If there is relatively less sodium and more potassium in your diet you’ll automatically be a little slimmer. The link between slimness and the sodium-potassium ratio is not earth shatteringly strong, but it is observable write epidemiologists at the University of Texas Southwestern Medical Center in the American Journal of Clinical Nutrition.
Some animal studies suggest that a diet containing large amounts of salt tends to facilitate the growth of fat deposits. [Obesity (Silver Spring). 2007 Sep;15(9):2200-8.] A few years ago Finnish epidemiologists also reported that people who consumed large amounts of salt were slightly fatter than people with a healthier salt intake.
So the discovery that Nishank Jain and his colleagues made is not so surprising. The researchers measured the amounts of sodium and potassium in the urine of nearly three thousand inhabitants of Dallas aged between 30 and 65. They also measured the subjects’ body composition using DXA scans. They noticed that the participants with a higher sodium-potassium ratio in their urine also had more body fat.
The researchers didn’t examine how the sodium-potassium ratio makes people fatter or thinner, but they do make a few suggestions.
“Salt intake is a major determinant of sugar-sweetened soft drink consumption, and soft drink consumption is associated with weight gain and incident diabetes mellitus”, the Americans write. “A diet high in fat is generally high in Na+ and low in K+.”
“Second, salt sensitivity may be related to insulin sensitivity through the interplay of an abnormal renin-angiotensin system. Thus, a diet high in Na+ and low in K+ may contribute to obesity.”
Salt is obviously the most important source of sodium in our diet. The food industry adds it to almost everything because salt is a powerful flavour enhancer, suppresses unpleasant aftertaste and on top of that it’s dirt-cheap. The more pre-processed food you eat, the more salt you consume.
Potassium is found in nearly all vegetables and fruit. The more of these you eat, the more potassium you’ll ingest.
Association of urinary sodium-to-potassium ratio with obesity in a multiethnic cohort.
Previous studies that reported an association of dietary Na(+) intake with metabolic syndrome were limited by the use of imprecise measures of obesity, Na(+) intake, or exclusion of multiethnic populations. The effect of dietary K(+) intake on obesity is less well described.
We hypothesized that high dietary Na(+) and low K(+), based on the ratio of urinary Na(+) to K(+) (U[Na(+)]/[K(+)]) in a first-void morning urinary sample, is independently associated with total body fat.
In a prospective population-based cohort, 2782 participants in the community-dwelling, probability-sampled, multiethnic Dallas Heart Study were analyzed. The primary outcome established a priori was total-body percentage fat (TBPF) measured by dual-energy X-ray absorptiometry. The main predictor was U[Na(+)]/[K(+)]. Robust linear regression was used to explore an independent association between U[Na(+)]/[K(+)] and TBPF. The analyses were stratified by sex and race after their effect modifications were analyzed.
Of the cohort, 55.4% were female, 49.8% African American, 30.8% white, 17.2% Hispanic, and 2.2% other races. The mean (±SD) age was 44 ± 10 y, BMI (in kg/m(2)) was 30 ± 7, TBPF was 32 ± 10%, and U[Na(+)]/[K(+)] was 4.2 ± 2.6; 12% had diabetes. In the unadjusted and adjusted models, TBPF increased by 0.75 (95% CI: 0.25, 1.25) and 0.43 (0.15, 0.72), respectively (P = 0.003 for both), for every 3-unit increase in U[Na(+)]/[K(+)]. A statistically significant interaction was found between race and U[Na(+)] /[K(+)], so that the non-African American races had a higher TBPF than did the African Americans per unit increase in U[Na(+)]/[K(+)] (P-interaction < 0.0001 for both). No interaction was found between sex and U[Na(+)]/[K(+)].
The ratio of dietary Na(+) to K(+) intake may be independently associated with TBPF, and this association may be more pronounced in non-African Americans. Future studies should explore whether easily measured spot U[Na(+)]/[K(+)] can be used to monitor dietary patterns and guide strategies for obesity management.
PMID: 24552753 [PubMed – in process] PMCID: PMC3985224