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

This was a human interventional study in healthy men and women over 55 years from the San Francisco Bay Area, with mean ages in the mid-60s and self-selected diets. Each active arm included 17 participants; baseline calcium intake was relatively high, and participants were followed for 6 months.

Older adults received oral potassium citrate for 6 months in two active regimens: 60 mmol/d with dose escalation over 9 weeks to nine tablets daily, of which three tablets were placebo, and 90 mmol/d with dose escalation over 9 weeks to nine active tablets daily. The intervention was compared with placebo tablets within the study design.

Potassium citrate improved calcium balance by neutralizing dietary acid load, reducing urinary calcium excretion, and lowering bone resorption markers, with the clearest benefit at 90 mmol/d. Net acid excretion fell significantly versus placebo in both arms, from 22.9 to -11.3 mmol/d at 60 mmol/d and from 17.0 to -29.5 mmol/d at 90 mmol/d, with p<0.001 for both. Net calcium balance at 6 months was 142 mg/d in the 90 mmol/d group versus -80 mg/d with placebo (p=0.02), while the 60 mmol/d group was not significant (p=0.18). Urine calcium decreased versus placebo in both active groups (p<0.01), fractional calcium absorption did not change, and intact PTH decreased significantly in the 90 mmol/d group (p=0.01). The authors concluded that potassium citrate may support skeletal health and could help prevent age-related bone loss, but longer trials are needed for bone density and fracture outcomes.

The trial was small, with only 17 participants per active arm, and lasted only 6 months. Outcomes were surrogate markers rather than bone density or fracture endpoints, limiting clinical interpretation. Generalizability is limited to relatively healthy older adults with high baseline calcium intake, and one participant developed hyperkalemia requiring withdrawal.