Protein intake at twice the RDA in older men increases circulatory concentrations of the microbiome metabolite Trimethylamine-N-Oxide (TMAO)

TY - JOUR

T1 - Protein intake at twice the RDA in older men increases circulatory concentrations of the microbiome metabolite Trimethylamine-N-Oxide (TMAO)

AU - Mitchell, Sarah M

AU - Milan, Amber M

AU - Mitchell, Cameron J

AU - Gillies, Nicola A

AU - D'Souza, Randall F

AU - Zeng, Nina

AU - Ramzan, Farha

AU - Sharma, Pankaja

AU - Knowles, Scott O

AU - Roy, Nicole C

AU - Sjödin, Anders Mikael

AU - Wagner, Karl-Heinz

AU - Zeisel, Steven H

AU - Cameron-Smith, David

N1 - CURIS 2019 NEXS 329

PY - 2019/9

Y1 - 2019/9

N2 - 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.

AB - 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.

KW - CVD

KW - CVD biomarkers

KW - Elderly

KW - High protein diet

KW - TMAO

UR - http://www.scopus.com/inward/record.url?scp=85072567090&partnerID=8YFLogxK

U2 - 10.3390/nu11092207

DO - 10.3390/nu11092207

M3 - Journal article

C2 - 31547446

AN - SCOPUS:85072567090

SN - 2072-6643

VL - 11

JO - Nutrients

JF - Nutrients

IS - 9

M1 - 2207

ER -