6 ms·

A High-Fat Diet Alters Crucial Aspects of Brain Dopamine Signaling

33 points by chegra 16y ago

metamemetics 16y ago
Questions a reader should ask: What was the percent fat in relation to carbohydrates/protein? From what I've read read both a low fat (<20%) and extremely high fat (75-80%) are healthier than a high fat diet (45%). What type of fat was added to their diets? All fats were not created equal.
sophacles 16y ago
So what does this mean? How does this change the motivation for working (for food etc). Can it be reversed? How does it interact with other dopamine processing and dopamine producing actvities (e.g. drugs, sex etc)?
yanowitz 16y ago
It's too hard to see what this means from the information in the article. What was the protein and carb content? Was it a low-protein diet or low-carb (I'm guessing low-protein given other study results)? How many rats? Were they obese to begin with? etc. etc.
warpwoof 16y ago
Interesting, but fairly useless article. I have no idea what this means. Maybe this is a good thing? Fat is satiating and helps you feel full. Also, a high-fat diet by implication means you've removed either protein or carbohydrate, if you're holding calories constant. A low carb diet, if low enough, puts your body in ketosis, and your brain switches from using glycogen for energy to ketones. For all we know the title could have been "A Low-Carb Diet Alters Crucial Aspects of Brain Dopamine Signaling."
sofuture 16y ago
The biggest thing reading 'Good Calories, Bad Calories' did for me, was make me question every single scientific study in much greater detail. It's shocking how much niche* scientific research makes it's way into the 'news', 'common knowledge' or even public policy. I don't mean this as a knock against this specific study -- however, we don't have enough information to conclude anything about it. * = where 'niche' implies a strict and specific set of conditions or even assumptions, reducing 'general applicability'
- WilliamLP 16y ago
  The big part of this article that raises my skepticism is that it's talking about rat studies without mentioning that there are very many well known, dramatic, and fundamental differences between rat and human metabolisms.
lgv 16y ago
Do rats eat fat in nature? I don't know anything about animal nutrition, but is this like feeding protein to say, rabbits, which are herbivores?
- SoftwareMaven 16y ago
  Rats are omnivores, eating a nice, balanced diet like us humans. However, even if they were straight herbivores, they could still find plenty of fats. Nuts are a significant food source for small mammals and tend to be fairly high in fat content.
terhechte 16y ago
Reminds me of the Science News Cycle: http://www.g2weather.com/.a/6a010535bea9f5970b0133f1e32582970b-800wi http://www.g2weather.com/.a/6a010535bea9f5970b0133f1e3258297... (image)
- endgame 16y ago
  Actual source: http://www.phdcomics.com/comics/archive.php?comicid=1174 http://www.phdcomics.com/comics/archive.php?comicid=1174
gojomo 16y ago
Dopamine systems are related to motivation, compulsions, and addictions. It's unclear whether the changes detected by this study would be correlated with more or less addictive behavior, task-persistence, long-range goal-seeking, executive function, etc. But, it suggests ideas for further research about diet and behavior.
TheEzEzz 16y ago
Here I was, excited to post a bunch of reasons why this paper doesn't really support its conclusion, only to find all the comments on HN already well informed and adequately skeptical.
donaldc 16y ago
I wish the article would be a little more specific about what kind of fat they're talking about. Saturated? Polyunsaturated? Raw? Processed? For example, if they're talking about processed polyunsaturated fat, it's probably a leap to apply the conclusions to raw butter.
- electromagnetic 16y ago
  It's also contradictory to existing research. They're saying a decrease in dopamine due to high-fat intake is linked to obesity, however high-sugar diets are known to increase dopamine release, which increases the bodies demand for sugars which leads to diabetes and obesity. If it's a choice between the two then to me it's better to be fat than fat and diabetic. You're also correct, polyunsaturated fat behaves wholly different than monounsaturated, or saturated, or hydrogenated. Even if they all have some effect, is one less or more dramatic than another? Finally, is this going to be useful to anyone in planning their diet to control weight or is it just more utter bunk like 'avoid eating carbs'. If I'm avoiding carbs and avoiding fat, I'm left eating ultra-lean-ground-beef and fat-reduced chicken, which means I'm on a ultra-less healthy version of the Atkins. Perhaps these diet doctors can simply say: Don't be a fat ass, exercise and eat a good mixture of protein, fat and carbs because excluding one is quite probably extremely bad for your health.
  - deleted 16y ago
    [deleted]
  - prodigal_erik 16y ago
    To me that sounds like the hedonic treadmill rather than a contradiction. Fat and sugar increase dopamine, the extra dopamine reduces the number and/or sensitivity of D2 receptors over time to compensate, and so your baseline declines until you need that extra dopamine hit just to get back to normal. And it sounds more useful for designing drug treatment than diet. If your eating isn't out of control, you don't have much of the problem the article is about.
    - electromagnetic 16y ago
deleted 16y ago
[deleted]
b0b0b0b 16y ago
reduced release sounds bad. but reduced reuptake sounds good!
malkia 16y ago
I guess that would explain why Cain killed Abel. Hehe, not really :)
jseifer 16y ago
Further information took a bit to track down but I found it here: http://www.ssib.org/web/past_programs/SSIB_2010_Abstracts.pdf http://www.ssib.org/web/past_programs/SSIB_2010_Abstracts.pd... The full article is available for purchase here: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WB2-5087F0J-19&_user=10&_coverDate=06%2F30%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d1ecda4fc9cdb9796fbe6992d14607d2 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi... though I wasn't willing to buy it. From the abstract: -- Consumption of a high fat diet affects phasic dopamine release and reuptake in the nucleus accumbens J.J. CONE 1,∗ , H.A. ROBBINS 2 , J.D. ROITMAN 2 , M.F. ROITMAN 1,2 1 Program in Neuroscience, University of Illinois at Chicago, USA 2 Dept of Psychology, University of Illinois at Chicago, Chicago, IL, USA The rate of obesity has climbed dramatically over the past several decades as food high in fat content has become more read- ily accessible. In the US alone, approximately one third of adults are considered obese. Obesity has been correlated with changes in the mesolimbic dopamine (DA) system. Human imaging stud- ies have revealed that DA terminal regions differentially respond to food depending on body mass index. In animal subjects, high fat diet exposure reduces motivated behavior and responses to amphetamine. Thus, high fat diet exposure may lead to obesity, in part, through feed forward mechanisms that suppress mesolimbic DA signaling. Here, we determined the effects of different durations of high fat diet exposure on phasic DA release evoked by electrical stimulation of the ventral tegmental area. Rats were given ad libi- tum access to either a high fat diet (60% kcal/g from fat; HFD) or a low fat diet (10% kcal/gm from fat; LFD). After different durations on the diet (2, 4 or 6 weeks), rats were anesthetized with urethane. Phasic spikes in DA concentration were evoked once every 2 min by stimulating the VTA and measured using fast scan cyclic voltam- metry at a carbon fiber microelectrode in the nucleus accumbens. DA function was assessed by altering the number, frequency, and intensity of current pulses before and up to 1 h after cocaine injec- tion. Cocaine caused a dramatic increase in evoked DA in LFD rats. In contrast, cocaine caused a much smaller increase in evoked DA in HFD rats. The data were modeled to determine if baseline and cocaine potentiated differences in evoked DA between LFD and HFD rats were due to changes in DA release, reuptake or both. The results demonstrate that high fat diet exposure results in dramatic changes in phasic DA signaling. Given its established role in reward, rein- forcement and motivation, these changes in phasic DA signaling likely contribute to further imbalance between energy intake and energy expenditure. doi:10.1016/j.appet.2010.04.046 -- The abstract still doesn't say what kind of fat it was (saturated, pufas, etc) only that it was 60% kcal/g for high fat and 10% kcal/g for low fat. The linked summary also says nothing about how they measured the dopamine effects which turned out to be anesthetizing the rats, giving them cocaine, and then measuring their dopamine levels. The study seemed to show that cocaine caused a dramatic increase in the dopamine levels of the low fat diet rats and much less of an increase in the high fat diet rats. As far as I can tell from that abstract: Low fat diet = much higher dopamine response from cocaine High fat diet = lower dopamine response from cocaine So the authors are concluding that the lower response will lead to eating more fat in order to get the dopamine reward. Further reading on dopamine: http://scienceblogs.com/developingintelligence/2007/02/dopamine_for_dummies.php http://scienceblogs.com/developingintelligence/2007/02/dopam...

33 points by chegra 16y ago

Questions a reader should ask: What was the percent fat in relation to carbohydrates/protein? From what I've read read both a low fat (<20%) and extremely high fat (75-80%) are healthier than a high fat diet (45%). What type of fat was added to their diets? All fats were not created equal.

sophacles 16y ago

So what does this mean? How does this change the motivation for working (for food etc). Can it be reversed? How does it interact with other dopamine processing and dopamine producing actvities (e.g. drugs, sex etc)?

yanowitz 16y ago

It's too hard to see what this means from the information in the article. What was the protein and carb content? Was it a low-protein diet or low-carb (I'm guessing low-protein given other study results)? How many rats? Were they obese to begin with? etc. etc.

warpwoof 16y ago

Interesting, but fairly useless article. I have no idea what this means. Maybe this is a good thing? Fat is satiating and helps you feel full. Also, a high-fat diet by implication means you've removed either protein or carbohydrate, if you're holding calories constant. A low carb diet, if low enough, puts your body in ketosis, and your brain switches from using glycogen for energy to ketones. For all we know the title could have been "A Low-Carb Diet Alters Crucial Aspects of Brain Dopamine Signaling."

sofuture 16y ago

The biggest thing reading 'Good Calories, Bad Calories' did for me, was make me question every single scientific study in much greater detail. It's shocking how much niche* scientific research makes it's way into the 'news', 'common knowledge' or even public policy. I don't mean this as a knock against this specific study -- however, we don't have enough information to conclude anything about it. * = where 'niche' implies a strict and specific set of conditions or even assumptions, reducing 'general applicability'

WilliamLP 16y ago
The big part of this article that raises my skepticism is that it's talking about rat studies without mentioning that there are very many well known, dramatic, and fundamental differences between rat and human metabolisms.

lgv 16y ago

Do rats eat fat in nature? I don't know anything about animal nutrition, but is this like feeding protein to say, rabbits, which are herbivores?

SoftwareMaven 16y ago
Rats are omnivores, eating a nice, balanced diet like us humans. However, even if they were straight herbivores, they could still find plenty of fats. Nuts are a significant food source for small mammals and tend to be fairly high in fat content.

terhechte 16y ago

Reminds me of the Science News Cycle: http://www.g2weather.com/.a/6a010535bea9f5970b0133f1e32582970b-800wi http://www.g2weather.com/.a/6a010535bea9f5970b0133f1e3258297... (image)

endgame 16y ago
Actual source: http://www.phdcomics.com/comics/archive.php?comicid=1174 http://www.phdcomics.com/comics/archive.php?comicid=1174

gojomo 16y ago

Dopamine systems are related to motivation, compulsions, and addictions. It's unclear whether the changes detected by this study would be correlated with more or less addictive behavior, task-persistence, long-range goal-seeking, executive function, etc. But, it suggests ideas for further research about diet and behavior.

TheEzEzz 16y ago

Here I was, excited to post a bunch of reasons why this paper doesn't really support its conclusion, only to find all the comments on HN already well informed and adequately skeptical.

donaldc 16y ago

I wish the article would be a little more specific about what kind of fat they're talking about. Saturated? Polyunsaturated? Raw? Processed? For example, if they're talking about processed polyunsaturated fat, it's probably a leap to apply the conclusions to raw butter.

electromagnetic 16y ago
It's also contradictory to existing research. They're saying a decrease in dopamine due to high-fat intake is linked to obesity, however high-sugar diets are known to increase dopamine release, which increases the bodies demand for sugars which leads to diabetes and obesity. If it's a choice between the two then to me it's better to be fat than fat and diabetic. You're also correct, polyunsaturated fat behaves wholly different than monounsaturated, or saturated, or hydrogenated. Even if they all have some effect, is one less or more dramatic than another? Finally, is this going to be useful to anyone in planning their diet to control weight or is it just more utter bunk like 'avoid eating carbs'. If I'm avoiding carbs and avoiding fat, I'm left eating ultra-lean-ground-beef and fat-reduced chicken, which means I'm on a ultra-less healthy version of the Atkins. Perhaps these diet doctors can simply say: Don't be a fat ass, exercise and eat a good mixture of protein, fat and carbs because excluding one is quite probably extremely bad for your health.
- deleted 16y ago
  [deleted]
- prodigal_erik 16y ago
  To me that sounds like the hedonic treadmill rather than a contradiction. Fat and sugar increase dopamine, the extra dopamine reduces the number and/or sensitivity of D2 receptors over time to compensate, and so your baseline declines until you need that extra dopamine hit just to get back to normal. And it sounds more useful for designing drug treatment than diet. If your eating isn't out of control, you don't have much of the problem the article is about.
  - electromagnetic 16y ago

deleted 16y ago

[deleted]

b0b0b0b 16y ago

reduced release sounds bad. but reduced reuptake sounds good!

malkia 16y ago

I guess that would explain why Cain killed Abel. Hehe, not really :)

jseifer 16y ago

Further information took a bit to track down but I found it here: http://www.ssib.org/web/past_programs/SSIB_2010_Abstracts.pdf http://www.ssib.org/web/past_programs/SSIB_2010_Abstracts.pd... The full article is available for purchase here: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WB2-5087F0J-19&_user=10&_coverDate=06%2F30%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d1ecda4fc9cdb9796fbe6992d14607d2 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi... though I wasn't willing to buy it. From the abstract: -- Consumption of a high fat diet affects phasic dopamine release and reuptake in the nucleus accumbens J.J. CONE 1,∗ , H.A. ROBBINS 2 , J.D. ROITMAN 2 , M.F. ROITMAN 1,2 1 Program in Neuroscience, University of Illinois at Chicago, USA 2 Dept of Psychology, University of Illinois at Chicago, Chicago, IL, USA The rate of obesity has climbed dramatically over the past several decades as food high in fat content has become more read- ily accessible. In the US alone, approximately one third of adults are considered obese. Obesity has been correlated with changes in the mesolimbic dopamine (DA) system. Human imaging stud- ies have revealed that DA terminal regions differentially respond to food depending on body mass index. In animal subjects, high fat diet exposure reduces motivated behavior and responses to amphetamine. Thus, high fat diet exposure may lead to obesity, in part, through feed forward mechanisms that suppress mesolimbic DA signaling. Here, we determined the effects of different durations of high fat diet exposure on phasic DA release evoked by electrical stimulation of the ventral tegmental area. Rats were given ad libi- tum access to either a high fat diet (60% kcal/g from fat; HFD) or a low fat diet (10% kcal/gm from fat; LFD). After different durations on the diet (2, 4 or 6 weeks), rats were anesthetized with urethane. Phasic spikes in DA concentration were evoked once every 2 min by stimulating the VTA and measured using fast scan cyclic voltam- metry at a carbon fiber microelectrode in the nucleus accumbens. DA function was assessed by altering the number, frequency, and intensity of current pulses before and up to 1 h after cocaine injec- tion. Cocaine caused a dramatic increase in evoked DA in LFD rats. In contrast, cocaine caused a much smaller increase in evoked DA in HFD rats. The data were modeled to determine if baseline and cocaine potentiated differences in evoked DA between LFD and HFD rats were due to changes in DA release, reuptake or both. The results demonstrate that high fat diet exposure results in dramatic changes in phasic DA signaling. Given its established role in reward, rein- forcement and motivation, these changes in phasic DA signaling likely contribute to further imbalance between energy intake and energy expenditure. doi:10.1016/j.appet.2010.04.046 -- The abstract still doesn't say what kind of fat it was (saturated, pufas, etc) only that it was 60% kcal/g for high fat and 10% kcal/g for low fat. The linked summary also says nothing about how they measured the dopamine effects which turned out to be anesthetizing the rats, giving them cocaine, and then measuring their dopamine levels. The study seemed to show that cocaine caused a dramatic increase in the dopamine levels of the low fat diet rats and much less of an increase in the high fat diet rats. As far as I can tell from that abstract: Low fat diet = much higher dopamine response from cocaine High fat diet = lower dopamine response from cocaine So the authors are concluding that the lower response will lead to eating more fat in order to get the dopamine reward. Further reading on dopamine: http://scienceblogs.com/developingintelligence/2007/02/dopamine_for_dummies.php http://scienceblogs.com/developingintelligence/2007/02/dopam...