The facts

A recent e-mail chain has some people concerned about grapefruit. The messages refer to a 2007 study in The British Journal of Cancer that found an increased risk of breast cancer among postmenopausal women who ate large amounts of grapefruit.

In the group of women, more than 46,000 overall, those who ate about a half a grapefruit every other day had a 30 per cent higher risk of breast cancer than those who ate none, even after other risk factors were taken into account. Scientists said they suspected that an enzyme in grapefruit known as CYP3A4 had the ability to increase estrogen.

But a more recent report, published this year in the same journal, reached a far different conclusion. That analysis used data from the Nurses' Health Study, which followed more than 77,000 women, 30 to 55, over many years. The scientists looked at the intake of both grapefruit and grapefruit juice and found no rise in breast cancer risk, either among women over all or among postmenopausal women.

Experts at the American Cancer Society said that there was insufficient evidence to change existing recommendations, but that women with concerns could cut back on grapefruit.

The bottomline

Studies have produced conflicting information on a link, if any, between grapefruit and breast cancer risk.