Sodium Intakes Around the World

Sodium intakes of different populations around the world became of interest to the medical research community with the publication of Dahl’s famous graph showing a positive straight-line relationship of dietary sodium intake to prevalence of hypertension. At that time populations were identified around the world with vastly different sodium intakes (and rates of hypertension) ranging up to about 10.6 g/d sodium (460 mmol/d) in north-east Japan. Dietary survey methods tend to underestimate sodium intakesand timed 24-hour urinary sodium excretion is considered the “gold standard” method to estimate intake (some 85–90% of ingested sodium is excreted through the kidneys). However, there is also some evidence to suggest that spot (casual) urine samples may give valid estimates of sodium excretion in a population. The INTERSALT Study provided standardized data on 24-hour urinary sodium excretion among 52 population samples in 32 countries, for the mid to late 1980s. The highest mean 24-hour urinary sodium excretion ranged from 260 mmol/d (6.0 g) in men and 230 mmol/d (5.3 g/d) in women in China and to 1 mmol/d (23 mg/d) among the Yanomamo Indians of Brazil. The INTERMAP Study provided standardized data on sodium intakes and 24-hour urinary sodium excretion in China, Japan, the United Kingdom of Great Britain and Northern Ireland, and the United States of America for the late 1990s. Although some downward trends in sodium consumption have been noted in the past in countries like Belgium and Japan where there have been public health campaigns to lower sodium in the community, for the most part mean sodium intakes have not changed much over the past 20 or more years. Sodium intakes tend to be higher in men than women, reflecting their higher food and energy intakes. Data in children and youngpeople suggest higher intakes in boys than girls and at older ages in both sexes, but there are serious methodological difficulties in obtaining reliable and valid dietary data in this age group. For all countries for which recent data are available, dietary sodium intakes are muchhigher than the physiological need of 10–20 mmol/d (230–460 mg/d). In industrialized countries, about 75% of sodium in the diet comes from manufactured foods and foods eaten away from home. Some children’s foods are extremely high in sodium. In Asian countries, high proportions of sodium in the diet come from salt added in cooking and from sauces such as soy and miso (in Japan). Representative samples of around 100 people (200 ifmen and women are to be considered separately), each providing a single timed 24-hour collection of urine for the estimation of sodium, would be required to monitor sodium intake in the community with a 95% confidence limit about the mean of c. +/- 12 mmol/d. Much larger samples might be needed if greater precision is required.

• http://www.who.int/dietphysicalactivity/Elliot-brown-2007.pdf