For at least a decade, physicians’ acceptance of meals, gifts, and other “perks” from drug companies has been a matter of public controversy and concern. But a new study provides some of the best evidence yet that industry marketing works: Doctors receiving even a single, inexpensive meal (the average value was less than $20) from a drug rep were more likely to prescribe the products being promoted, compared with doctors accepting no meals. The study showed a robust “dose effect,” as well: Physicians taking more meals, and more expensive meals, wrote even more prescriptions for the touted products.

The authors are careful to acknowledge that their study shows correlation, not causation. But their findings are supported by an immense body of research: Hundreds of other studies have examined the extent and impact of physicians’ ties to health care product manufacturers, from de minimus gifts to lucrative consulting arrangements. Some studies show a modest or slight effect; others document a strong impact. Industry is quick to deny the evidence or quibble over its interpretation, but the fact remains: Companies would not spend billions annually marketing to prescribers were the enterprise unprofitable.

The prevailing response to this problem has been to impose transparency, presuming “sunlight is the best disinfectant.” Physicians are now commonly expected to disclose their industry ties to employers, medical audiences, research funders, patients, and so forth. By the same token, the Affordable Care Act of 2010 included the Physician Payments Sunshine Act (PPSA). This provision requires drug, device, and other commercial health care entities to report to the federal government most gifts and payments over $10 to physicians and teaching hospitals; the government then posts the data on a public website, Open Payments. This has brought unprecedented transparency to medicine. Nearly all company gifts and payments to physicians are now a matter of public record.

Yet transparency is not enough. To be sure, people behave better when they know they are being watched. However, many physicians see nothing wrong with accepting industry perks, and they assume that patients feel the same. They may also view transparency as license: Whatever I take from companies is fine, so long as it is disclosed. The result is transparency for the sake of transparency, with little or no improvement in behavior.

Weak ethical guidance from medical organizations contributes to the problem. For instance, the American Medical Association’s (AMA) Code of Medical Ethics instructs physicians to “decline gifts for which reciprocity is expected or implied.” This advice is nonsensical: We know that the human impulse to reciprocate for even small gifts is powerful. The very purpose of gift-giving, researchers suggest, is to create feelings of obligation or indebtedness. There is no gift without reciprocity.

Academic medical centers (AMCs) also offer guidance to prescribers in their employ. In recent years, some AMCs have made great strides in implementing strong, clear policies: no industry meals or gifts allowed, and stringent oversight of other prescriber-industry exchanges. But many AMCs’ policies remain ethically vague, permitting dubious practices or advising physicians to decide for themselves what is appropriate.

Government has largely deferred to medicine on these matters, despite having considerable skin in the game. The U.S. Public Health Service (PHS) includes eight federal agencies which conduct and fund healthcare services and research—the largest, the National Institutes of Health (NIH), expends over $30 billion annually on basic, clinical, and translational biomedical and behavioral research, primarily through grants to universities, AMCs, and other research institutes. Yet PHS remains agnostic on how to protect the integrity of the research and patient care it supports, allowing each recipient institution to decide which industry ties are permissible.

So what can be done to ensure that medical treatment is guided by what is best for patients, not corporate profits? First, transparency efforts must be strengthened. The PPSA contains several significant reporting exemptions, including gifts and payments to physicians under $10; product samples (which are highly effective at influencing prescribing); and all gifts and payments to nurse practitioners, physician assistants and other non-physician prescribers. Eliminating these exemptions would bring full transparency to companies’ relationships with health care providers.

Second, moving beyond transparency, health care institutions and government should adopt clear ethical guidelines and policies for prescriber-industry ties. The recommendations promulgated by the Institute on Medicine and the Association of American Medical Colleges provide excellent models: These prohibit gratuitous interactions (e.g. gifts and meals in physicians’ offices) and outline strategies for managing arrangements with bona fide educational or scientific merit (e.g. industry scholarships for medical trainees, payments for serving on companies’ scientific advisory boards). Professional medical associations, AMCs, and other health care bodies should adopt and enforce these rigorous standards. Likewise, PHS should require that recipient institutions enact such strong policies to ensure the integrity of publicly funded health care research and services.

Third, the federal government should follow the lead of states that have outlawed some problematic marketing tactics. Vermont, Minnesota, and Massachusetts, for example, have enacted laws banning all or most company meals and gifts to prescribers. In these states, health care providers are free to interact with industry to learn about advances in medical research and patient care, but these interactions must stand on their own merits, not on the lure of meals or gifts. Moreover, Vermont, Maine, and New Hampshire have passed laws prohibiting “data mining,” a practice whereby companies purchase prescription data from pharmacies so as to tailor sales reps’ marketing messages when visiting prescribers. Companies are challenging state data-mining laws in the courts; however, legal analysis suggests that the federal HIPAA Privacy Rule may already prohibit data mining nationally, as it bars the use of protected health information for marketing purposes without patient authorization. The federal government should pursue these promising avenues for curtailing undue industry influence on prescribers.

So long as health care is a business, companies will endeavor to influence medical decision-making. Within this framework, we cannot eliminate the bias of the profit motive, but we can take action to make it as ineffective as possible. Full transparency, high ethical standards, and strong laws and policies would go a long way to ensuring that medical treatment is guided by patients’ needs, not corporate profits.