Monday, August 24, 2009

High fat diets make you fat and stupid (2)

While trying to understand what was going on in the "Deterioration of physical performance and cognitive function in rats with short-term high-fat feeding" paper by Andrew Murray I came across a similar paper by PubMed-ing "fructose insulin memory" or the like.

This paper provides more information and is very up front about added fructose! Here is what they did:


"In the present study we fed rats a diet high in saturated fats and simple sugars, and supplemented their water with high-fructose corn syrup. This diet increased fasting blood glucose levels and serum cholesterol and triglycerides. Additionally, we found that the diet impairs hippocampus-dependent learning, synaptic plasticity, and dendritic spine density. These adverse effects on brain function were associated with reduced levels of BDNF in the hippocampus and suggest that “Western” diets impair synaptic function and cognition by a mechanism involving reductions in BDNF and atrophy of dendritic spines"

The control diet was good old "standard NIH chow".

The high calorie diet was high in both saturated fat and glucose but was also supplemented with high fructose corn syrup as 20% of the drinking water.

This means that it was impossible for a rat to take a mouthful, any mouthful of food without a glucose load. It was also impossible to drink any water without a fructose load. Rats have to drink.

The most notable thing to me was the fructose in the water. If it was possible to do this with a fat/glucose combo, why add fructose to the drinking water? Answer: It's probably not possible to do this without the fructose. Is there any other possible answer? I guess you could suggest it's the equivalent of the Fanta with the big mac and extra fries... So would the big mac and fries be OK without the Fanta? That we'll not find out from this study because including a fat/glucose combo without fructose was not on the agenda.

I would guess that the fat stupid rats in Andrew Murray's study will have had a fair dose of fructose (as sucrose) in the 16% of calories they derived from carbohydrate. The control diet contained zero fructose.

There are many other points in the paper which are interesting when you take the Taubes view of obesity but they're not core to what is going on. Ultimately there is a lot of insulin sloshing around in the rats on their high fat diet.

Peter

3 comments:

Bris said...

This is totally bizarre. A 20% sugar solution is intolerably sweet for most people. Even soft drinks and fruit juices are <13% sugars. Rats aren't naturally sugar lovers - they like fat and starches.

LeenaS said...

B.t.w., the other diet (big mac without fanta and without french fries) has been documented in the movie Fathead.

And the answer was no. It did not make Tom Noughton fat, but slimmed him quite a bit. But then again, he is a human and not a lab rat.

Kennedy said...

I read this in the New York Times and was equally disappointed. All the comments to it were very disdainful of the fact they were still pedaling the whole 'fat is bad' angle though. They were swarmed by the good sense of the Paleo Community.

Reminds me of the Russians sending back samples from the Orange Juice Boris Spassky was drinking when he played Fischer at chess in the seventies. They were definitely onto something... just not tampering.