A reduction of sodium in food may not promote health

A new US review suggests that there is a normal range of human sodium intake defined by physiology and biological needs and not by the food supply.

The review included 129 studies, with a total of 50,060 participants, investigating the 24-hour urinary sodium excretion (UNaV) in defined populations of free-living people (1). The analysis showed that the participants’ sodium intake, as defined by 24-hour UNaV, was characterized by a narrow range that is reproducible over at least 5 decades and across 45 countries. The sodium intakes followed a classic normal distribution that depicts a narrow range with strict lower and upper limits of normality.

The researchers concluded that the finding, which reveals sodium intake has been unchanged over decades of observation and a wide array of societies, challenges the entrenched perceptions that sodium intake is increasing and that the postulated increase is due to the sodium content of the food supply. This data does not support those often-expressed opinions that current sodium intakes exceed physiological need, that they can be significantly reduced, and that the reduction can be maintained over time. Although there is increas- ing evidence showing that reduction of salt in food does not lead to decrease of cardiovascular disease risk; nevertheless, the recommended levels of sodium intake by American health organizations have been grad- ually but significantly decreased over the past 40 years, the scientists said.

The new US Institute of Medicine (IOM) report ‘Sodium Intake in Populations − Assessment of Evidence’ stated that evidence from studies on direct health outcomes is inconsistent and insufficient to conclude that lowering sodium intakes below 2,300 mg per day either increases or decreases the risk of developing cardio- vascular disease (including stroke and cardiovascular disease-related mortality) or all-cause mortality in the general US population (2). The researchers said that the findings of the IOM committee indicate the previ- ously established upper limit of sodium intake deemed safe (2,300 mg/day or 100 mmol/day) is not sup- ported by scientific evidence. Rather, it would be reasonable to conclude that the estimated healthy range for human sodium intake is 2,800–5,000 mg/day.

1. McCarron D. A. et al. Normal Range of Human Dietary Sodium Intake: A Perspective Based on 24-Hour Urinary Sodium Excretion Worldwide. Am J Hypertens. 2013; 26(10):1218–1223.
2. Institute of Medicine. Sodium Intake in Populations: Assessment of Evidence. 2013. www.iom.edu/Reports/2013/Sodium-Intake-in-Populations-Assessment-of-Evidence.aspx