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Comment by seanwilson | Hacker News Reader

Is this just a correlation or it's something more thorough?

People that have more money or are more health conscience tend to have better health could be another explanation.

Among my friends and coworkers, those who tend to eat more organic food also do a lot more physical activity/exercise than those who don't. This smells like correlation.

From the article: 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.

Even after these adjustments, the most frequent consumers of organic food had 76 percent fewer lymphomas, with 86 percent fewer non-Hodgkin’s lymphomas, and a 34 percent reduction in breast cancers that develop after menopause.

Granted, it could be that these socio-economic factors weren't adequately corrected for, but they did at least attempt to.

How do you even make those adjustments? Do we actually understand the impact on developing cancer that exercise has, for example?

The field of biostatistics is dedicated to answering those kinds of questions:

https://en.wikipedia.org/wiki/Biostatistics

The study controlled for income, other dietary factors, smoking, etc. Obviously there's only so much you can do along those lines in a self-reported study for a relatively rare phenomena (happily, not many people get cancer in a given year). But the effect seems pretty robust.

(interestingly, one thing they controlled for was ex-smokers, and not because they were less likely to eat organic but because they were more likely to do so, which I guess makes sense when you think about it, even if it seems counter-intuitive at first glance)

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