A review paper by the authors of the Cancer Research UK Epidemiology Unit, Oxford, UK; the Epidemiology Branch, National Cancer Institute, Bethesda, USA; and the Departments of Epidemiology and Nutrition, Harvard School of Public Health, Boston, USA published in the Public Health Nutrition Journal in February 2004, Volume 7, pp. 187-200, which deals with the connections between cancer and nutrition, suggests that diet is the second most common preventable factor for cancer after smoking.
It has been long known that there is a connection between cancer and nutrition. Just by comparing the current health condition of western, so-called “industrial” countries and non-industrial countries, which have not been Americanized as much as western countries, a clear link between nutrition and cancer can be seen. According to this paper it is thought that diet – how and what you eat – contributes to about 30% of cancers in industrial countries and about 20% in non-industrial countries. This difference mainly results from the different kind of nutrition that people eat. In most developing countries “western cancers” are far less frequent, which can be directly connected to a lower intake of foods such as meat, milk and cheese. At the same time other types of cancers can occur in developing countries. A reason to put an emphasis on nutrition and not so much on ‘genetic predisposition’ when talking about cancer is that, as stated by the review paper, “cancer rates often change in populations which migrate from one country to another”. Moving to a different country will undoubtedly also lead to a change in diet and lifestyle habits. The authors give an example of Japanese people moving to the U.S.A, which increased their rate of colorectal cancer similar to the Americans around them. In contrast the population in Japan at the time of the study had a very low rate for colorectal cancers (nowadays the western diet has also reached Japan). According to the review paper a strong correlation between meat consumption and colorectal cancer could be shown. Although there is not yet a definite mechanism to explain this, several mechanisms are in discussion. Study outcomes have also varied in different studies of meat consumption and colorectal cancer, as one study suggests that there is a difference when consuming fresh meat vs. preserved meat.
Interestingly many other studies have not found an increase in colorectal cancer rates in correlation with fish consumption.
The paper recommends for non-vegetarians to consume preserved and red meat at a “moderate” rate. Of course this clearly depends on your definition of moderate, but I would suggest to reduce meat consumption in general as much as possible. Another factor that increases the chance of getting cancer of the oral cavity, the pharynx, larynx, oesophagus, liver and the breast is alcohol. This increase is not linked to an alcoholic product in specific such as some brand of beer, wine or whiskey but has rather to do with the alcohol (ethanol) in general. The review states, that “a small (about 7%) increase in risk of breast cancer has been observed with approximately one drink per day”. Therefore reducing your alcohol consumption or even better avoiding it at all will help you reduce the chance of having cancer.
Turning away from what you should avoid, to what you should do: the review paper points out many times the beneficial effect of consuming fruits and vegetables. The review paper suggests we include at least 400g/day of fruits and vegetables in our meals. It also points out the need for physical activity and to maintain a healthy BMI “in the range of 18.5-25kg/m²”.
More important than all the numbers or specific information is what you take from this article. In general my advice is to live healthily and to invest some more dollars into healthy and organic food. It can make you feel better, and more awake during the day, since your body will get the vitamins and nutrients that it needs. In this sense the saying: “you are what you eat” really does get a different meaning from the moment you start eating healthy.