Nitrato urinário está positivamente associado com a força muscular em idosos, mas não em adultos: NHANES 2011-2012

Abstract

Introduction: Reduced muscle strength is associated with a higher risk of falls, reduced quality of life, functional dependence, hospitalizations, and mortality. Although more frequent with aging, it can also occur in young adults. Certain dietary components may influence muscle strength, and among the promising nutrients is nitrate (NO -), which is abundant in vegetables. Trials of NO - supplementation show reductions in blood pressure and improvements in aerobic performance; however, the effects of habitual NO3- intake on strength across different ages have not yet been fully clarified. Objective: To examine whether urinary nitrate is associated with muscle strength in younger and older adults from a nationally representative sample of the U.S. population. Methods: A cross-sectional study was conducted using publicly available data from the National Health and Nutrition Examination Survey (NHANES, 2011–2012). A total of 1,301 individuals aged 20 to 80 years (<60 years, n=902; ≥60 years, n=399) were included. Urinary nitrate levels were measured using ion chromatography coupled with tandem mass spectrometry and electrospray ionization. Muscle strength was assessed as combined handgrip strength, defined as the sum of the highest values from each hand. Linear regression analyses were performed to examine the association between urinary nitrate levels and muscle strength, with adjustment for potential confounders. Results: A positive association was observed between urinary nitrate levels and handgrip strength in older adults (β=0.00004; 95% CI: 0.00001–0.00007; p=0.009), but not in younger adults (β=0.000004; 95% CI: -0.00003– 0.00003; p=0.799). When urinary nitrate was normalized to urine osmolality, a positive association with handgrip strength was also observed in older adults (β = 0.017; 95% CI: 0.0004–0.034; p = 0.046), but not in younger adults. Conclusion: Urinary nitrate levels were positively associated with muscle strength in older adults, but not in younger adults.