Dietary fiber, kidney function, inflammation, and mortality risk.

Area of Science:

• Gerontology
• Nutritional Science
• Nephrology

Background:

• Previous research in the US population suggests a link between high dietary fiber intake and reduced inflammation and mortality in individuals with kidney dysfunction.
• This study sought to validate these findings in a Northern European cohort.

Purpose of the Study:

• To investigate the association between dietary fiber intake and kidney function, inflammation, and mortality in elderly Swedish men.
• To determine if the protective effects of dietary fiber are more pronounced in individuals with impaired kidney function.

Main Methods:

• Dietary fiber intake was assessed using 7-day dietary records from 1110 elderly men (aged 70-71) in the Uppsala Longitudinal Study of Adult Men.
• Renal function was estimated using serum cystatin C levels, and mortality was tracked over a median of 10.0 years.
• Statistical analyses adjusted for total energy intake and examined interactions between dietary fiber and kidney function.

Main Results:

• Higher dietary fiber intake was independently associated with better estimated glomerular filtration rate (eGFR) and lower levels of C-reactive protein (inflammation marker).
• Over the follow-up period, 300 participants died.
• A significant interaction was observed between dietary fiber intake and kidney dysfunction in predicting mortality; higher fiber intake was associated with lower mortality, especially in those with eGFR < 60 ml/min per 1.73 m(2).
• This survival benefit was primarily driven by a reduced incidence of cancer-related deaths in individuals with kidney dysfunction.

Conclusions:

• High dietary fiber intake is associated with enhanced kidney function and reduced inflammation in community-dwelling elderly men.
• Dietary fiber intake significantly reduces overall and cancer-specific mortality, particularly in elderly men with pre-existing kidney dysfunction.