TY - JOUR

T1 - Responsiveness of one-carbon metabolites to a high-protein diet in older men: Results from a 10-wk randomized controlled trial

AU - Gillies, Nicola A

AU - Milan, Amber M

AU - Chia, Pamela H P

AU - Sharma, Pankaja

AU - Mitchell, Sarah M

AU - Zeng, Nina

AU - Ramzan, Farha

AU - D'Souza, Randall F

AU - Mitchell, Cameron J

AU - Knowles, Scott O

AU - Andraos, Stephanie

AU - Sjödin, Anders

AU - Wagner, Karl Heinz

AU - Roy, Nicole C

AU - Cameron-Smith, David

N1 - Publisher Copyright: © 2021 Elsevier Inc.

PY - 2021

Y1 - 2021

N2 - Objectives: Dietary strategies to promote successful aging are divergent. Higher-protein diets are recommended to preserve skeletal muscle mass and physical function. Conversely, increased B-vitamin intake, supporting one-carbon (1C) metabolism, reduces the risk of cognitive decline and cardiovascular disease. On the hypothesis that higher protein intake through animal-based sources will benefit 1C regulation by the supply of B vitamins (folate, riboflavin, and vitamins B6 and B12) and methyl donors (choline) despite higher methionine intake, this study explored the effect of a higher-protein diet on 1C metabolite status in older men compared to current protein recommendations. Methods: Older men (age, 74 ± 3 y) were randomized to receive a diet for 10 wk containing either the recommended dietary allowance (RDA) of protein (0.8 g/kg body weight/d, n = 14), or double that amount (2RDA, n = 15), with differences in protein accounted for by modifying carbohydrate intake. Intervention diets were matched to each individual's energy requirements based on the Harris–Benedict equation and adjusted fortnightly as required depending on physical activity and satiety. Fasting plasma 1C metabolite concentrations were quantified by liquid chromatography coupled with mass spectrometry at baseline and after 10 wk of intervention. Results: Plasma homocysteine concentrations were reduced from baseline to follow-up with both diets. Changes in metabolite ratios reflective of betaine-dependent homocysteine remethylation were specific to the RDA diet, with an increase in the betaine-to-choline ratio and a decrease in the dimethylglycine-to-betaine ratio. Comparatively, increasing folate intake was positively associated with a change in choline concentration and inversely with the betaine-to-choline ratio for the 2RDA group. Conclusions: Adding to the known benefits of higher protein intake in older people, this study supports a reduction of homocysteine with increased consumption of animal-based protein, although the health effects of differential response of choline metabolites to a higher-protein diet remain uncertain.

AB - Objectives: Dietary strategies to promote successful aging are divergent. Higher-protein diets are recommended to preserve skeletal muscle mass and physical function. Conversely, increased B-vitamin intake, supporting one-carbon (1C) metabolism, reduces the risk of cognitive decline and cardiovascular disease. On the hypothesis that higher protein intake through animal-based sources will benefit 1C regulation by the supply of B vitamins (folate, riboflavin, and vitamins B6 and B12) and methyl donors (choline) despite higher methionine intake, this study explored the effect of a higher-protein diet on 1C metabolite status in older men compared to current protein recommendations. Methods: Older men (age, 74 ± 3 y) were randomized to receive a diet for 10 wk containing either the recommended dietary allowance (RDA) of protein (0.8 g/kg body weight/d, n = 14), or double that amount (2RDA, n = 15), with differences in protein accounted for by modifying carbohydrate intake. Intervention diets were matched to each individual's energy requirements based on the Harris–Benedict equation and adjusted fortnightly as required depending on physical activity and satiety. Fasting plasma 1C metabolite concentrations were quantified by liquid chromatography coupled with mass spectrometry at baseline and after 10 wk of intervention. Results: Plasma homocysteine concentrations were reduced from baseline to follow-up with both diets. Changes in metabolite ratios reflective of betaine-dependent homocysteine remethylation were specific to the RDA diet, with an increase in the betaine-to-choline ratio and a decrease in the dimethylglycine-to-betaine ratio. Comparatively, increasing folate intake was positively associated with a change in choline concentration and inversely with the betaine-to-choline ratio for the 2RDA group. Conclusions: Adding to the known benefits of higher protein intake in older people, this study supports a reduction of homocysteine with increased consumption of animal-based protein, although the health effects of differential response of choline metabolites to a higher-protein diet remain uncertain.

KW - Choline

KW - Elderly

KW - Folate

KW - Homocysteine

KW - Protein intake

KW - Vitamin B12

U2 - 10.1016/j.nut.2021.111231

DO - 10.1016/j.nut.2021.111231

M3 - Journal article

C2 - 33930787

AN - SCOPUS:85107084973

VL - 89

JO - Nutrition

JF - Nutrition

SN - 0899-9007

M1 - 111231

ER -