts within a broad mix of nutrients, be they carotenoids, tocopherols or other nutrient complexes. Of course, we should all eat liberally, with many vegetables and fruits daily. Unless you do your own cooking throughout your work day, have you seen such foods available in your sandwiches or in most restaurants?