Boron Intake and 24-hour Urinary Excretion in Long-term Omnivores, Vegetarians and Vegans: a Cross-sectional Study

Abstract

Abstract The trace element boron is a bioactive and potentially essential element for humans with a broad range of physiological effects. While dietary sources of boron are well known, significant knowledge gaps remain regarding boron intake in special dietary patterns. We estimated dietary boron intake and quantified urinary boron excretion in long-term lacto-ovo-vegetarians, vegans and omnivores in Germany. Dietary intake was estimated using weighed food diaries linked to existing databases. Boron excretion was measured using 24-hour urine samples. Differences between diet groups were compared using non-parametric tests (Kruskal–Wallis H test). The sample included 89 participants, including 28 lacto-ovo-vegetarians and 29 vegans. Vegans had the highest median boron intake (1913.38 (interquartile range: 1467.11-2615.14) µg/d), followed by lacto-ovo-vegetarians (1654.36 (1249.75-2366.01) µg/d) and omnivores (1515.35 (944.33-2067.52) µg/d). Interindividual boron intake varied largely, and ranged from 657.09 to 5835.74 µg/d. No participant exceeded the European Food Safety Authority tolerable upper intake level for boron (10 mg/day). Creatinine-corrected urinary boron excretion was highest in vegans (1559.20 (1150.62-2057.23) µg/g creatinine), followed by lacto-ovo-vegetarians (1235.40 (877.96-1814.61) µg/g creatinine) and omnivores (919.34 (639.18-1380.97) µg/g creatinine). Strong correlations between boron intakes and 24-hour urinary excretion were found in vegans ( r = 0.79) and omnivores ( r = 0.74) with p -values < 0.001 for both. The correlation in lacto-ovo-vegetarians was less pronounced ( r = 0.43). A higher urinary boron excretion was associated with a higher excretion of potassium in all dietary patterns and specifically phosphorus in vegans ( r = 0.57, p < 0.001). Our data suggest that boron intake varies across different dietary patterns. We provide first insights in boron status in German lacto-ovo-vegetarians and vegans.