According to a study that included more than 500,000 participants, people who add salt to their meals are at greater risk of premature death from any cause. European Heart JournalToday (Monday).
Those who add salt to their diets regularly or never had to have it added had a 28% greater chance of dying young than those who did not. The general population is estimated to have three-quarters of a million people between 40 and 70 who die before they reach the age of 69. One in hundred people may be at risk due to salty foods, as shown in the current study.
The study also found that people who add salt to their food more often than those who don’t or rarely do so have a lower chance of living to old age. The life expectancy for women and men over 50 was cut by 1.5 and 2.28 years, respectively, if they added salt to their meals regularly.
Researchers at Tulane University School of Public Health and Tropical Medicine (New Orleans, USA) say that their findings have multiple implications for public health.
He said, “To my knowledge our study is not the first to examine the relationship between salt in foods and premature deaths.” It provides new evidence that supports recommendations to change eating habits to improve health. Even a small reduction in sodium intake (by adding less or none salt to food at dinner) can have substantial health benefits, especially if this is done in the population.
It is not easy to assess your overall sodium intake. Many foods, especially processed and pre-prepared foods, are high in salt before they reach the table. Most studies that assess salt intake through urine tests only require one test, so they do not reflect the usual behavior. Additionally, high-salt foods are often accompanied with potassium-rich foods, such as fruits and vegetables. This is good news for us. [1]. Potassium has been shown to reduce the risk of developing heart disease and metabolic conditions like diabetes. However, sodium can increase the risk of stroke and high blood pressure.
The researchers decided to examine whether people add salt to their food at the table. This was independent of salt added during cooking.
Prof. Qi said that “Adding salt at the table to food is a common eating habit that is directly related an individual’s long term preference for salty foods and their habitual salt intake.” “Addition of salt to food at the table in the Western diet accounts for 22%-20% of total sodium intake. It provides an excellent way to examine the association between habitual sodium intakes and the risk of dying.”
Researchers analysed data from 501 379 participants in the UK Biobank study. Participants were asked via touch screen whether salt was added to their food between 2006 and 2010. Participants who chose not to answer the question were excluded from the analysis. The researchers adjusted their analyses in order to consider factors that could impact outcomes such as age and sex, race and deprivation, body weight index (BMI), smoking and alcohol intake, diet, and medical conditions like diabetes, heart disease, and cancer. The average (or median) time they followed participants was nine years. Premature deaths were defined as those who die before the age of 75.
The researchers discovered that salting foods can increase the risk of premature deaths from all causes. They also found that people who ate more fruits and vegetables had a lower chance of dying. However, this was not statistically significant.
Prof. Qi stated that “we were not surprised” by the finding, as potassium is a major component of many fruits and vegetables. This has protective effects and lowers the risk of premature death.
He stated that “Our study is the first to show a link between salting foods and death, so further research is needed before we can make recommendations.”
An editorial accompanying the paper [2]Annika Rosengren, a professor of medicine and senior researcher at the Sahlgrenska Academy in Gothenburg, Sweden who wasn’t involved in the research, wrote that the net result of a drastic decrease of salt intake for individuals remains disputed.
She writes that “Given all the indications that very low sodium intake may not be beneficial or even harmful”, it is important to differentiate between individual recommendations and population-level actions.
She concluded that “classic epidemiology” argues that the population-wide approach has a greater net effect (having a small effect on many people) than targeting high-risk people (which can have a large impact but only a few people). Early detection and treatment for hypertension is the best and most evidence-based way to prevent cardiovascular disease. Lifestyle modifications and salt-reduction strategies at a societal level can lower mean blood pressure, which will result in fewer people becoming hypertensive, needing treatment and getting sick. It is unlikely that adding salt to foods will cause harm and may help to reduce the population’s blood pressure.
The large number of participants in Prof. Qi’s study is a strength. However, it has its limitations. There is the possibility that salting food may indicate a poor lifestyle or lower socio-economic status. Analyses attempted to adjust for this. Furthermore, there is no information about the amount of salt added to foods. Lastly, participation in UK Biobank is voluntary. Therefore, the results are not representative to the general population. Further studies will be needed to confirm these findings in other populations.
Professor Qi and his collaborators will continue to study the relationship between salt in foods and chronic diseases like diabetes and cardiovascular disease. They expect to conduct clinical trials that will test the impact of salt reduction on health outcomes.
[1]Tacos, which often contain vegetables and are typically salty, are an example of a food that can also include vegetables.
[2]Annika Rosengren: “Salt — The sweet spot?” European Heart Journal. doi:10.1093/eurheartj/ehac336
