Salt and heart disease

Does high salt always mean impending cardiovascular disease (CVD)? Several studies insist on the danger of over-consuming salt. High salt is even considered a worldwide endemic. It is believed to contribute to a generation of high blood pressure (Suckling & Swift, 2015). Evidence of salt reduction in hypertensives supports reduction to decrease the risk of death from CVD. There is compellingly strong evidence that decreasing salt intake lowers blood pressure and reduces CVD risk (He & MacGregor, 2018). The WHO has set a goal of lowering salt intake from its present level and adults with hypertension are thought to benefit the most from that program (Wang et al., 2016).

While reducing salt intake has emerged as a leading target with many guidelines, these guidelines are mostly based on clinical trials. No large randomized trials have been done on low sodium intake for CVD (O’donnell et al., 2013). Prospective cohort studies examining the connection between sodium intake and CVD have been mixed and some recent studies reported a connection between having low sodium intake and an increased risk of CVD related death. There are very different interpretations of the same data that the controversy is likely to remain unresolved until larger and more definitive randomized controlled trials are conducted to determine the effect of low sodium intake on CVD (O’donnell et al., 2013).

Sodium is a necessary mineral that was poorly distributed in man’s ancestral environment (Hurley & Johnson, 2015). Evolutionary selection pressured his/her physiologically with hormones and neural circuits to seek sodium for ingestion. Deficiency triggers these hormones and neural circuits to elicit a craving for salt and a reward when salty foods are obtained (Hurley & Johnson, 2015). Consequently, sodium deficiency has negative psychological states like anhedonia, impaired cognition, and fatigue. Further, animal studies have shown the expression of the ACE2 receptor is down-regulated in response to a high sodium intake (Post, Dullaart, & Bakker, 2020). Resultantly, low sodium may cause cellular damage with a certain virus load and increase the risk of severe and possibly fatal COVID-19 infection. 

There is as much a danger to not intaking enough salt as there is with too much. The key is to discover the correct balance for optimal bodily function. We may never be absolutely sure how much salt we need, but we do know we need it.

References

He, F. J., & MacGregor, G. A. (2018). Role of salt intake in prevention of cardiovascular disease: Controversies and challenges. Nature Reviews. Cardiology, 15(6), 371–377. https://doi.org/10.1038/s41569-018-0004-1

Hurley, S. W., & Johnson, A. K. (2015). The biopsychology of salt hunger and sodium deficiency. Pflugers Archiv : European Journal of Physiology, 467(3), 445–456. https://doi.org/10.1007/s00424-014-1676-y

O’Donnell, M. J., Mente, A., Smyth, A., & Yusuf, S. (2013). Salt intake and cardiovascular disease: Why are the data inconsistent? European Heart Journal, 34(14), 1034–1040. https://doi.org/10.1093/eurheartj/ehs409

Suckling, R. J., & Swift, P. A. (2015). The health impacts of dietary sodium and a low-salt diet. Clinical Medicine, 15(6), 585–588. https://doi.org/10.7861/clinmedicine.15-6-585

Post, A., Dullaart, R. P. F., & Bakker, S. J. L. (2020). Is low sodium intake a risk factor for severe and fatal COVID-19 infection? European Journal of Internal Medicine, 75, 109. https://doi.org/10.1016/j.ejim.2020.04.003

Wang, M., Moran, A. E., Liu, J., Coxson, P. G., Penko, J., Goldman, L., Bibbins-Domingo, K., & Zhao, D. (2016). Projected Impact of Salt Restriction on Prevention of Cardiovascular Disease in China: A Modeling Study. PloS One, 11(2), e0146820. https://doi.org/10.1371/journal.pone.0146820