By Dr. Terry Simpson
When my good friend Evo Terra mentioned his desire to go on this special one-month diet, it was initially going to consist of just beer. Beer wouldn’t contain enough protein (9.6 grams a day for the six beers), nor would it contain enough other micronutrients. To add some protein to the diet, I suggested he consume a few sausages to fit the October theme, and Evo didn’t take much persuading. Plus, it would give me a reason to make my favorite, reindeer sausage, as his inaugural meal.
If you have been influenced by popular press and are aghast at what Evo did, you’re probably wondering how a physician could condone such a diet. The answer is simple: because we needed to know.
There are a lot of myths about what a person should eat to become fit, lose weight, and generally maintain their health. What we think we know about how the body reacts to the foods we put inside it and what we really know are two different things. Our brains are all-too easily influenced by the latest popular book-based or fad diet, and we assume that the secret is in eating vegetables, or protein, or … whatever. Such is the fickle nature of conventional wisdom.
If you follow the “protein” diets–such as Paleo or Atkins–you would assume that sausages are okay, but beer should be horrible. If you’re a follower of vegetable-based diets, you’d be okay philosophically with the beer, but you could never eat sausages that contain actual meat.
Where do we get those ideas, and is there real science behind them? We get them from popular press. We get them from cherry-picking scientific data. And we get them from our own prejudices.
This month, Evo is embarking on a diet that is at odds with the two great themes of American diets; he is not eating “clean” or “pure” foods and is instead eating “processed foods.” Therefore, his diet should be doomed to failure.
Here is the problem: Most of what you have read or heard about diets has more baloney than the sausages that Evo will eat. But those diets do make good sound bites. “Veggies are good for you so only eat those,” or alternatively, “Cavemen evolved to eat natural food and we have messed up the world by processing food so it has to be bad.”
The most dangerous assumptions about diets come from “population studies,” where researchers get food diaries from some individuals, look at the overall health of those studied, and then apply those findings to an entire population. Often, it’s just bad science.
Here are a few popular ones you may have heard of over the years, along with the myths they’ve generated.
Seven Countries Study
From the 1960s through the 1970s, cholesterol was offered up as a serious health threat. Both the American Heart Association and the “McGovern Report” (http://en.wikipedia.org/wiki/George_McGovern) that set national dietary policy in 1977 cited findings from the Seven Countries Study (http://en.wikipedia.org/wiki/Seven_Countries_Study) as evidence for their official statements clearly showing dietary cholesterol is bad for you, me, and everyone else. This study was a subgroup of a larger study that set policy about saturated fat and cholesterol for the United States for years.
Ancel Keys, a physiologist, architected and promoted the Seven Countries Study, establishing the conclusion that serum cholesterol was strongly associated with heart disease. That part is true. High levels of cholesterol in blood show a dramatic correlation with the incidence of heart disease and stroke. Where Keys got into trouble was making the leap that a diet low in cholesterol would reduce heart disease. His first assumption was that dietary cholesterol would impact blood cholesterol, but it does so only very modestly. His second assumption was that saturated fat would impact heart disease, but years of studies have failed to show evidence that saturated fat impacts blood cholesterol or increases heart disease.
But here’s the rub: The statistical data from the Seven Countries Study did not back up Keys’s conclusion. The Seven Countries study does not explain the “French paradox” (http://en.wikipedia.org/wiki/French_paradox). The French have a diet rich in saturated fats from both meats and dairy, and yet have one of the lowest rates of heart disease in the western world. This paradox could not be ignored, but the study did ignore it. Later people tried to invoke the increased red wine consumption as some magic counter to the saturated fat. The other data point the study ignored was the Japanese had significantly increased consumption of meats after WWII and yet still showed a reduction in strokes and heart disease. Today, we know the “epidemic” of heart disease in those decades was more attributed to the increase in cigarette smoking than dietary changes.
Later in his life, Keys recanted his position, saying cholesterol wasn’t so important. He then discovered olive oil, and was one of the founders of the Mediterranean Diet. He lived to be 101.
The China Study – VEGETARIAN MANIFESTO
Many vegetarians and vegans cite the China Study (http://en.wikipedia.org/wiki/China%E2%80%93Cornell%E2%80%93Oxford_Project) as The Study showing that eating vegetables will reduce not only heart disease, but also cancer. This study was then summarized in a best-selling book filled with conclusions and anecdotes, but no real science. According to the study, residents of rural China who continued to eat their traditional diet showed a remarkably low incidence of heart disease. Working on the hypothesis that diet played a key role, the lead author, T. Colin Campbell, drew blood from people in the villages and then pooled the samples together. (Yes, he took blood from individuals, then mixed all samples together for analysis instead of looking at each individual member of the community with their health issues and their blood chemistries–how a real study should work). Based on the data from a sample size of 100, he came to the conclusion (oddly enough reinforcing his own bias) that those with a diet high in vegetable proteins lived the longest, and that animal proteins were the primary cause of heart disease, cancer, and halitosis (okay, maybe not halitosis.)
The primary flaw of the study is the same flaw in all population studies: bad data. In this case, the data of the actual causes of death was lacking. Yes, the incidence of heart disease in China is greater than it was 40 years ago. But it isn’t because heart disease has increased nor because they are eating more protein. It’s because when a person died of heart disease 40 years ago, the cause of death was often recorded as something else. To this day heart disease in China is underreported, and in the day when there were no doctors in these villages it was dramatically underreported.
Most of the data in the study, when critically examined, supports the opposite conclusion of the “findings” Campbell suggests in his book. For example, one village had an extremely higher per-capita consumption of meat–twice that of the US population at the time. Yet the villagers had the lowest incidence of cancer and heart disease. These data also showed that the higher the amounts of processed wheat and sugar in the diets of the villagers in the study, the greater incidence of heart disease. Statistical outliers? More like evidence of the null hypothesis.
Here’s the reality. People who lived in rural China during the time of data collection were classic omnivores. They ate–and by all accounts still eat–any and all protein sources available. Mammals, birds, insects … If it flies, walks, crawls, swims, or slithers on the ground, it’s quite literally fair game. But when asked by well-meaning researchers in stiff lab coats to detail their protein sources? Well … pride is a strong motivator. Self-selected surveys are always suspect. Direct observation paints a vastly different picture.
The Norwegian Study
The decrease in heart disease during World War 2 in Norway is cited (most often by vegetarians) as proof that animal proteins lead to heart disease. Their conclusion? Heart disease went down because Norwegians had less animal protein available to them. But that conclusion is incorrect.
In 1940, Norway was invaded and occupied by Nazi Germany. Over the course of the next four years, the Germans confiscated nearly all the livestock to feed Nazi soldiers. In the Norwegian population, land-based animal protein consumption was suddenly and almost completely absent, while fish-based protein shot up over 200%. Also sugars, flours, and processed goods were highly rationed and hence available only on a very limited basis. During this time the Norske were forced to forage for plants and eat more fish to survive. Records indicate a noticeable drop in death from heart disease during the German occupation.
The popularized vegetarian conclusion is that it was the absence of red meat that caused the rate of heart disease to decrease in this population. However, this conclusion ignores a key fact: In wartime, the chance of dying from other causes such as trauma (guns), pneumonia, and other infectious diseases increases dramatically. People who die from pneumonia miss their chance of dying from heart disease.
But what about the data itself? Does it really support the meat-as-the-bad-guy conclusion? Read this excerpt from an issue of “Proceedings of the Nutrition Society” called “Food Conditions in Norway During the War, 1939-45”:
“During the first year [starting in spring of 1940] the rationing included all imported foods, bread, fats, sugar, coffee, cocoa, syrup, and coffee substitute. In the second year [starting in late 1941] all kinds of meat and pork, eggs, milk and dairy products were rationed”
No reduction in red meat the first year, and not until late in the second year? Then the mortality drop for 1941 cannot be linked to a reduction in animal protein that clearly didn’t happen. Hence the obvious question that I ask pro-vegetarians: “So you are telling me that if someone with heart disease immediately becomes a vegetarian, they won’t have a heart attack?”
In reality, it appears that Norway suffered from increasing fish (a great source of Omega 3 fatty acids). They grew and ate a lot of potatoes, but had a low amount of refined sugars and almost no margarine (I don’t know a respectable Norwegian today who cooks with margarine). But that’s really not why heart disease went down.
As mentioned previously, heart disease takes time to kill you. War doesn’t. The increase of mortality from infectious diseases like pneumonia killed more Norwegians during this time than any other time.
Paleo Diet: Cavemen knew better
Until someone invents a time machine, data collection on the daily habits and lifestyles of Paleolithic man isn’t feasible. We cannot even make valid assumptions of people who lived during World War II, so imagine the leaps of faith required to conclude what the caveman ate. While there are people left in the world who still gather and hunt as they did in the Paleolithic era, we don’t have good data about their overall health or whether they die from heart disease or other causes of death. Keep in mind that most hunter-gatherer societies–of yesterday and today–are ravaged by infectious disease, killing them long before heart disease will. And we certainly cannot conclude that for 250,000 years we were disease free, had few cavities, or lived in the proverbial Garden of Eden, harmonious with nature. This is made up. Totally made up. But it sells a lot of books, and justifies eating bacon.
Strong Heart Studies -– The Pima Indians
When I arrived as a vascular surgeon to Arizona, I was told that the Pima Indians had something special about them, as they didn’t suffer from heart disease. This conventional wisdom was so prevalent that a study was created, the Strong Heart Study (http://www.ncbi.nlm.nih.gov/pubmed/2260546), to try to determine what the Pima Indians had that made them immune from today’s heart disease. Immunity would not be a bad thing since they unfortunately have the highest incidence of type 2 diabetes in the world. (http://www.ncbi.nlm.nih.gov/pubmed/2260546) As it turns out, closer examination revealed that the hearts of Pima Indians were no different from anyone else’s and their rate of death from heart disease was actually higher than that of the general US population.
At the root of this embarrassing conclusion was, once again, poor data collection. This time, on “the most well-studied population in the world.” The Pima Indians had been studied for years by the National Institutes of Health, which even had an outpost there for collecting health data. In addition, these Native Americans received their health care from the Indian Health Service, with a hospital on the reservation and tertiary care in the metropolitan Phoenix Indian Medical Center. Even with the backing of the NIH–a fully staffed health service–the statistics collected and recorded were clearly poor. For years they concluded that Pima Indians had a low rate of heart disease, yet their own study showed this was a false assumption from the beginning. So consider this: If the NIH can make such a bungle, then imagine data collection taking place in a third-world country, without constant oversight, without highly trained researchers, and without modern recording devices. You’re likely to find hastily scribed pencil markings in record books just a few decades ago.
The statistics about mortality rates from any population survey are suspect. Conclusions drawn from poor data are useless. The common threads in the popular studies about diet are filled with confirmation bias of the authors.
With Evo’s diet, we examined not only his weight but also his body fat, total body water, and muscle mass. We also took blood draws to examine his blood count lipids and liver profiles. Based on that data, we were prepared to stop the diet if he took a turn for the worse. (Spoiler alert: He actually got healthier. We’ll detail that later.)
Physician disclaimer time: Do not attempt this diet on your own. You need a physician’s supervision for something like this. We need to examine this diet on many more individuals and get good data before we recommend this without a physician’s supervision. Please share this book with your doctor if you’re considering something similar. We’ll even autograph a copy for you or sign your e-book reader with a sharpie.