Reducing sodium intake by less frequently adding salt to food after it is cooked is associated with a reduced risk of ischemic heart disease (IHD), heart failure (HF) and stroke, according to a study published Nov. 28 in JACC. Furthermore, the lowest frequency of adding salt to foods combined with the DASH diet was associated with the lowest risk of cardiovascular disease (CVD) in the study.

Hao Ma, MD, PhD, et al., examined the relationship between the frequency of adding salt to food (never/rarely, sometimes, usually, always) and incident cardiovascular disease risk in a prospective cohort of 176,570 participants (about 56 years old and 55% women) from the UK Biobank. At baseline, researchers collected information from participants using a web-based questionnaire on the frequency of adding salt; a 24-hour dietary recall was conducted at baseline and over one to five rounds over a three-year period. A DASH diet score was calculated to evaluate the joint association of diet and adding salt to food on cardiovascular disease risk. The 24-hour sodium excretion was estimated using casual spot urinary concentrations. Data on cardiovascular disease events were collected through medical history and data on hospital admissions, questionnaires and death register data.

Over the median 11.8 years of follow-up, the number of documented incident cases was 9,963 for total cardiovascular disease events (IHD, HF and stroke); 6,993 for IHD; 2,007 for stroke; and 2,269 for HF.

Researchers found a lower frequency of adding salt to food was significantly related to a lower risk of total cardiovascular events; the adjusted hazard ratios (HRs) were 0.77 for never/rarely, 0.79 for sometimes and 0.81 for usually adding salt (p for trend <0.001). The strongest association was seen for HF: adjusted HRs were 0.63, 0.65 and 0.70, respectively, for the frequency groups, (p for trend <0.001). While there was also a significant association for risk of IHD, none was observed for stroke.

Higher modified DASH scores were associated with lower risk of total cardiovascular disease, IHD, HF and stroke. Participants with the lowest frequency of adding salt to foods (never/rarely) and the highest tertile of modified DASH diet score had the lowest risk of cardiovascular disease events (HR, 0.64).

Participants most likely to less frequently add salt, compared with a higher frequency of adding salt, were more likely to be women, White, have a lower body mass index, not a current smoker, more physically active and have moderate alcohol consumption. They also had a higher prevalence of high blood pressure and chronic kidney disease, but a lower prevalence of cancer. These participants were also more likely to adhere to a DASH-style diet and consumed more fruits, vegetables, nuts and legumes, whole grains, low-fat dietary but less sugar-sweetened drinks or red/processed meats than those with a higher frequency of adding salt to foods.

In a related editorial comment, Sara Ghoneim, MD, writes that the study is promising, builds on previous reports, and alludes to the potential impact of long-term salt preferences on total cardiovascular risk.

“A major limitation of the study is the self-reported frequency of adding salt to foods and the enrollment of participants only from the UK, limiting generalizability to other populations with different eating behaviors,” Ghoneim writes. “The findings of the present study are encouraging and are poised to expand our understanding of salt-related behavioral interventions on cardiovascular health.” 

“Overall, we found that people who don’t shake on a little additional salt to their foods very often had a much lower risk of heart disease events, regardless of lifestyle factors and pre-existing disease,” said Lu Qi, MD, PhD, HCA Regents Distinguished Chair and professor at the School of Public Health and Tropical Medicine at Tulane University in New Orleans. “We also found that when patients combine a DASH diet with a low frequency of adding salt, they had the lowest heart disease risk. This is meaningful as reducing additional salt to food, not removing salt entirely, is an incredibly modifiable risk factor that we can hopefully encourage our patients to make without much sacrifice.”

Clinical Topics: Cardiovascular Care Team, Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Prevention, Acute Heart Failure, Diet, Hypertension

Keywords: Meat, Sugars, Sodium, Fabaceae, Sodium, Dietary, Heart Diseases, Alcohol Drinking, Heart Disease Risk Factors, Myocardial Ischemia, Neoplasms, Stroke, Renal Insufficiency, Chronic, Life Style, Heart Failure, Feeding Behavior, Hypertension, Risk Factors, Whole Grains, Tropical Medicine, Sugar-Sweetened Beverages, Smokers, Self Report, Prevalence, Preexisting Condition Coverage, Nuts, Fruit, Body Mass Index, Biological Specimen Banks, Follow-Up Studies, Prospective Studies, Vegetables, Dietary Approaches To Stop Hypertension, Cardiovascular Diseases

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