A new study has revealed that a diet rich in tomato may help protect at-risk postmenopausal women from breast cancer.

The study found eating a diet high in tomatoes had a positive effect on the level of hormones that play a role in regulating fat and sugar metabolism.

"The advantages of eating plenty of tomatoes and tomato-based products, even for a short period, were clearly evident in our findings," the study's first author, Adana Llanos from Rutgers University, said.

"Eating fruits and vegetables, which are rich in essential nutrients, vitamins, minerals and phytochemicals such as lycopene, conveys significant benefits. Based on this data, we believe regular consumption of at least the daily recommended servings of fruits and vegetables would promote breast cancer prevention in an at-risk population," Llanos said.

The longitudinal cross-over study examined the effects of both tomato-rich and soy-rich diets in a group of 70 postmenopausal women. For 10 weeks, the women ate tomato products containing at least 25 milligrams of lycopene daily.

For a separate 10-week period, the participants consumed at least 40 grams of soy protein daily. Before each test period began, the women were instructed to abstain from eating both tomato and soy products for two weeks.

When they followed the tomato-rich diet, participants' levels of adiponectin - a hormone involved in regulating blood sugar and fat levels - climbed 9 percent. The effect was slightly stronger in women who had a lower body mass index.

The study is published in journal of Clinical Endocrinology and Metabolism.