Potassium citrate supplementation results in sustained improvement in calcium balance in older men and women

Journal of Bone and Mineral Research

Mar 2013

DOI: 10.1002/jbmr.1764

Citations:78

Influential Citations:2

Interventional (Human) Studies

Enhanced Details

Methods

Design: randomized, double-blind, placebo-controlled trial with three arms (placebo, potassium citrate 60 mmol/d, potassium citrate 90 mmol/d). 52 healthy men and women over 55 years old (mean age 65.2 ± 6.2); 18 placebo, 17 in 60 mmol/d, 17 in 90 mmol/d. Baseline urinary calcium excretion was above median values; exclusions included GI intolerance to potassium, hyperkalemia risk, renal disease, and metabolic bone disease. Participants were advised to maintain ~600 mg/day calcium intake; calcium citrate and vitamin D3 were provided to achieve intake targets.

Intervention

Potassium citrate tablets, 60 mmol/day or 90 mmol/day, taken orally for 6 months. Dosing escalated to nine tablets/day over 9 weeks; 60 mmol/day corresponded to 6 active tablets + 3 placebo tablets daily, 90 mmol/day used 9 active tablets daily. A 2-week run-in with placebo established tolerance for taking nine potassium citrate/placebo tablets daily.

Results

Potassium citrate reduced net acid excretion at 6 months vs placebo (60 mmol/d: 11.3 mmol/d; 90 mmol/d: 29.5 mmol/d vs placebo 16.1 mmol/d; p<0.001 for each vs placebo). 24-hour urine calcium decreased with potassium citrate (60 mmol/d: −46 mg/d; 90 mmol/d: −59 mg/d vs placebo). Fractional calcium absorption did not change. Net calcium balance improved with 90 mmol/d (142 ± 80 mg/d) vs placebo (80 ± 54 mg/d; p=0.02); 60 mmol/d improved but not significantly (33 ± 66 mg/d; p=0.18). Serum CTX decreased in both potassium citrate groups; bsALP did not change; intact PTH decreased only in the 90 mmol/d group; 1,25(OH)2D and 25-OH vitamin D largely unchanged. Authors conclude that potassium citrate can positively influence the calcium economy and may benefit skeletal health by neutralizing dietary acid, with greater balance benefit at the higher dose; longer-term trials are needed to assess effects on bone density and fracture outcomes.

Limitations

Small sample size (n=52) and 6-month duration limit generalizability and power for bone turnover and fracture outcomes; predominantly white female sample; no direct bone density or fracture outcomes measured; one participant withdrew due to hyperkalemia; one participant’s calcium-balance data were excluded due to incomplete stool collection; long-term safety and adherence in diverse populations remain to be established.

Abstract

The dietary acid load created by the typical Western diet may adversely impact the skeleton by disrupting calcium metabolism. Whether neutralizing dietary acid with alkaline potassium salts results in sustained improvements in calcium balance remains controversial. In this randomized, double‐blind, placebo‐controlled study, 52 men and women (mean age 65.2 ± 6.2 years) were randomly assigned to potassium citrate 60 mmol/d, 90 mmol/d, or placebo daily with measurements of bone turnover markers, net acid excretion, and calcium metabolism, including intestinal fractional calcium absorption and calcium balance, obtained at baseline and at 6 months. At 6 months, net acid excretion was significantly lower in both treatment groups compared to placebo and it was negative, meaning subjects' dietary acid was completely neutralized (−11.3 mmol/d on 60 mmol/d; −29.5 mmol/d on 90 mmol/d, p < 0.001 compared to placebo). At 6 months, 24‐hour urine calcium was significantly reduced in persons taking potassium citrate 60 mmol/d (−46 ± 15.9 mg/d) and 90 mmol/d (−59 ± 31.6 mg/d) compared with placebo (p < 0.01). Fractional calcium absorption was not changed by potassium citrate supplementation. Net calcium balance was significantly improved in participants taking potassium citrate 90 mmol/d compared to placebo (142 ± 80 mg/d on 90 mmol/d versus −80 ± 54 mg/d on placebo; p = 0.02). Calcium balance was also improved on potassium citrate 60 mmol/d, but this did not reach statistical significance (p = 0.18). Serum C‐telopeptide decreased significantly in both potassium citrate groups compared to placebo (−34.6 ± 39.1 ng/L on 90 mmol/d, p = 0.05; −71.6 ± 40.7 ng/L on 60 mmol/d, p = 0.02) whereas bone‐specific alkaline phosphatase did not change. Intact parathyroid hormone was significantly decreased in the 90 mmol/d group (p = 0.01). Readily available, safe, and easily administered in an oral form, potassium citrate has the potential to improve skeletal health. Longer‐term trials with definitive outcomes such as bone density and fracture are needed. © 2013 American Society for Bone and Mineral Research. show less