Nutrition and primary prevention of breast cancer: foods, nutrients and breast cancer risk.

Worldwide, each year approximately one million women are newly diagnosed with breast cancer (BC), in Germany 65 new cases per 100,000 inhabitants are registered, yearly. The fact that incidence has been rising in parallel with economic development indicates that environmental factors might play a role in the causation of BC. Migrational data have pointed to nutrition as one of the more relevant external factors involved. Preventive dietary advice often includes a reduction of alcohol, red meat and animal fat and increasing the intake of vegetables, fruit and fibre and lately, phyto-estrogens from various sources. Clearly, the scientific basis for these recommendations appears sparse. The available prospective data from epidemiological studies and interventional trials do not support the overall hypothesis that higher fat-intakes are a relevant risk factor for BC development, more important seems the relative distribution of various fatty acids. A non-vegetarian eating habit (consumption of animal products) per se does not elevate BC risk, while consumption of broiled or deep fried meats cannot be ruled out as a risk factor in genetically susceptible individuals. It appears prudent to abstain from regular and increased alcohol consumption. This should be particularly true for pubescent girls, in whom glandular breast tissue is particularly vulnerable. In general, if alcohol is consumed on a regular basis, a sufficient supply of fresh vegetables and fruit is essential. While there is no overall protective effect of a high fruit and vegetable consumption speculation remains over possible beneficial effects of certain subcategories, especially brassica vegetables like broccoli, cauliflower and cabbage. In essence, regional differences in BC incidence are probably partially attributable to life long dietary habits. There is no need to adopt a foreign dietary plan in order to protect oneself against BC. Traditional western diets also have their beneficial ingredients that should be regular constituents in our meals. Lignans from traditionally made sourdough rye bread, linseed/flaxseed and berries are local sources of potentially canceroprotective phyto-estrogens. Furthermore, indole-3-carbinol rich cabbage species might contribute to BC protection by diet. Nevertheless, clear cut recommendations for or against single nutrients or secondary plant metabolites are not yet possible, lacking sufficient data on individual bioavailability, safety and long term outcome. BC prevention by dietary means therefore relies on an individually tailored mixed diet, rich in basic foods and traditional manufacturing and cooking methods.