Potential renal acid load in the diet of children and adolescents: impact of food groups, age and time trends.

OBJECTIVE: The impact of acid-base balance on health is widely accepted. Here, we describe the potential renal acid load (PRAL) in the diet of healthy German children and adolescents. DESIGN: The Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study is an ongoing longitudinal (open cohort) study (start 1985) collecting detailed data on diet, growth, development and metabolism in infants, children and adolescents. SETTING: Research Institute of Child Nutrition, Dortmund. SUBJECTS: Seven hundred and twenty children and adolescents (351 boys and 369 girls), aged 3-18 years, provided 4187 yearly collected 3-day dietary records between 1995 and 2005. RESULTS: Mean daily PRAL was positive in all age/sex groups (6-21 mEq day-1), and significantly higher in boys than in girls after the age of 8 years, even when calculated as mEq MJ-1. Fruits, vegetables and potatoes had a negative impact on PRAL; cheese, dairy products, cereals/bread and meat/fish/eggs had a positive impact. In a mixed linear model, PRAL, expressed as mEq day-1 and mEq MJ-1, remained stable during the study period, since time trends of PRAL-relevant food groups countervail each other. PRAL intake (mEq MJ-1) was significantly positively associated (P < 0.0001) with fat intake (% of energy intake, %E), but negatively with carbohydrate intake (%E; P < 0.0001). CONCLUSIONS: The analysis of dietary habits in our sample of German children and adolescents showed a moderate excess of acidity. Especially older boys should be encouraged to eat more potatoes and vegetables as good sources of dietary alkalinity. The PRAL concept is compatible with current concepts for a healthy diet.