Consistency of Adherence to a Vegan Diet on Acid‐Base Balance: A Randomized Controlled Trial in Healthy Omnivore College Students

Abstract

Much research has focused on the health benefits of vegetarian diets. Generally, vegetarian diets are low in cholesterol and saturated fat and high in fiber and phytochemicals, diet characteristics linked to low risk for hypertension, ischemic heart disease, type 2 diabetes, and some cancers. The high fruit and vegetable intake paired with the absence of flesh foods also affords vegetarian diets an alkalizing effect in comparison to omnivorous diets, a property related to healthy metabolic profiles in terms of insulin sensitivity, hepatic function, and cardiometabolic risk. Although it is well documented that vegetarian diets, particularly vegan diets, are linked to low dietary acid loads, these diets are difficult to sustain for extended periods and <3% of Americans are reportedly vegetarian. No research has been published that describes how consistently one must follow a vegan diet to impact in vivo acid‐base balance and nutrient intake profiles. This study compared the change in dietary acid load and urine pH of university students following a vegan diet for either seven (VEG7, n=8), three (VEG3, n=8), or two (VEG2, n=7) 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/m2). Following the 1‐wk intervention, outcome measures did not vary between the VEG2 and VEG3 groups, and these groups were collapsed for the final analyses (VEG2+3). The 24‐h urine pH was raised after seven consistent days of vegan diet adherence (+0.52±0.69 units) and was unchanged after 2–3 days of vegan diet adherence over the course of a week (−0.02±0.56 units), and these changes differed significantly between groups (p=0.048). Seven consistent days of vegan diet adherence reduced the average daily dietary cholesterol intake by 156.4±115.5 mg compared to a 92.3±144.9 mg reduction for individuals adhering to a vegan diet 2 or 3 days per week (p<0.001). Fiber and sodium intakes tended to improve to a greater degree in the VEG7 group in comparison to the VEG2+3 group, but these differences did not achieve statistical significance (0.05<p<0.10). There were no differences for the change in daily energy intakes or daily fat intakes between groups during the 1‐week intervention. Thus, there were measurable health benefits for omnivores who adhered to a vegan diet for seven consecutive days that were not observed in omnivores who adhered to a vegan diet 2 or 3 days per week.Support or Funding InformationResearch Support: Graduate and Professional Student Association, Arizona State University