Red meat consumption has been linked to diabetes, cardiovascular disease, and several types of cancer (breast, colorectal, stomach, bladder, prostate, and lymphoma). There are plausible mechanisms: meat is a source of carcinogens, iron that may increase oxidative damage, and saturated fat. But correlation and plausibility are not enough to establish causation. Is red meat really dangerous? If so, how great is the risk? A couple of recent studies have tried to shed light on these questions, but they have raised more questions than they have answered.
A Systematic Review and Meta-Analysis
A new study in Circulation, “Red and Processed Meat Consumption and Risk of Incident Coronary Heart Disease, Stroke, and Diabetes Mellitus. A Systematic Review and Meta-Analysis,” by Micha, Wallace and Mozaffarian, is a systematic review of the literature. It analyzed 17 prospective cohort studies and 3 case-control studies, with a total of 1.2 million subjects. As far as I can judge, it appears to be a well-done systematic review with excellent methodology and multiple precautions. They even looked for things like publication bias (which they did not find).
They found that the consumption of processed meats, but not red meats, is associated with a higher incidence of coronary heart disease and diabetes. (Processed meats include bacon, sausage, ham, hot dogs, salami, luncheon meat and other cured meats.) The increased risk per 50 gram serving of processed meats per day was 42% for heart disease and 19% for diabetes. Unprocessed red meats were not associated with CHD and were associated with a nonsignificant trend towards higher risk of diabetes. They found no association with stroke, but this was based only on 3 studies.
We know that drinking alcohol during pregnancy can cause birth defects; the government-mandated warnings on alcoholic beverage labels constantly remind us of that fact. But toxicologists remind us that the poison is in the dose: what is the dose of alcohol that causes birth defects? Heavy drinking can cause fetal alcohol syndrome, but there is no evidence that light to moderate drinking can cause it. Alcohol has been implicated in a number of other adverse effects on pregnancy and on the fetus. We simply don’t know if there is a threshold dose below which alcohol intake is safe, so the default position of most medical authorities has been to advise total abstinence during pregnancy. This is not a truly evidence-based recommendation, but rather an invocation of the precautionary principle. Those advising complete abstinence have been accused of paternalism and bias by wine-lovers and other critics, for instance here and here.
The literature on alcohol and pregnancy is extensive and confusing. It addresses many different endpoints, looking at effects on children and on the pregnancy itself. The studies are inconsistent in how they define “moderate” or “light” drinking, and they rely on self-reports that may not be accurate.
It would be impossible to read and accurately summarize such a large body of literature (over 21,000 hits on PubMed!), but here are a few examples that illustrate the scope, diversity, and conflicting results of these studies: (more…)
For most of human history, doctors have killed their patients more often than they have saved them. An excellent new book, Taking the Medicine: A Short History of Medicine’s Beautiful Idea, and Our Difficulty Swallowing It, by Druin Burch, MD, describes medicine’s bleak past, how better ways of thinking led to modern successes, and how failure to adopt those better ways of thinking continues to impede medical progress.
The moral is not that doctors once did foolish things. The moral is that even the best of people let themselves down when they rely on untested theories and that these failures kill people and stain history. Bleeding and mercury have gone out of fashion, untested certainties and overconfidence have not.
Burch’s conversation with his rowing coach epitomizes the problem:
“I want you to keep your heart rate at 85% of max for the next hour and a half.”
“Because it’s the best way to improve your fitness.”
“How do you know?”
“Because I’ve done it before and it worked. Because that’s what the people who win the Olympics do. I know, I’ve trained some of them.”
“But has anyone actually done an experiment?”
“What on earth are you talking about?”
This book is Burch’s answer to his coach’s question. Medicine’s “beautiful idea” is that we should test all hypotheses and beliefs using the kind of tests that are reliable for determining the truth. Instead of going by tradition, authority, theory, common sense, or personal experience, we now have effective tools to find out for sure whether a treatment really works. (more…)
Last week I wrote about the CME presentations at an obesity course put on by the American Society of Bariatric Physicians. I saved the most controversial one for last. Dr. Kendall Gerdes is a former president of the American Academy of Environmental Medicine, which I have previously written about. The AAEM is not recognized by the American Board of Medical Specialties and is categorized by Quackwatch as a questionable organization. Dr. Gerdes spoke on food allergies and food addiction.
I wasn’t convinced: I thought much of what he said was questionable. I thought, as a challenge for our readers, it might be an interesting exercise to present his information without comment and let readers look for flaws and form their own opinions. At the end, I’ll offer some suggestions of things to think about.
He described the concept of food addiction as a powerful tool to free patients from compulsive eating. Patients may “have the experience of” being addicted to foods or have symptoms of hunger and of just not feeling well. Specific symptoms of food addiction include fatigue, fibromyalgia, GI symptoms, cardiac arrhythmias, asthma, rhinitis, arthritis and seizures. There is no “gold standard” way to diagnose food allergies. He relies mainly on avoidance and challenge. (more…)
The American Society of Bariatric Physicians recently invited me to speak at their continuing medical education (CME) conference on obesity in Seattle. They got my name from Stephen Barrett of Quackwatch and asked if I could speak about questionable weight loss treatments like HGH, MIC (methionine, inositol and choline), and the HCG Diet. I seized the opportunity to discuss how to evaluate any medical claim, with examples from alternative medicine as well as from weight loss. My title was “Questionable Evidence for Questionable Treatments.” I talked about some of the things that can go wrong in clinical trials and why simply finding reports of positive randomized controlled trials (RCT) is not enough. I advocated rigorously science-based medicine and recommended the SBM website.
Several people came up afterwards to express their thanks and their agreement, but some of the questions from the audience were rather hostile. One man said he was a military doctor and he was using and teaching acupuncture (which I had criticized as a bad example of “tooth fairy science” in my talk). I asked for his opinion of battlefield acupuncture and he just said “No comment.” A couple of people thought science wasn’t enough and thought it was okay to prescribe questionable treatments when there was no proven effective treatment. I responded that I had no objection as long as the patient was told the facts and not given the false impression that the questionable treatment had been tested and shown to work.
I was glad for the chance to meet some of the ASBP members. I had never met a bariatric physician and was interested to learn about their practices and philosophies. I had never really thought about the fact that most obese patients had associated diseases like hypertension and diabetes, so their overall management could be very complex. I attended the whole obesity course: some of what I heard was educational, some of it was questionable, and some of it was frankly disturbing. (more…)
In his new book Breakthrough! How the 10 Greatest Discoveries in Medicine Saved Millions and Changed Our View of the World Jon Queijo describes what he believes are the 10 greatest discoveries. 9 of them are uncontroversial discoveries that have been on other top-10 lists, but his 10th choice is one that no other list of top discoveries has ever included. He realizes that, and even admits in his introduction that a former editor of The New England Journal of Medicine refused to review his book because there is no such thing as alternative medicine, only treatments that work and treatments that don’t. But he “respectfully disagrees.”
Hippocrates’ discovery that disease had natural causes, sanitation, germ theory, anesthesia, X-rays, vaccines, antibiotics, genetics, and treatments for mental disorders are all worthy candidates for the list. But Queijo ludicrously lists the “rediscovery of alternative medicine” as the tenth “great discovery.” He presents no evidence (because there is no evidence) that alternative medicine has “saved millions” or that it has saved anyone. He doesn’t realize that alternative medicine represents a betrayal of exactly the kind of rigorous scientific thinking and testing that led to all the other discoveries. His list of ten breakthroughs is actually a list of 9 breakthroughs and one breakdown. (more…)
An article entitled “The Burden of Suboptimal Breastfeeding in the United States: A Pediatric Cost Analysis,” by Bartick and Reinhold, was published in Pediatrics 2010 April 5. According to this news report, it showed that 900 babies’ lives and billions of dollars could be saved every year in the U.S. if we could get 90% of mothers to breastfeed for at least 6 months. It says breastfeeding has been shown to reduce the risk of stomach viruses, ear infections, asthma, juvenile diabetes, Sudden Infant Death Syndrome and even childhood leukemia.
This new study did not provide any new evidence. It simply took risk ratios from a three year old government report, extrapolated, and estimated the costs.
Science isn’t the only game in town. Literature can teach us things about the world that science can’t. It can give us vicarious experience and insight into other minds. Two recently published novels illuminate why perfectly rational people might reject the help of scientific medicine and prefer to die a little sooner but to die on their own terms. (more…)
Anticoagulation is advised for patients who have had a blood clot or who are at increased risk of blood clots because of atrial fibrillation, artificial heart valves, or other conditions. Over 30 million prescriptions are written every year in the US for the anticoagulant warfarin, best known under the brand name Coumadin. Originally developed as a rat poison, warfarin has proved very effective in preventing blood clots and saving lives; but too much anticoagulation leads to the opposite problem: bleeding. A high level of Coumadin might prevent a stroke from a blood clot only to cause a stroke from an intracranial bleed. The effect varies from person to person and from day to day depending on things like the amount of vitamin K in the diet and interactions with other medications. It requires careful monitoring with blood tests, and it is tricky because there is a delay between changing the dose and seeing the results.
In his book The Language of Life, Francis Collins predicts that Coumadin will be the first drug for which the so-called Dx-Rx paradigm — a genetic test (Dx) followed by a prescription (Rx) — will enter mainstream medical practice. FDA economists have estimated that by formally integrating genetic testing into routine warfarin therapy, the US alone would avoid 85,000 serious bleeding events and 17,000 strokes annually.
A recent news release from the American College of Cardiology described a paper at their annual meeting reporting a study of
896 people who, shortly after beginning warfarin therapy, gave a blood sample or cheek swab that was analyzed for expression of two genes — CYP2C9 and VKORC1 — that revealed sensitivity to warfarin. People with high sensitivity were put on a reduced dose of warfarin and had frequent blood tests. People with low sensitivity were given a higher dose of warfarin.
During the first six months that they took warfarin, those who underwent genetic testing were 31 percent less likely to be hospitalized for any reason and 29 percent less likely to be hospitalized for bleeding or thromboembolism than were a group that did not have genetic testing.
Epstein said that the cost of the genetic testing — $250 to $400 — would be justified by reduced hospitalization costs.
At this point, I don’t believe this study. I’ll explain why I’m skeptical. (more…)
In September 2008 I wrote a post on Misleading Ads for Back Pain Treatment. with particular attention to the bogus claims for the DRX 9000.
The Canadian Broadcasting Company (CBC) show “Marketplace” has just done a scathing exposé of so-called nonsurgical spinal decompression treatment with machines like the DRX 9000 and of some of the unscrupulous practitioners who offer it. Between the hidden camera footage and the weasel words of the chiropractor they interview, it’s quite entertaining.