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Walnuts Consumed by Healthy Adults Provide Less Available Energy than Predicted by the Atwater Factors.
J Nutr. 2016 Jan; 146(1):9-13.JN

Abstract

BACKGROUND

Previous studies have shown that the metabolizable energy (ME) content (energy available to the body) of certain nuts is less than predicted by the Atwater factors. However, very few nuts have been investigated to date, and no information is available regarding the ME of walnuts.

OBJECTIVE

A study was conducted to determine the ME of walnuts when consumed as part of a typical American diet.

METHODS

Healthy adults (n = 18; mean age = 53.1 y; body mass index = 28.8 kg/m(2)) participated in a randomized crossover study with 2 treatment periods (3 wk each). The study was a fully controlled dietary feeding intervention in which the same base diet was consumed during each treatment period; the base diet was unsupplemented during one feeding period and supplemented with 42 g walnuts/d during the other feeding period. Base diet foods were reduced in equal proportions during the walnut period to achieve isocaloric food intake during the 2 periods. After a 9 d diet acclimation period, subjects collected all urine and feces for ∼1 wk (as marked by a Brilliant Blue fecal collection marker) for analysis of energy content. Administered diets, walnuts, and fecal and urine samples were subjected to bomb calorimetry, and the resulting data were used to calculate the ME of the walnuts.

RESULTS

One 28-g serving of walnuts contained 146 kcal (5.22 kcal/g), 39 kcal/serving less than the calculated value of 185 kcal/serving (6.61 kcal/g). The ME of the walnuts was 21% less than that predicted by the Atwater factors (P < 0.0001).

CONCLUSION

Consistent with other tree nuts, Atwater factors overestimate the metabolizable energy value of walnuts. These results could help explain the observations that consumers of nuts do not gain excessive weight and could improve the accuracy of food labeling. This trial was registered at clinicaltrials.gov as NCT01832909.

Authors+Show Affiliations

USDA, Agricultural Research Service, Beltsville Human Nutrition Research Center, Beltsville, MD David.Baer@ars.usda.gov.USDA, Agricultural Research Service, Beltsville Human Nutrition Research Center, Beltsville, MD.USDA, Agricultural Research Service, Beltsville Human Nutrition Research Center, Beltsville, MD.

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

26581681

Citation

Baer, David J., et al. "Walnuts Consumed By Healthy Adults Provide Less Available Energy Than Predicted By the Atwater Factors." The Journal of Nutrition, vol. 146, no. 1, 2016, pp. 9-13.
Baer DJ, Gebauer SK, Novotny JA. Walnuts Consumed by Healthy Adults Provide Less Available Energy than Predicted by the Atwater Factors. J Nutr. 2016;146(1):9-13.
Baer, D. J., Gebauer, S. K., & Novotny, J. A. (2016). Walnuts Consumed by Healthy Adults Provide Less Available Energy than Predicted by the Atwater Factors. The Journal of Nutrition, 146(1), 9-13. https://doi.org/10.3945/jn.115.217372
Baer DJ, Gebauer SK, Novotny JA. Walnuts Consumed By Healthy Adults Provide Less Available Energy Than Predicted By the Atwater Factors. J Nutr. 2016;146(1):9-13. PubMed PMID: 26581681.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Walnuts Consumed by Healthy Adults Provide Less Available Energy than Predicted by the Atwater Factors. AU - Baer,David J, AU - Gebauer,Sarah K, AU - Novotny,Janet A, Y1 - 2015/11/18/ PY - 2015/05/18/received PY - 2015/10/19/accepted PY - 2015/11/20/entrez PY - 2015/11/20/pubmed PY - 2016/5/11/medline KW - Atwater factors KW - calories KW - macronutrient digestibility KW - metabolizable energy KW - nuts KW - walnuts SP - 9 EP - 13 JF - The Journal of nutrition JO - J. Nutr. VL - 146 IS - 1 N2 - BACKGROUND: Previous studies have shown that the metabolizable energy (ME) content (energy available to the body) of certain nuts is less than predicted by the Atwater factors. However, very few nuts have been investigated to date, and no information is available regarding the ME of walnuts. OBJECTIVE: A study was conducted to determine the ME of walnuts when consumed as part of a typical American diet. METHODS: Healthy adults (n = 18; mean age = 53.1 y; body mass index = 28.8 kg/m(2)) participated in a randomized crossover study with 2 treatment periods (3 wk each). The study was a fully controlled dietary feeding intervention in which the same base diet was consumed during each treatment period; the base diet was unsupplemented during one feeding period and supplemented with 42 g walnuts/d during the other feeding period. Base diet foods were reduced in equal proportions during the walnut period to achieve isocaloric food intake during the 2 periods. After a 9 d diet acclimation period, subjects collected all urine and feces for ∼1 wk (as marked by a Brilliant Blue fecal collection marker) for analysis of energy content. Administered diets, walnuts, and fecal and urine samples were subjected to bomb calorimetry, and the resulting data were used to calculate the ME of the walnuts. RESULTS: One 28-g serving of walnuts contained 146 kcal (5.22 kcal/g), 39 kcal/serving less than the calculated value of 185 kcal/serving (6.61 kcal/g). The ME of the walnuts was 21% less than that predicted by the Atwater factors (P < 0.0001). CONCLUSION: Consistent with other tree nuts, Atwater factors overestimate the metabolizable energy value of walnuts. These results could help explain the observations that consumers of nuts do not gain excessive weight and could improve the accuracy of food labeling. This trial was registered at clinicaltrials.gov as NCT01832909. SN - 1541-6100 UR - https://www.unboundmedicine.com/medline/citation/26581681/Walnuts_Consumed_by_Healthy_Adults_Provide_Less_Available_Energy_than_Predicted_by_the_Atwater_Factors_ L2 - https://academic.oup.com/jn/article-lookup/doi/10.3945/jn.115.217372 DB - PRIME DP - Unbound Medicine ER -