High protein diets could shrink your brain?

This article just came out the other day  http://www.sciencedaily.com/releases/2009/10/091020192206.htm and the more detailed version here.   http://www.molecularneurodegeneration.com/content/4/1/40

Since human physiology and diet are so important to the work we do at CrossFit SWARM I take the time to read the articles that come across my desk.  I find it very enlightening to read them with an open mind, but a close eye to the scientific methods used or not used.  So, will a high protein diet lead to Alzheimer’s Disease?  If there is evidence of that I certianly want to know it.  So, let’s read the article and discuss.

Lets look at the first part of the article:

One of the many reasons to pick a low-calorie, low-fat diet rich in vegetables, fruits, and fish is that a host of epidemiological studies have suggested that such a diet may delay the onset or slow the progression of Alzheimer’s disease (AD). Now a study published in BioMed Central’s open access journal Molecular Neurodegeneration tests the effects of several diets, head-to-head, for their effects on AD pathology in a mouse model of the disease. Although the researchers were focused on triggers for brain plaque formation, they also found that, unexpectedly, a high protein diet apparently led to a smaller brain.

Issue number 1 – The scientists designed their study focus on triggers for brain plaque formation, but they found no difference between the 4 diets.   They then quickly change focus to an unexpected factor that turned up during the study and state that the high protein diet led to a smaller brain in the mice.

Issue 2 – The article starts off  ”pick a low-calorie, low-fat diet rich in vegetables, fruits, and fish is that a host of epidemiological studies have suggested that such a diet may delay the onset or slow the progression of Alzheimer’s disease (AD)” This study didn’t calorie restrict, this study didn’t say what foods they feed the mice only their macro nutrients so where did this line come from?  The bias of the study scientists is already showing.  This kind of bias is the same that has led us down the dietary black hole we’ve been heading down since the 1950′s and Ancel Keys.

Let’s move on now to the four diets chosen for this study.

(1) reference (regular) commercial chow; (2) high fat/low carbohydrate custom chow (60 kcal% fat/ 30 kcal% protein/ 10 kcal% carbohydrate); (3) high protein/low carbohydrate custom chow (60 kcal% protein/ 30 kcal% fat/ 10 kcal% carbohydrate); or (4) high carbohydrate/low fat custom chow (60 kcal% carbohydrate/ 30 kcal% protein/ 10 kcal% fat).

They fed the groups of mice in four different feeds:

1. Regular commercial chow (without informing us what the commercial feed’s macro-nutrient values were)
2. High Fat / Some Protein/ Little Carb
3. High Protien / Some Fat / Little Carb
4. High Carb / Some Protein / Little Fat

Got that?  Now, the high protein, high fat diet,  high carb diet and regular mice chow diet (yes, that would be all four of the diets!) saw no differences in plaque formation in the brains of the rats.

The researchers then looked at the brain and body weight of the mice, as well as plaque build up and differences in the structure of several brain regions that are involved in the memory defect underlying AD.

Unexpectedly, mice fed a high protein/low carbohydrate diet had brains five percent lighter that all the others, and regions of their hippocampus were less developed. This result was a surprise, and, until researchers test this effect on non-transgenic mice, it is unclear whether the loss of brain mass is associated with AD-type plaque. But some studies in the published literature led the authors to put forward a tentative theory that a high protein diet may leave neurones more vulnerable to AD plaque. Mice on a high fat diet had raised levels of plaque proteins, but this had no effect on plaque burden.

Look at the breakdown of the high protein diet (60% protein,30% fat, 10% carb) if you are going to eat 10% carb you need to eat higher fat to support your body (even a mouses body).   60/30/10 would be harmful to any human because your brain needs fuel to grow or sustain size/function.  You can either get this fuel by eating carbs or fats and if you restrict both you are going to see brain cell loss.

Aside from transgenic mice, the pressing question is whether these data have implications for the human brain.

Hold on! Are you saying that mice and humans are different?  I think we might need another study to look at this discovery!

However, in the absence of a study of the effects of a high protein/low carbohydrate diet on nontransgenic mice, one cannot be certain how much, if any, of the loss of brain mass exhibited by high protein/low carbohydrate diet-fed TgCRND8 mice was due to an interaction between cerebral amyloidosis and diet. Given the recent evidence that certain factors favor the maintenance of cognitive function in the face of substantial structural neuropathology, we propose that there might also exist factors that sensitize brain neurons to some forms of neurotoxicity, including, perhaps, amyloid neurotoxicity. Identification of these factors could help reconcile the poor clinicopathological correlation between cognitive status and structural neuropathology, including amyloid pathology.

We have a winner.   The scientists state  at the end of the study that they have NO DATA to link the effects of a high protein/low carb diet to Alzheimer’s Disease.  Wasn’t the point of the study to link one of the diets to AD?  But, since they did not come up with their intended results, now seems like the time to launch into a diatribe of their biases and opinions on dietary input instead but the study also didn’t point out ANY negative’s associated with having a smaller brain size. As you read the second half of the above quote you see the words “propose” “perhaps” and “could” all based on yet another uncited scientist’s theory “Given the recent evidence that certain factors favor the maintenance of cognitive function in the face of substantial structural neuropathology”.  Again, unproven and not good science.

What does this all mean?

This study has  no data linking Alzheimer’s disease (AD) to any diet, but plenty of opinion.  Now the real question is who funded this ‘ground-breaking’ science….