Lucía Pienovi¹, Celia Sintes¹, Daiana Lozano¹, Caterina Rufo², Carmen Marino Donangelo^1,

Yerba mate (Ilex paraguariensis) tea is a caffeine-containing beverage habitually consumed in South-America and increasingly consumed worldwide. Mate consumption could adversely affect calcium homeostasis through caffeine-mediated increased urinary calcium loss. The aim of this study was to assess the change of urinary calcium in response to an acute mate tea load and to examine associations with habitual mate consumption, dietary caffeine, dietary calcium and bone mass status, in young adult women (20-37y, n=30). The women participated in two acute load tests, mate-tea (∼300 mg caffeine) and water, in a cross-over-designed study with 7d wash-out period. Each woman was her own control. Calcium was measured in 4h urine post-load (UCa). Habitual mate consumption, and dietary caffeine and calcium, were assessed by questionnaires. Bone mineral density (BMD) at total body, femur and lumbar spine was measured by dual-X-ray-absorptiometry. Habitual mate and dietary caffeine median intakes were 293 mL/d and 207 mg/d, respectively. Mean dietary calcium was 1103 mg/d. Median BMD z-scores were within the normal range. UCa increased with acute mate load compared to water (median increase 15.9 mg, paired t-test, p<0.001). Increased UCa with acute mate load (UCa) correlated directly with dietary calcium (r=0.556, p=0.001) and trochanter BMD z-score (r=0.380, p=0.042), and inversely with habitual mate intake (r=-0.524, p=0.003) and total dietary caffeine (r=-0.445, p=0.014). UCa was higher in women with habitual mate intake <250 mL/d compared to ≥250 mL/d, and in those with total dietary caffeine <150 mg/d compared to ≥150 mg/d, adjusting for dietary calcium and trochanter BMD z-score (multifactor ANOVA, p<0.05). Habitual mate consumption and total dietary caffeine appeared to attenuate the calciuric response to the acute mate tea load in the women regardless of dietary calcium and bone mass status. This suggests physiologic adaptation to chronic caffeine exposure in women which habitually consume mate.

calcium, caffeine, Ilex paraguariensis, bone mineral density, adult women