A little bit of booze, the conventional wisdom goes, can be good for you. But the evidence for that claim—beyond anecdotal accounts that a nip of whiskey can nip a cold in the bud—is surprisingly thin. Alcohol studies usually look backwards, comparing participants’ historical drinking habits with their health problems. But it’s hard to prove that alcohol caused those problems. The best alcohol study would randomly require people to either drink or abstain—but for many public health researchers, that’s always seemed like a bridge too far.

Today, though, the National Institutes of Health is planning just such an experiment. The Moderate Alcohol and Cardiovascular Health study, now in progress on four continents, is poised to be a breakthrough in public health: the first time that researchers have followed a group of people randomized to receive a daily drink or nothing at all. But it’s also the first time the NIH has offered the $1 trillion-plus alcoholic beverage industry a chance to sponsor a project. That exchange of money, along with the study leaders’ failure to guard against outside influence, are jeopardizing the study’s credibility before it has even enrolled its first participant.

The study has its origin, strangely enough, in tea. Back in 2006, researchers thought tea drinkers might have fewer heart attacks. So Kenneth Mukamal, an epidemiologist at the Harvard-affiliated Beth Israel Deaconess Medical Center in Boston, recruited at-risk adults and told them to drink either three cups of black tea a day or three cups of water. Getting participants to stick to the program is notoriously difficult, so to make sure they were drinking their tea, Mukumal tested urine samples from a subgroup of participants for gallic acid, a tea breakdown product. After six months, they ran the numbers: Tea had virtually no effect on a person’s cardiovascular risk.

The results from the tea study may have been moot, but that gallic acid-measuring test was the proof of concept Mukamal needed for a different study. In 2008, Mukamal began giving participants an alcoholic drink—a mix of ethanol with Crystal Light or a Kraft lemonade mix—comparing their health markers to a control group that got lemonade without the booze. But people wouldn’t drink the ethanol. Like in the tea study, Mukamal was tracking whether his participants stuck to the program, and a blood test that rises with alcohol intake was actually higher in the non-alcoholic group than the alcohol group. A randomized trial to test alcohol’s benefits, Mukamal concluded, would have to let the participants choose a drink they actually liked.

Enter the National Institute on Alcohol Abuse and Alcoholism. In 2014, the institute solicited Mukamal to plan a six-year study of 7,000 subjects at risk of heart disease, pitting a daily alcoholic drink against total abstinence. They’d track heart attacks, strokes, heart-related chest pain, and death—the most comprehensive study of the heart impacts of daily drinking ever done, focusing on adults 50 and over. Instead of giving subjects a mix prepared by research pharmacists, though, the study would reimburse them for the drink of their choice.

Paying for more than 3,500 daily drinks for six years, it turns out, is expensive. The NIH would need more funding—and soon, a team stepped up to the plate. The Foundation of the NIH, a little-known 20-year-old non-profit that calls on donors to support NIH science, was talking to alcohol corporations. By the fall of 2014, the study was relying on the industry for “separate contributions to the Foundation of the NIH beyond what the NIAAA could afford,” as Mukamal put it in an e-mail to a prospective collaborator. Later that year, Congress encouraged the NIH to sponsor the study, but lawmakers didn’t provide any money. Five corporations—Anheuser-Busch InBev, Diageo, Pernod Ricard, Heineken, and Carlsberg—have since provided a total of $67 million. The foundation is seeking another $23 million, according to its director of development, Julie Wolf-Rodda.