Low Carb Diets ‘Damage Arteries’

So blares the headline at the BBC news article the other day. What really annoys me though, is that this is tabloid medicine at its worse. Actually the “science” isn’t a lot better to be honest. I decided to investigate further. This link gives more detail on the story (though not enough by far): http://www.bidmc.org/News/InResearch/2009/August/LowCarbDiets.aspx

So I ask you, since when did a 12 week experiment, satisfy the desire to investigate the “long-term effects on vascular health.“ Mice only live a few years, so doing a whole lifetime study and actually measuring what counts wouldn’t be unreasonable, i.e.: actual mortality rates rather than guessing the outcome and quality of life (measured by activity levels say). I say guessing because as you’ll see, most of the increased factors they normally associate with heart disease were absent.

Before I get into that though, here are some details missing from the BBC article, on the actual composition of the diets. They only studied 3 permutations it seems:

  1. a standard diet of mouse “chow” (65 percent carbohydrate; 15 percent fat; 20 percent protein);
  2. a “Western diet” in keeping with the average human diet (43 percent carbohydrate; 42 percent fat; 15 percent protein; and 0.15 percent cholesterol);
  3. a low-carb/high-protein diet (12 percent carbohydrate; 43 percent fat; 45 percent protein; and 0.15 percent cholesterol).

They don’t however say how the percentage was split up. I assume it was calories, but it could have been weight or scoops maybe?

Why scientists such as these fail to do a thorough job is beyond me. Any mathematician will tell you, you can’t take 3 points on a graph and use that to predict a complicated trend. Similarly ask any scientist how to test for a specific correlation, and they’ll tell you change just one variable at a time, something these researchers also failed to do. If they were really trying to test the effects of carbs in the diet, they would have kept the ratios of protein : fat the same, but in each one it’s a different ratio. This alone makes the entire “study” a pointless waste, as you cannot work out what single factor might have caused the effect.

E.g. if only doing 3 tests as above, then something like this would have been significantly better as only 1 macro nutrient ratio changes:

  1. 70% carbs, 15% fat, 15% protein
  2. 40% carbs, 30% fat, 30% protein
  3. 10% carbs, 45% fat, 45% protein

Already it becomes more complicated however, as what do you do with total calories? Do you increase protein and fat as carbs reduce, in order to maintain a consistent calorie count? Or do you keep absolute calories of protein and fat constant, and let absolute calorie count reduce in line with the carb reduction? See, straight away you need to double the number of tests, and we haven’t even got to look at differing protein to fat ratios yet!

In the end, they should have done dozens of diets, of varying compositions. Not only looking at scientifically derived permutations as above, but also looking as specific commercial diets. (2) above happens to coincide with the Zone Diet proportions for example. Why not do Weight Watchers, Atkins, South Beach, Eskimo, Japanese, et al?

However, ignoring all that for the moment and assuming some actual value may be derived from this poor excuse for science. Let’s have a look at some of their findings. One key interesting point was:

“…the study also found that standard markers of cardiovascular risk, including cholesterol, were not changed in the animals fed the low-carb diet, despite the clear evidence of increased vascular disease.”

More evidence confirming that cholesterol does not in fact cause heart disease and the cholesterol hypothesis is a con, but I digress! It goes on to say:

“the usual markers thought to contribute to vascular disease, including the animals’ cholesterol and triglyceride levels, oxidative stress, insulin and glucose, as well as levels of some inflammatory cytokines… there was either no difference in measurements… or the numbers slightly favored the low-carb cohort,”

So they are saying that all the usual “well known” indicators of heart disease were either unchanged on the low carb diet, or better. Yet they have chosen to pick out the one indicator that went the other way, and highlighted that. Is this an example of that crazy saying that it’s the exception that proves the rule?!?

Basically there’s nothing to conclude from this little test. The test wasn’t big enough, wasn’t complete, wasn’t rigorous and wasn’t long enough to draw any conclusions. The fact that the classic markers were contradictory should be enough to show that. At the end of the day, what counts, and what is often missing from so called scientific studies (including most Statin research, but don’t get me started on those!) is the only measure that counts: actual mortality rates.

It is unforgivable for people to be warned off diets that conclusively make them thinner and healthier, because of a few weeks poor study of a few mice. Getting back to what really annoys me though, is the prat that the BBC rolled out to comment on it. He said:

“For now, it appears that a moderate and balanced diet, coupled with regular exercise, is probably best for most people.”

No shit Sherlock! The issue as ever, is what does “moderate and balanced” actually mean? Certainly it doesn’t mean what what Professor Alan Maryon-Davis, president, UK Faculty of Public Health, said:

“This research helps to back up the basic message that our diet should contain more starchy carbohydrate, not less”

My jaw hit the floor when I read that. You can’t draw that conclusion from this study at all. It’s a shameless example of someone using this doubtful study to spout his own personal agenda and draw wild conclusions from it. What these types fail to do, is define what they mean by “balanced”. Certainly in my book, balanced does not mean a diet where carbs out number protein and fat combined by 2:1, as the so called normal diet in this test was. How is that balanced? Muppets, they make me so cross!

{ 6 comments… add one }
  • Liam 27 August 2009, 12:39 pm

    I’ve already extensively commented on this on CF message board.

    I totally agree with this blog and I am also really annoyed by this ‘research’. I think it’s dangerously un-balanced.

    The concerning thing for me is that it took me a long time to persuade my wife that ‘The Zone’ was on balance (and logically) a better way of eating. After hearing about this ‘research’ on the BBC news she started questioning the benefit of reducing carbs in favour of more protein and good fat. Took a long time to explain the flaws in the research and the reason for the bias due to the people doing the research. I wonder how many other newbies to reduced carb nutrition plans will abandon it because of this journalism.

    Really the research isn’t to blame, it’s the irresponsible British media hyping this limited research up out of proportion.

  • Stephen Guy-Clarke 28 August 2009, 10:41 am

    Why do Eskimos, who typically eat a diet loaded with animal fat, have very low rates of heart disease?
    The answer is that high cholesterol isn’t the cause of heart disease – oxidised cholesterol is.
    That’s the opinion of many alternative physicians including Philip Lee Miller MD, founder and director of the Los Gatos Longevity Institute in California. ‘ I’m one of those people who have been saying for 30 years that cholesterol does not cause heart disease,’
    he says. ‘It’s a recruit in the process, like a soldier is a recruit in a war, but it does not cause the war.’
    Dr Miller, like the majority of medical professionals, recognises that the lowering of LDL cholesterol plays a critical role in preventing hardening of the arteries. He knows that excess cholesterol in the bloodstream can be subjected to oxidation (the same oxygen-sparked, cell destroying process that rusts iron or turns an apple brown after it has been cut).
    The destructive process of oxidation is literally inflammatory – it’s like a fire in the body.
    ‘The immune system, your body’s fire service, rushes foam cells to the area to douse the blaze. But just as firemen sometimes have to axe down a door to get into a burning building, the anti-inflammatory process can damage the lining of the artery. This roughened, injured area is a perfect foundation for the build-up of plaque, the truly evil plug that clogs arteries and triggers heart attacks’.

    ‘Oxidized LDL starts an inflammatory reaction that the body tries to heal, but the healing causes more problems than it resolves, ‘ says Dr Miller. The best way to prevent this heart-hurting process, he says, is to prevent the oxidation of LDL cholesterol – and the
    best way to do that, he adds, is to make sure you get enough of the antioxidants vitamin E, vitamin C, and glutathione.

    Antioxidants work by calming unstable oxygen molecules called free radicals, which are responsible for oxidising cells. When antioxidants neutralise free radicals, they are on a type of suicide mission. The antioxidants themselves are oxidised or, in chemical terms, reduced.

    Fortunately, the body has a system to help ensure that there are always plenty of antioxidants available, Dr Miller says. When vitamin C is oxidised, vitamin E comes to the rescue, donating some of its molecules to restore the vitamin C to its full antioxidant
    status. In the process, the vitamin E is reduced, but the glutathione replenishes it. That’s why you need all three nutrients, says Dr Miller.

  • Colin McNulty 28 August 2009, 8:52 pm

    I agree Liam, the tabloids have a lot to answer for.

    Thanks for the post Stephen. I agree that Cholesterol doesn’t cause CVD, but I’m not too sure about the Oxidised Cholesterol theory.

  • Mathilda 3 July 2011, 2:02 pm

    Mice are not humans and didn’t evolved to eat a meat based diet high in fat and low in carbs the way humans have. I’m shocked that any idiot could think the effect of an unnatural-for-mice diet could have any relevance to human responses to low carb diets.

  • Medical 24 July 2011, 2:13 pm

    I really think the whole diet thing gets over analysed. It’s quite simple in any reasonably balanced diet; there is a direct correlation between what goes in your mouth and how much weight you body stores as fat. The only variable is how much you burn off. Balanced diet, reasonably fit lifestyle. I feel the endless diet permutations are only trying to reinvent the wheel!

  • Colin McNulty 25 July 2011, 6:46 am

    Mathilda, if mice have the same basic insulin and glucagon hormonal response to food (or more specifically blood sugar levels) as humans, then I can see how experiments on mice could be a good place to start dietary research. But we agree, this was not good science.

    Medical(!), sorry it’s not as simple as that. Weight gain = calories in – calories burned, has been thoroughly disproved as a simplistic dietary theory, it’s just the mainstream media hasn’t quite caught on yet. You are right though that a balanced diet is good. The question is, what does “balanced” mean? Certainly the modern western diet of 70-80% carbs isn’t balanced in my book.

    If you scratch at the surface of mainstream dietary advice, you’ll find that it’s all based on a flimsy pack of cards. The bottom layer of which is the American Grain Farmers’ lobby who are trying to protect their massive profits by telling everyone to eat less fat and more carbs (read grains) because there are less calories in grains.

    Read this post for a better explanation of why our current dietary advice is a load of old tosh:


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