Beta-Carotene--Protection Against Thyroid Cancer

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Beta-Carotene -- Protection Against Thyroid Cancer

D'Avanzo B, Ron E, La Vecchia C, et al. Selected micronutrient intake and thyroid carcinoma risk. Cancer 1997; 79:2186-92.

Summary: In three areas in northern Italy, 399 men and women aged 16 to 72 years with thyroid cancer were studied. As matched controls, 617 men and women aged 16 to 74 years with non-neoplastic conditions were selected. Each study volunteer gave a diet history on 29 foods and various other information about their lifestyle and medical history. Micronutrient intake was estimated from the diet recall. Higher vitamin A intake was shown to be associated with increased risk of thyroid cancer odds ratio (1.52 in the highest quartile of intake). Beta-carotene, however, had an inverse relationship (odds ratio 0.58 in the highest quartile of intake). Vitamins C and E showed a similar though weaker protective effect.

Controlling for age, sex, calorie intake, history of benign thyroid disease and betacarotene intake eliminated the protective effect for vitamins C and E. The authors contend this shows that the previously noted protective effect was probably a marker effect for carotenoid intake. Beta-carotene's protective effect was only enhanced when other factors were taken into consideration. Beta- carotene intake was shown to be protective against papillary and follicular types of thyroid neoplasms. No other nutrient was protective in both types. Women received greater benefit from higher intakes of beta-carotene and vitamins C and E, though the smaller numbers of men in the study made the importance of this finding unclear. The authors conclude carotenoids appear to reduce the risk of thyroid carcinoma, while other micronutrients do not. Higher vitamin A intake may be a marker for higher intake of animal products (eggs, dairy products, liver) and not a true risk factor for thyroid cancer.

Article copyright Natural Product Research Consultants, Inc.

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By E. Yarnell

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