According to a new study of over 500,000 people, persons who add more salt to their cooked meal at the table are at a greater risk of dying prematurely for any cause.
The study’s findings were published in the journal European Heart Journal. Those who constantly added salt to their diet had a 28% higher chance of dying prematurely than those who never or seldom added salt. In the general population, around three out of every hundred adults aged 40 to 69 die prematurely.
The present study’s increased risk from always adding salt to food predicts that one extra person in every hundred may die prematurely in this age range.
Furthermore, the study discovered that persons who constantly added salt had a lower life expectancy than those who never or seldom used salt. At the age of 50, women and men who constantly added salt to their diet had 1.5 years and 2.28 years less life expectancy, respectively, than those who never or seldom did.
The researchers, lead by Professor Lu Qi of Tulane University School of Public Health and Tropical Medicine in New Orleans, USA, claim that their findings have a number of public health implications.
“To the best of my knowledge,” he added, “this study is the first to analyse the relationship between adding salt to foods and early mortality.” “It adds new data to support suggestions to change eating habits for better health. Even a moderate reduction in sodium consumption, accomplished by adding less or no salt to meals at the table, is likely to result in significant health advantages, particularly when achieved in the general population.”
Assessing total sodium consumption is notoriously difficult due to the high quantities of salt added to many meals, particularly pre-prepared and processed foods, before they ever reach the table. Studies examining salt consumption using urine testing frequently use only one pee test and hence may not necessarily reflect typical behaviour.
Furthermore, foods high in salt are frequently accompanied with foods high in potassium, such as fruit and vegetables, which is beneficial to humans. Potassium is known to lower the risk of heart disease and metabolic illnesses like diabetes, but salt raises the risk of cancer, high blood pressure, and stroke.
For these reasons, the researchers decided to examine whether or not people added salt to their dishes at the table, rather than whether or not salt was applied during cooking.
“At the table salting is a frequent eating behaviour that is strongly tied to an individual’s long-term taste for salty-tasting meals and habitual salt consumption,” Prof. Qi explained.
“Adding salt at the table accounts for 6-20% of total salt intake in the Western diet and provides a new tool to analyse the connection between habitual sodium intake and the risk of mortality.”
The researchers examined data from 501,379 participants in the UK Biobank project. Participants were asked if they added salt to their foods I never/rarely, (ii) occasionally, (iii) regularly, (iv) always, or (v) choose not to respond when they joined the research between 2006 and 2010. Those who choose not to respond were excluded from the analysis.
Age, gender, race, deprivation, body mass index (BMI), smoking, alcohol intake, physical activity, food, and medical disorders such as diabetes, cancer, and heart and blood vessel illnesses were all factors considered by the researchers. The individuals were tracked for a median (average) of nine years. Premature death was defined as death occurring before the age of 75.
In addition to discovering that always adding salt to foods was associated with a higher risk of premature death from any cause and a reduction in life expectancy, the researchers discovered that these risks were reduced slightly in people who consumed the most fruits and vegetables, though these findings were not statistically significant.
“We were not shocked by this conclusion because fruits and vegetables are high in potassium, which has preventive benefits and is linked to a decreased risk of early mortality,” Prof. Qi stated.
“Because our study is the first to indicate a link between adding salt to foods and mortality,” he continued, “additional research is needed to corroborate the findings before making recommendations.”
Professor Annika Rosengren, a senior researcher and professor of medicine at the Sahlgrenska Academy, University of Gothenburg, Sweden, who was not involved with the research, writes in an accompanying editorial  that the net effect of a drastic reduction in salt intake for individuals remains controversial.
“This conclusion did not surprise us because fruits and vegetables are high in potassium, which has preventive benefits and is linked to a decreased risk of early mortality,” Prof. Qi added.
“Because our study is the first to indicate a link between adding salt to foods and mortality,” he continued, “additional research is required to confirm the findings before making recommendations.”
Professor Annika Rosengren, a senior researcher and professor of medicine at the Sahlgrenska Academy, University of Gothenburg, Sweden, who was not involved in the research, writes in an editorial accompanying the paper , that the net effect of a drastic reduction in salt intake for individuals remains controversial.
“Given the multiple evidence that a very low salt consumption may not be advantageous, or perhaps dangerous,” she adds, “it is vital to distinguish between advice on an individual basis and population-level activities.”
Salt in Diet and Blood Pressure
“Classic epidemiology indicates that the population-wide strategy (having a minor effect in many people) achieves a higher net benefit than targeting high-risk individuals,” she concludes (a large effect but only achieved in a small number of people). Early detection and treatment of hypertension, including lifestyle modifications, is the obvious and evidence-based strategy for preventing cardiovascular disease in individuals, whereas salt-reduction strategies at the societal level will lower population mean blood pressure levels, resulting in fewer people developing hypertension, requiring treatment, and becoming sick.
Not adding excess salt to food is unlikely to be detrimental and may contribute to community blood pressure-lowering measures.”
The vast number of participants involved in Prof. Qi’s study is one of its strengths. It also has some limitations, including: the possibility that adding salt to food is an indication of an unhealthy lifestyle and lower socioeconomic status, though analyses attempted to account for this; no information on the amount of salt added; adding salt may be related to total energy intake and intertwined with intake of other foods; Because participation in the UK Biobank is voluntary, the results are not typical of the broader population; consequently, more research is needed to corroborate the findings in other groups.