03 December 2008

Study finds vegetarians have smaller brains

Supports Chapter 13: Homo carnivorous

Scientists at the Department of Physiology, Anatomy and Genetics, University of Oxford, have discovered that going veggie could be bad for your brain – with those on a meat-free diet six times more likely to suffer brain shrinkage.

The study involved tests and brain scans on community-dwelling volunteers aged 61 to 87 years without cognitive impairment at enrolment, over a period of five years. When the volunteers were retested five years later the medics found those with the lowest levels of vitamin B12 were also the most likely to have brain shrinkage. It confirms earlier research showing a link between brain atrophy and low levels of B12.

Vegans are the most likely to be deficient because the best sources of the vitamin are meat, particularly liver, milk and fish.

This study confirms other findings, covered in Trick and Treat, which shows that overall human brain sizes have reduced by an average 11% since we adopted an agricultural diet based on cereal grains rather than the meat-based diet of our Palaeolithic ancestors.

Vogiatzoglou A, et al. Vitamin B12 status and rate of brain volume loss in community-dwelling elderly. Neurology 2008; 71(11): 826-32.


Anonymous said...

When I was in high school (a hundred years ago) I had a physics teacher who (and I don't know why he was on this topic during a physics lecture, by the way...)sternly told us the reason he felt some children were smarter than others was because they as infants and toddlers consumed more eggs than their counterparts. I thought he was nuts at the time, having been brainwashed by the eggs-are-horrible-cholesterol-death-information that was dominant at the time. But it's true, isn't it? Egg yolks are a great source of B vitamins, B vitamins are needed for proper brain development early on in life, and now, this study...all related, perhaps...

Barry Groves said...

Hi Adam

Eggs are the best source of pretty much all the nutrients we need for a healthy life.

Yes, they are high in cholesterol. But then, cholesterol is a bulding block of so many of the body's hormones, body cells, immune system, brain and nervous system and more, that I doubt it is possible to eat too many.

It might be of interest that, in Poland, it is quite common for people to eat only egg yolks; the whites are used in the building industry. American, who are generally much less healthy, eat the whites and leave the yolks! Says a lot, doesn't it?

Ellen said...

Dr. Groves: I've just finished reading a book by Henry Lorin called Alzheimer's Solved. In it, he hypothesizes that the brain shrinkage seen in Alzheimer's patients is caused by the lack of dietary cholesterol availablity for repair of neuron cell walls. (Although studies have shown infants make all the cholesterol they need, other studies have shown that adult brains utilize dietary cholesterol).

Mr. Lorin states further that the amyloid molecules found in the plaques of Alzheimer brains are used as a temporary repair mechanism because of the lack of available cholesterol molecules. There is also a paper by Iwo Bohr published in Lipid World which puts forth a similar hypothesis.

It seems to me that vegetarians would show brain shrinkage because they don't get enough dietary cholesterol..

What are your thoughts on this?

Barry Groves said...

Hi Ellen

I'm not an expert in this aspect, but Lorin could well be correct.

The brain does use a large amount of cholesterol; it is so important that the brain has its own supply, and doesn't have to rely on that produced in the liver.

The 'Tau' protein tangles seen in Alzheimer's have puzzled me as tau proteins are made via the mevalonate pathway, which is the pathway over which cholesterol is also synthesised. I couldn't see why the body would make a substance which is essential (cholesterol) and another which seems to be harmful (tau proteins).

This could well be the explanation: tau proteins are made when cholesterol level is too low for some reason.

But the brain shrinkage seen in vegetarians is a general shrinkage. It isn't necessarily connected to Alzheimer's.