Adding Salt to Food and the Risk of Premature Death
abstract
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Access this abstract nowAIMS
We analyzed whether the frequency of adding salt to foods was associated with the hazard of premature mortality and life expectancy.
METHODS AND RESULTS
A total of 501 379 participants from UK biobank who completed the questionnaire on the frequency of adding salt to foods at baseline. The information on the frequency of adding salt to foods (do not include salt used in cooking) was collected through a touch-screen questionnaire at baseline. We found graded relationships between higher frequency of adding salt to foods and higher concentrations of spot urinary sodium or estimated 24-h sodium excretion. During a median of 9.0 years of follow-up, 18 474 premature deaths were documented. The multivariable hazard ratios [95% confidence interval (CI)] of all-cause premature mortality across the increasing frequency of adding salt to foods were 1.00 (reference), 1.02 (0.99, 1.06), 1.07 (1.02, 1.11), and 1.28 (1.20, 1.35) (P-trend < 0.001). We found that intakes of fruits and vegetables significantly modified the associations between the frequency of adding salt to foods and all-cause premature mortality, which were more pronounced in participants with low intakes than those with high intakes of these foods (P-interaction = 0.02). In addition, compared with the never/rarely group, always adding salt to foods was related to 1.50 (95% CI, 0.72-2.30) and 2.28 (95% CI, 1.66-2.90) years lower life expectancy at the age of 50 years in women and men, respectively.
CONCLUSIONS
Our findings indicate that higher frequency of adding salt to foods is associated with a higher hazard of all-cause premature mortality and lower life expectancy.
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Additional Info
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Adding salt to foods and hazard of premature mortality
Eur Heart J 2022 Jul 10;[EPub Ahead of Print], H Ma, Q Xue, X Wang, X Li, OH Franco, Y Li, Y Heianza, JE Manson, L QiFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Adding salt to food at the table is a common eating behavior directly related to an individual’s long-term preference for salty tasting foods and habitual salt intake. Qi et al analyzed data from 501,379 people participating in the UK Biobank study and being followed for a median of 9 years. These people were classified according to their salt addition at the table into 4 groups: never/rarely, sometimes, usually, and always.
The findings documented an increasing risk of all-cause premature mortality with increasing frequency of adding salt at the table, after adjustment for sex, age, race, smoking history, moderate drinking habit, body mass index (BMI), physical activity, Townsend deprivation index, high cholesterol, chronic kidney disease, diabetes, cardiovascular disease, and cancer. An analysis of cause-specific premature mortality showed that adding salt at the table was associated with an increased risk of cardiovascular mortality and cancer mortality, but not of dementia mortality or respiratory mortality. Not surprisingly, the increased risk of premature mortality diminished with increasing intakes of food high in potassium, such as fruits and vegetables.
The authors concluded that their study “indicates that the higher frequency of adding salt to foods is associated with a higher hazard of all-cause premature mortality and lower life expectancy” and extrapolated from this conclusion “our findings also support the notion that even a modest reduction in sodium intake is likely to result in substantial health benefits, especially when it is achieved in the general population.”
Unfortunately, the issue is not quite as straightforward as the authors let us believe. The difference in 24-hour sodium intake between those who never/rarely added salt and those who always did is a minuscule 0.16 g or less than 4%. It is highly unlikely that such negligible quantity has any impact on blood pressure, not to speak on cardiovascular mortality or life expectancy. I submit that people who routinely add salt to their food exhibit a complete disregard to any health measures in their diet. In the study of Qi et al, they consistently consumed more red meat, processed meat, less fish, and less fruits and vegetables than those who did not salt their food. Not surprisingly, most, if not all, cardiovascular risk factors were significantly higher in those who always added salt compared with those who never/rarely did. They they were less likely to have a healthy lifestyle. but more likely to be male, not of White race, and to have a higher BMI and Townsend deprivation index as well as a higher prevalence of diabetes and cardiovascular diseases. However, the prevalence of hypertension was numerically lower in those who always added salt compared with those who never/rarely did (54.6% vs 56.1%).
Thus, the bad habit of mindlessly adding salt at the table is simply a powerful marker for an unhealthy diet and lifestyle. The paper of Qi et al is a thorough and sophisticated statistical exercise in adjusting for multiple confounders, but, in my opinion, has little, if anything, to do with salt intake.