Effects of a pulse-based, guidelines-aligned diet on biomarkers relevant to aging: Results from the PRODMED1 randomized controlled crossover feeding trial.

BACKGROUND AND AIMS

Pulse-based diets are naturally low in methionine, an amino acid whose restriction has been linked to improved metabolic health and longevity. This study evaluated how a pulse-protein diet (PPD), relative to a meat-protein diet (MPD), both aligned with the Dietary Guidelines for Americans (DGA), influenced cardiometabolic and iron-related biomarkers relevant to aging in older adults.

METHODS

This Protein-Distinct Macronutrient-Equivalent Diet 1 (PRODMED1) trial was conducted among Midwestern adults aged ≥60 years. Participants consumed MPD and PPD for eight weeks each, separated by ≥2-week washout. Primary protein sources (162g/d lean pork vs. 331.6g/d pulses) contributed ≥45% of total dietary protein. Diets were matched for total iron, energy, and macronutrients but differed in heme iron and methionine. Primary outcomes were ferritin, fasting blood glucose, and trimethylamine N-oxide (TMAO); secondary outcomes included inflammation, body composition, lipid-related cardiovascular risk biomarkers, and circulating biogenic amines. Analyses were conducted using robust linear mixed-effects models, adjusted for covariates.

RESULTS

Forty-seven participants completed the trial (72% women; age 69.2 ± 6.6 years; BMI 28.6 ± 5.4 kg/m²). Regardless of protein source, both diets improved biomarkers of glucose and lipid metabolism except HDL (all, p<0.05; no between-diet differences), while TMAO remained unchanged. Total and visceral fat mass declined (both, p<0.0001; no between-diet differences), with a greater reduction in the visceral-to-total fat ratio during PPD vs. MPD (p<0.05). PPD demonstrated a larger increase in ferritin relative to MPD (PPD: +15.7 ng/mL vs. MPD: +7.0 ng/mL; between-diet p=0.027), and CRP decreased in both groups (both, p≤0.001, no between-diet differences). MPD and PPD resulted in distinct circulating biogenic amine profiles (p=0.001).

CONCLUSIONS

High-quality DGA-aligned diets improved cardiovascular risk factors irrespective of primary protein sources, underscoring the importance of overall dietary-matrix quality. However, the pulse-based diet conferred additional benefits to visceral-to-total fat ratio and iron status, supporting pulses as a feasible, nutrient-dense, and effective dietary strategy with potential relevance for promoting healthspan in aging populations.

CLINICAL TRIAL REGISTRY

The trial is registered at www.

CLINICALTRIALS

gov as NCT05577858 on October 11, 2022.

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