The U.S. Department of Agriculture says Americans should be eating a diet high in fruits and vegetables and low in refined grains and added sugars. However, through the billions of dollars in subsidies the USDA doles out each year, it is saying something quite different.

Overwhelmingly, tax dollars dedicated to supporting the nation’s food system go to crops that end up as ingredients in the most highly processed and unhealthy foods. Consequently, those foods are cheap, and now they make up most of the American diet, costing tens of thousands of lives and billions of dollars in health care costs each year.

It is a lunacy that has us encouraging farmers to grow the very crops that are killing us, and it has to stop.

The subsidies handed out every five years through the Farm Bill — more than $5 billion each year for corn and soybeans alone — favor large-scale farms that produce huge amounts of a single crop.

Those crops — mostly corn and soybeans, but also wheat, rice, sorghum and others — largely become feed for the cattle that source the country’s cheap, high-fat meat supply, or they are processed into sweeteners such as high fructose corn syrup for soft drinks and high-calorie fruit juices, or as filler for fatty packaged foods.

That’s why soda and snack cakes are so cheap, and so profitable for the companies that make them, while fresh produce remains relatively expensive.

Shoppers have noticed. According to a new study published in JAMA Internal Medicine, more than half of the calories consumed by Americans now come from federally subsidized food.

What’s more, the younger, poorer and less educated the person, the more subidized food they are apt to eat, and the more likely they are to suffer from obesity, elevated inflammation and abnormal cholesterol.

Americans are buying what they can afford — what government subsidies allow them to afford — and it is making them sick. The problem isn’t that people are allowed to buy sugary snacks with food stamps, it’s that sugary snacks and other unhealthy foods are all people on food stamps can afford.

A few small changes could make all the difference.

According to the Union of Concerned Scientists, more than 127,000 deaths and $17 billion in medical costs could be saved each year if Americans simply increased consumption of fruits and vegetables to the level recommended by the USDA’s MyPlate dietary guidelines.

We don’t even have to disrupt the subsidy system much — just making small investments in local growers of fruits and vegetables would do enough to bring down the cost of healthy food, while supporting small-scale, local agriculture to boot.

Other changes would help too. Farmers who received subsidies for commodities are not allowed to grow a variety of crops, a restriction that favors large-scale, nationwide producers over smaller regional farms. Lending for small farms is also too tight, crimping the ability of those farms to contribute to the local food system.

It’s not an accident that we’re in this place — processed food is the most profitable to sell, and subsidies only make it more so.

But what’s good for food companies is killing Americans, and it’s high time our policies reflect that.