The lower-than-expected metabolizable energy may explain the lack of association between nut intake and weight gain

Advances in Nutrition is set to publish the first-ever systematic review of the body of evidence on the metabolizable energy content and lipid bioaccessibility of tree nuts and peanuts.

The authors of the review searched the PubMed, Medline, CINAHL, Cochrane and Embase databases to June 2021. To be eligible for inclusion, studies needed to: 1) include adults ≥18 years (except for in vitro studies); 2) explore the consumption of tree nuts typically included in nutrition research and/or peanuts, in the form of either whole nuts, chopped nuts, nut butters or nut flours; and 3) assess the metabolizable energy as lipid release (in vitro studies) or fecal energy and/or fat excretion (human studies). A total of 21 studies were included. Data were synthesized via narrative synthesis and results were reported in summary tables.

The findings suggest that the metabolizable energy of nuts is lower than what would be expected according to the Atwater factors (a common system for allocating energy values to foods), apparently due to lower lipid release during digestion and higher fecal fat excretion in people with nut-containing diets. Metabolizable energy was impacted by nut type, physical processing and heat treatment.

These results may partially explain the lack of an effect of nut consumption on body weight reported in the scientific literature. The lower metabolizable energy of nuts observed in this study has implications for the development of food composition databases, food labeling and dietary guidelines.

This study was supported by Nuts for Life.

Nikodijevic, C. J., Probst, Y. C., Tan, S., Neale, E. P. (2023). The metabolizable energy and lipid bioaccessibility of tree nuts and peanuts: a systematic review with narrative synthesis of human and in vitro studies. Advances in Nutrition.

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