A new epidemiological study finds a correlation with eating a highly processed diet at age 3 and later slightly lower IQ (by a few points). The study compared diets of children from ages 3 to 8 – the diets fell into three categories: high in processed food, traditional (meat and potatoes) and “health conscious” (lots of salads and fish). They found a difference only in the high in processed food diet with the lower IQ.

From one point of view, the lesson to be drawn from this study is obvious – growing kids have a high metabolic and nutritional demand, the brain is particularly demanding, and therefore suboptimal nutrition can be a drag on development. This effect is clear in children who are undernourished. It remains unclear if there are significant difference in children who are well-fed but who have diets which are not considered healthful. This study suggests there is a small difference.

But I must point out that this is an epidemiological, not experimental, study. So the children were not randomized to different diets. The researchers controlled for the obvious confounding factors, like socio-economic group and breast feeding, but there are potentially many other confounding factors that were not controlled for. For example – parents who rely on processed food might do so because they have little time to cook or prepare better meals. These same parent may spend less quality time with their children. Or parents who allow their kids to eat mainly processed foods may be more permissive in general. I wonder, for example,  if they controlled for television watching or video-game playing.

Given the small size of the effect in this study and the observational, rather than experimental, design of the study I don’t think we can draw any firm conclusions from the results. At best the results are interesting and require further study.

I do think we need to examine the processed food industry, on many levels – salt content, calorie content, and overall nutritional content. I do not see any reason why processed food cannot be as healthful as whole food. It seems to me that many people assume this is not the case, based upon nothing but the naturalistic fallacy. It should only depend on what is put into the processed food. Manufacturers are under marketing pressure to make their products affordable and tasty, and so they manipulate the content to have good mouth feel (which usually means fat) and good taste (fat, sugar, and salt) and a long shelf life (salt).

Processed food is not necessarily lacking in vitamins, minerals, or quality proteins or fats as building blocks. It depends on the specific product.

We should resist the urge to make processed food into an automatic villain. Rather we should demand from the industry transparency in what is in their products, and demand more healthful products with less salt, fewer calories, and more complete nutrition. There has been some shift in this direction, but it’s not clear if it has had any significant impact. It seems that manufacturers use whatever the latest health food fad is for marketing. If people want low fat, then they will have low fat products with tons of sugar. If they want low carbs, then they up the fat. Probably some combination of regulation and savvy consumers will be necessary to reform the industry.