Blood Pressure

Taking blood pressureEvidence shows that eating a low salt diet reduces blood pressure.

How does salt increase blood pressure?

As the salt content of our blood increases, our blood vessels retain water to try to keep the salt concentration balanced. This extra water increases the amount of blood in our vessels causing high blood pressure.

Why is high blood pressure bad for our health?

High blood pressure puts a strain on our blood vessels. It can also damage our heart, which has to work harder pumping blood at such high pressure around our bodies. This damage can lead to heart failure and can increase our risk of having a heart attack or stroke.

Over time, high blood pressure can damage and weaken our arteries. This can cause illness and death, especially if the damaged section bursts in the brain or in the aorta, our main artery.

High blood pressure can also narrow blood vessels (arteries, veins and capillaries) because the walls of the blood vessels thicken and harden due to all the hard work that they are doing to handle the increased pressure. When this happens, the blood flow is reduced. This can damage the organs receiving the blood. A blood clot could also block a narrow artery, cutting off blood supply to part of the body.

As they get thicker and stiffer, our blood vessels also get less elastic. This causes further pressure increases as it means blood is getting pumped into a rigid system that can’t absorb any of the pressure.

Ongoing high blood pressure is the leading risk factor for cardiovascular disease, including strokes, heart attacks, heart failure and arterial aneurysms. High blood pressure is also the second leading cause of chronic kidney failure.

Nearly 30% of Australians have high blood pressure, and over half of these people are unaware that they have it.

Low salt, low blood pressure

There is very strong evidence that links salt intake to blood pressure. Reducing your salt intake will help lower your blood pressure and your risk of health problems such as cardiovascular disease and kidney failure.

A reduction in salt intake of 1.7 grams per day^ results in a 2-5 mm Hg fall in systolic blood pressure. Recent evidence* suggests that a reduction in salt intake of 25 to 35% could lead to a 20% or greater reduction in risk of heart attacks and stroke.

^Summary of evidence statement on the relationships between dietary electrolytes and cardiovascular disease National Heart Foundation of Australia October 2006

*Cook NR, Cutler JA, Obarzanek E, Buring JE, Rexrode KM, Kumanyika SK, Appel LJ, Whelton PK. Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP). British Medical Journal. 391476048, doi:10.1136/bmj.39147.604896.55