How bad is eating a lot of salt for me?

Eating a lot of salt raises your blood pressure. That has been firmly established: in a carefully designed study, blood pressure already differed by 8 mmHg after just one week between people who ate a lot of salt and people who ate little. An average drop in arterial pressure of 4 mmHg was seen in people who switched from a high-salt to a low-salt diet. This effect occurred in the majority of middle-aged and older adults, including people who were already taking blood-pressure-lowering medication.

That higher blood pressure translates into a greater risk of cardiovascular disease. An analysis of 36 studies involving more than 616,000 participants found a clear linear relationship: every additional gram of sodium per day increased the risk of a cardiovascular event by around 6%. People who ate the most salt had a 19% higher chance of such a condition than those who ate the least. A comparable result came from a large prospective study with careful urine measurements: those in the highest intake group had as much as 60% greater risk of a heart attack, stroke, or similar event. These are associations, not proof that every individual is equally sensitive, but the pattern is strikingly consistent.

Outside of cardiovascular disease, salt also appears as a risk factor in other areas. A high salt intake is associated with an increased risk of stomach cancer, kidney stones, and lower bone density. The figures here are less precise than those for blood pressure and heart disease, but the associations are real. Anyone who wants healthy bones in later life therefore has an extra reason to keep an eye on their salt use.

On the other hand, salt is not an enemy you need to avoid entirely. In endurance athletes who sweat a great deal and simultaneously drink too much water without replenishing enough salt, blood sodium levels can drop to dangerously low levels. That is a serious but specific situation, and not an argument for more salt in everyday life.

What helps to limit the effect of salt? First, simply eating less of it. A broadly healthy diet with less salt can lower blood pressure by around 3.5 mmHg and reduce the risk of cardiovascular disease by around 30%. Second, getting more potassium through vegetables, fruit, and legumes is associated with an 18% lower cardiovascular risk per additional gram of potassium per day. Potassium partly offsets the harmful effect of sodium. That does not mean you can eat unlimited salt as long as you eat enough vegetables, but it does show that the dietary context matters.