09 January 2008

Jury Out On Organic Health Benefits

According to Ecologist online, there is precisely one scientific study, as of September 2007, that shows "a direct positive health impact from eating organic food." The benefit is in a fairly narrow circumstance and the health harm fairly modest.

The research showed that infants fed organic dairy products, and whose mothers had also eaten organic dairy during pregnancy, had a 36 per cent lower incidence of eczema than those who consumed conventional dairy products.

Of course, the best health choice for an infant is not to use any dairy products other than breast milk at all, a proposition for which there is very strong evidence. Also, pregnant women are a natural place to look for health benefits, as the hypersensitivity of pregnant women to environmental factors is well established.

The study, as it is narrow, however, does not determine more broadly if there are health risks, as well as benefits, to organic food. Recent cases of food poisoning from organic spinach make clear that organic doesn't mean risk free. Fertilizers are used to encourage healthy growth in plants and pesticides are meant to prevent insects from harming plants. Insect infected plants (as a result of not using pesticides) could also pose health risks, and the fact that something is "natural" doesn't mean that it is safe. Nature is full of poisonous plants and pathogens every bit as bad as those we devise ourselves. In the same vein, "herbal" does not mean safe, it means "not proven to be safe and effective."

This doesn't mean that there aren't health benefits from eating organic, and there isn't any evidence of which I am aware that eating organic is on average less healthy than eating conventional food. There is suggestive evidence that shows that there are real differences, at a statistical level anyway, between organic and non-organic food that one can plausibly imagine might have health benefits. But, the same study makes clear that the evidence that health benefits actually result from these differences is inconclusive. Certainly, the evidence of health benefits is surprisingly slim to form a basis for what is a several decades old major agricultural industry whose marketing has been based to a great extent upon the personal health benefits of eating organic food.

On the other hand, in part, the lack of proof arises from the difficulty in proving the health benefits of something like eating organic foods and the lack of an obvious sponsor for such an expensive study. No one small organic farmer can afford that, and even associations of organic farmers tend to be small and cash strapped. Any study attempting to prove that there are health benefits from eating organic food also runs up against the usual confounding difficulties involved in any study of large populations of human subjects.

Organic dairy product use, for example, normally isn't an independent variable from other plausible lifestyle issues with important health impacts. For example, it is safe to guess that people who make an effort to buy organic produce, on average, eat more fruits and vegetables than those who do not. Likewise, in the American context, at least, an "organic lifestyle" is also correlated with affluence, access to health care, and individuals who pay attention to their own personal health and exercise regimes. In our current economy it takes more time and money to buy organic, involuntarily excluding the poor and those with little leisure time. It is, of course, uncontroversial that eating more fruits and vegetables, getting more exercise, and being able to access health care when appropriate, and for that matter, on average, affluence (which, for example, makes it less likely that you will live near a toxic chemical emitting industrial facility or in a home with lead pipes), is good for your health. Even if organic foods were actually, on average, slightly worse for you from a health perspective than conventional foods, we would expect people who follow the American version of the "organic lifestyle" to be healthier.

There are proven benefits of organic farming that do not involve personal health. Most importantly, organic farming is far less reliant upon petroleum based fertilizers, reducing the oil dependency of our economy. As oil prices rise, organic food should actually become cheaper than conventional food (of course, a century ago, almost all food was organic). Likewise, there is evidence that pesticides and fertilizers are harmful to the natural environment, and may pose health risks to farmers. But, the main solidly fact based reasons to buy organic are altruistic and environmental in nature, not personal health based.


Anonymous said...

Your "lack of proof" may more be a result of you not being aware of the many, many studies showing the benefits of organics and the harmful effects of conventional farming. Here are a few: http://green.msn.com/articles/article.aspx?aid=295>1=10725

Andrew Oh-Willeke said...

You provided five links.

The first one was a bad link and I couldn't find the article. An article on the topic at the same site is this one. It concurs with me that there are differences in pesticide exposure between organics and non-organics, but that the levels received from eating conventional foods is so low that it isn't clear whether or not it is clinically significant, and the alleged nutritional benefits have not been established to be consistent (i.e. a result of organic farming as opposed to just a result of quality farming), or significant for the quantity of foods that normal people eat in the context of a larger healthy diet. It confirms my observation about sustainability "crop yields were about 20 percent lower in organic systems. But . . . in some cases, organic farming methods used less than half the fertilizer and energy of conventional methods. Thus, organic farming methods may ultimately be more sustainable than chemical-intensive farming."

The second echos the study I cite which shows that organic produce is distinguishable from non-organic produce in certain ways, and that the distinctions could plausibly could lead to health benefits, but doesn't actually show any health benefits.

The third (ehponline) shows that pesticide and fertilizer use on farms is corrollated to a statistically significant level with increased incidence of autism spectrum disorders among mothers who were living near these pollution sources at the time the pollution was being emitted in the weeks of pregnancy (the first eight) which is associated the development of the systems impaired in pregnancy. Specifically, it found that "models comparing
children of mothers living within 500 m [about three city blocks in distance] of field sites with the highest nonzero quartile of
organochlorine poundage to those with mothers not living near field sites suggested an odds ratio
for ASD of 6.1 (95% confidence interval, 2.4–15.3). ASD risk increased with the poundage of
organochlorine applied and decreased with distance from field sites."

The second to last link (Organic Center 101) involves pregnant women using organic milk and meat and is dated August 2007. This is similar in design to the first study I linked to in my post, and is also conducted in Europe, at almost the same time. But, unlike the study I cite, I says that organic dairy and meat changes breast milk composition in a way that in theory ought to be good, rather than linking it to a health outcome. There is only a health benefit if rumenic acid levels in breast milk of comparable women who do not eat organic doesn't meet an infant's needs, something not established by the study. It is a bit like saying that Vitamin C levels are higher in people who drink a tall glass of orange juice every day and also take a vitamin supplement. Maybe it is good, but there is nothing in the study that shows that this is the case.

The last of the links (Organic Center 102) shows that pestisides are harmful to pregnant farmers who encounter them occupationally.

In short, all of those links agree with my post that the evidence of actual health benefits from eating organic food is slim, even though organic may have health benefits and may be a good thing for other reasons.