We all know there is a certain balance that is needed when it comes to nutrition. We need to get a variety of nutrients in our diet and avoid consuming too much of foods that may cause us harm. Salt is an essential mineral that our bodies need for transmitting nerve impulses, contracting and relaxing muscles, and maintaining the right balance of water and minerals. However, eating too much salt can be bad for our health. 

How much salt should you have? 

The World Health Organisation recommends that adults should consume less than 5 g of salt each day; this amount is sufficient for maintaining plasma volume and normal cell function. Processed foods often have a high salt content as this is used to help preserve the food. Therefore, as they often include foods such as processed meat, refined cereals, and packaged snacks, US and Western-style diets are more likely to contain excessive amounts of salt.

The average salt consumption in the UK has been reported at 8 g/day and a review of salt intake in Australian adults suggested the average intake to be 9.6 g/day; both figures are well above the recommended daily amount. 

To put this into perspective, a full English breakfast with two rashers of bacon, two sausages, black pudding, a fried egg, mushrooms, beans, tomato, and bread and butter could contain 6 g of salt: that’s already over your daily allowance before any extra salt or sauce is added and before accounting for lunch and dinner. It can be easy to overconsume salt across the day, particularly with the convenience of processed and pre-packaged foods. 

Negative impacts of too much salt

Excess salt in your body can impact your arterial pressure and cause deficits in the vascular endothelium (cells that line the arteries, capillaries, and veins), which can negatively impact blood clotting, fluid volume, and blood vessel function. Consuming too much salt regularly may make you more likely to experience health issues such as hypertension (high blood pressure) or cardiovascular disease due to the damaging effect salt can have on our blood vessels. 

Excessive salt intake can also cause microvascular rarefaction, which is a reduction in the number of arterioles and capillaries, a  process that can lead to an increase in blood pressure.

One study found that when salt intake was increased for 3 days, a 24% reduction in microvascular density was observed.

Microvascular rarefaction can also have a negative impact on your endurance performance, as it reduces your capillary density. A higher capillary density is associated with better performance in endurance events due to more effective delivery of oxygen to working muscles. Therefore, to help performance and general blood vessel health, it is important to manage your salt intake.

Benefits of decreasing salt intake

One study which looked at the effect of salt reduction in white, black, and Asian individuals, found that subjects who reduced their average salt intake from 9.7 g/day to 6.5 g/day developed lower blood pressure and increased capillary density. 

In hypertensive patients, even with blood pressure that isn’t too high, decreasing salt consumption can have beneficial effects on microcirculation through improvements to structural and functional capillary rarefactions. Aiming to reduce your daily salt intake to less than 6 g a day may help to maintain healthy microcirculation, helping your arterioles and capillaries to work more effectively. This may also help to improve your endurance performance by allowing blood to reach your muscles more efficiently to supply energy for prolonged periods. 

References

Aaron, K.J., & Sanders, P.W. (2014). Role of Dietary Salt and Potassium Intake in Cardiovascular Health and Disease: A Review of the Evidence. Mayo Clinic Proceedings. 88, (9), 987–995.

Action on salt. Breakfast survey - Action on Salt. https://www.actiononsalt.org.uk/news/surveys/2008/breakfast-2008/ 

Agócos, R., Sugár D., & Szabó, A.J. (2020). Is too much salt harmful? Yes. Pediatric Nephrology. 35, 1777-1785.

Boegehold, M.A. (2013). The Effect of High Salt Intake on Endothelial Function: Reduced Vascular Nitric Oxide in the Absence of Hypertension. Journal of Vascular Research. 50, (6), 458-467.

Caraher, M., & Hughes, N. (2019). Tackling salt consumption outside the home. British Medical Journal. 364, 1-2.

Guideline: Sodium Intake for Adults and Children. (2012). World Health Organization.

Hansen-Smith, F.M., Morris, L.W., Greene, A.S., & Lombard, J.H. (1996). Rapid Microvessel Rarefaction With Elevated Salt Intake and Reduced Renal Mass Hypertension in Rats. Correlation Research. 79, (2), 324-330. 

He, F.J., Marciniak, M., Markandu, N.D., Antonios, T.F., & MacGregos, G.A. (2010). Effect of Modest Salt Reduction on Skin Capillary Rarefaction in White, Black, and Asian Individuals With Mild Hypertension. Hypertension. 56, (2), 253-259. 

Kwong, E.J.L., Whiting, S., Bunge, A.C., Leven, Y., Breda, J., Rakovac, I., Cappuccio, F.P., & Wickramasinghe, K. (2022). Population-level salt intake in the WHO European Region in 2022: a systematic review. Public Health Nutrition. 

Land, M., Neal, B.C., Johnson, C., Nowson, C.A., Margerison, C., & Petersen, K.S. (2018). Salt consumption by Australian adults: a systematic review and meta-analysis. The Medical Journal of Australia. 208, (2), 75-81.

Marketou, M.E., Maragkoudakis, S., Anastasiou, I., Nakou, H., Plataki, M., Vardas, P.E., & Parthenakis, F.I. (2019). Salt-induced effects on microvascular function: A critical factor in hypertension mediated organ damage. Journal of Clinical Hypertension. 21, 749-757. 

Rajendran, P., Rengarajan, T., Thangavel, J., Nishigaki, Y., Sakthisekaran, D., Sethi, G., & Nishigaki, I. (2013). The Vascular Endothelium and Human Diseases. International Journal of Biological Science. 9, (10), 10570-1069.