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

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This cross-sectional secondary analysis estimated boron intake from two-day weighed food diaries and measured 24-hour urinary boron by ICP-MS in 89 young German adults following omnivorous, lacto-ovo-vegetarian or vegan diets. Vegans had the highest estimated intake and excretion, although intake differences were not statistically significant. Intake and excretion were strongly correlated in vegans and omnivores.

Key numbers

  • Estimated boron intake, median (IQR): omnivores 1515.35 µg/d (944.33 to 2067.52); lacto-ovo-vegetarians 1654.36 µg/d (1249.75 to 2366.01); vegans 1913.38 µg/d (1467.11 to 2615.14); P = 0.104 (Fig. 1, p. 5).
  • Range of individual estimated intakes: 657.09 to 5835.74 µg/d (Results, p. 4).
  • 24-hour urinary boron, median (IQR): all 1415.39 µg/24 h (1053.61 to 2169.99); omnivores 1159.06 (875.72 to 1908.27); lacto-ovo-vegetarians 1498.50 (1025.20 to 2000.31); vegans 1848.59 (1326.51 to 2397.14); P = 0.019 (Table 2, p. 5).
  • Creatinine-corrected urinary boron, median: all 1214.56 µg/g creatinine; omnivores 919.34; lacto-ovo-vegetarians 1235.40; vegans 1559.20; P < 0.001 (Table 2, p. 5).
  • Correlation of intake with excretion: r = 0.74 omnivores, 0.45 lacto-ovo-vegetarians, 0.79 vegans (Fig. 3).
  • Analytical detection limit for urinary boron: 0.21 µg/L (Methods, p. 3).
  • No participant exceeded the EFSA tolerable upper intake level, stated in this paper as 10 mg/day (10,000 µg/d) (Results, p. 4).

Methods (brief)

Participants from the German LAKE study (urine collected October 2024 to January 2025) kept weighed food diaries for two consecutive days and collected a 24-hour urine on day 2. Boron intake was calculated from a compiled table of boron contents for 212 foods, relying mainly on US data plus soy and algae data, with local tap water and mean German mineral water values. Urinary boron was measured by ICP-MS (NexION 2000) with yttrium and terbium internal standards and Seronorm urine quality control at two levels.

Evidence fitness

Supports estimated boron intakes and urinary excretion for young German adults by diet pattern and the use of 24-hour urine as an intake marker. It does not support representative population intakes (small student-heavy sample) and its intake estimates depend on non-German food composition data.

Limitations

Small, young, highly educated sample; two diary days only; intake estimates rely on US-based food boron data. Partly funded by a scientific award to one author (Dr. Wolfgang Hevert-Preis 2024); authors declared no competing interests.

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