Diary Writing

Ready to Move Past Little Fibs in Eating Patterns

Little fibs are among the biggest challenges in nutrition research. These little fibs show up in food diaries – self-reports of what a person in a nutrition study has eaten. People misremember, they fudge, or they might write down what they wish they had eaten. Mostly, people try to be honest, but little fibs add up and introduce systematic bias into study results. And that bias is unpredictable.

Not long ago, a group of distinguished obesity researchers pointed out that self-reports of caloric intake are so unreliable that they should be abandoned. Likewise, some researchers are questioning the value of self-reported dietary data for formulating dietary guidelines. Discussion of these issues tends to break down. Some scientists have a hard time walking away from flawed data when it’s the only data they have.

But a series of four papers in the new issue of the American Journal of Clinical Nutrition suggest we may be ready to resolve those unproductive arguments. The emerging science of metabolomics is providing a solution that looks ever more promising.

Metabolomics is the study of small molecules in biological samples. Patterns of metabolites provide clues to health status and dietary patterns. In one of the AJCN studies this month, Mary Playdon and colleagues demonstrate how serum metabolites can serve as a good proxy for diet quality.

Reviewing this and two other papers in the same issue of AJCN, Lorraine Brennan concludes:

We now have had approximately ten years of reported associations between food intake and biomarkers. Although there is no question about the links, it is now imperative to move these biomarkers into practice.

Perhaps soon we can put arguments about food diaries behind us. Facts are stubborn and, at the same time, helpful. But to learn from facts, we have to start collecting them. Metabolomics may soon help us move past the little fibs embedded in food diaries.

Click here for the study by Playdon et al and here for the commentary by Brennan. For a study of dietary patterns and markers of cardiometabolic health, click here. And for a study of biomarkers in a controlled feeding study, click here.

Diary Writing, photograph © Fredrik Rubensson / flickr

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February 11, 2017