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Protein intake at twice the RDA in older men increases circulatory concentrations of the microbiome metabolite trimethylamine-n-oxide (TMAO)

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posted on 2023-05-03, 18:08 authored by Sarah Mitchell, Amber MilanAmber Milan, Cameron Mitchell, Nicole Gillies, Randall D'Souza, Nina Zeng, Farha Ramzan, Pankaja Sharma, Scott KnowlesScott Knowles, Nicole Roy, Anders Sjodin, Karl-Heinz Wagner, Steven Zeisel, David Cameron-Smith
Higher dietary protein intake is increasingly recommended for the elderly; however, high protein diets have also been linked to increased cardiovascular disease (CVD) risk. Trimethylamine-N-oxide (TMAO) is a bacterial metabolite derived from choline and carnitine abundant from animal protein-rich foods. TMAO may be a novel biomarker for heightened CVD risk. The purpose of this study was to assess the impact of a high protein diet on TMAO. Healthy men (74.2 ± 3.6 years, n = 29) were randomised to consume the recommended dietary allowance of protein (RDA: 0.8 g protein/kg bodyweight/day) or twice the RDA (2RDA) as part of a supplied diet for 10 weeks. Fasting blood samples were collected pre- and post-intervention for measurement of TMAO, blood lipids, glucose tolerance, insulin sensitivity, and inflammatory biomarkers. An oral glucose tolerance test was also performed. In comparison with RDA, the 2RDA diet increased circulatory TMAO (p = 0.002) but unexpectedly decreased renal excretion of TMAO (p = 0.003). LDL cholesterol was increased in 2RDA compared to RDA (p = 0.049), but no differences in other biomarkers of CVD risk and insulin sensitivity were evident between groups. In conclusion, circulatory TMAO is responsive to changes in dietary protein intake in older healthy males.

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© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Language

  • English

Does this contain Māori information or data?

  • No

Publisher

MDPI

Journal title

Nutrients

ISSN

2072-6643

Citation

Mitchell, S. M., Milan, A. M., Mitchell, C. J., Gillies, N. A., D’Souza, R. F., Zeng, N., … Cameron-Smith, D. (2019). Protein intake at twice the RDA in older men increases circulatory concentrations of the microbiome metabolite trimethylamine-n-oxide (TMAO). Nutrients, 11(9), 2207. doi:10.3390/nu11092207

Contract number

A21246

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