A recent study claims to confirm what a lot of people felt they already knew: eating organic can reduce your risk of getting cancer. But a closer look at the details reveals a different story.
When you ask people about the safety of our food supply, pesticides nearly always top the list of concerns. Specifically, people worry that exposure to pesticides in their food increases the risk of cancer.
On a gut level, this seems like a no-brainer. When we consume food that has been treated with pesticides, we consume trace amounts of these chemicals. And many of these compounds have been categorized as possible or probable carcinogens. How could taking in more pesticides NOT increase our cancer risk?
And yet, the available evidence didn’t seem to line up with this seemingly obvious conclusion. In 2014, for example, a ten-year study of more than a half million British women found that those who always ate organic food had essentially the same risk of getting cancer as those who never did.
This year, however, a French study seemed to find the opposite. Researchers analyzed the diets of almost 70,000 people and concluded that “a higher frequency of organic food consumption was associated with a reduced risk of cancer.”
Finally, a study confirmed what a lot of people felt that they already knew: eating organic can reduce your risk of getting cancer. Duh. Case closed.
Having looked at the details of this study, I’m not ready to close that case just yet. But before we dig into that, let’s take a brief detour to examine another closely-related belief: Eating more fruits and vegetables reduces cancer risk.
Why Would Eating Fruits and Vegetables Decrease Cancer Risk?
According to the FDA’s Pesticide Monitoring Program, your biggest dietary exposure to pesticides is from the non-organic fruits and vegetables you consume. The more non-organic fruits and vegetables you eat, the higher your likely pesticide exposure. And pesticides give you cancer, right?
And yet, some studies suggest that people who eat more fruits and vegetables have lower incidence of cancer—even if they are eating conventional fruits and vegetables.
For example, a long term study of almost 200,000 women found that those who averaged five or more servings of fruits and vegetables a day cut their risk of breast cancer by 10% compared with those who ate 2.5 servings a day or fewer (which is close to average intake).
Now, a 10 percent reduction in risk is fairly modest. Instead of 10 out of 200 women getting a breast cancer diagnosis, only nine out of 200 did. Still, if you’re that one who dodged the bullet, those extra servings of peas and carrots will probably seem more than worth it.
Other studies have found only a weak association between fruit and vegetable consumption and cancer risk—or none at all. This surprises a lot of people. After all, we talk so much about all the cancer-fighting phytochemicals found in fruits and vegetables. You’d think the cancer fighting effect of eating them would be more dramatic.
I think the link between fruit and vegetable intake and cancer risk might be more indirect. Eating more fruits and vegetables can help you maintain a healthier body weight—and that is unequivocally associated with lower cancer risk.
But the point I’m trying to make here is that if pesticide exposure increased cancer risk, we might expect to see more cancer in people who ate more conventionally-grown fruits and vegetables, because their exposure to pesticides would be larger. And yet this does not appear to be the case. While eating more fruits and vegetables may not reduce your cancer risk as much as we might have hoped, it certainly doesn’t increase it.
So with that in mind, let's look at the details of this French study.
Does Buying Organic Reduce Your Pesticide Exposure?
The authors (like many consumers) hypothesized that those who ate a lot of organic foods would have a lower risk of developing cancer because of a lower exposure to pesticide residues.
To test this hypothesis, the researchers came up with something called the Organic Food Score. To calculate this, they asked participants to say how often they consumed 16 different categories of organic foods. If you usually consumed a category of organic food, you got two points. Consuming organic sometimes got you 1 point, and never eating organic for that category earned you 0 points. The points for all 16 categories were then tallied up for a score from 0 to 32.
Although each category was weighted equally in the score, they were hardly equivalent in terms of their potential pesticide load. For example, two of the 16 categories (dairy products and eggs) are foods that generally have no detectable pesticide residues.