Previous studies have linked both high and low salt consumption to an increased risk of cardiovascular disease, leaving people confused about how much is actually safe to consume. But now new research has thrown a spanner in the works, so to speak, claiming that “moderate” salt intake may actually be best for managing cardiovascular health.
Currently, World Health Organisation guidelines recommend sodium intake should be reduced to less than 2 grams per day, although this is yet to be achieved in any country around the world. Researchers from McMaster University in Canada believe communities where average levels of sodium consumption above 5g per day should be targeted, rather than focusing on reducing moderate levels even further.
The results were published in The Lancet Journal after researchers observed more than 90,000 people from 300 different communities in 18 countries.
“No country has managed to reduce levels of sodium consumption from moderate to very low (below 2g/day), and our study shows we should be far more concerned about targeting communities and countries with high average sodium intake (above 5g/day, such as China) and bringing them down to the moderate range (3 to 5g/day),” research author Professor Andrew Mente said.
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Researchers used data from the ongoing Prospective Urban Rural Epidemiology study, which analysed urine samples to estimate sodium and potassium intake. Average follow-up for participants was 8.1 years, which saw 3,695 people die and 3,543 experience major cardiovascular events. This included 1,372 myocardial infarctions, 1,965 strokes, 343 heart failures and 914 cardiovascular deaths.
Researchers discovered that higher sodium intake was linked with increased blood pressure and increased incidence of stroke. The study also noticed that the link was prominent in communities with very high sodium intake.
“Our study adds to growing evidence to suggest that, at moderate intake, sodium may have a beneficial role in cardiovascular health, but a potentially more harmful role when intake is very high or very low,” Mente said. “This is the relationship we would expect for any essential nutrient and health. Our bodies need essential nutrients like sodium, but the question is how much.”
Researchers explained that recommendations to lower sodium consumption to less than 2g/day is based on short-term trials of sodium intake and blood pressure and the assumption that any approach to reduce blood pressure will translate into lower risk of cardiovascular disease.
Lower sodium intake can reduce blood pressure, but researchers argue that at very low levels it can trigger adverse elevations of certain hormones that can, in turn, increase the risk of death and cardiovascular disease.
Researchers also discovered that increasing levels of potassium through diets of fruit and vegetables can decrease the rate of stroke, cardiovascular death and total mortality, although they couldn’t conclude whether this was because of a healthier diet or whether the potassium itself was protective.
“Our findings support other research recommending an all-round healthy diet with an emphasis on fruit and vegetables, dairy foods, potatoes, nuts and beans,” co-author Professor Martin O’Donnell added. “Very high sodium consumption (above 5g/day) is harmful, but the amount that is consumed by the majority of people does not appear to be linked to an increased risk of cardiovascular disease or death.