It had been thought just one chemical, lycopene, had an anti-cancer effect.
But researchers at the Universities of Illinois and Ohio State found lycopene's effect is boosted by other chemicals in the fruit.
The finding, in the Journal of the National Cancer Institute, suggests lycopene-only dietary supplements have only a limited effect.
Lead researcher Professor John Erdman said: "It has been unclear whether lycopene itself is protective.
"This study suggests that lycopene is one factor involved in reducing the risk of prostate cancer.
"But it also suggests that taking lycopene as a dietary supplement is not as effective as eating whole tomatoes.
"We believe people should consume whole tomato products - in pastas, in salads, in tomato juice and even on pizza."
The researchers exposed laboratory rats to a chemical that causes prostate cancer, and then fed them on diets containing whole tomato powder, pure lycopene or no lycopene at all.
Source BBC News
A cup of cocoa a day may help to keep the doctor away.
A study by scientists in the United States has found that a cup of hot cocoa is rich in powerful antioxidants.
Previous studies have also shown these chemicals, which can protect against a range of diseases and reduce the effects of ageing, are found in cocoa.
However, this latest study suggests cocoa may be richer in antioxidants than better known "healthy" drinks like tea and red wine.Source BBC News
There's sweet news about hot cocoa: Researchers at Cornell University have shown that the popular winter beverage contains more antioxidants per cup than a similar serving of red wine or tea and may be a healthier choice.
The study adds to growing evidence of the health benefits of cocoa and points to a tasty alternative in the quest to maintain a diet rich in healthy antioxidants, chemicals that have been shown to fight cancer, heart disease and aging, the researchers say.
Their study, which they say is the most complete comparison to date of the total antioxidant content of these three popular beverages, will appear in the Dec. 3 issue of the Journal of Agricultural and Food Chemistry, a peer-reviewed journal of the American Chemical Society, the world's largest scientific society.
Source American Chemical Society
Just half a teaspoon of cinnamon a day significantly reduces blood sugar levels in diabetics, a new study has found. The effect, which can be produced even by soaking a cinnamon stick your tea, could also benefit millions of non-diabetics who have blood sugar problem but are unaware of it.
The discovery was initially made by accident, by Richard Anderson at the US Department of Agriculture's Human Nutrition Research Center in Beltsville, Maryland.
Source New Scientist
Green tea could form the basis of a new generation of HIV drugs, say experts.
Scientists in Japan have found a component of green tea can stop HIV from binding to healthy immune cells, which is how the virus spreads.
Their laboratory tests suggest a chemical called Epigallocatechin Gallate (EGCG) protects cells.
Writing in the Journal of Allergy and Clinical Immunology, the scientists said the discovery could lead to new treatments to fight the disease.Source BBC News
A type of herb called buckwheat may be beneficial in the management of diabetes, say researchers.
Extracts of the seed lowered blood glucose levels by up to 19% when it was fed to diabetic rats.
Scientists at the University of Manitoba in Canada say diabetics should consider including the grain in their diet, or taking dietary supplements.
The study, part funded by the food industry, is published in the Journal of Agricultural and Food Chemistry.
Lead researcher Dr Carla Taylor said: "With diabetes on the rise, incorporation of buckwheat into the diet could help provide a safe, easy and inexpensive way to lower glucose levels and reduce the risk of complications associated with the disease, including heart, nerve and kidney problems.
"Buckwheat won't cure diabetes, but we'd like to evaluate its inclusion in food products as a management aid."Source BBC News