The Study
Urinary Potential Renal Acid Load (uPRAL) among Vegans Versus Omnivores and Its Association with Bone Health in the Cross-Sectional Risks and Benefits of a Vegan Diet Study
This study looked at what vegans and meat-eaters eat and how it shows up in their pee, then checked their bone strength. It found that vegans' pee is less acidic and their bones are a bit weaker — but it didn't prove that one causes the other. It's like noticing that people who wear hats have more sunburns — but you can't say hats cause sunburns without more info.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
This study looked at whether eating only plants makes your bones healthier by making your body less acidic.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 544 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Even though vegans had a more alkaline diet, their bones were slightly weaker, and this wasn't because of acid load — meaning other factors like calcium or vitamin D may matter more.
- 2Vegans had much less acid in their urine (34.5 mEq lower) and higher urine pH, but their heel bones were 3.7% weaker than omnivores' bones — and this weakness wasn't linked to how acidic their diet was.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Nutrients
Year
2022
Authors
Katharina J. Penczynski, T. Remer, J. Menzel, K. Abraham, C. Weikert
Related Content
Claims (6)
In people with normal or slightly acidic urine pH, there is no measurable link between the body's acid-base balance and bone health. Alkaline diets do not improve bone health in this group.
In healthy adults aged 30–60 with moderate protein intake, vegan diets result in lower urinary acid load and higher urine pH than omnivorous diets, but these changes are not linked to differences in bone health as measured by calcaneal ultrasound.
Vegans in the study had 3.7% lower heel bone strength as measured by broadband ultrasound attenuation than omnivores, even though their urine showed less acidity, indicating that factors other than dietary acidity affect bone strength in vegans.
Healthy adults who follow a vegan diet and consume moderate amounts of protein excrete less sulfate and phosphate in their urine than omnivores, because their diet contains less animal protein, which produces fewer acid-forming metabolic byproducts.
A single day's urine sample does not accurately reflect a person's long-term dietary acid-base balance because daily food choices vary too much, making uPRAL an unreliable measure in studies that collect data only once.
Consuming citric acid and malic acid through food increases the amount of acid in the bloodstream and lowers the pH of the body's internal environment.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.