Black women who tend to eat foods more likely to lead to higher blood sugar may have slightly greater risk for uterine fibroids, suggest study findings.

Uterine fibroids - noncancerous growths that often cause heavy menstrual bleeding and cramping during childbearing years - are 2 to 3 times more likely in black women than in other American women.

Rose Radin of Boston University and colleagues studied nearly 21,900 premenopausal black women, they report in the American Journal of Clinical Nutrition.

Subjects filled out food questionnaires in 1995 and 2001, and the investigators calculated the women’s glycemic index and glycemic load, two indicators of how the food they ate was likely to affect their blood sugar levels.

Low glycemic index and load foods - apples or whole beans for example - gradually release sugars into the blood. By contrast, those with high glycemic index and load, such as sugary drinks and pastries, white bread, and white rice, release sugars rapidly and cause the body to release hormones to compensate for blood sugar spikes.

Between 1997 through 2007, Radin’s team found 5800 women with uterine fibroids diagnosed during ultrasound or hysterectomy.

Those with higher versus lower glycemic index levels generally had greater fibroid risk after allowing for multiple other factors potentially associated with the development of fibroids.

Also, women younger than 35 years with higher glycemic load had greater fibroid risk than their counterparts with the lowest glycemic load.

For instance, in younger women, there were 27 cases per thousand women per year, Radin said. By comparison, she and colleagues noted 33 uterine fibroid cases among those younger women with the highest glycemic load.

Scientists are not sure why diet might affect the growth of fibroids. One possibility, however, is the effect of foods on blood sugar. Higher-carbohydrate diets can lead to higher insulin levels, which are in turn linked to levels of other hormones thought to encourage fibroid growth, Radin told Reuters Health by email.

The link between diet and fibroids, though small in the current study, requires confirmation in additional studies, the authors note. For example, the study did not test actual blood sugar levels, although about 3 percent of the population reported a diagnosis of diabetes. The study could not determine whether the relationship would be different among women with normal ranges of blood sugars as opposed to higher diabetic ranges.

Because of the need for further study, Radin would not recommend a particular diet to avoid fibroid risk.

However, foods with high glycemic index and load are established risk factors for diabetes and heart disease, Radin cautioned. These associations alone, she said, “are good reasons to cut back on foods that tend to cause blood sugar to spike.”

SOURCE: American Journal of Clinical Nutrition, published online March 3, 2010.