Are Policies to Cut Sugar Intake Justified?

One key article of faith for many people in nutrition, obesity, and health is that Americans are consuming too much added sugar for optimal health. The 2015 Dietary Guidelines Advisory Committee recommends in their recent report that “added sugars should be reduced in the diet and not replaced with low-calorie sweeteners.” But today in the Journal of the American Medical Association, two respected obesity researchers, Nikhil Dhurandhar and Diana Thomas, are asking whether policies to cut sugar intake are justified by scientific data.

Dhurandhar chairs the Department of Nutritional Sciences at Texas Tech University and presently serves as President of the Obesity Society. Thomas is Director of the Center for Quantitative Obesity Research at Montclair State University.

Dhurandhar and Thomas point out that the scientific link between excess cardiovascular mortality and added sugar consumption is not fully defined:

Although added sugar intake may increase CVD risk factors, the causal relationship between sugar ingestion, CVD risk factors, and CVD mortality remains unclear.

In other words, we don’t really know that excessive sugar consumption actually causes the excess risk that is associated with it. Causality is a devilish problem to work out, but ignoring the problem can lead to regrets.

And beyond that problem, there’s the problem of how much added sugar consumption is too much. Two different scientific bodies — the World Health Organization (WHO) and the Institute of Medicine (IOM) — intensively reviewed the evidence and reached different conclusions. WHO concluded that the recommendation should be to limit added sugar consumption to 10% of total calories. IOM concluded that the evidence supported a higher threshold, 25%.

This makes a difference because relatively few Americans exceed the IOM recommendation, while a majority exceed the WHO recommendation. Does it makes sense to nudge the entire population to cut its consumption of added sugar? That really depends upon what the right threshold is for improved health. And conclusions about that are based on very educated guesses, not actual proof.

Commenting on the publication, Thomas said, “Our real conclusion is that this has not been fully resolved.”

Jumping into population-wide experiments on nutrition sometimes works out badly. Perhaps we need a scientific consensus on added sugar guidance first.

Click here to read the publication by Dhurandhar and Thomas, here to read a recent study of cardiovascular risk and added sugar, and here for a controlled study of sugar and clinical measures of cardiometabolic  risk.

Sugaring Season, photograph © Chiot’s Run / flickr

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