Dietary fiber intake and urinary creatinine: methodological implications for epidemiological studies

Area of Science:

• Environmental Health
• Nutritional Epidemiology
• Biomarkers

Background:

• Urinary creatinine (UCR) is vital for estimating renal function and correcting urinary dilution in exposure studies.
• Factors like protein intake, age, and diabetes influence UCR variability, necessitating adjustments for epidemiological comparability.
• Emerging research indicates dietary fiber may positively impact renal function.

Purpose of the Study:

• To investigate the relationship between dietary fiber intake and urinary creatinine (UCR) levels.
• To assess the methodological implications of dietary fiber intake for studies employing UCR-corrected measurements.

Main Methods:

• A cross-sectional study analyzed UCR, dietary fiber intake, age, and other UCR-related factors in 801 women in Northern Mexico (2007-2009).
• Statistical analysis estimated the association between dietary fiber intake and UCR, adjusting for age.

Main Results:

• The median dietary fiber intake was 33.14 g/day, exceeding adequate intake levels for adult women.
• An estimated 10.04 mg/dL increase in UCR was associated with every 10 g/day increase in dietary fiber intake, after age adjustment.
• Primary fiber sources included corn tortillas, raw onions, flour tortillas, and beans.

Conclusions:

• Dietary fiber intake is positively associated with urinary creatinine levels.
• Epidemiological studies using UCR adjustments should consider controlling for dietary fiber intake.
• Accounting for dietary fiber intake is essential for enhancing the comparability of UCR-corrected data across diverse populations with varying dietary patterns.