The U.S. white working class is in big trouble. The data is piling up.

Economists Anne Case and Angus Deaton have a new paper out, exploring mortality trends in the U.S. The results confirm the finding of their famous 2015 study — white Americans without college degrees are dying in increasing numbers, even as other groups in and outside the country live longer. And the negative trends continued over the past year.

The problem appears to be specific to white Americans.

Mortality rates among blacks and Hispanics continue to fall; in 1999, the mortality rate of white non-Hispanics ages 50-54 with only a high school degree was 30 percent lower than the mortality rate of blacks in the same age group; by 2015, it was 30 percent higher. There are similar crossovers between white and black mortality in all age groups from 25-29 to 60-64.

In contrast to the U.S., mortality rates in Europe are falling for those with low levels of educational attainment, and are doing so more rapidly than mortality rates for those with higher levels of education.

Why is this happening? Case and Deaton don’t really know. Obesity would seem to be a culprit, but it’s also up among black Americans and British people, whose mortality rates from heart disease have fallen. Deaths from suicide, alcoholism and drug overdoses — what the authors collectively call “deaths of despair” — have been climbing rapidly. But they only account for a minority of the increase. And no one knows the definitive reason for white despair.

One tempting explanation — especially for those on the political right — might be that immigration and diversity are causing white people to lose a sense of community and cultural homogeneity, driving them to self-destruction. But mortality rates for working-class white people in Europe, which are experiencing even bigger fights over immigration, have fallen very rapidly in recent years. Europe also casts doubt on the hypothesis that the decline in marriage is to blame, because marriage also fell in European countries and among black Americans.

Case and Deaton instead suggest economic causes — lack of opportunity, economic insecurity and inequality. But this is hard to square with falling mortality for black Americans, who also suffered mightily in the Great Recession and have been on the losing end of increasing inequality.

So the reason for the increase in non-college white mortality remains a mystery, for now. Perhaps it will always just be a mysterious nationwide episode of anomie, like the massive increase in Russian death rates after the Soviet Union’s fall.

But whatever the cause, I know of one policy that would go a long way toward fighting the baleful trend — national health care.

A national health service — which also goes by the names of single-payer health care and socialized medicine — would drive down the price of basic health care. Because an NHS would be such a huge customer, it would be able to use its market power to get better deals from providers. This is probably why the same health-care treatments and services cost so much less in Europe than in the U.S. — those other countries have their governments do the bargaining.

This already works in the U.S. Medicare, the single-payer system that ensures the elderly, has seen much lower cost growth than private health insurance, even though Medicare isn’t yet allowed by law to negotiate for cheaper drugs.

Another way an American NHS would be able to help the white working class is by having doctors monitor patients’ behavior. In the U.K., doctors ask patients about their alcohol consumption, exercise and other habits at free checkups. There’s some evidence that this sort of checkup doesn’t increase health in Canada, but that may be because Canadians already mostly avoid heroin, alcoholism and suicide. A U.S. NHS would be able to check patients’ mental health (to prevent suicide), their alcohol intake, their opiate and other drug use, and a variety of warning signs.

Finally, an NHS could prevent overuse of opioids. Prescription of painkillers has been a major factor in the opiate epidemic, which has hit the white working class hard. Drug manufacturers, however, have lobbied to preserve widespread access to opioids. These companies have also given doctors incentives and perks — essentially, bribes — to keep prescribing these dangerous drugs. An NHS would be able to resist lobbying pressure and make sure doctors didn’t have an incentive to hand out too many opioid pills.

A NHS wouldn’t require the creation of a new bureaucracy — it would just require expanding Medicare to cover the whole nation. There’s already a campaign to do this, led by none other than Sen. Bernie Sanders. An NHS also wouldn’t prevent rich people from buying expensive or rapid treatment in private markets.

So while an NHS might not solve all the health problems of the U.S. white working class, it would go a long way toward doing so.

Unfortunately, the health-care proposal that Trump backed went in the opposite direction, reducing health coverage rather than expanding it.

Noah Smith is a Bloomberg View columnist.