Key takeaways
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Importance
The self-reported frequency of adding salt to foods could reflect a person’s long-term preference for the taste of salt, and salt intake has been associated with an increased risk of cardiovascular diseases (CVD). It is still unknown whether self-reported addition of salt to food is associated with an increased risk of chronic kidney disease (CKD).
Aim
To prospectively examine the association of self-reported frequency of adding salt to food with incident risk of CKD in a general adult population.
Design, environment and participants
This population-based cohort study assessed UK Biobank participants aged 37 to 73 years who did not have CKD at baseline. Participants were enrolled between 2006 and 2010 and were followed prospectively for diagnosis of the disease. Data was analyzed from October 2022 to April 2023.
Exposure
Self-reported frequency of adding salt to foods, categorized as never or rarely, sometimes, usually, and always.
Main results and measures
Incident CKD cases were defined using diagnosis codes. Hazard ratios (HRs) and 95% CIs were calculated using Cox proportional hazards models. Models were adjusted for several potential confounders, including age, sex, race and ethnicity, Townsend Deprivation Index, estimated glomerular filtration rate (eGFR), body mass index (BMI). , smoking, alcohol consumption, regular physical activity, high cholesterol, diabetes, cardiovascular diseases, hypertension, infectious diseases, immune diseases and use of nephrotoxic drugs at the beginning of the study.
Results
Within a cohort of 465,288 people (mean [SD] age 56.32 [8.08] years; 255,102 female participants [54.83%]; 210,186 male participants [45.17%]), participants with the highest self-reported frequency of adding salt to food were more likely to have a higher BMI, a higher Townsend Deprivation Index score, and a decreased baseline eGFR compared to those who reported a lower frequency of adding salt to food.
Participants who added salt to their foods were also more likely than those who did not add salt to their foods to be current smokers and have diabetes or cardiovascular disease at the start of the study.
During a median (IQR) follow-up of 11.8 (1.4) years, 22,031 incidents of CKD were documented. A higher self-reported frequency of adding salt to food was significantly associated with an increased risk of CKD after adjustment for covariates.
Compared with those who reported never or rarely adding salt to foods, those who reported sometimes adding salt to foods (adjusted HR [aHR], 1.04; 95% CI, 1.00-1. 07), those who reported that they usually added salt to foods (aHR, 1.07; 95% CI, 1.02-1.11), and those who reported that they always added salt to foods (aHR, 1.07; 11; 95% CI, 1.05-1.18) had an increased risk of CKD (P for trend <0.001). Additionally, eGFR, BMI, and physical activity significantly modified the associations, which were more pronounced among participants with higher eGFR, lower BMI, or lower level of physical activity.
Conclusions and relevance
In this cohort study of 465,288 people, a higher self-reported frequency of adding salt to food was associated with an increased risk of CKD in the general population. These findings suggest that reducing the frequency with which salt is added to foods at the table could be a valuable strategy to reduce the risk of CKD in the general population.
Comments
Adding salt to food is associated with increased risk of CKD in the general population
People who habitually add an extra pinch of salt to their meals are doing their kidneys no favors, new research confirms. The finding held even after the researchers took into account other health problems, such as being overweight, lack of exercise, smoking and/or drinking.
The bottom line: "Adding salt to foods is associated with an increased risk of chronic kidney disease in the general population," concluded a team led by Dr. Lu Qi of Tulane University’s Obesity Research Center in New Orleans. Qi and his colleagues recently published studies showing that adding salt to foods increases the chances of heart disease, type 2 diabetes and a shorter life expectancy.
However, the links between table salt and the odds of kidney disease in the general population had not been well researched, Qi’s group noted. To remedy this, they analyzed data from more than 465,000 people, with an average age of 56, who did not have kidney disease when they registered in a British health database known as UK Biobank. Participants’ health and lifestyle were tracked from 2006 to 2023.
According to the researchers, more than 22,000 cases of kidney disease emerged during the study period. Compared to people who never or rarely added salt to their food, people who did so were more likely to develop kidney problems. The risk increased with how often people said they consumed table salt.
For example, compared to those who never ate it, people who said they "sometimes" added extra salt had a 4% higher risk of kidney disease; those who "usually" added salt had a 7% increased risk, and those who "always" added salt saw their risk increase by 11%.
Those risk estimates came after Qi’s team took into account lifestyle factors that often accompany excessive salt consumption: overweight/obesity, smoking, drinking, lack of exercise, diabetes, hypertension and other problems. .
The study was published in the journal JAMA Network Open .
There are many physiological problems linking high sodium intake and poorer kidney function, the researchers noted, including hormonal changes and "increased oxidative stress" in the twin organs.
According to the Tulane researchers, their findings "support reducing the addition of salt to foods as a potential intervention strategy for the prevention of chronic kidney disease."
SOURCE : JAMA Network Open , December 28, 2023
