(P17-004-24) Subgroup Differences in Urinary Sodium and Calcium Excretion in Healthy Men and Women in Response to a High Salt Diet

Objectives: Previous research suggests that dietary mineral ratios such as calcium to sodium can disturb calcium and sodium retention and metabolism, and potentially impact the risks associated with osteoporosis and hypertension. Our objective was to compare subgroup differences in 48-hour urinary sodium and calcium excretion in response to a high-salt diet among healthy individuals.

Methods: Fifty-five healthy people aged 18-35 were provided with a controlled diet with high salt levels (3700 mg/sodium/day) and 757 mg/calcium/day for 2 days. Sixteen participants were White (8 women and 8 men) and the remaining 39 were non-White (22 women and 17 men). Two 24-hour urine samples were collected during the dietary intervention. Urinary calcium and sodium excretion were quantified using Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). Data were analyzed using an unpaired t-test.

Results: White participants showed higher urinary calcium (p ≤ 0.05) and a trend of higher urinary sodium (p = 0.060) excretion during the 24-48 hour compared to non-White subjects after consumption of the high-salt diet. Among White women, significantly higher urinary calcium excretion was observed during both 0-24 and 24-48 hour intervals (p < 0.05) compared to non-White women. In contrast, there was a trend of higher urinary sodium excretion during the 24–48-hour period (p = 0.053) in White men compared to non-White men.

Conclusions: These findings suggest that changes in urinary calcium excretion in response to dietary salt intake may be detectable within a single day of consumption among subgroups, especially in women. These preliminary results support the need for a large-scale clinical trial, currently underway, to explore sex and racial differences in calcium and sodium metabolism in response to dietary salt, with an ultimate goal in developing personalized dietary strategies to mitigate the risk of osteoporosis and hypertension.

Funding Sources: National Dairy Council