Effect of potassium citrate supplementation or increased fruit and vegetable intake on bone metabolism in healthy postmenopausal women: a randomized controlled trial.
What this study found
Overall, neither potassium citrate supplementation nor increased fruit and vegetable intake produced sustained improvements in bone turnover or bone mineral density over 2 years. Time-by-arm interactions were not significant for P1NP, CTX, or fDPD/Cr across follow-up, and the authors concluded that alkali provision from fruits and vegetables does not explain long-term bone benefits. A short-term effect was seen only for fDPD/Cr at 4 to 6 weeks, where the high-dose and low-dose potassium citrate groups differed after Bonferroni post hoc testing (P=0.047), but this was not sustained. Baseline…
- Study & population
- Randomized controlled trial in healthy postmenopausal women, approximately 55 to 65 years old, recruited from the community in Aberdeen, Scotland.
- Intervention
- Participants were randomized to oral potassium citrate capsules at either a high dose of 2.16 g daily (55.5 mEq alkali) or a low dose of 0.72 g daily (18.5 mEq alkali) for 2 years, or to a dietary intervention targeting an additional 300 g per day of fruit and vegetables.
- Key limitation
- Each active arm was modest in size (high-dose n=70, low-dose n=70, diet n=66), limiting power for small effects.
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Open PDFOriginal abstract
BACKGROUND Alkali provision may explain why fruit and vegetables benefit bone health. OBJECTIVE We aimed to determine the effects of alkali-providing potassium citrate (double-blind) and fruit and vegetable intake (single-blind) on bone turnover over 2 y. DESIGN We conducted a randomized placebo-controlled trial in 276 postmenopausal women (aged 55-65 y). Women were randomly assigned to 4 groups: high-dose potassium citrate (55.5 mEq/d), low-dose potassium citrate (18.5 mEq/d), placebo, and 300 g additional fruit and vegetables/d (equivalent of 18.5 mEq alkali). Serum and fasted urine for bone markers were collected at baseline and at 3, 6, 12, 18, and 24 mo. An additional urine sample was collected at 4-6 wk. Bone mineral density (BMD) was measured at baseline and 2 y. RESULTS Repeated-measures ANOVA showed no difference between groups for urinary free deoxypyridinoline cross-links relative to creatinine (fDPD/Cr), serum N-terminal propeptide of type 1 collagen, or beta C-terminal telopeptide, although, at 4-6 wk, fDPD/Cr was lower in the high-dose potassium citrate group (P = 0.04). Mean +/- SD spine BMD loss in the placebo group (1.8 +/- 3.9%) did not differ significantly from that in the treatment groups (2.1 +/- 3.2%; P = 0.88). Hip BMD loss in the placebo and low-dose potassium citrate groups was 1.3 +/- 2.3% and 2.2 +/- 2.3%, respectively (P = 0.14). CONCLUSIONS Two-year potassium citrate supplementation does not reduce bone turnover or increase BMD in healthy postmenopausal women, which suggests that alkali provision does not explain any long-term benefit of fruit and vegetable intake on bone.