Associations of Increased Plant Protein Intake Ratio with Adherence of Low-Protein Diet, Acid-Base Status, and Body Composition in CKD Stage 3–5

<b>Background/Objectives</b>: Increasing evidence indicates that a vegetarian diet may provide renal protection and improve metabolic health in patients with chronic kidney disease (CKD). However, transitioning from an omnivorous to a vegetarian diet can be challenging. A more practical alternative could be to increase the consumption of plant protein. In this cross-sectional study, we investigated the association between increased plant protein intake and adherence to a low-protein diet (LPD) and the effect on biochemical parameters, body composition, and muscle strength in patients with non-dialysis CKD stages 3-5. <b>Methods</b>: The daily dietary intake of 377 patients, aged 68.5 ± 12.1 years, was evaluated using a quantitative food frequency questionnaire. Plant protein intake percentage was calculated as (daily plant protein intake/total protein intake) × 100%, and the potential renal acid load (PRAL) was estimated. A LPD was defined as a diet with a daily protein intake of <0.8 g/kg of body weight. Anthropometric measurements, body composition, and handgrip strength were assessed in a subgroup comprising 260 patients. The lean tissue index (LTI) and fat tissue index (FTI) were calculated by dividing lean mass and fat mass (kg) by the height in m², respectively. <b>Results</b>: Of the included 377 patients, 69.5% adhered to the LPD. Further, a 10% increase in plant protein intake was associated with a 20% increase in the likelihood of LPD adherence (OR, 1.20, 95% CI, 1.06 to 1.37), lower PRAL (β = -1.10 per 10% increase, 95% CI, -1.63 to -0.57), and higher serum bicarbonate levels (β = 0.24, 95% CI, 0.02 to 0.45). Analysis of the 260-patient subgroup revealed that a 10% increase in plant protein intake was associated with lower body mass index (β = -0.82, 95% CI, -1.05 to -0.59), FTI (β = -0.71, 95% CI, -1.01 to -0.40), waist circumference (β = -2.11, 95% CI, -2.80 to -1.41), hip circumference (β = -1.25, 95% CI, -1.75 to -0.75), waist-to-hip ratio (β = -0.91, 95% CI, -1.44 to -0.38), and waist-to-height ratio (β = -1.25, 95% CI, -1.71 to -0.80). There was no significant association between increased plant protein intake and LTI and handgrip strength. <b>Conclusions</b>: Increased intake of plant protein can reduce dietary acid load, alleviate metabolic acidosis, and potentially improve adiposity parameters without compromising lean mass and handgrip strength.