Increased Urinary Calcium in Response to Acute Mate Tea Intake Is Inversely Associated with Habitual Mate Intake But Is Not Related to Bone Mass Status in Young Adult Women

Abstract Objectives Yerba mate (Ilex paraguariensis) tea (mate for short) is a caffeine-containing beverage habitually consumed in Uruguay, Argentina, Paraguay and southern Brazil. Mate consumption may increase urinary calcium loss. The aim of this study was to determine the change in urinary calcium excretion in response to acute mate intake and to examine associations with habitual mate and total caffeine intake, dietary calcium and bone mass status, in young adult women (n = 32; 20–37 y; non-obese). Methods Each woman participated in two acute load tests [mate intake (300 mg caffeine), and water intake (no caffeine)] in a randomized cross-over designed study with 7 d wash-out period between tests. Calcium was measured in total 4 h urine post-test. Habitual calcium and caffeine intakes were assessed by a food/beverage frequency questionnaire. Total body (TB), femoral neck (FN) and lumbar-spine (LS) bone mineral density (BMD) were measured by Dual-X-Ray-Absorptiometry. Results Dietary calcium and caffeine intakes were 1138 ± 409 mg/d and 257 ± 192 mg/d, respectively. Habitual mate consumption ranged from 0–2000 mL/d (median: 286 mL/d). Five women were not mate consumers. TB-BMD, FN-BMD, and LS-BMD Z scores were 0.36 ± 0.70, −0.14 ± 0.60, and −0.08 ± 0.73, respectively. Calcium in 4 h urine increased 15.2 ± 10.9 mg/d with acute mate intake compared to water intake (P < 0.001, paired t-test). On average, calcium excretion in 4 h urine doubled with mate intake compared to water. The increase in urinary calcium with acute mate intake was inversely correlated with habitual mate consumption (r = −0.439, P = 0.015) and total caffeine intake (r = −0.403, P = 0.025), and directly correlated with habitual calcium intake (r = 0.444, P = 0.02). The increase in urinary calcium in response to acute mate intake was on average 32–52% lower in women habitually consuming >500 mL mate/d, or >300 mg caffeine/d, compared to women consuming <140 mL mate/d, or < 100 mg caffeine/d (P < 0.05, Kruskal Wallis). No associations were observed between the urinary calcium response to acute mate intake and BMD Z scores (P > 0.5). Conclusions The calciuric response to acute mate intake in young adult women is attenuated by increased habitual consumption of mate and/or total dietary caffeine but it is not related to bone mass status. Funding Sources PEDECIBA, Uruguay.