Congress created the Supplemental Nutrition Assistance Program, known as SNAP, or food stamps, “to alleviate . . . hunger and malnutrition” and to “permit low-income households to obtain a more nutritious diet through normal channels of trade,” in the words of the federal statute establishing the program.

It’s a good goal. Whether SNAP is optimally designed to achieve it is a separate question, to which the answer seems to be “no,” according to new research commissioned by the Agriculture Department.

The report, published in November, found that SNAP households spend 20 percent of their benefits, typically about $255 per month per household, on sweetened beverages (including both sodas and non-fizzy drinks), desserts, salty snacks, candy and sugar.

That’s right: One of every five SNAP dollars goes to items that are perfectly permissible under the program’s rules but utterly lack nutritional value — and may contribute to chronic conditions such as diabetes and obesity.

Data in the report came from a large-scale survey of grocery store purchases in 2011. Applied to the program’s annual spending of $66 billion in fiscal 2016, they would translate into $13.2 billion worth of SNAP-funded junk food.

Numbers like these cry out for common-sense reform: a prohibition on the use of SNAP benefits to buy sodas and, if possible, other nutritionally empty products.

Such changes have been proposed by everyone from then-New York Mayor Michael Bloomberg to the nonprofit Physicians Committee for Responsible Medicine but keep getting shot down by powerful food-industry lobbies.

Lately, these corporations have been getting de facto backing from journalists and policy intellectuals. When the New York Times published a front-page article on the USDA-backed study last month, Mother Jones vilified the paper for “shaming” the poor.

Writing for The Post, Jared Bernstein and Ben Spielberg of the Center on Budget and Policy Priorities suggested it was “paternalism” to curb the poor’s SNAP options in the name of health.

Accusing the Times of stereotyping the poor as irresponsible, the critics noted that SNAP households’ junk-food consumption in the USDA-backed study may be high but is still roughly equivalent to that of non-SNAP households.

This is an accurate reading of the report — and a non sequitur. Taxpayers, through their representatives, have no legitimate interest in purely private food purchases; they do have a right to be concerned how federal money is spent, especially when it is being spent contrary to Congress’s express intent, and contrary to the best interests of the intended beneficiaries.

Bernstein and Spielberg say that’s hypocrisy, since no such strings are attached to consumption subsidies for better-off Americans: “Should the rest of us be able to weigh in on the home purchases of those claiming the mortgage interest deduction?” they ask.

As it happens, only “qualified homes” meeting certain (albeit very permissive) criteria get that deduction. The main point, though, is that it’s pretty late to be decrying SNAP’s paternalism, since the program has never been about pure freedom of choice. It already bans certain items: wine and beer; restaurant meals; even soup from a grocery store’s prepared-food bar. The separate Women, Infants and Children (WIC) nutritional program limits purchases to a list of healthful foods.

Another objection is that banning junk-food purchases would be a lot of bureaucratic hassle for no practical benefit. SNAP participants usually have cash income, often in excess of the $51 in monthly junk-food spending implied by the USDA-backed study. So they would simply buy their Sprite with dollar bills instead of their SNAP-funded debit card, the argument goes.

Maybe, maybe not — certainly junk-food companies did not lobby so hard against SNAP reform because they thought it wouldn’t affect their sales. (By the way, if people can still get the same amount of junk food even after a ban, is the ban all that “paternalistic”?)

In either case, a ban would at least clarify lines of financial responsibility for junk-food purchases, bolstering SNAP’s overall legitimacy.

And that is a crucial point: For all its shortcomings, SNAP is a vital element of the social safety net that helps lift millions of people out of poverty each year, many of them children. It needs all the legitimacy it can get.

Those who argue for the SNAP status quo may do so with good intentions, because they fear that airing concerns about SNAP’s junk-food subsidy plays into the hands of conservative budget-cutters looking for reasons to gut the program.

The opposite is just as likely to be true: A SNAP purged of sodas or candy, or both, could be less vulnerable to cuts.

Supporters could seek full funding, not in unholy de facto alliance with Big Junk Food, as they do now, but armed with a truly compelling argument: Every dollar for SNAP will help nourish the poor, just as Congress intended.

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