from Hacker News

The Role of Diet on the Gut Microbiome, Mood and Happiness

by mrleinad on 4/26/23, 1:06 PM with 209 comments

by blakesterz on 4/26/23, 3:09 PM

  "After the diet change, we observed significant changes in measures of anxiety, well-being and happiness, and without changes in gut microbiome diversity. We found strong correlations between greater consumption of fat and protein to lower anxiety and depression, while consuming higher percentages of carbohydrates was associated with increased stress, anxiety, and depression."

I think most of us would agree that makes sense? Eat like crap, feel like crap?

  "We also found strong negative correlations between total calories and total fiber intake with gut microbiome diversity without correlations to measures of mental health, mood or happiness.... inversely correlated with gut microbiome diversity."

I kept reading this second paragraph trying to understand the "without correlations" part. And also the negative correlations part. And then the full-text has this, which helped I think:

   "Furthermore, total calories and fiber had a negative correlation with gut microbiome diversity, and anxiety and depression decrease as the gut diversity increases."

by RugnirViking on 4/26/23, 2:54 PM
Interesting. Note this has not yet been peer-reviewed, so findings must be taken with an especially large pinch of salt even compared to your average paper. In this case, they only looked at 20 adults over 2 weeks, so I feel that any conclusions drawn here are circumstancial at best.
Apparently the reseach was funded by NIH and therefore at least partly the taxpayer. Seems like a bit of a strange study to fund, in my opinion nothing useful can possibly result from such a tiny study. I tried tracking down the specific grant they were given (they mention NIH award UL1 TR-002378 in the disclosure section of the paper but I can't find anything from that)
by Balooga on 4/26/23, 6:21 PM
I lost about 70lbs in about 10 months by cutting out processed foods, cutting out foods with added sugar, eating foods having a low glycemic index, eating a lot of chicken, whole vegetables, whole fruit. And by not juicing, and not drinking smoothies.
I also did a lot of strength training so as to lose fat and not muscle.
I didn't try to reduce the amount of calories I was eating, just change where those calories were coming from.
Weight went poof. Energy went way up and my mood improved.
by volleygman180 on 4/26/23, 3:13 PM
I'm glad to see more studies on this, as it's long been misunderstood how strong of a connection there is between the gut microbiome and mental health. Some go as far to referring to the gut as our second-brain, due to its critical role.
Serotonin (the moood-regulating neurotransmitter), for instance, is produced _primarily_ in the gut (up to 95% of it). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6469458/#:~:tex....
by mattwest on 4/26/23, 5:24 PM
Last year, I started an experiment with my diet.
It started with the idea of eating as cheaply as possible with nutrient dense foods, but I started off with an elimination diet.
I chose 2-3 "meals" that I could easily prep and only cost $2-4 each. Mostly eggs, ground beef, white rice, potatoes. I quickly added bell peppers and onions.
I tracked macros, and filled in the micros with new additions. Calories as well of course.
The result was fantastic.
1. I got really fast at cooking, and even now that I cook more complex meals, I'm much faster than before. Probably because I introduced new ingredients gradually and maintained efficiency in the kitchen.
2. My ability to eyeball macros on a plate is pretty good now. It's much easier to regulate my energy levels because of this. I can also guess my bodyweight within ~5lbs before checking the scale.
3. I figured out what I digest most easily. As an athlete, I can't really afford to have days where I'm "bathroom dependent".
The consistency in all these aspects has greatly improved my life.
If you want to get better at cooking, understand your body better, save time, and eat a healthier diet, this method might work well for you.
Disclaimer: after the first 2-3 weeks, I switched from 100% compliance to ~80% compliance. That way I get the benefits of regimented eating without going crazy. Even if you eat healthy, it's not good to obsess over calories and food options.
by runlaszlorun on 4/26/23, 3:07 PM
I’ll confess that I’ve only read the abstract, but was totally confused by this apparent contradiction…
> We found strong correlations between greater consumption of fat and protein to lower anxiety and depression
vs
> We have shown that changing diet affects mood and happiness, that greater fat and carbohydrate intake is directly associated with anxiety and depression
The first says fat reduces anxiety and depression. The second seems to imply it reduces it- unless “directly associated” actually means “negatively correlated”??
Also, are they saying that increased fiber reduces gut biome diversity?
-edited for typo-
by r_singh on 4/26/23, 2:54 PM
Has anyone researched the opposite? Like the role of mood and happiness on the gut microbiome.
I was diagnosed with Celiac 5 years ago, could never gain weight and had my share of struggles with anxiety etc.
I recently found a counsellor who told me to stop overthinking, seeking knowledge and a few other things which after following I gained 5 kilos and became a happier person.
I always thought my gut was to blame but a few simple practices seem to be fixing my gut too.
by jaredhallen on 4/27/23, 2:37 AM
> We found strong correlations between greater consumption of fat and protein to lower anxiety and depression...
> ...that greater fat and carbohydrate intake is directly associated with anxiety and depression and inversely correlated with gut microbiome diversity.
So which is it when it comes to fat? My experience says fat and fiber make me feel good. Carbohydrates bad. Protein, neither good nor bad.
by charlysisto on 4/26/23, 7:11 PM
I don't know much about the gut microbiome, but it is pretty well established now that the ketones produced by fasting (or diet mimicking it like keto) have a powerful effect on the brain : as an alternative to glucose for fuelling neurone, and a signaling molecule to mitochondria for mitophagy (the cleaning up of the damaged ones) and mitogenesis. These processes can reactivate and repair group of neurones compromised by oxydative stress or insuline resistance and thus heal the mind.
See Chris Palmer book : "Brain Energy" or Bikman's : "What makes Us Sick" or Gundry the "Keto Code"... All saying the same thing although with different perspectives. Yes the Brain is just another organ and we're starting to discover ways to trigger self healing processes which can leverage and/or take over the common chemical oriented cures mimicking neurotransmitters...
It started 100 years ago at the Mayo clinic were they cured epileptic children with strict keto diet. Quit fascinating !
by amanaplanacanal on 4/26/23, 3:07 PM
This doesn’t seem to be worded very well:
> greater fat and carbohydrate intake is directly associated with anxiety and depression
Carbohydrate was positively correlated, and fat was negatively correlated with anxiety and depression.
by DoreenMichele on 4/26/23, 7:39 PM
Some outtakes:
Bacteroides is predominant in people eating large amounts of protein (e.g. Western diet)
Human studies have shown an increase in gut bacterial translocation in mood disorders.6,7 For example, in major depressive disorder there are significant increases in Bacteroidetes, Proteobacteria, and Actinobacteria and decreases in Firmicutes compared to controls.
The benefits of ketogenic diets for controlling severe epilepsy may be mediated by the gut microbiome, as the effects can be reproduced in animal models by direct manipulation of gut bacterial enterotypes without changing diet.
by coding123 on 4/26/23, 3:28 PM
My wife has to eat protein (in her case meat) with carbs. If she eats carbs with no protein she has anxiety. It's so awesome that we are finally studying things like this.
by tulio_ribeiro on 4/26/23, 9:35 PM
I've read some studies that suggest that the gut microbiome can influence mood and behavior through the vagus nerve, which connects the gut and the brain. For example, this[1] study showed that mice fed with a probiotic bacteria had lower depressive and anxious behaviors than mice whose vagus nerve was cut. Another study[2] showed that oral treatment with antidepressants altered the gut microbiome and increased vagal activity in rats, and that blocking the vagus nerve abolished the antidepressive effects. These studies imply that the gut-brain axis is more complex than just diet and microbiome diversity. Maybe there are other factors that mediate the effects of fat, protein and carbohydrates on mood and mental health. What do you think?
[1] https://medium.com/microbial-instincts/how-gut-microbes-talk...
[2] https://www.nature.com/articles/s41598-019-50807-8
by DrThunder on 4/26/23, 5:26 PM
Does this mean the all knowing FDA is wrong? They told me Frosted mini-wheats, Lucky Charms, cheerios are better than ground beef, cheddar, eggs, and butter.
by GuB-42 on 4/26/23, 8:40 PM
The introduction seems to be contradicting itself
> We found strong correlations between greater consumption of fat and protein to lower anxiety and depression
> greater fat and carbohydrate intake is directly associated with anxiety and depression
So? Is fat good or bad? (apparently, from the rest of the article, it is good)
by mrinterweb on 4/26/23, 5:46 PM
> For this pilot study, we enrolled 20 adults to follow this protocol
Is that even a large enough of a sample size to draw a conclusion from? Probably a big enough sample size to get funding for a larger study, but not big enough to draw general conclusions from.
by blastro on 4/26/23, 3:28 PM
I sleep much better after eating basic food that my microbiome seems to enjoy: white rice.
by SamoyedFurFluff on 4/26/23, 3:15 PM
Since this study only explored a 2 week change, does anyone have any info on more permanent changes? I’m uninterested in temporarily having less anxiety for 2 weeks. I would like to know what’s my anxiety after 2 years!
by orzig on 4/26/23, 5:11 PM
Look at the plots, there is one huge outlier in the small number of overall samples which is driving a lot of the results. I don’t even disagree with the conclusions, but this is not strong evidence for it.
by nimbius on 4/26/23, 3:05 PM
I believe the study is onto something pretty conclusive. Speaking anecdotally, ive never eaten anything from Chipotle that didnt leave me with a haunting sensation of fear and remorse.
by Beaver117 on 4/27/23, 1:24 AM
I'm so disappointed at the state of HN. Instead of good faith discussion we have a bunch of keto anti-carb people pushing their narrative. Did you forget that a large number of people are Asian, eat large servings of carbs (rice) every day and live longer and are healthier overall than western people?
Wasn't the standard bodybuilder diet chicken, rice, and broccoli?
All of a sudden carbs are now "crap" and everyone tries to be in ketosis 24/7.
by SCAQTony on 4/26/23, 4:01 PM
I was disappointed how vague carbs were defined, but I suspect we can all agree the best diet for an omnivore is the least processed food is the best choice. Anything that comes in a box or can should be suspect. Soup is best when the broth is made from leftover chicken bones and the rest of it with chicken meat and raw veggies. Fruit is better than candy, fish is better than bacon. YMMV
by sofaygo on 4/26/23, 7:29 PM
Anecdotally, I agree with the conclusions the researchers propose. From an academic perspective, this study is poorly done, with an abstract that fails to fully encapsulate their findings.
While this is a topic that is very important and deserves the attention,people shouldn’t be mislead into taking this paper at face value.
by d23 on 4/26/23, 7:51 PM
> We found strong correlations between greater consumption of fat and protein to lower anxiety and depression
> We have shown that changing diet affects mood and happiness, that greater fat and carbohydrate intake is directly associated with anxiety and depression
What?
by jononomo on 4/26/23, 6:03 PM
"We found strong correlations between greater consumption of fat and protein to lower anxiety and depression while consuming higher percentages of carbohydrates was associated with increased stress, anxiety, and depression."
by robwwilliams on 4/26/23, 6:50 PM
Interesting general topic but this is a tiny short term unreviewed study that is getting way more attention than deserved. Twenty subjects over a few week is not a serious effort.
by xapata on 4/26/23, 3:51 PM
N = 20.
Sounds like p-hacking to me.
by aszantu on 4/26/23, 3:28 PM
that's literally me... I've observed that it takes about 4 days between carb consumption and mental breakdown. Also before the mental breakdown appears, the smell changes from nice to sour. The sour smell seems to be connected to high stress, it's really hard to remove from clothes.
by jononomo on 4/26/23, 6:06 PM
Dr. Georgia Ede, a Harvard psychiatrist, has found that eliminating plants entirely from your diet leads to phenomenal mental health outcomes. Her findings jive well with the results reported in this paper. Her website is https://www.diagnosisdiet.com/
by keyle on 4/26/23, 10:45 PM
"... we enrolled 20 adults" ... for 2 weeks?
Is that really all it takes to produce a study now?
by Llamamoe on 4/26/23, 3:06 PM
I recommend this overview of effect of human diet on the gut microbiome: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6950569/?report...
Tl;dr is that while the gut microbiome varies by diet, it's largely stable after around 3 years of age, and even extreme dietary changes only result in impermanent shifts in relative abundances and function of your bacteria.
by fnord77 on 4/26/23, 7:01 PM
n = 20
by throwawaaarrgh on 4/26/23, 7:44 PM
Last year, I went on a diet of only strawberry flavored candy peeps. I lost 50 lbs, my skin cleared up, and I feel like I have more energy. Clearly an all candy diet is something we need more research on, as it seems the status quo is to undersell the advantages of this high sucrose diet.
Disclaimer: I now have Type 2 diabetes.