A new study published in The American Journal of Clinical Nutrition is reporting an association with eating meat and weight gain. This is a fairly robust epidemiological study, but at the same time is a good example of how such information is poorly reported in the media, leading to public confusion.
The data is taken from the European Prospective Investigation into Cancer and Nutrition–Physical Activity, Nutrition, Alcohol, Cessation of Smoking, Eating Out of Home and Obesity (EPIC-PANACEA) project. This is a long term epidemiological study involving hundreds of thousands of individuals, and is therefore a great source of data. We are likely to see many publications from from it. This one looked at the association of meat eating – poultry, red meat, and processed meat – with total weight. From the methods:
A total of 103,455 men and 270,348 women aged 25–70 y were recruited between 1992 and 2000 in 10 European countries. Diet was assessed at baseline with the use of country-specific validated questionnaires. A dietary calibration study was conducted in a representative subsample of the cohort. Weight and height were measured at baseline and self-reported at follow-up in most centers. Associations between energy from meat (kcal/d) and annual weight change (g/y) were assessed with the use of linear mixed models, controlled for age, sex, total energy intake, physical activity, dietary patterns, and other potential confounders.
Over a year ago I wrote about The China Study, a book by T. Colin Campbell and his son based on a huge epidemiologic study of diet and health done in China. The book’s major thesis is that we could prevent or cure most disease (heart disease, cancer, diabetes, autoimmune diseases, bone, kidney, eye and other diseases) by eating a whole foods plant-based diet, drastically reducing our protein intake, and avoiding meat and dairy products entirely.
I noticed a number of things in the book that bothered me. I found evidence of sloppy citations, cherry-picked references, omission of data that contradicted the thesis, and recommendations that went beyond the data. I concluded:
He marshals a lot of evidence, but is it sufficient to support his recommendation that everyone give up animal protein entirely, including dairy products? I don’t think so.
The China Study involved 367 variables and 8000 correlations. I said I would leave it to others to comment on the study design and the statistical analysis, and now someone has done just that. Denise Minger devoted a month and a half to examining the raw data to see how closely Campbell’s claims aligned with the data he drew from; she found many weaknesses and errors. (more…)
Some of the most rewarding interactions we have with our pets involve food. Most dogs respond with gratifying enthusiasm to being fed, and this activity is an important part of the human-animal bond. Providing food is also part of the parent/child dynamic that in many ways characterizes our relationships with our pets. Giving food is an expression of affection and a symbol of our duty of care to our pets.
Because of these emotional resonances, pet owners are often very concerned about giving their pets the “right” food to maintain health and, if possible, to prevent or treat disease. This has allowed the development of a large, and profitable commercial pet food industry that aggressively markets diets with health-related claims. This industry resembles in some ways the pharmaceutical industry. It is regulated by the FDA, and also by individual states, according to a somewhat Byzantine set of standards established by the FFDCA (the guiding document governing the FDA) and by the Association of American Feed Control Officials (AAFCO), a private organization made up primarily of state and federal feed control officials. Thanks to this regulatory structure, imperfect though it is, there is a good deal of solid science and research behind the products and claims the industry produces.
In 1952 Martin Gardner, who just passed away this week at the age of 95, wrote about organic farming in his book Fads and Fallacies in the Name of Science. He characterized it as a food fad without scientific justification. Now, 58 years later, the science has not changed much at all.
A recent review of the literature of the last 50 years shows that there is no evidence for health benefits from eating an organic diet. The only exception to this was evidence for a lower risk of eczema in children eating organic dairy products. But with so many potential correlations to look for, this can just be noise in the data.
Another important conclusion of this systematic review is the paucity of good research into organic food – they identified only 12 relevant trials. So while there is a lack of evidence for health benefits from eating an organic diet, we do not have enough high-quality studies to say this question has been definitively answered. It is surprising, given the fact that organic food was controversial in the 1950s, that so little good research has been done over the last half-century.
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.
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…)
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.
I get all sorts of mail. I get mail from whining Scientologists, suffering patients, angry quacks—and I get lots of promotional material. I get letters from publishers wanting me to review books, letters from pseudo-bloggers wanting me to plug their advertiblog—really, just about anything you can imagine.
Most of the time I just hit “delete”; it’s obvious that they’ve never read my blog and they’re just casting a wide net for some link love. But a recent email from a PR firm piqued my interest: (it’s a long letter, and I won’t be offended if you simply reference it rather than read the whole thing now):
March 4, 2010
Today I went to the one-day, 2nd Yale Research Symposium on Complementary and Integrative Medicine. Many of you will recall that the first version of this conference occurred in April, 2008. According to Yale’s Continuing Medical Education website, the first conference “featured presentations from experts in CAM/IM from Yale and other leading medical institutions and drew national and international attention.” That is true: some of the national attention can be reviewed here, here, here, and here; the international attention is here. (Sorry about the flippancy; it was irresistible)
I’ve not been to a conference promising similar content since about 2001, and in general I’ve no particular wish to do so. This one was different: Steve Novella, in his day job a Yale neurologist, had been invited to be part of a Moderated Discussion on Evidence and Plausibility in the Context of CAM Research and Clinical Practice. This was not to be missed.