A Cure for Pervasive Bias

We learned this week of yet another instance when pervasive bias distorted nutrition policy. In PLOS Medicine, Cristin Kearns and Stanton Glantz analyze documents from the 1960s that the sugar industry submitted to a committee formulating research priorities for the National Caries Program. They conclude that the industry successfully diverted the panel’s attention away from research into limiting sugar consumption — thus protecting their business interests. And they go on to say this means that:

Industry opposition to current policy proposals — including a World Health Organization guideline on sugars proposed in 2014 and changes to the nutrition facts panel on packaged food in the US proposed in 2014 by the US Food and Drug Administration — should be carefully scrutinized to ensure that industry interests do not supersede public health goals.

Healthy skepticism is indeed warranted, especially regarding details of nutrition policy that have become highly polarized. Financial interests of industry are an important source of bias. Other sources of bias are important as well, especially in the realm of nutrition and obesity.

Exposure bias can be an important factor when an idea is repeated so frequently that it comes to be accepted as true in the absence of actual evidence. In nutrition and obesity this type of bias is important because some associations are observed so frequently that a causal relationship is assumed to exist. One such example is the false belief that breast feeding prevents childhood obesity.

Another source of bias is the sense of moral imperative that surrounds many aspects of nutrition. In the face of a moral imperative, critical thinking can be set aside. Dietary practices have important implications in many religious traditions. Echoing such traditions, dietary fads can develop a cult following. The language of moral imperatives can even find its way into nutrition literature. A relevant example is the portrayal of sugar as a toxin in the journal Nature. Bias that comes from a sense of moral imperative has been described as white hat bias.

Without a doubt, bias is pervasive in many forms. Explicit financial interests are important sources, but hardly the only ones. Anyone who proclaims that they are free of bias should be regarded with extreme skepticism.

The only reliable cure for pervasive bias is scientific rigor paired with critical thinking.

Click here to read the publication in PLOS Medicine, here to read more from the Washington Post, and here to read more about bias affecting nutrition science.

Thinking, photograph © Cristián Arismendi / flickr

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