Comments
I know from personal experience that eating sugar does induce more anxiety in me. This might sound weird but I can "physically feel" in my head a certain anxiety when e.g. I think about something awkward. This "physical feel" stopped being there when I stopped eating sweets for a few weeks. One reason why I try to keep my sugar intake down (the other being in danger of getting diabetes...).
Thus, I wholly believe this study.
I believe most people are not notability adversely affected by sugar and a small subset of the population, like myself, are acutely affected. The former does not invalidate the latter. Sarah Wilson of “I quit sugar” fame started off with a zero sugar crusade then later ameliorated her advice in an apparent effort to generalize her advice for a wider audience. I think advice should be tailored by conditioning on what category a person fits into. I would go further and suggest that a zero sugar diet should also have zero fruit. As a ADHD sugar addict I would generally substitute sugar with fruit and that prevented me from finding out that even my ostensibly healthy diet had too much sugar in it.
do you substitute your fruits with vegetables? Maybe I should try it as well but then again my daily apple is one of my highlights.
The most direct substitution was cheese, lactose does not appear to have the same effect on me as fructose or sucrose.
I mostly eat kale for vegetables, this also helps with subclinical insulin resistance and inflammation. I think roasting vegetables may end up being too sweet.
I did an extended 5 day water fast to kick start the microbiome changes I undertook it as an experiment and the effectiveness in lifting brain fog suggested that it likely had a microbiome component.
By ThinkBeat 2025-06-1520:22 It is important to note that extended water fasting will have adverse effects for some people. It is not recommended to do it for that long.
"" The water fast lasts for 24–72 hours. You should not water fast for longer than this without medical supervision because of health risks. "" https://www.healthline.com/nutrition/water-fasting
Would you mind citing which kind of cheese you eat? Because much cheese has little to no lactose, and also goat lactose does not necessarily have the same effect as cow lactose. Finally, the fats and proteins in cheese affect digestion and possibly sugar absorption.
By Y_Y 2025-06-1621:33 > Lactose is a disaccharide composed of galactose and glucose and has the molecular formula C₁₂H₂₂O₁₁.
What could be different?
Do you mean that relative amount of lactose? I believe it's that's not different in the raw material.[0]
[0] https://www.canr.msu.edu/news/goat-milk-versus-cow-milk-a-co...
Honestly when battling sugar cravings it would be rather large chunks of parmesan cheese because I find it rather sweet. I assumed that was due to lactose but perhaps I'm wrong about that. It could also be that even a small amount of lactose tastes sweet after a while of not eating sugar.
By esperent 2025-06-161:01 Parmesan has close to zero lactose. However, it has an extremely high level of free glutamate, up to 1.6%, which is why it tastes delicious and makes other food taste delicious. Probably should avoid it, along with MSG, if you have blood pressure issues. Probably fine otherwise.
By esperent 2025-06-161:05 Really depends on the cheese. Most has less than milk but for some like cottage cheese it's still pretty high. Other hard cheeses like parmesan it's basically zero.
You could use a rule of thumb that hard/aged cheeses are low lactose. But there's outliers like brie/camembert that are very low lactose even when relatively fresh.
By reliablereason 2025-06-1518:322 reply You say sugar, but are you referring to glucose or fructose?
There is a meaningful amount of scientific literature connecting fructose and inflammation.
The AVERAGE human can only digest about 30g of fructose a day. Some substantially more, some substantially less.
A can of soda or three apples is about 30g of fructose.
Inflammation (high- and low grade)then being a second step linking to anxiety.
I am talking about the sugar in sweets. My daily apple does not appear to heighten my anxiety.
By reliablereason 2025-06-1519:125 reply I have heard people say that eating fibers together with fructose(like when eating a apple) reduces the impact of fructose, as fibers create a lining on the gut wall reducing the absorption rate.
Sounds reasonable. But i have had a hard time finding evidence verifying that hypotesis.
By NoPicklez 2025-06-160:55 Its in most nutrition textbooks, it's partly why fiber is so important.
Eating fiber with any carbohydrates reduces the absorption rate. It's partly why eating an Apple is better for you than eating a lolly despite both being high in sugar.
By vanderZwan 2025-06-166:02 I think you have to look for "glycemic index" and learn about its mechanisms, which in your defense is not an obvious term to search for.
By j-conn 2025-06-1614:53 I’m not sure about that mechanism, but the impact on blood sugar is quantified as “glycemic index” and “glycemic load.”
By cwmoore 2025-06-1619:20 Serotonigenic microbes digest fiber into feelgood neurotransmitters.
You're welcome.
By xdavidliu 2025-06-1519:52 i'm pretty sure this saying is well agreed upon by the mainstream medical community. (not a medical pro myself, but follow a lot of articles and podcasts from mainstream sources)
By snovv_crash 2025-06-1522:241 reply Athletes consume 50g of fructose (and 50g of glucose) per hour. It's actually fairly easy to train yourself to this level.
> Athletes consume 50g of fructose (and 50g of glucose) per hour
...while actively competing in endurance events. They don't do this while sitting on the couch in the evening. And it's very specifically only endurance trained athletes who do this, sprinters would never need to consume that much sugar.
It's a valid point though, a sugary snack or sports drink directly before hitting the gym for a hard workout session is probably fine, as long as your blood wasn't already saturated with glucose from earlier sugary foods, and as long as you don't have insulin resistance.
By snovv_crash 2025-06-1722:441 reply Sure, but that all has nothing to do with digestion, that has to do with blood sugar levels and what your body does with the energy afterwards. Digesting 30g of fructose per day is not any kind of biological limit, in contrast to what GGP claimed.
By esperent 2025-06-2010:54 It's a biological limit without long term health effects, unless you're burning it off with intense exercise.
Sugar? Why not caffeine?
I swear that a 4+ week coffee and caffeinated holiday improved emotional regulation and turns down OCD behaviours and anxiety.
Not sure if this is microbiota-related or related to down-regulation of neuroreceptors activated by coffee compounds.
I’ve heard arguments such as “well… caffeine is cleared within hours so a weeks-long effect is placebo”. Say what you want.
By NoPicklez 2025-06-160:32 Well I don't think they're saying that wouldn't happen with caffeine, just that this is their experience with sugar.
By iaaan 2025-06-1519:14 I recently started consuming relatively large amounts of fiber (standard daily dose of whole psyllium husks mixed with water) and I feel noticeably less anxious than on days when I don't take it. Fiber has been shown to interact somehow (I'm not super familiar) with the body's insulin levels. I wonder if it is related to what TFA is saying.
By McAlpine5892 2025-06-1620:281 reply Most of my adult life I've suffered from DPDR. In recent years I've been able to get somewhat of a handle on it.
While I never pinned down the cause exactly, my talk therapist and I came to the realization that some meals would trigger it. Usually those meals were obviously bad for my health, so I started avoiding them.
> This might sound weird but I can "physically feel" in my head a certain anxiety
Why I commented. DPDR is in the same box as anxiety and, yeah, I could literally feel this weird pressure in my head. An actual physical sensation. Seems like we had different cause and side effects but it's so good to read there's someone else out there.
Glad you found something that worked for you. There's so much we don't know about our bodies.
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[0] https://en.wikipedia.org/wiki/Depersonalization-derealizatio...
By Tarsul 2025-06-1622:24 Thank you for posting. You made my day as well :)
By veunes 2025-06-1518:10 It's wild how much your gut can mess with your brain chemistry
By mountainriver 2025-06-160:52 Yes same, my anxiety is completely gone on keto. It’s just really hard to constantly be in keto, so I limit my carbs which helps but isn’t quite the same
By amelius 2025-06-1521:08 I get a similar feeling when drinking milk. Maybe I'm becoming intolerant.
Can you explain your jump from gut microbiota to sugar? Aside from sugar being one food that passes through our digestion, I'm not certain why you have singled it out.
By kelipso 2025-06-1518:19 Just from basic principles, what you eat affects your gut microbiome because different bacteria reproduce more or less from you eating different foods.
By iknowstuff 2025-06-1518:322 reply Heads up, I don’t think there’s a link between eating sugar and risk of developing diabetes. Obesity is a risk factor but not sugar itself.
By strken 2025-06-1522:39 https://www.sciencedirect.com/science/article/pii/S216183132...
There's a complicated relationship, according to this meta-analysis. Eating sugar in isolation from other sources of nutrition is a risk factor. Eating fruit, or eating sweetened foods with redeeming qualities like yoghurt and wholegrain cereal, is probably inversely correlated (with lower confidence). These seem to be true even when controlling for BMI.
Looking at the meta-analysis, it's hard to say there's no link. The authors suggest that fibre might mitigate the impact, and that adding sugar to otherwise healthy foods might encourage higher consumption of them.
By Tarsul 2025-06-1519:12 Maybe. But eating sweets makes me eat more anyway. Which leads to me gaining weight. So it's the same anyhow.
I think it makes sense that our microbiome should be able to trigger such a response. If your microbiome is changing, it means that some microbe is gaining numbers it didn't previously have, and your current bodily functions, such as your immune system, aren't stopping it. That doesn't necessarily mean your immune system is compromised, but if it is then it would probably be good not to spend a lot of time around other individuals, especially large groups or strangers. Other reasons for your microbiome to be shifting, like a sudden change in diet or enviroment, could also be indicative of an issue like food shortages or territorial change where it would also be good to minimize your exposure to and reliance on others. Finally, depending on what exactly is gaining a foothold, you could potentially be a threat to your kin if you come around them. Developing a social fear response to certain changes in gut microbiome could thus be quite beneficial for most social creatures.
The problem with Evolutionary Psychology is that it’s easy to construct this sort of “just so” story for pretty much any causal link, and they are not falsifiable.
IMO the simpler hypothesis here is that this isn’t anything adaptive, it’s just another example of how biology is like spaghetti code; changing one chemical signal will affect an essentially random set of downstream systems, some of which can be causally connected to psychology/behavior.
Could also be like climate change, where it correctly describes a broad phenomenon, but cannot be used to identify or classify any individual event. E.g., Wildfires are probably getting worse because of climate change, but it's difficult to say if the Pacific Palisades fire would not have happened in a cooler global climate.
So, is microbiome-mediated social anxiety selected for as an advantageous trait for societies subject to communicable diseases and the travails of nomadism? Maybe. Did YOUR microbiome-mediated social anxiety arise because it was advantageous for your community? Probably impossible to say.
Also, a hole in GP's logic: you would expect protective social anxiety to arise in people whose situation hasn't much changed except that they've encountered people whose has (as with sedentary villagers encountering nomads who may or may not be about to ransack their settlement).
By softsound 2025-06-1518:31 Wildfires are worse in areas where the wrong type of trees were planted as well which is common in logging areas or places cheaply "reforested" that don't do much research on what should be growing there. Wildfires themselves aren't bad per say either as certain trees only grow from fires. Not to say that climate change isn't a factor though, but there are a lot of varibles too.
> you would expect protective social anxiety to arise in people whose situation hasn't much changed except that they've encountered people whose has (as with sedentary villagers encountering nomads who may or may not be about to ransack their settlement).
No, you would not expect that. If rats that self-isolate when their gut micro-biomes change avoid diseases that other rats get afflicted with, then evolution will lead to the mechanism spreading through the rats over time. The rats do not need to know why self-isolating helps, they do not need to even know that self-isolating helps, and they do not need to be in the position where it would help the most.
By h2zizzle 2025-06-1614:26 GP's hypothesis is that diet/environment microbiome changes induce a protective social anxiety. However, a nomadic population - the most likely to exhibit those changes - are successful when exhibiting prosocial or confrontational characteristics, the opposite of social anxiety. Social anxiety is most protective for sedentary groups, who probably should be suspicious of outsiders.
Nothing you said contradicts this, and I'm not sure how to square the circle, even though microbiome-mediated behavior as an explanation for broad, otherwise irrational behavior patterns is attractive.
By asdff 2025-06-1517:55 That isn't a problem because no one speaks of these suppositions in terms of "just so" but in terms of "could be due to." If you want to prove something as just so you have to do a lot more work describing a mechanism of action and that involves reaching into a different toolbox.
By jjk166 2025-06-160:57 > IMO the simpler hypothesis here is that this isn’t anything adaptive, it’s just another example of how biology is like spaghetti code; changing one chemical signal will affect an essentially random set of downstream systems, some of which can be causally connected to psychology/behavior.
That's not a competing hypothesis. Obviously the change to the gut affects other things, some of which happen to impact psychology and behavior.
The question is why does this particular change to gut microbiome have such a similar impact on two different species that diverged many tens of millions of years ago? "It just does" is not a very satisfying answer.
By troll_v_bridge 2025-06-1517:48 Which would still be natural selection though.
By veunes 2025-06-1518:11 Makes me wonder how many other "maladaptive" responses today actually had adaptive roots in a different context
How is it not beneficial for the individual to avoid threats to their health and safety?
By amelius 2025-06-1614:07 I mean the individual who is sick is now sent into a downward spiral of anxiety and frustration instead of evolution helping them (e.g. by making others take care of them, etc.)
Which is to say, maladaptive. Despite all the people wishing evolution worked at the group level, it doesn't. Groups don't have offspring, individuals do, and thus things that are bad for the individual are extinguished regardless of their effect on the group.
If you look closely enough, even individuals aren't the true units of evolution, for the same reason; competing alleles is where the real action is.
By saltcured 2025-06-1519:57 When thinking about evolutionary forces, you cannot conflate "positive" outcome with survival and reproduction. An individual might survive and produce offspring via effects that make the individual unhappy in their own life and/or with shortened life.
It's only when an effect causes death or infertility prior to normal reproductive phases that we can really say it has a direct evolutionary pressure. Anything that happens later is always going to be through secondary, social effects on how their condition supports or hinders their offspring from reproducing further generations.
By energy123 2025-06-1519:13 Alleles are shared with kin which gives rise to multilevel selection effects in rare but real scenarios.
By MarkusQ 2025-06-1520:26 Voting me down doesn't change the fact that group selection is a myth. A myth that some people are fervently attached to, but a myth nonetheless. Groups simply don't reproduce at a rate or fidelity to allow evolution at the group level over the time scales in question.
E pur si muove.
I've seen probiotic supplements that have strains that claim to help with anxiety and depression, but I've never really looked into them because I'm quite skeptical they do anything. But if anyone is familiar with them and has any feedback I'd be interested to hear it.
This is only anecdotal, but probiotic supplements absolutely had a large impact on my social anxiety. I can't remember for the life of me where I heard it, but I specifically looked for ones that with strains were "dirt-based" - PB-8 is the one I currently take. Looking back, I realized just how directly getting anxious was tied to having an upset stomach for me. The first week or so was a bit rough, but after that it's been smooth sailing. The supplements are so cheap that I think it's worth trying for a bit. Kombucha/other fermented foods may also have a positive impact.
Caveat: I have never been diagnosed with an anxiety disorder, so things may different in that case.
By pogue 2025-06-183:26 Was your anxiety caused by your upset stomach you think? Or was it unrelated?
There's this one person who claims to have found out that theses probiotics need to be amplified into a megadose, and subsequently they cured themselves from social anxiety. I'm not sure if there are other people who have replicated, but the initial report seems trustworthy. See https://pdfcoffee.com/experimental-treatment-for-social-phob...
Aside from the other red flags in that link, the author claims to be able to get rid of SAD symptoms in "about 45 minutes" which strongly suggests a placebo effect to me (or at least not an effect from changes in their microbiome).
By Geee 2025-06-1620:43 Yeah, that's odd for sure.
By pogue 2025-06-1522:36 That's very interesting. Making your own yogurt sounds like it could be easy to do and you could potentially just use OTC probiotic capsules or powder.
I posted some studies above about two probiotic strains that have specifically been studied for mood enhancement aka "psychobiotics": Lactobacillus helveticus Rosell-52 and Bifidobacterium longum Rosell-175.
By briankelly 2025-06-160:111 reply I’ve seen people who seem to know what they’re talking about cast doubt that you could create your own probiotic yogurt in a typical kitchen since other strains are likely to dominate without a sterile environment and careful methods.
By Geee 2025-06-163:05 The strain you want has a huge headstart, and there shouldn't be much bacteria in boiled milk to begin with. Containers can be also sterilized with boiling water. Then keep it cool after it's done (14 hours). It doesn't seem likely that some other strain would dominate, but who knows.
I've had a LOT of gut problems in my life. I have a physically broken stomach, have had to have stomach surgery in the past, and probably will have to do it again soon.
Most probiotics I've taken did nothing. The only ones that seem to actually work for me are these: https://drohhiraprobiotics.com/
Not sure why it works, but anecdotally, they do.
Other things that have helped significantly – cutting out alcohol.
Fermented foods are way more helpful IME. I've even found kombucha protective against mildly spoiled food.
I can also attest to having my first alcoholic drink in a while and it screwing me up for a week.
I've always been skeptical of probiotic supplements in general mostly because they are stored/shipped in unrefrigerated environments. I believe in most cases the bacteria would end up dead before you even ingested it. However, some companies have developed strains that can withstand some amount of heat. But you never know where they've been stored/for how long/etc.
I remember speaking to someone who had the suggestion to try fermenting food with probiotic supplements, as that would be the only realistic way to know if they were still alive.
There are vendors that do sell probiotic supplements that come shipped in dry ice that people with Crohn's disease & other GI ailments. I don't remember the name of the company that sold them though.
But, I agree that yogurt or saurkraut/kimchi and other fermented products would be a good way to get some gut bacteria. Those would be great to use after you came off antibiotics, but it wouldn't necessarily help with genital mental health/anxiety (as far as I'm aware).
Interestingly, yeast has neurotransmitters and neurotransmitter precursors in it such as tryptophan and serotonin. [1]
Having said all that, I decided to look up the "mood enhancing" probiotic strains I've seen being sold in OTC supplements. The two strains I see are Lactobacillus helveticus Rosell-52 and Bifidobacterium longum Rosell-175 (there may be others I'm unaware of). The studies are quite small, unfortunately. (I didn't read all of them though) [2] [3] [4] [5].
Finally, this is quite a unique term I haven't come across: Psychobiotics!
Psychobiotics are probiotics that have the characteristics of modulating central nervous system (CNS) functions or reconciled actions by the gut–brain axis (GBA) through neural, humoral and metabolic pathways to improve gastrointestinal activity as well as anxiolytic and even antidepressant abilities. [6]
[1] Melatonin and Other Tryptophan Metabolites Produced by Yeasts: Implications in Cardiovascular and Neurodegenerative Diseases https://pmc.ncbi.nlm.nih.gov/articles/PMC4718080/
[2] Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects https://pubmed.ncbi.nlm.nih.gov/20974015/
[3] Probiotics Promising for Mild to Moderate Depression https://www.medscape.com/viewarticle/881877
[4] The effect of Lactobacillus helveticus fermented milk on sleep and health perception in elderly subjects https://pubmed.ncbi.nlm.nih.gov/17851460/
[5] One Giant Leap from Mouse to Man: The Microbiota–Gut–Brain Axis in Mood Disorders and Translational Challenges Moving towards Human Clinical Trials https://pmc.ncbi.nlm.nih.gov/articles/PMC8840472/
[6] Exploring the Potential of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 as Promising Psychobiotics Using SHIME https://pmc.ncbi.nlm.nih.gov/articles/PMC10056475/
By ac29 2025-06-1615:12 > I've always been skeptical of probiotic supplements in general mostly because they are stored/shipped in unrefrigerated environments. I believe in most cases the bacteria would end up dead before you even ingested it. However, some companies have developed strains that can withstand some amount of heat. But you never know where they've been stored/for how long/etc.
Probiotics in pill/capsule form are generally freeze dried, so they are much less temperature sensitive than live bacteria.
yeah I had serious gut problems for years and no probiotic ever did the slightest thing. Anecdotally I can’t differentiate them from snake oil.
But Metamucil changed my life dramatically over a span of a few weeks. Never had the type of symptoms it’s indicated for, which everyone I mention it to just assumes. But it fixed me somehow.
By pogue 2025-06-1518:12 I was recently talking about fiber & fiber supplements on here in a thread about a new type of fiber that was shown in a study to help with weight loss.
Acetylated cellulose suppresses mass through commensals consuming carbohydrates https://news.ycombinator.com/item?id=44219171
By rpozarickij 2025-06-166:31 One doctor recommended this brand to me too not long ago, but I'm a bit worried that this probiotic contains histamine-producing bacteria since I have some histamine sensitivity.
And overall I'm a bit hesitant about consuming too many strains at once.
So far I've been having success with S. boulardii CNCM I-745 (which is actually a probiotic yeast) and I'm trying out L. rhamnosus GG.
Bifidobacterium infantis 35624 also looks interesting.
By asdff 2025-06-1517:57 I'm not sure how many probiotics will make it through the stomach acid. One would think suppository would be vastly more effective: parachute directly onto the battlefield.
After trying a lot of things what worked for me was cutting out negative food; usually gluten, lactose, fructose. Probiotics never did anything for me.
Nothing specific, simply your own stomach. Every human is different. Some people can eat spicy foods, some people can't. Best strategy is to learn for yourself what make you happy when you wake up and what makes you feel bad. Listen to your own body, make changes.
By BLKNSLVR 2025-06-165:14 Thanks for clarifying. I agree with your answer. Do what works for you!
Since the advent of "gluten free" foods, specifically for coeliacs, the fact foods get advertised as "X free" leads a percentage of the population to believe that X is therefore bad and should be avoided for as-a-general-rule health reasons rather than health reasons limited to those who get complications as a result of X.
Whether or not the effect in the paper turns out to be true and reproducible, the supplements you've seen almost certainly don't do anything unless you're wiping out your established gut microbiota with antibiotics first. Your existing microbiota are entrenched and in a very good position to defend themselves from any weakened intruders you might intentionally introduce. Meanwhile, supplement companies really like to make exaggerated claims.
By pogue 2025-06-1519:00 I posted some links to papers I came across here: https://news.ycombinator.com/item?id=44284165
It's a very fair and valid question as to whether a probiotic supplement:
A) Survives being packaged and stored in a warehouse for an indeterminate amount of time B) Being shipped in the back of a truck/airplane C) If the bacteria is still alive whether it can make it through the GI tract to even have any effect whatsoever
I don't know whether this has been studied. I know Consumer Labs does yearly tests on various supplements, probiotics included, but it's a subscription service and you need to subscribe to see the results. I have subscribed to them in the past and found their testing and articles quite helpful. I
In their tests, ConsumerLab found that the number of viable cells in probiotic products ranged from 1 million to 225 billion per recommended serving.
Additionally, some products were contaminated with harmful bacteria, such as Pseudomonas aeruginosa, which poses a risk to immunocompromised individuals and infants.
The company also noted that the enteric coating of some products did not function properly, potentially affecting the delivery of the probiotics to the gut. (Brave AI Search summary of the article below) [1]
ConsumerLab Tests Reveal Best Probiotic Supplements and Those With Quality Issues https://www.consumerlab.com/news/best-probiotic-supplements/...
By ac29 2025-06-1615:19 > Whether or not the effect in the paper turns out to be true and reproducible, the supplements you've seen almost certainly don't do anything unless you're wiping out your established gut microbiota with antibiotics first. Your existing microbiota are entrenched and in a very good position to defend themselves from any weakened intruders you might intentionally introduce.
There is an ton of probiotic research that shows probiotics can survive transit to the gut and reproduce there.
Even without probiotic supplmentaion, you microbiome absolutely can and will change over time.
By kenjackson 2025-06-1517:411 reply Strongly second this ask.
So long as it isn’t eating the variety of fresh fruits and vegetables that produce gut serotonin in the microbial breakdown of complex carbohydrates and fiber, right?
Eating fresh fruits and veggies is a great general health advice but unlikely to shift your gut microbiome meaningfully (unless you are eating some specific fruits or fruit skins in specific conditions).
And randomly eating healthy stuff is probably not going to shift your biome in a particular direction nor eliminate the cause of biome issues.
I eat healthy including a lot of whole fruit, nuts, dried fruits, dark green veggies and grass finished meats and there are still times I have my biome be a bit off.
By cwmoore 2025-06-1522:46 “Unlikely”, “randomly”, and “probably” had me nervous about your contribution to this discussion.
I do appreciate the quantitative precision at the end of your last sentence.
By kenjackson 2025-06-1521:101 reply Why wouldn’t it be? Do you know which ones exhibit the desired characteristic?
The ones that aren’t food shaped name brand products or fruit colored sugar water.
By kenjackson 2025-06-163:48 I’m fairly certain that is not accurate given I was vegetarian for over a decade.
