When Dr. Barry Meisenberg attends lunchtime medical talks at the University of Maryland Medical Center, he usually doesn't eat - not even a carrot or a potato chip.
He abstains to avoid what he sees as a conflict of interest.
The talks are often sponsored by pharmaceutical and medical device companies, which supply the food, too. Meisenberg, a hematology professor at the medical school, decided a decade ago that taking gifts or money - including food, travel expenses and payments for speeches and research - could cloud his judgment about how to treat patients.
"I wanted to be free of any concerns about my reputation," he said. "The data show that we are being influenced, even by small gifts."
Meisenberg is among a growing number of doctors and researchers who have decided to stop taking money and gifts from medical companies.
Perhaps more importantly, medical institutions and professional organizations are taking similar steps - creating rules and guidelines for employees and members. At the same time, several members of Congress are developing legislation that would focus more attention on relationships between doctors and drug and device makers.
"The climate is changing," said Dr. Peter Libby, chief of cardiology at Brigham and Women's Hospital in Boston. "I think these limits will become more and more common in the future."
Libby decided to stop taking money from medical companies four months ago, after he was criticized for working on a documentary funded largely by pharmaceutical companies. Although the money had no effect on his judgment, he said, he realized that he had created the appearance of a conflict of interest.
"My credibility, and the perception of my integrity, are worth more than the bucks," he said.
And those bucks are enormous. Every year, the pharmaceutical industry spends more than $20 billion in the United States on promotional activities - continuing education programs for doctors, conferences, speeches, meals, gifts and other inducements to use a particular medicine or product.
"The bottom line is that relationships with industry are ubiquitous and are found in all aspects of medicine and research today," said Eric Campbell, an associate professor of health care policy at Harvard University.
Over the past decade, he's conduced six studies of the issue, all of which found high levels of doctor-industry linkage. The most recent research, involving 3,000 doctors, found that more than 90 percent had accepted gifts or payments.
Dr. Thomas Stossel is part of that 90 percent. The Harvard Medical School hematologist says he has no problem eating free meals or accepting fees for speeches or research. Like most doctors, he says the relationships have no effect on his ability to deliver good, objective care.
"Show me the evidence that we have a real, practical problem here," he said. "This is grossly overblown."
Even so, after four decades in practice, Stossel predicts that gifts and payments will soon be more tightly regulated.
"I'm not going to fight it," he said.
The pharmaceutical industry says it is open to proposals for change but contends that, in general, the current arrangement does not pose ethical problems.
"We think that interactions between our companies and health care professionals are important," said Lori Reilly, vice president for policy and research for the Pharmaceutical Research and Manufacturers of America, an industry trade group.
Reilly noted that the industry has self-imposed restrictions: For example, drug sales representatives cannot pay for doctors' entertainment.
But some pharmaceutical companies seem prepared to go further. Last week, Eli Lilly, one of the world's largest, released a statement supporting federal oversight of gifts and payments.
Lilly realizes that some changes should be made, according to spokesman Edward Sagebiel. "There's a deteriorating trust in our industry that really threatens the long-term viability of our industry," he said.
Though the company favors some limits, its officials believe that gifts and payments are a necessary and appropriate part of the relationship between doctors and industry, he said.
While critics have called unsuccessfully for limits on gifts and payments to doctors for decades, several events have changed the terrain in recent years.
Maine, Minnesota, Vermont, West Virginia and the District of Columbia have enacted laws requiring drug and medical device manufacturers to publicly report payments and gifts to doctors that relate to marketing.
The reports revealed that some doctors were making tens of thousands of dollars annually working with companies whose drugs they promoted and prescribed.
This year, researchers reported that Merck, which makes the painkiller Vioxx, wrote overly positive journal articles about the controversial drug and then paid scientists who had little or no involvement with the research to become official "authors."
New neuroscience research also has fueled the criticism. Using cutting-edge tests that can reveal brain activity as it changes from second to second, scientists have shown that even small gifts can alter our choices.
"Gifts affect the decision-making process in ways that are very hard to control," said Michael J. Friedlander, director of the Baylor University neuroscience department, which has done much of the new work. "Even when you are aware of it, even when you want to be objective, you can't help it. Your brain controls you."
Overall, many say, there's a growing understanding that the billions of dollars in drug marketing money have made a mark on doctors.
"We've sold our profession to the for-profit pharmaceutical and medical device companies," said Dr. Catherine D. DeAngelis, editor of the Journal of the American Medical Association. "They wouldn't be spending that money if it didn't have an effect."
Last month, DeAngelis, who says she's never taken money or gifts from a medical company, wrote a strongly worded editorial in the influential journal, calling for an end to gifts and payments.
Also last month, the Association of American Medical Colleges, the trade group for all academic medical institutions, released a report on industry funding that called for tighter restrictions on doctor-industry relationships. The proposal will be voted on this spring.
"The fact of the matter is, gifts do change doctors' judgment," said Dr. David Korn, the AAMC president. He notes that some doctors earn hundreds of thousands of dollars a year simply by giving speeches at industry events.
Korn and most other critics emphasize that they don't want a complete break with drug and device makers. They say the private sector can provide legitimate scientific and financial input to researchers and practitioners. But they say the situation has spun out of control.
Some institutions have set limits. In 2006, the University of Pennsylvania and Stanford University prohibited doctors from accepting industry gifts of any size - including drug samples - even at private-practice, off-campus clinics. Both set tight controls on continuing medical education courses, often sponsored by pharmaceutical companies to promote specific drugs.
The Johns Hopkins University and the University of Maryland allow doctors and researchers to accept gifts that have "educational value" and to earn money for company-sponsored speeches. Officials at both schools say the policies are under discussion and might be tightened in response to the new AAMC guidelines.
Congress is also interested. The Senate Committee on Aging has held three hearings on the issue, and last fall, Sens. Herb Kohl, a Wisconsin Democrat, and Charles E. Grassley, an Iowa Republican, introduced a bill that would require companies to report gifts and payments to doctors. The bill could end up as part of this year's Medicare legislative package, while a companion bill is making its way through the House.
"It's all about transparency," said Grassley. "American consumers ought to know whether their doctors might have a vested interest in prescribing certain drugs."