Dietary Protein Intake and Low Muscle Strength in Women with Breast Cancer: An Association Study

Women with breast cancer experience body composition and dietary changes, which may lead to reduced muscle strength (MS) and muscle mass. This study aimed to analyze the relationship between MS and dietary protein intake in this population. A cross-sectional study was conducted with women aged over 20 years diagnosed within ≤12 months. Sociodemographic, behavioral, clinical, and anthropometric data were collected. MS was assessed based on handgrip strength. Food intake was estimated using a food frequency questionnaire. Adjusted binary logistic regression was performed (p < 0.05). The sample comprised 149 women (mean age: 55.6 ± 11.2 years). Most participants self-identified as black or brown (67.1%), had invasive lobular carcinoma (66.4%), and were overweight (35.6%), while 28.2% exhibited low grip strength. The group with low MS had higher intakes of carbohydrates, plant protein, and magnesium as well as lower intakes of total fat, total protein, and animal protein (p < 0.05 for all). Each additional gram/day of animal protein was associated with a 7% reduction in the likelihood of having low muscle strength (β = −0.042; OR = 0.93; 95% CI: 0.921–0.977; p = 0.035). Animal protein intake was inversely associated with low muscle strength in women with breast cancer.