High-fat diet is bad for the brain

[clavicula]

Published online: 26 October 2004; | doi:10.1038/news041025-11
High-fat diet is bad for the brain
Jim Giles
Animal studies show that fatty food causes cognitive decline.





Now there's one more reason not to eat junk food.

© Punchstock

When the star of the movie Super Size Me ate only McDonald's for a month, his physical health went down the tube. Now researchers have warned that such diets could hit mental abilities too.

Although this idea has been suggested before, a slew of animal studies, unveiled on 25 October, all conclude that learning and memory suffer when fat intake rises. Rats and mice raised on the rodent equivalent of junk food struggle to learn their way around a maze and take longer to recall the solution to problems they have already solved, researchers said at the annual meeting of the Society for Neuroscience, held in San Diego.

In one experiment, rats were asked to remember the position of platforms in a pool of water; the animals are motivated to do so because they dislike swimming. Two groups took the test: controls and a set that had munched on a high-fat and high-cholesterol diet for eight weeks. "Those on the high-fat diet made many more mistakes," says Ann-Charlotte Granholm of the Medical University of South Carolina in Charleston.

Another study challenged mice to learn how to navigate a maze without running over areas that gave them mild electric shocks. When John Morley and colleagues at Saint Louis University in Missouri tested the mice a week after they had learned the task, those raised on a high-fat diet took significantly longer to remember how to avoid the shocks.

Trans-fat trouble

Morley's group speculates that triglyceride, a cholesterol-like substance that is found at high levels in rats on a high-fat diet, could be causing at least some of the cognitive damage. Morley says that when rats take a drug that cuts triglyceride levels but that does not cut weight, their performance on the memory tasks improves.

Memory problems have also been documented in diabetics suffering from high levels of triglyceride, but both Morley and Granholm say little work has been done on the cognitive impact of such diets in humans.

"We believe, on the basis of these data, that high-fat diets are bad for cognition," says Barry Levin, a physician at the New Jersey Medical School in East Orange. "But we need a note of caution: we work on rats and this may not extrapolate to humans."

Granholm says, however, that there is enough evidence for people to avoid certain kinds of foods, such as those containing trans-fatty acids (trans-fats), which are known to raise levels of triglyceride and cholesterol.

Trans-fats are found in everything from cereals to margarine and bread, and manufacturers prefer them to other fats because they prevent food going off. "Decreasing the shelf life of the foods you eat might increase your own shelf life," notes Levin.

[DebPenny]

Another study challenged mice to learn how to navigate a maze without running over areas that gave them mild electric shocks. When John Morley and colleagues at Saint Louis University in Missouri tested the mice a week after they had learned the task, those raised on a high-fat diet took significantly longer to remember how to avoid the shocks.
How mean, burning their poor little feet!

However, what really gets me is their misconception that fats increase triglycerides. If that were true, my triglycerides shouldn't be in the 80s. Maybe transfats raise cholesterol, but carbs raise triglycerides.

[Fhyreworks]

Is "high fat" even a natural diet for a mouse? Just curious.

Debbie

[tom sawyer]

Low carb diets made the rats tougher, so they didn't care about the measly little electric shocks. They got where they were going faster.

This is an assinine study, and yet another example of money wasted by academia. You could easily do these types of cognition studies on humans and not have to extrapolate from an animal model. Instead, all we know is a little about what the proper diet is, for a rat. Whoopie.

I've not noticed ANY change in cognitive abilities since being on LC. Still can't decide whether to be a rocket scientist or fry cook though.

[Nancy LC]

I thought triglycerides were associated with a high carbohydrate diet.

[K Walt]

I've been eating high-fat for a long time now, and . . . and. . . well I was going to say something, but. . . . what was the question again?

[EvelynS]

Low carb diets reliably lower triglycerides. Study after study shows it. In Lutz's patients, they were lowered on average by 50% in 3 months. All patients had a significant reduction in triglycerides, even the older ones, and those not on a weight loss diet. They were still low after 2 years.

[DebPenny]

Low carb diets made the rats tougher, so they didn't care about the measly little electric shocks. They got where they were going faster.
Ah, but the poor little guys weren't getting a low-carb diet, they were getting a high-fat, mouse-junk-food diet. Maybe if they had gotten a low-carb diet, they might have had tough feet. :rolleyes:

This is an assinine study, and yet another example of money wasted by academia. You could easily do these types of cognition studies on humans and not have to extrapolate from an animal model. Instead, all we know is a little about what the proper diet is, for a rat. Whoopie.

I've not noticed ANY change in cognitive abilities since being on LC. Still can't decide whether to be a rocket scientist or fry cook though.
I've notice a change in my cognitive ability, it's gotten better. Also, they didn't study low-carb, they studied high-fat (supposedly the equivalent of a junk-food diet for mice) and a 'normal' mouse diet, whatever that is. Then they proceeded to speculate with no idea about what they were talking.

Low carb diets reliably lower triglycerides. Study after study shows it. In Lutz's patients, they were lowered on average by 50% in 3 months. All patients had a significant reduction in triglycerides, even the older ones, and those not on a weight loss diet. They were still low after 2 years.
You bet, and my triglycerides are low enough to prove it. But again, they didn't study low-carb. :confused:

[tom sawyer]

Went to fire off a nasty email to St. Louis University concerning this quack Morley's waste of research money, and happened upon his biography. He seems to be quite the favorite of the big pharma.

http://www.thedoctorwillseeyounow.com/articles/bios/senior_living.shtml

[Groggy60]

They interspersed the term high fat with junk food, mentioning the McDonalds movie. They never said what the animals were actually fed. High fat, high carb, high transfat, high fructose???

[ItsTheWooo]

It doesn't even matter what the animals were fed.

The researchers admit the correlation between the cognitive decline and diet was that the sort of diet they fed the rats significantly raised triglyceride levels. When triglyceride levels were brought to a lower level cognitive functioning improved.

With that said, ironically this study is inadvertently advocating a low carb (high fat) diet, as reducing carbs is the easiest and quickest way to bring triglycerides down for humans.

It's my theory that a high triglyceride level is indicative of profound metabolic/energy processing abnormalities. Cognitive function declines not because of the triglycerides or any food substance in particular, but because your brain isn't being fueled adequately due to the metabolic disorder.
Low triglycerides correlate with good metabolic functioning and energy processing. The latter also correlates with improved cognitive functioning. So the link is indirect - high energy levels/better metabolic functioning improves cognitive functioning, and also is marked by low triglycerides.

In human beings the most common metabolic disorder is related to eating a diet too high in carbohydrate. The human body isn't designed to accommodate a high carb diet over a long period of time, and sooner or later (depending on diet and genetic predisposition) you get metabolic disease, characterized by high triglycerides. The triglycerides are formed when your body is in a fat-storing and creating, rather than energy-utilizing state. Your body being in a fat storing / creating mode rather than an energy burning/using one is, IMO, both symptomatic and causative of complications of metabolic disease. Hyperinsulinemia, carb sensitivity, insulin insensitivity, etc both cause and are made worse by the cycle of fat storing/energy conserving.

Now, perhaps mice aren't equipped to handle a high fat diet. Maybe a mouse needs to eat other food sources. Maybe eating too much fat, for a mouse, causes similar metabolic disorders that too much carbs cause for humans. Either way, one thing is certain. For human beings, the quickest and easiest way to improve metabolic functioning and markers/symptoms of such (perception of well being, energy, triglycerides) is by reducing carbohydrate. Virtually everyone sees their triglycerides decrease on a low carb diet. Low carb diets are, by definition, higher fat diets. Perhaps some do better with less fat than others, but either way this study in no way justifies nor supports the low fat diet. A low fat diet is a high carb diet, and it's very clear that when it comes to metabolic health, high carb is almost always worse than high fat for anyone who tries it.

[tortoise]

Here's another report of the same study (which is not published, BTW, it was presented at a meeting, so we are at the mercy of the press to give us the details):

http://www.thewbalchannel.com/health/3854070/detail.html

Notice that it starts: "High-fat diets may do more than wreak havoc on your waistline -- new research finds that a diet high in fat and empty calories causes memory loss."

Read: High in fat and refined carbs, I have no doubt. This kind of reporting drives me nuts.

[mio1996]

The researchers admit the correlation between the cognitive decline and diet was that the sort of diet they fed the rats significantly raised triglyceride levels. When triglyceride levels were brought to a lower level cognitive functioning improved.

With that said, ironically this study is inadvertently advocating a low carb (high fat) diet, as reducing carbs is the easiest and quickest way to bring triglycerides down for humans.



That's exactly what I thought when I read that article, Wooo. Logically, if raising triglycerides decreases cognitive ability then a low carb diet should improve cognitive ability since virtually everyone on such a diet experiences a marked decrease in triglyceride level.

[mio1996]

Here's another report of the same study (which is not published, BTW, it was presented at a meeting, so we are at the mercy of the press to give us the details):

http://www.thewbalchannel.com/health/3854070/detail.html

Notice that it starts: "High-fat diets may do more than wreak havoc on your waistline -- new research finds that a diet high in fat and empty calories causes memory loss."

Read: High in fat and refined carbs, I have no doubt. This kind of reporting drives me nuts.

Notice how they left "empty calories" out of the headline so that anyone just skimming headlines would believe that high fat alone will kill your brain. These people are pathetic in their desire to prove the evils of fat.

[Quinadal]

Is "high fat" even a natural diet for a mouse? Just curious.

Debbie
Actually, yes, BUT it's all plant-based fat, not cholesterol. Ever have gerbils or hamsters? They'd KILL each other for a macademia nut!

[fitchic]

Makes sense -- I mean, if you're cramming yourself full of nothing but high fat foods, you're not going to have much energy to think on. Such being said, I don't think that you can't eat things like fast food, as the super size me guy says in his documentary. It's just important to keep in mind a little bit of variety in your diet.

[eepobee]

Makes sense -- I mean, if you're cramming yourself full of nothing but high fat foods, you're not going to have much energy to think on.

actually, i doesn't make sense. fat is full of energy (9 calories/gram as compared to 4 calories/gram for carbs and protein) and your brain knows how to utilize it. in fact, brain function has been shown to improve on low-carb, high-fat diets.

[pecan]

makes sense if you're cramming your body full of nothing but poor high-fat choices (um, cake, ice cream, whoppers, fries, etc?)

how can someone say eating salmon and almonds is going to impare your memory...these fats IMPROVE brain function! ugh, how easy it is to become disgusted with these studies!