In Germany, around 340,000 people a year are diagnosed with cancer. Around 210,000 die as a consequence of the disease. Thus cancer is the second greatest killer, after heart and circulatory diseases. About a third of all cancer cases, experts believe, are due to poor eating habits (1).
In their 2008 report the German Nutrition Society (Deutsche Gesellschaft für Ernährung, DGE) investigated the risk relationship between dietary factors and malignant tumors in various organs (2). The report is based on a systematic analysis of the available scientific literature, taking into account the design and quality of the studies. The level of reliability of the evidence for increased risk, reduced risk or no effect is designated as "convincing", “probable”, “possible” or “insufficient.”
- Alcohol has the greatest cancer-inducing potential: there is convincing evidence that it increases the risk of developing tumors in the mouth, throat, larynx, esophagus, large intestine, rectum, breast and liver. A meta-analysis of 111 trials shows: for each 10 g of alcohol consumed per day the risk of developing breast cancer rises by around 10%. Ten grams of alcohol is equivalent to around 125 ml of wine or 250 ml beer.
- Red meat and meat products probably increase the risk of developing cancer of the large intestine or rectum, according to the evidence.
- Evidence that fat and saturated fatty acids increase the risk of developing breast cancer after the menopause is classed as possible, while the evidence for an elevated risk regarding cancer of the large intestine, rectum, lung, ovaries, uterus or prostate is judged to be insufficient.
- In contrast, fruit and vegetables demonstrate preventive potential. It is probable that they reduce the risk of developing cancer of the mouth, throat, larynx, esophagus, stomach and large intestine. An analysis of 14 cohort studies investigated the association of risk between consumption of fruit and vegetables and tumors of the large intestine, and compared a high intake of fruit and vegetables (800 g/day) with a low intake (200 g/day). The calculated risk reduction was 26%. It is possible that fruit and vegetables protect against tumors of the kidney and the rectum. For lung cancer, evidence shows a probable risk reduction through fruit consumption, and a possible one for vegetables. With regard to prostatic and ovarian cancer the evidence for an influence of fruit and vegetable consumption is insufficient.
- There is a possible connection between omega-3 fatty acids and a reduction in the risk of developing colorectal tumors.
- Milk and dairy products, as well as a diet high in fiber, probably reduce the risk for cancer of the large intestine. Results from the EPIC study (European Prospective Investigation into Cancer) show that men with a fiber intake of 31 g per day have a round 21% lower risk of developing colorectal carcinomas than men whose daily fiber intake is less than 18 g. The same reduction of risk was observed for women with an intake of 24 g as compared to 16 g fiber per day.
The results of the 2008 Nutrition Report confirm the recommendations of the DGE for a balanced diet in respect of cancer prevention. It should be rich in vegetables and fruit (for adults 400 g of vegetables and 250 g of fruit per day), and many fiber-rich cereal products, combined with a moderate consumption of meat and meat products (approximately 300 to 600 g/week). In particular, consumption of red meat should be reduced and alcohol avoided.