In a mouse model, researchers at the University of Missouri found that the compound apigenin, which is found in parsley, celery and other whole foods, was effective in slowing breast tumor growth.

This may be an effective alternative to hormone replacement therapy, especially since some of the synthetic hormones — like medroxyprogesterone acetate — used in such treatments may actually exacerbate tumors.

Apigenin was shown to hinder the formation of blood vessels in tumors, which stops or slows their growth, and also reduce the number of growths found in the rodents. However, the compound was not effective in preventing the onset of breast cancer in the first place.

The compound is also found in oranges, apples and nuts. The researchers said they have not yet determined how much apigenin should be recommended for treatment in humans, but that it's likely beneficial to eat foods that contain it.

"It's probably a good idea to eat a little parsley and some fruit every day to ensure the minimal amount. However, you can also find this compound in pill supplements in the health-food section of many stores," said lead author Salman Hyder.