The new study published in the prestigious Journal Of the American Medical Association (JAMA):
Association of Frequency of Organic Food Consumption With Cancer Risk, JAMA Internal Medicine, 22 October 2018
A higher frequency of organic food consumption was associated with a reduced risk of cancer. Although the study findings need to be confirmed, promoting organic food consumption in the general population could be a promising preventive strategy against cancer.
My first reaction:
I expected the researchers to adjust for some variables that would account for class-related differences. They did:
Participants in the French study also provided information about their general health status, their occupation, education, income and other details, like whether they smoked. Since people who eat organic food tend to be health-conscious and may benefit from other healthful behaviors, and also tend to have higher incomes and more years of education than those who don’t eat organic, the researchers made adjustments to account for differences in these characteristics, as well as such factors as physical activity, smoking, use of alcohol, a family history of cancer and weight.
– Can Eating Organic Food Lower Your Cancer Risk?, Roni Caryn Rabin at the New York Times, 23 October 2018
Here’s what Patrick Clinton at New Food Economy said:
One of the good things about the study is that it tried to correct for alternative possibilities — the idea that something else, like income or education or exercise habits, might be causing the reduction in cancer.
– A New Study Says Organic Food Cuts Cancer Risk By 25 Percent. Take That With A Massive Grain Of Salt
But it’s impossible to account for everything class-related that could impact such a slow-growing disease like cancer (they only assessed after 5 years which is pretty short in a cancer epidemiological study, but it’s still telling). Some variables they didn’t account for: sleep, stress, crime, air pollution, water contamination.
People at the lower end of the socioeconomic ladder get more cancers than those at the upper end. Eating organic food may not in itself be reducing cancer risk. It may just be a marker, a class marker, a proxy measure.
Something else Clinton said:
Here’s part of the authors’ analysis: “When considering different subgroups, the results herein were no longer statistically significant in younger adults, men [who made up less than a quarter of the study], participants with only a high school diploma and with no family history of cancer, never smokers and current smokers, and participants with a high overall dietary quality.” Participants with a high overall dietary quality? That sure sounds like a concession that if you eat a good diet, organic food doesn’t provide additional protection against cancer. And arguably that’s a direct contradiction of the point the article is trying to make.
All those groups lost their statistical significance. So … more study is needed. One thing that would help is backing up the food records with blood work. But even then you can’t tell where, say, the pesticides in their blood are coming from. Might not be the food.
Study limitations aside, it’s worrisome that their strongest association was between organic food and lymphomas, which are cancers known to be linked to pesticides. From the New York Times:
Even after these adjustments, the most frequent consumers of organic food had 76 percent fewer lymphomas, with 86 percent fewer non-Hodgkin’s lymphomas.
The reductions in lymphomas may not be all that surprising. Epidemiological studies have consistently found a higher incidence of some lymphomas among people like farmers and farm workers who are exposed to certain pesticides through their work.
The International Agency for Research on Cancer has classified three pesticides commonly used in farming — glyphosate, malathion and diazinon — as probable human carcinogens, and linked all three to non-Hodgkin’s lymphoma.
I believe organic food – any food grown with fewer chemicals – is healthier, for both people and the planet. But telling people to eat organic, to do something without making sure they have the ability to do it is mean. As one commenter, RC, in the New York Times article put it:
“The goal should be to reduce or eliminate as many potential toxins from our food supply as possible, not just provide safer food for the well-to-do and more toxic food for everyone else.”