I was all set to spend part of today pointing out the many flaws in the latest “Low-Carb Kills!” study, but Denise Minger beat me to it. She wrote pretty much what I would’ve written, so I’ll let her do the talking on that subject. I’ll save my comments for an article written by Dr. Dean Ornish, who of course jumped all over this lousy study as proof that we should all live on low-fat vegetarian diets.
But first, in case you missed them, here are some of the headlines and lead paragraphs generated by media reporting on the study:
Low-carb, high meat diet has high risks
Comparing the health effects of two diets over more than two decades, researchers from Harvard School of Public Health and the University of Singapore found consumption of a low-carbohydrate, vegetable-based plan resulted in reduced rates of death from cardiovascular disease and cancer, and a lower rate of all-cause death overall, whereas animal-based low-carbohydrate diet were associated with a higher risk for overall mortality.
“You can have the initial Atkins-type of low-carb diet, which is loaded with sausages, bacon, steaks, and you can have healthy versions of the low-carb diet with more vegetable- or plant-based protein and fat,” said Dr Frank Hu, lead author of the study, published in the Annals of Internal Medicine.
Low carb diets might be deadly
A big concern about low carb diets is the source of fat and protein. Researchers say emphasis on fat and protein is associated with higher mortality from all causes of death in both men and women.
Vegetable-based low carb diets, on the other hand, are associated with lower mortality rates. Researchers say while the idea behind the diets are similar, the differences that affect mortality lie in specific fatty acids, protein, fiber and other vitamins.
Okay, you get the idea. An Atkins-type diet loaded with meat will kill you. Now here’s some of what Denise Minger — the same young blogger who recently shredded the China Study — had to say about the study:
Some of these “low carbers” were eating up to 60% of their diet as carbohydrates (first decile), which-last time I checked-is kind of not low-carb. Even the lowest low-carb eaters were still eating over 37% of their calories from carbohydrates. Whoever decided to call this study “low carbohydrate” is nuttier than a squirrel turd.
Folks in the Animal Group were more likely to smoke and had higher BMIs than adherents of the Vegetable Group. Along with influencing mortality outcomes, this suggests the Animal Food group, in the aggregate, may have been somewhat less health-conscious than the dieters lumped into the vegetable category. And that’s the type of thing that has repercussions for other diet and lifestyle choices that weren’t measured in the study.
The Vegetable Group was nowhere near plant-based: They derived almost 30% of their daily calories from animal sources (animal fat and animal protein), versus about 45% for the Animal Group. If we compare the middle (fifth) decile, the Vegetable Group was eating a greater percent of total calories from animal foods than the Animal Group was. D’oh!
For the Vegetable Group, cancer and cardiovascular mortality was lower in the tenth decile than the first decile, even though both deciles ate exactly the same amount of red meat and nearly the same amount of total animal foods. This suggests animal products aren’t the driving force behind differences in mortality rates.
Similarly, at the fifth decile, the Vegetable Group had a lower cardiovascular mortality hazard ratio than the Animal Group (0.99 versus 1.21), even though the Vegetable Group was eating a slightly greater proportion of animal foods (33.3% versus 29.9% of total energy for women; 32.9% versus 31% for men).
Bottom line: In this study, when you look closer at the data, differences in mortality appear to be unrelated to animal product consumption. Changes in cancer and cardiovascular risk ratios occur out of sync with changes in animal food intake.
I’ve read the full study, and it’s a joke. In addition to what Ms. Minger wrote, the first thing I noticed is that the researchers used food questionnaires to determine who was on a (ahem, ahem) “low-carb” diet. One group answered a total of 14 questionnaires between 1980 and 2002, and another group answered 10 questionnaires between 1986 and 2002. From this, the researchers supposedly can make very specific conclusions about total intakes of animal protein and fats versus vegetable proteins and fats.
Then there’s old missing-data problem. You can pretty much guess how they handled that:
A multiple imputation procedure was used with 20 rounds of imputation and included all covariates to account for missing dietary and covariate data. The analysis was repeated by using noncumulative updating of dietary information, in which we used the most recent diet data to predict mortality rate.
Same as in the recent low-fat vs. low-carb study: they performed mathematical magic to fill in the missing data. As Dr. Mike Eades like to say, if you torture the data long enough, it will tell you whatever you want to hear. This data appears to have been water-boarded until it screamed “Yes! Yes! Animal foods are deadly!”
So naturally, Dean Ornish decided this is the kind of unimpeachable study that proves he’s been right all along, as he wrote in the Huffington post under the dramatic headline:
Atkins Diet Increases All-Cause Mortality
I’ve got to hand it to you, Dr. Ornish … most anti-fat hysterics manage to write at least a paragraph or two before they start misconstruing the facts. But you told a whopper right there in the headline. The Atkins Diet? Say what?
As I noticed immediately and Ms. Minger pointed out as well, even if we grant that the researchers could accurately determine dietary intake from a dozen questionnaires mailed out over 20 years, these people weren’t on anything close to the Atkins diet. At the high end, their diets were 60% carbohydrates. At the lowest end, the diets were 37% carbohydrates. According to the study tables, the average calorie intake was right around 2000 calories per day (which sounds low to me, but we’ll roll with it). So let’s do the math:
(2000 * .37) / 4 = 185 carbohydrates per day … for the lowest carb group.
Could you please point out a page in any of the Atkins books where he recommends consuming 185 carbohydrates per day? The Atkins diet starts at 20 grams per day and gradually increases the carbs until weight-loss slows down — which for most of us is well under 100 grams per day. I rarely consume more than 50. That makes my diet less than 10% carbohydrates.
Dr. Ornish, whenever yet another clinical study demonstrates that people on low-carb diets experience greater improvements in cardiovascular markers than people on low-fat diets, you immediately say the results are illegitimate because the low-fat dieters didn’t restrict their fats as much as you recommend. Okay, fair enough: if they get 20% of their calories from fat, it’s not really the Ornish diet.
But when people in an observational (not clinical) study consume 185 carbs per day — at least three times what most Atkins dieters consume — that somehow becomes the Atkins Diet. Very consistent of you.
However, all-cause mortality rates as well as cardiovascular mortality rates were decreased in those eating a plant-based diet low in animal protein and low in refined carbohydrates. Although this plant-based diet was called an “Eco-Atkins” diet, it’s essentially the same diet that I have been recommending and studying for more than 30 years.
No, Dr. Ornish, you recommend a very low-fat (10% of calories) vegetarian diet. As Ms. Minger pointed out (and as the study data clearly shows), people in the group labeled “plant-based low-carb” were getting 20% to 30% of their calories from animal products. They consumed more than twice as much animal protein as vegetable protein, more animal fat than vegetable fat, and got nearly 30% of their overall calories from fat — and yet, according to the study, they experienced lower-than-average mortality rates. So if you believe this study is accurate, it doesn’t support the diet you recommend at all.
In many debates with Dr. Atkins before he died, I always made the point that it’s important to look at actual measures of disease, including mortality, not just risk factors such as HDL cholesterol. This is the first study that examined mortality rates in those consuming an Atkins diet, and it confirms what I’ve been saying all along: an Atkins diet is not healthful and may shorten your lifespan.
I can see why you’re pooh-poohing cardiovascular markers these days, since the Atkins diet keeps winning that battle in clinical research. (Although let’s be honest: you spent a lot of years bragging how your diet lowers LDL.) And I agree that what matters is longevity and health, not an impressive lipid panel.
But once again, this study has zip to do with the Atkins diet. These folks were consuming between 185 and 300 grams of carbohydrates per day. So “the first study that examined mortality rates in those consuming an Atkins diet” did no such thing.
And of course, it’s nothing more than an observational study based on food questionnaires and a fair amount of “imputed” data. It’s not a controlled study, so the results don’t tell us anything conclusive. If animal fats and proteins caused cardiovascular disease, we’d see those results repeated consistently around the world. But we don’t … that’s why there’s a French Paradox, a Spanish Paradox, a Swiss Paradox, an Indian Paradox, etc.
Your body makes HDL to remove excessive cholesterol from your body. Eating a stick of butter will raise HDL, but butter is not good for your heart. Pfizer discontinued a study of its drug, torcetrapib, which raised HDL but actually increased risk of heart attacks.
So let me get this straight … excess cholesterol causes heart disease, HDL removes cholesterol from your body, but foods that raise your HDL aren’t good for you. And we know this because a drug that artificially raised HDL produced a higher heart-attack rate. Makes sense. But I noticed you conveniently failed to mention that the Pfizer drug also dramatically lowered LDL. So using Ornish logic here, a diet that lowers my LDL isn’t good for me. That means I should avoid the Ornish diet.
Or here’s another possibility: artificially raising or lowering any type of cholesterol with drugs is pointless and possibly harmful. It’s not the same as improving lipid profiles through a better diet, because the high HDL is just a biomarker for good cardiovascular health, not health itself. Since you’re such a fan of observational studies, you can’t ignore the observation that HDL is strongly associated with a reduced risk of heart disease. The Atkins diet (the real Atkins diet, that is) raises HDL. It’s a diet, not a drug.
And if butter isn’t good for the heart, I guess that explains the screamingly high rate of heart disease in France, where they consume four times as much butter as Americans. No, wait … didn’t I just mention something called the French Paradox? Well, it’s probably because of all those other good health habits practiced by the French, such as higher rates of drinking, smoking, and visiting your mistress for an hour or two before going home for dinner.
By the way, Dr. Ornish, if you’ve done the research, you’re aware of the many intervention studies that attempted to lower rates of heart disease through low-fat diets, but failed miserably. You claim you succeeded (of course, you also had your subjects give up sugar and flour, quit smoking, exercise, and take stress-reduction classes). Perhaps so. But if the results aren’t consistent and repeatable, they’re not scientifically valid. As Karl Popper would say, if your theory is that all swans are white, it doesn’t matter how many white swans you show me; as soon as I point out some black swans, your theory is invalid.
Conversely, a whole foods plant-based diet that’s also low in refined carbohydrates may reverse coronary heart disease and beneficially affect the progression of prostate cancer and even improve gene expression despite reductions in HDL.
A whole-foods diet of any kind that’s low in refined carbohydrates will prevent disease. Make it a balanced whole-foods diet instead of a vegetarian whole-foods diet, and you can keep your HDL high, too.
Finally, what’s good for you is also good for our planet. Livestock consumption causes more global warming than all forms of transportation combined. It takes 10 times more energy to produce animal-based protein than plant-based protein.
I’m not at all surprised you’ve swallowed the vegan nonsense about how meat production causes global warming and uses 10 times the energy to produce. The figures about how much energy is required to raise cattle are, as Lierre Keith pointed out, based on the notion that cattle are supposed to eat grains. They’re not. Cattle are supposed to eat grass.
I’ll bet you’re also blissfully unaware of how much fossil-fuel fertilizer is required to grow an acre of soybeans. Not your fault, really: the United Nations, which originally made the absurd statement about cattle being responsible for global warming (based on nothing resembling actual evidence), managed to ignore that one as well. In fact, a recent book written by a former editor of The Ecogolist concludes that vegetable oils leave a larger “carbon footprint” than animal fats. If we really want to save the planet by changing our food preferences, the answer is to raise our animals in pastures and stop farming grains.
But thanks for making it clear to us where you’re really coming from, Dr. Ornish: you believe eating meat is wrong. Just admit it. This isn’t about science for you; it’s about your version of morality. That’s why you’re able to ignore every bit of clinical evidence that doesn’t support your beliefs, then embrace one lousy observational study as if it were handed down on stone tablets from on high.
Now if you’ll excuse me, my steak is nearly done.