Metabolic

Is a calorie a calorie? Not always when it comes to almonds

Researchers at the University of Toronto have found that when the food source is almonds, a labeled calorie is not the same as a digested and absorbed calorie.

The results should help allay concerns that almonds contribute to weight gain, which persist despite the well-recognized benefits of nuts as a plant-based source of protein, vitamins, and minerals.

“Nuts have been widely considered healthy for the past two decades, but mail messages about nuts are often accompanied by a disclaimer that they are high in fat and energy,” said John Sievenpiper, the study’s lead researcher and associate professor on the departments in Nutrition and Medicine at the Temerty Faculty of Medicine.

John Sievenpiper

John Sievenpiper, University of Toronto. Photo credit: University of Toronto

“We still see this limitation in the media and on the Internet today, and it has been part of many clinical guidelines, although that is changing,” said Sievenpiper, who is also a staff doctor and researcher at St. Michael’s Hospital, Unity Health, Toronto.

“Other researchers have shown that there is a bioavailability problem with nuts and that a labeled calorie may not be an ingested calorie. This study quantifies this effect with almonds in a relevant population, ”said Sievenpiper.

Mayo Clinic Proceedings published the results recently.

The researchers found that after digestion, about 20 percent of the calories, mostly from fat in almonds, were not absorbed, which they observed in stool samples. This means that the study participants take in about two percent less energy from their diet.

A person who eats the same amount of almonds on a daily diet of 2,000 to 3,000 calories would absorb 40 to 60 fewer calories than would be predicted by Atwater factors, on which many food labels are based. This could result in a weight loss of up to 2.9 kilograms or 6.3 pounds per year unless compensation is made in the form of increased intake or decreased energy expenditure.

The study participants didn’t gain weight, which is in line with most high-quality studies measuring nut consumption and weight gain, some of which have been linked to weight loss, Sievenpiper said.

Stephanie Nishi

Dr. Stephanie Nishi, University of Toronto. Photo credit: University of Toronto

Researchers used a randomized crossover study to study 22 women and men with high cholesterol who underwent a series of three month long dietary interventions separated by a one week washout period.

All study participants consumed an NCEP Step 2 diet (low in saturated fat and cholesterol, part of the US National Cholesterol Education Program). The three dietary interventions were full-dose almonds (75 grams per day, or three-quarters of a cup); Half-dose almonds plus half-dose muffins; and full-dose muffins as study controls.

The nutritional makeup of the muffins matched the amount of protein, fiber, and fats in the almonds.

“A unique aspect of this study is evaluating people with high cholesterol who are at higher risk for cardiovascular disease,” said Stephanie Nishi, a PhD student in nutrition at the time of the study and now a postdoctoral fellow at the University of Rovira i Virgili in Spain.

“This has never been done in this population, and it’s important because because of the evidence of nut consumption and heart health, this group usually gets a lot of messages to eat more nuts,” Nishi said.

Nishi and Sievenpiper both said there was a huge gap between the number of nuts people should consume and the number of nuts they actually eat, in general and in populations at risk for cardiovascular and others Diseases exist.

Other barriers resulting from weight gain concerns are counterproductive.

Diabetes Canada recently adjusted its guidelines, based in part on the study’s results, to avoid the stigma surrounding nuts and weight gain, said Sievenpiper, who contributed to guidelines for patients with diabetes and other metabolic disorders, as well as cardiovascular disease .

Reference: “Almond Bioavailability in a Randomized Crossover Study: Is a Calorie a Calorie?” by Stephanie K. Nishi RD, PhD; Cyril WC Kendall PhD; Richard P. Bazinet PhD; Anthony J. Hanley PhD; Elena M. Comelli PhD; David JA Jenkins, PhD, DSc and John L. Sievenpiper, PhD, April 11, 2021, Mayo Clinic Proceedings.
DOI: 10.1016 / j.mayocp.2021.01.026

Funding: PSI Graham Farquharson Knowledge Translation Scholarship and a Sun Life Financial New Investigator Award from the Banting and Best Diabetes Center and the Almond Board of California

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