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Laura Dolson

Will Low-Carb Clog Your Arteries?

By August 30, 2009

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alt When I returned from my vacation last week, I turned my TV on to hear the following news: "A low-carbohydrate high-protein diet...may lead to heart problems. Here's why: according to a study, animals placed on a low-carbohydrate high-protein diet showed significant plaque buildup in their arteries." The segment concluded with the statement, "The study being done with rats applies to humans as well." Meanwhile, footage of people eating chips and salsa(??) was shown in the background, as well as mice in cages. (KSBW-TV)

Oh, man. What now? Of course, I had to figure out what was going on, and it turned out that the media was flooded with similar stories, with headlines such as "Atkins-style diets can clog up arteries", "Low-carb diets could increase heart attack risk", "Low-carb diets damage arteries", and "Health risk from low-carb diets". I also had several emails from concerned readers. Of course, it was important for me to understand the implications of this latest study.

One thing I've discovered since becoming a health writer is that oftentimes the media gets it wrong in their reporting of research, and this was no exception. Reading the study for myself, I found out the following:

- The subjects in the study were genetically-altered mice. It turns out regular mice don't get clogged arteries, so they have to use genetically-altered ones. One question I have is "genetically-altered to get clogged arteries in response to what"? I do not know the answer to this.

- The low-carb group was eating an amount of protein far above that recommended in any low-carb diet book you will find: 45%. The head researcher, Sin Yin Foo, has been quoted as saying that "We had a diet specially made that would mimic a typical low-carb diet." Where did he get the idea that this is typical? Not likely from any of the popular low-carb diet books such as Atkins, Protein Power, South Beach, etc. In general, protein recommendations for low-carb diets are well within the recommendations of the Institute of Medicine, which set a maximum of 35% of calories from protein (and most people don't get nearly that high, as for most people a diet which gets a third of its calories from protein is simply unpalatable -- in other words, kind of gross). Dr. Foo probably got his information by listening to the prevalent myths about low-carb eating -- too bad he wasn't a little more careful.

- In any case, the mice did not react the same way humans do to low-carb diets. How do I know this? Because of a chart which showed that of the three diet groups, the mice on the low-carb diet had by far the highest triglycerides. This is the opposite of how almost all humans react. Lowered triglycerides has been called "a hallmark of the low-carbohydrate diet", with some physicians even using triglyceride levels to tell if their patients are sticking with their diets. So if the mice didn't respond typically to a low-carb diet in this way, how else did their response differ from humans? We just don't know.

- As they grew, the low-carb group naturally ate less, and gained 28% less weight than the other mice.

- In their literature review, as far as I can tell, the many studies showing benefits from low-carb eating were totally ignored.

The Bottom Line

Based on the results of this study, I advise the following:

- Wait for human studies before taking this seriously. The scientific literature is full of animal studies that turned out to be irrelevant in humans. Rest assured there is a strong scientific basis for carbohydrate restriction for people.

- Avoid eating more than the recommended 35% protein in your diet (don't worry, it's doubtful you are doing this unless you are trying to eat a diet which is low in both carbs and fat -- not generally a good idea).

- Under no circumstances should you consume High-Protein Mouse Chow as your primary food (though a little nibble now and then is not likely to hurt you).

Photo: Sandy Jones/Getty Images

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August 31, 2009 at 9:53 pm
(1) Gracie says:

This is so crazy! My lipids have plummeted! Thankfully I am not a genetically altered mouse, they seem to have issues!

September 1, 2009 at 2:29 am
(2) Michael Netsch says:

Very interesting! But I want to point out that there is indeed a diet that recommends an insanely amount of protein intake. The popular Scarsdale Diet from the 70s by Dr. Herman Tarnower recommends upping your protein intake to 43%.

September 1, 2009 at 12:51 pm
(3) Jennifer Eloff says:

Well done debunking this study, Laura! :-)

September 4, 2009 at 9:30 pm
(4) jim stamps says:

I have lost 163 lbs and my chol. dropped from 265 to 125 on a low carb diet. My bp is 112/65

September 6, 2009 at 3:26 pm
(5) Paul N says:

From reading the studies abstract I noticed the high proportion of protein, but also got the pression all the mice gained weight. Where the mice over fed?

Any how, I applied those diet ratios to my diet, set at mantainec calories and I got about 2 grams protein per lb of body weight. That’s 2 times more than many diets recomend to low carbing athletes.

August 16, 2013 at 4:44 am
(6) Gerard says:

Thanks for pointing out the ‘genetically altered’ part.

The diet part was extreme enough without that genetic component. I always recommend the ‘golden ratio’ to people on this diet — 2 to 1 fat to protein ratio. On a low carb diet, this means 80% fat 20% protein, give or take a few percentage points.

This is because if you aren’t properly ketogenic, your protein excesses will get converted to carbs, including the protein that makes up your lean muscle. Which means a carb equivelant 15% + 45% = 60% carb diet with other hormones such as cortisol helping to break things down.

And if that is too many carbs for the body to handle, then while the protein won’t get broken down as fast, the body will still release insulin both converting carbs to fat and storing the 40% dietary fat.

Duke University has done some very credible research into low carb diets. One of the things they found is that at any given caloric intake, replacing carb calories with fat calories helps with weight loss and other beneficial effects.

Looks like there is a full court press with regards to the medical industry targeting things that actually help people: diet, supplements, glucosamine / condroitin, Omega 3′s..

They are losing much credibility. Looks like I’ll only go to them for surgery, and I’m hoping I will never have to do even that…

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