I was excited to see an article, “A Look at the Low-Carbohydrate Diet,” in the December 3, 2009, New England Journal of Medicine. I was quickly disappointed.
Expecting a scholarly review of low-carb eating in humans, I found an exposition of a diet study in mice. And not just your garden-variety mice. These were a lab strain deficient in apolipoprotein E, which makes them particularly susceptible to atherosclerosis when fed a “Western” high-fat, moderate-protein, moderate-carbohydrate diet instead of standard lab chow.
Click on the HeartWire reference below for a discussion of the original mouse research. I wrote a short post about it in August, 2009.
The article author, Dr. Steven R. Smith, states the usual concern that high-fat (especially saturated fat), high-protein, low-carb diets may cause cardiovascular disease such as atherosclerosis (hardening of the arteries). He doesn’t mention the scientific evidence showing little or no role of total and saturated fat in cardiovascular disease.
I give credit to him for mentioning that high-fat low-carb diets area associated with improvement in several cardiovascular risk factors such as HDL cholesterol and blood pressure. He thought they also improve ( lower) LDL cholesterol levels—not something I’ve been impressed with. He didn’t mention the lowering of triglycerides so often seen.
Dr. Smith explains that, compared with controls, mice eating the Western high-fat low-carb diet demonstrated progression of atherosclerosis, perhaps mediated by elevated nonesterified fatty acids and low numbers of endothelial progenitor cells. These are not yet considered classic cardiovascular risk factors in humans.
To quote Dr. Smith, his main point is that . . .
The work of Foo et al suggests that the [high-fat low-carb] diet might increase the risk of cardiovascular disease through mechanisms that have nothing to do with these “usual suspects” [e.g., LDL and HDL cholesterol, blood pressure, C-reactive protein] and so provides a note of caution against reliance on the traditional cardiovascular risk factors as a gauge of safety.
He rightfully calls for investigation of these issues in humans, but . . .
In the meantime, the ageless advice applies to the consumer of the [high-fat low-carb] diet and other fad diets: caveat emptor.
Take Home Points
I agree that human studies are needed.
As the evidence in favor of the safety and efficacy of high-fat low-carb diets increases, the reigning medical establishment is looking for new ways to discredit them. This attempt is pathetic.
Unfortunately, the typical physician reading NEJM will skim this article and conclude, “Yeah, I was right—the Atkins diet causes heart disease. Low-fat high-carb is still the best.”
If you have beloved pet mice that are deficient in apolipoprotein E, don’t feed them a high-fat low-carb diet.
Steve Parker, M.D.
Smith, Steven R. A Look at the Low-Carbohydrate Diet. New England Journal of Medicine, 361 (2009): 2,286-2,288. [This may cost you $10 USD.]
Foo, S.Y., et al. Vascular effects of a low-carbohydrate high-protein diet. Proceedings of the National Academy of Sciences of the United States of America, 106 (2009): 15418-15423. doi: 10.1073/pnas.0970995106 [This may cost you $10 USD.]
Busko, Marlene. Atherosclerosis heightened in mice fed low-carb, high-protein diet. HeartWire, August 26, 2009. [Free]