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Source: Chiaffarino F, et al. Diet and uterine myomas. Obstet Gynecol 1999;94:395-398.
Design/Setting/Subjects: Data from a case-control study on risk factors for uterine myomas conducted in Italy between 1986 and 1997. The study compared 843 cases of women hospitalized for fibroid surgery (and whose myomas were diagnosed within the past two years) to 1,557 women age 55 and younger who had no history of fibroids or hysterectomy and were admitted to the hospital for acute non-gynecological, non-oncological conditions.
Results: Consumption of beef and other red meat was associated with an increased risk of developing fibroids; consumption of green vegetables was associated with a protective effect. Consumption of fish was also associated with a protective effect. There was no association found for consumption of other index foods (milk, cheese, butter, eggs, oil, margarine, liver, carrots, whole-grain foods, coffee, or tea). Multivariate odds ratios in the upper tertile were 1.7 (95% confidence interval [CI] 1.4-2.2) for beef and other red meat; 1.3 (CI 1.0-1.6) for ham; 0.5 (CI 0.4-0.6) for green vegetables; 0.7 (CI 0.6-0.9) for fish; and 0.8 (CI 0.6-1.0) for fruit.
Funding: Not stated.
Comments: It is common lore among alternative medicine practitioners that consumption of animal products (meat, dairy products, and eggs) causes or worsens fibroids. However, the reasoning behind this is based on theory or speculation rather than data. This interesting study supports the possibility that frequent meat consumption may be associated with fibroids. (There was no association found for consumption of milk, cheese, or eggs.)
The distribution of cases and controls was not even; women with uterine myomas were more educated, more frequently premenopausal, and less frequently smokers than controls. One of the limitations of this study, as the researchers point out, is that although average weekly frequencies of consumption were noted, there was no attempt to quantify intake. Additionally, control subjects did not undergo sonograms, so the actual incidence of fibroids is unknown in the control group. The use of index foods can also be misleading. It would have made more sense to group dairy products (questions were asked about milk, cheese, and butter, but not yogurt or ice cream). Possible mechanisms for the association were not discussed. It is quite possible that high levels of meat intake is a marker for other health habits or socioeconomic factors. Another possibility is an effect on estrogen levels. Meat is high in fat, and in premenopausal women, low-fat diets reduce endogenous estrogen levels.1 Also, estrogenic hormones are used as growth promoters in cattle and chickens and residues may be in meat (although they probably would be in milk as well).
1. Boyd NF, et al. Effects of a low-fat high-carbohydrate diet on plasma sex hormones in premenopausal women: Results from a randomized controlled trial. Canadian Diet and Breast Cancer Prevention Study Group. Br J Cancer 1997;76:127-135.