Impacts of minimally-processed omnivorous vs lacto-ovo-vegetarian diets on insulin sensitivity, lipid profile, and adiposity in older adults: Secondary findings from a randomized crossover feeding trial
Abstract
BACKGROUND AND AIMS
The aging population in the U.S. faces increased cardiometabolic risk, reducing healthspan and increasing public health burden. These vulnerabilities may be compounded by ultra-processed food (UPF). No feeding trial has evaluated UPF reduction in older adults within the framework of Dietary Guidelines for Americans (DGA). This study addressed the gap using representative omnivorous and lacto-ovo vegetarian patterns.
METHODS
The secondary outcomes of the Protein-Distinct Macronutrient-Equivalent Diet 2 (PRODMED2) trial compared two DGA-aligned, low-UPF diets with each other and with a high-UPF habitual baseline (BSL) diet in 36 community-dwelling older adults. The diets featured minimally processed pork (MPP) and lentils (MPL) as representative animal- and plant-based primary proteins, each provided for 8 weeks without calorie restriction and separated by a 2-week washout. Diet compositions and intakes, body composition, cardiometabolic biomarkers, and hormones linked to nutrient sensing and energy balance were measured before and after interventions, with a subset of measures repeated at ∼1-year post-intervention follow-up (FUP). Data were primarily analyzed using robust linear mixed-effects models adjusted for covariates.
RESULTS
Switching from a high-UPF BSL (∼50%E) to either low-UPF diets (∼13%E), unintentionally lowered energy intake (Δ-333 vs Δ-437 kcal/d, MPP vs MPL), resulting in reductions in body weight (Δ-3.8 vs Δ-4.4 kg), and fat mass (Δ-2.6 vs…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design.
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