Extra salt at the table increases mortality risk

People who regularly add salt to their foods may face a lower life expectancy, according to a new study (Eur Heart J. 2022;ehac208). 

Salt is staple used to add and enhance the flavor of food across the globe. According to the World Health Organization (WHO), the average person consumes 9 to 12 grams of salt per day—more than double the recommended intake of less than 5 grams of salt per day. Too much salt, WHO reported, is linked to poor cardiovascular health, including high blood pressure and high cholesterol.  

The present study, published in the European Heart Journal, tapped self-reported data and urine samples provided by more than 500,000 participants of the UK Biobank, a large-scale biomedical database of people living in the UK, to evaluate the effects of adding salt to food on mortality. At baseline, participants were asked to disclose whether they add salt to their food at the table, excluding salt added during cooking, and were asked to select one of five options: never/rarely; sometimes; usually; always; or prefer not to answer. Urine analyses were consistent with self-reported salt added to food, indicating lower concentrations of urinary sodium in people who reported “never/rarely” adding salt to their foods compared to those who “sometimes,” “usually” or “always” added salt.  

Participants also completed 24-hour dietary recalls between 2009 and 2012, which were used to determine mean values of total energy, red meat, processed meat, fish, vegetable and fruit intake. 

During a median of 9 years of follow-up, researchers recorded 18,474 premature deaths—defined as deaths occurring before age 75. Results showed those who reported always adding salt to their food had a 28% increased risk of dying prematurely from any cause compared to people who never/rarely add salt to their food. At the age of 50, life expectancy dropped 1.5 and 2.3 years for women and men in this group, respectively. At age 60, life expectancy dropped by 1.4 years for women and 2 years for men.  

The results also showed an association between adding salt to food and cause-specific mortality, including cardiovascular disease (CVD) and cancer mortality. Higher frequency of adding salt to foods was also significantly associated with certain types of CVD, including stroke mortality.  

“In this study, instead of assessing the amount of sodium intake, we provided a unique perspective to evaluate the association between salt usage behaviors and mortality,” researchers wrote. “The frequency of adding salt to foods reflects a person's long-term salt taste preference, and it is less likely to be affected by the large day-to-day variations in sodium intake.” 

Very few previous studies have examined the relationship between the frequency of adding salt to foods and health outcomes. 

The study also revealed some good news for high-frequency salt adders: A diet packed with fruits and vegetables may offset the potential effects of a diet high in added salt. 

“Interestingly, we found the positive association of adding salt to foods with hazard of all-cause premature mortality appeared to be attenuated with increasing levels of total vegetables and fruits intake,” researchers wrote. “Higher frequency of adding salt to foods was significantly associated with higher hazard of premature mortality in participants with low level of total vegetables and fruits, whereas the association was not significant in those with high level of total vegetables and fruits.”