Adding salt to meals at the table is linked to an earlier death, according to a study of 500,000 middle-aged Britons.
Researchers found that always adding salt to food knocks more than two years off life expectancy for men and one-and-a-half years for women. This does not include seasoning during the cooking process.
The study did not definitively rule out other factors, such as salt consumption being a proxy for a generally less healthy lifestyle, but the team behind the work said the evidence was compelling enough that people should consider avoiding seasoning their meals.
“To my knowledge, our study is the first to assess the relation between adding salt to foods and premature death,” said Prof Lu Qi of Tulane University School of Public Health and Tropical Medicine in New Orleans, who led the work. “Even a modest reduction in sodium intake, by adding less or no salt to food at the table, is likely to result in substantial health benefits, especially when it is achieved in the general population.”
The findings were based on research involving more than 500,000 participants in the UK Biobank study, who were followed for an average of nine years. When joining the study between 2006 and 2010, they were asked, via a touchscreen questionnaire, whether they added salt to their foods and how often they did so.
Salt intake is difficult to accurately track because many processed foods contain high levels of salt and direct measurement by urine tests does not necessarily provide a snapshot indicative of overall intake. Roughly 70% of sodium intake in western populations comes from processed and prepared foods, with 8-20% deriving from salt added at the table. However, adding salt is a very good indicator of a person’s preference for salty tasting foods, so the team focused their analysis on this measurement.
Compared with those who never or rarely added salt, those who always seasoned their food had a 28% increased risk of dying prematurely. At the age of 50, men and women who always added salt had a life expectancy 2.3 years and 1.5 years shorter respectively.
Other factors that could affect outcomes, including age, sex, ethnicity, deprivation, body mass index, smoking, alcohol intake, physical activity, diet and medical conditions such as diabetes, cancer and heart disease, were accounted for.
Prof Annika Rosengren, a senior researcher at the Sahlgrenska Academy at the University of Gothenburg, who was not involved with the research, said that while some health advice was straightforward – there are no downsides to stopping smoking – for salt there is an optimal level, meaning it cannot be removed from the diet entirely. It is hard to pinpoint the “sweet spot” in terms of health for any given individual.
“So far, what the collective evidence about salt seems to indicate is that healthy people consuming what constitutes normal levels of ordinary salt need not worry too much about their salt intake,” she said.
For this group, counterbalancing salt intake with a diet rich in fruit and vegetables should be a priority. However, those at high risk of heart disease should probably cut down. “Not adding extra salt to already prepared foods is one way of achieving this,” she said.