Sunday, December 02, 2007

When is a high fat diet not a high fat diet?

When it's a high carbohydrate diet! Preferably a high sucrose diet. The simple way to prove a high fat diet is bad for you is to use a rat or mouse, and feed it sugar, then describe this as a high fat diet in your abstract without specifying exact composition. "Normal" rat food in the USA for toxicology testing used to be NIH-07, at around 5% fat. There were so many problems with renal failure and heart failure that the diet was reformulated in the mid 1990s to the NTP-2000 diet, with just under 10% fat. The spectacular benefits were:

"The NTP-2000 diet prevented nephrocalcinosis and decreased the severity of nephropathy and cardiomyopathy, the common lesions of F344 rats in 13-week studies"

Notice it only took 13 weeks to get the problems and they certainly didn't go away on NTP-2000. Makes you wonder how they can assess drug toxicity in rats this sick from their diet! The other problem on the NIH-07 diet was cancer by 13 weeks, but that didn't seem to improve on the NTP-2000 diet at all. Still looks like chronic carbohydrate poisoning to me.

But the botttom line is that any diet with > 10% fat can theoretically be described as high fat for a lab rat. Up at 45% fat most junk science is happy to use the label "High Fat".

The comments about cardiomyopathy in the above paper are interesting as I came across this paper, only in abstract for unfortunately, but it gives the idea.

They compared the effects of 10% fat "normal" rat food with 45% fat diet, accurately described as "Western" diet, and also with a diet containing 60% of calories as fat. For a rat I would suggest 80% fat might be a better suggestion, but they got the goods at 60% anyway, so good for them. Here's the best section from the abstract

"Oleate oxidation in heart muscle ex vivo increased with high fat diet at all time points investigated. In contrast, cardiac oleate oxidation increased with western diet in the acute, short and intermediate term, but not in the long term. Consistent with fatty acid oxidation maladaptation, cardiac power decreased with long term western diet only"

When you use a genuine high fat diet there are no adverse effects on heart muscle function.

I like their introduction sentence too:

"Obesity and diabetes are associated with increased fatty acid availability in excess of muscle fatty acid oxidation capacity. This mismatch is implicated in the pathogenesis of cardiac contractile dysfunction and also in the development of skeletal muscle insulin resistance".

If you read my post on insulin resistance you'll know why.

Just checked on who did this excellent research and it looks like Taegtmeyer, the group leader, is USA based. Very unusual for me to cite an american paper, unless from one of the few islands of common sense such as Volek et al, but here it is and it's good.

Peter

4 comments:

Bruce K said...

"Still looks like chronic carbohydrate poisoning to me."

I believe that casein poisoning and PUFA poisoning are also a factor in these studies. The results would be different, IMO, if animals were fed potatoes, fresh raw honey, cheeses, butter, fresh meat, fresh eggs, and so forth. Of course, nobody's going to spring for a study like that, so we get processed "Western" diets.

mtflight said...

From the Paleo Diet Newsletter Vol 4, No.2 page 2 "Lectins, Inflammation and Atherosclerosis" Dr. Cordain mentions:
"It is known that high-fat diets (which increase the rate of oxidized LDL formation) cause the glycocalyx size and mass to be reduced 18, as do inflammatory cytokines19."


I looked up the reference, and the so-called "high-fat diet" contains as follows:

15% cacao butter,
0.5% cholate,
1% cholesterol,
40.5% sucrose,
10% corn starch,
1% corn oil, and
4.7% cellulose
(Diet-N; Hope Farms)

(what is the remaining 27%?), right off the bat the 40.5% sucrose and 10% corn starch is a joke, and no wonder it induced "systemic high cholesterol and triglyceride levels"... it raised insulin levels stimulating increased HMG-CoA Reductase, and triglyceride production (probably lowered HDL too).

Cordain is anti-saturated fat, so this does not surprise me, but I thought he was with the low-carb camp.

http://ajpheart.physiology.org/cgi/content/full/290/2/H915
"Atherogenic region and diet diminish glycocalyx dimension and increase intima-to-media ratios at murine carotid artery bifurcation"

mtflight said...

Furthermore, there is no reference here: "It is known that high-fat diets (which increase the rate of oxidized LDL formation)"

Which fats? polyunsaturated ones? transfats? small dense LDL is more readily oxidized and is usually correlated with high carb, lower fat diets.

Peter said...

Hi mtflight,

Cordian cites an interesting study. All you have to do is cross out the word "fat" from the unreferenced claim, substitute "sucrose" and you have another statement supporting Yudkin's hypothesis that sucrose is the primary cause of heart disease... Probably through effects, amongst others, on the glycocalyx.

I'm not sure Cordain is in any camp other than the Cordain camp. I think he is very good at writing successful grant applications and his science is lousy.

His work essentially takes out sugar, grains and dairy. Mostly this is good. The pro fruit and PUFA, anti sat and cholesterol, are what I can't see the logic to. I've just had about two weeks of eating strawberries, maybe another week or two to go. Where would a North American native find kiwi fruits in March? Hee hee, don't say Walmart!

Peter