It's no secret there are strong correlations between how much foods cost and how much we consume them, with things like soda taxes being proposed across the world as a powerful tool for fighting obesity.

But what if you were to broaden the scope of that kind of thinking, reducing what it costs to buy a whole range of healthy foods, while simultaneously hiking prices on unhealthy alternatives?

According to new projections, the economic ripples of taxing unhealthy foods while subsidising healthy options would end up saving thousands of American lives every year – even if the price adjustments were only small.

"This is the first time, to our knowledge, that national data sets have been pooled and analysed to investigate the influence of food subsidies and taxes on disparities in cardiometabolic deaths in the United States," says epidemiologist José L. Peñalvo from Tufts University.

"We found that modest price changes on healthy and unhealthy foods would help decrease overall cardiometabolic deaths… [with] the largest changes coming from reducing the prices of fruits and vegetables and increasing the price of sugary drinks."

Peñalvo's team sourced data from the National Health and Nutrition Examination Survey (NHANES) in 2012, analysing comparative risk for cardiometabolic diseases, including diabetes, heart disease, or stroke.

They also looked at levels of consumption for seven different kinds of foods: four healthy options (fruits, vegetables, whole grains, and nuts/seeds) and three not so healthy (processed meat, unprocessed red meats, and sugar-sweetened beverages).

To figure out the potential health benefits if the costs of these foods were changed, the researchers modelled two different kinds of price interventions.

In one, food prices were altered by just 10 percent via either subsidy or tax – meaning healthy options became 10 percent cheaper, while unhealthy choices got 10 percent more expensive. In the other intervention, prices were adjusted by 30 percent up or down.

Per the team's calculations, a 10 percent price change on the seven foods would result in an estimated 23,000 deaths per year being prevented, equivalent to 3.4 percent of all cardiometabolic disease deaths in the US.

Not bad for a relatively small price adjustment – but the 30 percent price change would yield even more saved lives.

According to the researchers, a 30 percent subsidy/tax would lead to approximately 63,000 less deaths from cardiometabolic disease annually (nearly 10 percent of all such deaths).

Deaths due to stroke and diabetes saw the greatest impact from the interventions. Among the American populace, the group benefiting the most from the price alterations would be those with a high school education or lower.

"Our findings on disparities are particularly relevant today, with growing inequities in diet and cardiometabolic disease," says one of the team, Dariush Mozaffarian.

"The current strategies, such as education campaigns or food labelling, have improved overall dietary habits, but much less so among people with lower socioeconomic status."

Of course, while the findings are striking, they're not particularly surprising.

"We know the answer. Food is the number one cause of poor health in America," Mozaffarian explained in an opinion piece in September.

"Poor diet is not just about individual choice, but about the systems that make eating poorly the default for most Americans."

Previous research by some of the same team found a national program to subsidise the cost of fruits and vegetables by 10 percent could save 150,000 lives over 15 years, while a national 10 percent soda tax could save 30,000 lives.

In a country with now more obese Americans than merely overweight Americans – and a world with more obese people than skinny people – it's clear we need to do something.

"[P]oor diet causes nearly half of all US deaths due to heart disease, stroke, and diabetes," Mozaffarian writes.

"Through modest steps, we can achieve real reform that makes healthier eating the new normal, improves health, and actually reduces costs."

The findings are reported in BMC Medicine.