We know consuming too much salt raises blood pressure, which in turn can lead to cardiovascular problems. A new study has now quantified this relationship as a public health message in clear, stark terms.

Looking at health data on adults in China, the study authors estimate that a reduction of just 1 gram in daily salt intake would be enough to prevent 9 million cases of stroke and heart attack between now and 2030.

With 4 million of those cases likely to be fatal, such a simple measure could save a lot of lives.

In China, average daily salt consumption sits at 11 grams, way above the 5 grams recommended by the World Health Organization (WHO). The researchers pulled together the latest stats on population size, salt consumption, blood pressure and disease rates.

"Previous estimations of the health impact of reducing salt intake in China used either obsolete or otherwise unreliable data sources and did not account for the more prolonged effect of salt reduction on blood pressure over several years," write the researchers in their published paper.

The team looked at two other scenarios besides the single gram drop: a reduction of 3.2 grams per day (a 30 percent drop from the average) by 2025, and reducing salt intake to the recommended 5 grams per day by 2030.

If those targets are hit, up to twice as many deaths related to cardiovascular disease could be prevented, due to the estimated reduction in systolic blood pressure.

However, the researchers emphasize that the reduction would have to be consistent over several years. Education programs run in Chinese schools suggest most of the population wouldn't find it too difficult to hit that 1 gram per day target.

"Other trials, on low-sodium high-potassium salt substitutes, health education to home cooks and restaurant interventions are ongoing or have recently been completed, some of which have already shown promising results," write the researchers.

Cardiovascular disease accounts for a massive 40 percent of deaths in China, with urbanization – and the associated increase in eating processed and takeaway foods – thought to be one of the main contributing factors.

While the authors of this study only looked at a potential reduction in cases of cardiovascular disease, they suggest that lowering salt intake would have multiple other benefits too. Too much salt has also been linked to certain types of cancers and various kidney problems, for example.

The Chinese government has launched a Healthy China 2030 campaign to try to hit its target of a daily salt intake of just 5 grams. That won't be easy with a population of 1.4 billion people, but the numbers produced in this study are compelling.

"A salt reduction programme that is workable, coherent, sustainable and targeting current and upcoming major dietary sources of salt in China is urgently needed," write the researchers.

The research has been published in BMJ Nutrition, Prevention & Health.