A paper appeared recently in the prestigious Proceedings of the National Academy of Sciences (PNAS) that seems to have a whole lot of people on edge. If you read the press accounts of this study, you might think anyone stupid enough to follow a low-carb diet would be doomed to certain death from heart attack. But is that the case? Or is it simply another instance of the media either failing to understand how science works or, worse, misreporting to get a better story?
I suspect the latter, but before we get into it, I need to go over a few blog housekeeping issues.
As I’m sure everyone has noticed, the look of this blog has changed – as has the look of the entire website. Our designer and tech guys have been struggling to get everything working right, but, finally, my incessant whining got to them, and they went ahead and put the thing up in its not-completed state. Please bear with us – it will ultimately work as it’s supposed to. If you are having a problem, send me a description in the comments section. Make sure you tell me what kind of computer you’re using (Mac (Intel or pre-Intel) or PC) and which browser (Firefox, Internet Explorer, Safari, etc.) so that the gurus will know what to do to fix it.
I know the comments are screwed up right now, but don’t worry, they’ll be fixed. Go ahead and comment away. They’ll ultimately be up in a form you can recognize.
Once we get the blogs and website how they’re supposed to be, I’ll write a post describing all the features.
Also, our world-changing project has been slightly delayed through no fault of our own. The new date for revelation has been pushed back from Sept 1 to Sept 15. Sorry. It’s been a real PITA for us, too.
Now, back to the PNAS paper.
As we all know, media reports can be totally misleading or even downright false. Reporters have their own biases that creep into their work, and even when reporters think they are presenting the facts, they often report just one side of a story and ignore the other. And, as we’ve seen from the previous post on the vitamin D-bate, reporters may just report a story in a way that makes for better reading without any regard for the substance of the issues.
The PNAS paper reported a study on genetically modified rodents, engineered to be more susceptible to heart disease. As I’ve written many times in these pages, mice and rats aren’t just furry little humans – they are a different species altogether. And although they are often used for medical experiments, the conclusions from the experiments cannot be applied to humans. Like observational studies, rodent data can be used to establish hypotheses about human health and disease, hypotheses that can then be tested for validity.
In this case, the data on these genetically-engineered mice can’t even be extrapolated to normal mice much less humans. Knowing just this much about the study tells us that whatever it shows has little relevance to us. But that’s not what the media took away from the story.
The BBC came out with the following headlines that were picked up by a number of other media sources:
Low-carb diets ‘damage arteries’
And followed up with:
Low-carb slimming diets may clog arteries and increase the risk of heart attacks and strokes, a study suggests.
Diets based on eating lots of meat, fish and cheese, while restricting carbohydrates have grown in popularity in recent years.
But the Beth Israel Deaconess Medical Center in the US found such habits caused artery damage in tests on mice.
The researchers and independent experts both agreed a balanced diet was the best option.
Hmmm. Sounds pretty brutal doesn’t it. No hesitance there. No equivocation. Just a head on reporting of the facts. I don’t think so.
Why not? A number of reasons. First, these researchers basically had a bias going in that low-carb diets cause heart disease even though they lower cholesterol and bring about other positive changes in lipid values, most notably reducing triglycerides, increasing HDL levels, and changing LDL particles from the small type B to the larger type A variety. All of which changes, by the way, supposedly reduce the risk for heart disease.
The lead author of the study, Shi Yin Foo, MD, PhD, a clinical cardiologist,
first embarked on this investigation after seeing heart-attack patients who were on these diets – and after observing Rosenzweig [the researcher in whose lab she worked] himself following a low-carbohydrate regimen.
“Over lunch, I’d ask Tony [the aforementioned Rosenzweig] how he could eat that food and would tell him about the last low-carb patient I’d admitted to the hospital,” says Foo. “Tony would counter by noting that there were no controls for my observations.”
“Finally,” adds Rosenzweig, “I asked Shi Yin to do the mouse experiment – so that we could know what happens in the blood vessels and so that I could eat in peace.”
Do you think Dr. Foo has a little skin in this game? Think she might have a motive for stacking the deck a little in setting this experiment up in a way that encourages a certain outcome? This was not what you would call an unbiased quest for the truth.
I want to comment on something here as an aside. I don’t know how old Dr. Foo is, but since she’s working in someone else’s lab, I would think she’s probably fairly new to the medical game. She may have admitted a patient or two to the hospital with heart attacks, who, under questioning, may have admitted to following a low-carb diet at some point. But I’m willing to put my experience with low-carb diets up against hers any day. MD and I have followed over 10,000 patients on low-carb diets and have never had a single one have a heart attack. So, I really doubt that Dr. Foo has admitted many – if any – patients who are actively following a low-carb diet. But it does make for a good story.
Second, we’ve already mentioned that the mice were genetically engineered to be more susceptible to heart disease, so data generated from these rodents can’t be extrapolated even to other mice let alone to humans.
Third, the diet used wasn’t even a typical low-carb diet. The researchers
had a diet specially made that would mimic a typical low-carb diet,” explains Foo. “In order to keep the calorie count the same in all three diets, we had to substitute a nutrient to replace the carbohydrates. We decided to substitute protein because that is what people typically do when they are on these diets.”
Oh, really? This one statement shows Dr. Foo’s ignorance of low-carbohydrate dieting. People don’t typically “substitute protein” when they go on a low-carb diet. As anyone knows who has been on one, people substitute fat, the macronutrient that provides most of the calories on any low-carb diet. The mice in this study were getting 45 percent of their calories from protein, which can be done, but isn’t what one finds in most typical low-carb diets.
MD and I have been traveling extensively lately, so I hadn’t really had the time yet to delve deeply into this study, but, fortunately, as it turns out, I didn’t have to. Others have done it for me.
The Nutrition & Metabolism Society issued a press release on the paper to all its members. You can read it in full below:
Researchers use mutant mice genetically engineered to be susceptible to heart disease to ‘prove’ carbohydrate restricted diets may harm arteries.
Defects in ApoE -/- result in defects in processing blood cholesterol.
As human studies continue to show the benefits of low carbohydrate diets and the general failure of low-fat diets, it is necessary for the nutritional establishment to find more and more obscure methods of attacking dietary carbohydrate restriction.
One method is to prepare mutant animal models, to use odd diets that humans would never consume, call them low carbohydrate diets and then show some deficit. Because mice are not generally susceptible to atherosclerosis, it was necessary for Foo and coworkers to use an ApoE-/- mutant and a ridiculously high protein diet to vilify low carbohydrate diets which have been a useful alternative for many people suffering from obesity, diabetes and metabolic syndrome.
In keeping with the traditions in scientific research, the authors do not cite the numerous studies showing benefit of low carbohydrate diets compared to the low fat diet that has been in place during the obesity and diabetes epidemic. That the NIH and other government agencies continue to fund this kind of biased research is probably a minor political problem in health care but should still be of concern to people who are confused about what their diet should be.
According to Dr. Richard D. Feinman, Biochemistry Professor at Downstate Medical Center in NY, “It is a mistake to consider one experiment in a mouse mutant over riding the scientific literature where similar research trials on actual human beings clearly show benefit of carbohydrate restriction for all markers of metabolic syndrome. For some reason these studies are not the ones picked up by the media. I suppose actual advances in science aren’t hot topics for headline news stories when it concerns the proven benefits of carbohydrate restriction.
Volek JS, Ballard KD, Silvestre R, Judelson DA, Quann EE, Forsythe CE, Fernandez ML, Kraemer WJ: Effects of dietary carbohydrate restriction vs low-fat diet on flow-mediated dilation. Metabolism 2009.
Volek JS, Phinney SD, Forsythe CE, Quann EE, Wood RJ, Puglisi MJ, Kraemer WJ, Bibus DM, Fernandez ML, Feinman RD: Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids 2009, 44(4):297-309.
Of course, as you might expect, the press release wasn’t picked up by any of the major media outlets.
Jimmy Moore weighed in on the issue in an article in the Examiner.com in which he quotes numerous experts who have their say on this study.
And, Peter at Hyperlipid wrote two great posts taking the researchers to task and exploring the kind of protein used and various other aspects of this study. (Here and here.)
So, I was left with nothing more to add other than to say what I’ve said countless times before: Don’t rely on media reports to tell you anything.
(With apologies to Philip K. Dick for the title of this post.)