Examining the Impact of Adherence to a Vegan Diet on Acid-Base Balance in Healthy Adults

Kelly Cosgrove, Carol S. Johnston

Acidogenic diets, commonly measured by the potential renal acid load (PRAL), have been linked with metabolic diseases including insulin resistance, hepatic dysfunction, and cardiometabolic risk. Vegan diets are linked to low dietary acid loads, but the degree of adherence to a vegan diet to demonstrate this benefit is unknown. This study compared the change in PRAL and urine pH of omnivores who followed a vegan diet for either 2, 3, or 7 days over one week. Healthy adults were recruited from a campus population and randomly assigned to one of the three groups: VEG7 (vegan diet followed for seven consecutive days); VEG3 (vegan diet followed for three evenly spaced days over one week); or VEG2 (vegan diet followed for two evenly spaced days over one week). Gender, age, and body mass index did not differ between groups (overall: 21.8 ± 2.4 y and 24.4 ± 5.6 kg/m(2)). Following the one week intervention, outcome measures did not vary between the VEG2 and VEG3 groups, and these groups were collapsed for the final analyses. The 24-h urine pH was raised after seven consistent days of vegan diet adherence and was unchanged after 2-3 days of vegan diet adherence over the course of a week (+0.52 ± 0.69 and -0.02 ± 0.56 respectively, p = 0.048). However, dietary PRAL scores fell significantly in both dietary groups during the 7-day trial. Since low dietary PRAL scores have been related to improve metabolic parameters, adoption of a vegan diets for several days per week should be explored as a diet strategy to lower disease risk.