Renal Functional Reserve in Lacto-vegetarian Adolescents

Abstract

A high-protein meal causes an increase in the glomerular filtration rate (GFR) and is a tool to assess renal functional reserve. This study aimed to assess the GFR and renal functional reserve in lacto-vegetarians who had abstained from protein from animal sources for years. Twenty healthy lacto-vegetarian adolescents (LVA) aged 12-15 years including ten males and ten females were recruited. They had consumed no meat, poultry, fish or eggs for 1.0 - 4.8 years (average 2.13 ± 1.03 years). An age-and-sex matched control group composed of adolescents who regularly consumed a mixed diet from both animal and vegetable sources (MDA). The baseline GFR was assessed in each subject using the 24-hour creatinine clearance method. Then each subject consumed a meal containing 1.2 grams of protein per kg body weight in the form of steamed chicken breast. After this meal, urine and blood specimens were collected for GFR assessment every 30 minutes for three-and-a-half hours. The result showed that the LVA had a lower baseline GFR compared to the MDA ( 72.6 ± 7.7 Vs 89.3 ± 14.9 ml/min/1.73 m²). A high-protein meal caused an increase in GFR of 60.3 per cent in the LVA and 76.3 per cent in the MDA. The LVA group whose protein intake was rather low and who had abstained from animal protein for several years showed a smaller and slower response to the renal-hyperfiltration effect of a high animal-protein diet. This might be due to changes in gastro-intestinal digestion and absorption of protein, or changes in renal hemodynamics, other renal functions or structures. In addition, the study revealed that the LVA group has lower body weight, height, body surface area, hemoglobin, serum cholesterol and uric acid concentrations. The female LVA reached menarche at a later age compared to the MDA group. In conclusion, lacto-vegetarian adolescents showed a lower baseline GFR and less renal functional reserve compared to those regularly consuming protein from animal sources.