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Monday, March 31, 2014

Organic food does not protect against cancer

The Soil Association[1] was founded in 1946 and today is the main body for the certification of organic farms in the UK. It’s website has a section on pesticides, which states the following: “Around 31,000 tonnes of chemicals are used in farming in the UK each year to kill weeds, insects and other pests that attack crops. There is surprisingly little control over how these chemicals are used in the non-organic sector and in what quantities or combinations. What we do know is that 150 of the available 311 pesticides commonly used have been identified as potentially causing cancer and many of us would have been exposed to these pesticides before we were born”. It then goes on to state: ”Even food that we think is healthy, such as non-organic Cox's apples, can be sprayed 18 times. The most dangerous chemicals used in farming, such as organophosphates, have been linked with a range of problems including cancer, decreasing male fertility, foetal abnormalities, chronic fatigue syndrome in children and Parkinson's disease”. This linking of organic food with a reduced exposure to so-called cancer-causing pesticides is a widely held belief among organic food advocates.
That view within the organic movement is unlikely to be changed by a recent study refuting this belief but the majority of people who are made to worry about this alleged pesticide-cancer link will take solace from its findings. The paper, published in the British Journal of Cancer[2] was based on data from The Million Women study, which was based on a million women screened for breast cancer, followed these women over a 12 year period with questionnaires on lifestyle completed at baseline and at years 3, 8 and 12. In the year 3 questionnaire, women were asked about their consumption of organic food within categories, “never”, “sometimes”, “usually” or “always”. A total of 751,975 provided data on their organic food intake in year 3. In this particular study part of the study, women were excluded if they had changed their diet in the previous 5 years because of an illness. That then left the researchers with data on 623,080 women.

At the outset of the study, 30% of women reported never consuming organic food, 63% sometimes consumed organic food and 7% reported always or usually eating organic food. During the follow up period of almost 9 years, a total of 53,769 women were diagnosed with some form of cancer. The authors looked at the relative risk of 16 cancers across the frequency of use of organic food. They controlled for age, area of residence, body mass index, smoking, physical activity, alcohol intake, age at first birth, fibre intake and type of meat intake. Compared to women who never consumed organic food, there was a 9% greater incidence of cancer among women who usually or always consumed organic food. The one exception was Non-Hodgkin Lymphoma (NHL) where those who usually or always consumed organic food had a 21% lower risk of NHL than women who never consumed organic food.

Already the organic movement is claiming that the 21% reduction in NHL is proof that pesticides are a causative factor in cancer. However, NHL in the UK accounts for just 4% of all cancers. Thus there were 161,215 cases of cancer among UK women in 2011 of which 155,358 or 96% of all cases did not involve NHL with cancer of the breast, bowel, lung, uterus and ovaries accounting for 62% of all cancers[3]. No matter what way the organic advocates dredge the data, the simple fact remains that the consumption of organic food had no overall protective effect against cancer (indeed it was 9% higher in the organic food consumers).
Plants maintain a natural defence system against pests and thus the overall load of exposure to natural pesticide is enormous concerned to our exposure to pesticides used in agriculture whether for commercial or organic agriculture. Data shows that using the rodent carcinogenic model, of the plants natural pesticides, 55% were positive carcinogens and 45% were not[4]. All available data show that about half of all naturally derived chemicals are positive in the rat carcinogenic model. The figure for all synthetic chemicals is also about 50%. Natural doesn’t equate with safety. Think of hemlock, magic mushrooms, opium, caffeine and nicotine to name a few.

People make all sorts of decisions about their lifestyle including diet. Some opt to be vegetarian. Some prefer to eat organic food. Some choose food based on a perceived allergy. The reasons are endless. So live and let live but please don’t preach about the health virtues of organic food to consumers who are not so inclined for whatever reason. Enjoy your food whatever your choice and let others enjoy theirs. There are many great challenges facing us in terms of public health nutrition. This paper, the first of its kind, has binned the claim of the organic food movement that consuming conventionally farmed foods can lead to exposure to cancer causing pesticides.

[2] Bradbury KE et al 2014 March 24 (e print ahead of publication)
[4] Ames BN & Gold LS (1997) FASEB J. 1Nov;11(13):1041-52

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