The findings from a study funded with matching grants from the American Institute for Cancer Research and the California Walnut Commission, involving mice specially created to develop tumors suggest, walnuts contain compounds useful in preventing breast cancer.

While, one group of mice was given a regular diet, another group was fed a daily diet comprising of 2-ounces of walnuts in human terms. The walnut eating group of mice had a much lower incidence of breast tumors, including fewer glands with tumors and tumors if any were much smaller in size.

As per molecular analysis, tumour resistance in the mice was due to increased consumption of omega-3 fatty acids, antioxidants and phytosterols found in walnuts, which findings will be presented Tuesday at the annual meeting of the American Association for Cancer Research in Denver.

Researcher Dr Elaine Hardman, of Marshall University School of Medicine confirms, saying: 'With dietary interventions, you see multiple mechanisms when working with the whole food. It is clear that walnuts contribute to a healthy diet that can reduce breast cancer,' and suggests that even though the study was done with mice, humans would also benefit by eating more walnuts.

'Walnuts are better than cookies, french fries or potato chips when you need a snack,' Hardman said. 'We know that a healthy diet overall prevents all manner of chronic diseases.'

While, it is clear walnuts contribute to a healthy diet that can reduce breast cancer, previous research also suggests eating walnuts at the end of a meal may help cut the damage fatty food does to the arteries. Rich in compounds that help reduce hardening of the arteries and keep them flexible, currently evidence is far stronger for walnuts reducing the risk of heart disease than for their anti-cancer properties.

Anna Denny, a nutrition scientist at the British Nutrition Foundation says: 'Although, nuts are high in fat (and thus calories), the fatty acids in nuts are predominantly good unsaturated fatty acids. Other additional components of nuts that may contribute to a reduction in heart disease and cancer risk include fibre and bio-active compounds. Among the many bio-active compounds found in nuts are phytosterols and flavonoids.'

However, more research is required before we can begin to attribute specific health benefits to specific bioactive compounds in nuts, since nuts contain a complex mixture of different bio-active compounds.

With age being the strongest risk factor for breast cancer, with 80% of breast cancers occurring in women aged 50-plus, screening is important, including making lifestyle changes, keeping a healthy body weight, limiting alcohol intake and taking regular exercise, to reduce the risk of breast cancer.