Gut Microbiome impact on Health and Fitness

firef1y72 wrote: »

GaleHawkins wrote: »

Autism symptoms reduced nearly 50 percent two years after fecal transplant

https://sciencedaily.com/releases/2019/04/190409093725.htm

"In a new study, "Long-term benefit of Microbiota Transfer Therapy in Autism Symptoms and Gut Microbiota," published in Scientific Reports, Arizona State University researchers Rosa Krajmalnik-Brown, Ph.D., James Adams, Ph.D, and lead author Dae-Wook Kang, Ph.D, demonstrate long-term beneficial effects for children diagnosed with ASD through a revolutionary technique known as Microbiota Transfer Therapy (MTT), a special type of fecal transplant originally pioneered by Dr. Thomas Borody, an Australian gastroenterologist. Remarkably, improvements in gut health and autism symptoms appear to persist long after treatment.

At two years post-treatment, most of the initial improvements in gut symptoms remained. In addition, parents reported a slow steady reduction of ASD symptoms during treatment and over the next two years. A professional evaluator found a 45% reduction in core ASD symptoms (language, social interaction and behavior) at two years post-treatment compared to before treatment began.

"We are finding a very strong connection between the microbes that live in our intestines and signals that travel to the brain," said Krajmalnik-Brown, a professor at the Biodesign Swette Center for Environmental Biotechnology at the Biodesign Institute and ASU's School for Sustainable Engineering and the Built Environment. "Two years later, the children are doing even better, which is amazing."

"Many kids with autism have gastrointestinal problems, and some studies, including ours, have found that those children also have worse autism-related symptoms," said Krajmalnik-Brown. "In many cases, when you are able to treat those gastrointestinal problems, their behavior improves."

Roughly 30-50% of all people with autism have chronic gastrointestinal (GI) problems, primarily constipation and/or diarrhea that can last for many years. That chronic discomfort and pain can cause irritability, decreased attention and learning, and negatively impact behavior.

An earlier study with only vancomycin (an antibiotic) had found major temporary improvements in GI and autism symptoms, but the benefits were lost a few weeks after treatment stopped despite use of over-the-counter probiotics.

So, the question at hand was what's going on in the gut, and how does it affect both physical and behavioral symptoms of autism, and how can we develop a long-lasting treatment?

Krajmalnik-Brown, Kang and Adams have shown that by transferring healthy microbiota to individuals lacking certain gut bacteria, it is possible to "donate" a more diverse set of bacteria into the patient and improve gut health.

In Australia, Fecal Microbiota Transplantation (FMT) was initially developed by Borody. At his Centre for Digestive Diseases in Sydney, Borody has overseen more than 18,000 FMTs for various disorders since 1987. He pioneered in Australia the use of FMT for colitis and Clostridium difficile infection, and was the first to use oral FMT to treat children with ASD. Only one dose of FMT is usually enough to cure C. Difficile infections, but his patients with autism were far harder to treat. He discovered that three months of daily FMT was required to treat his autism patients, but eventually resulted in significant improvements in both GI and autism symptoms.

Based on his experience with his patients, Borody led the design of the clinical treatment used at ASU for this study....."

CHILD’S RISK OF AUTISM CAN CHANGE BASED ON HEALTH OF MOTHER’S GUT

https://newsweek.com/autism-gut-health-signs-prevention-pregnancy-women-1031661

"New research suggests that the risk of developing autism is determined by the mother’s gut during pregnancy.

Scientists at the University of Virginia School of Medicine were able to analyze pregnant women’s microbiomes to determine the child’s risk of developing autism. The study, published July 2 in The Journal of Immunology, also researched how to use this finding to halt the development of autism-like neurodevelopmental disorders in mice.

“Our study was interested in understanding how the microbiome, which is the community of microbes that live within our gut, can shift susceptibility to autism-spectrum disorder,” John Lukens, assistant professor at the University of Virginia and lead author on the study, told Newsweek. To do this, the team studied, in part, interleukin-17a.

“It’s kind of the middleman between the gut and the brain,” Lukens says. Scientists at the Massachusetts Institute of Technology found that the inflammatory molecule interleukin-17a, or IL-17a, can influence the development of autism-like disorders in the brain. IL-17a has also been found to influence the development of multiple sclerosis and rheumatoid arthritis.

“What it can do during pregnancy is alter how the brain is developed and wired,” Lukens explains..... "

As someone who is autistic I'm going to call you out.
There are no such thing as autism "symptoms", because autism in NOT A DISEASE, it is a neurological condition, our brains are wired a little differently to a neurotypical and no 2 people with autism are the same or have the same issues with the nt world. We are not ill and no treatment is going to cure us. We do learn to a greater or lesser degree to fit a little better in to your world, but having someone else's cr@p stuck up my bum is not going to magically re-wire my brain and to be honest I wouldn't want it to.

Apologies in advance for rolling a number if points in this thread into one answer.

For context, my partner and his three children are all on the spectrum - under the the old style diagnosis, they have Aspergers. Here in the UK ASD is considered a neurological condition - it is not a disease and its not a mental health "problem".

In the interest of full disclosure, my partner and his children all have a range of food intolerances and their day to day lives along with their coping mechanisms are eased by exlcuding these foods from their diets. Certainly the children show more ADHD type symptoms if they do not exclude these foods.

I dont know how anyone can exclude one part of the body from the other in terms of understanding how it works or its impact when it works differently than expected under the 'norms' whether that be the brain, the digestion or anything else for that matter etc

I would question causal assumptions when all we can do is correlate data points - but I wouldnt exclude them entirely either. So I dont think we can ever say that gut microbiom issues cause ASD but then we can't say that ASD causes microbiom issues either. I have food intolerances and I dont have ASD.

What we can (probably ?) say is that when one part of the body is outside the range of what is considered 'usual', there may be other issues within the body. Another example could be that peri-meonpausal women are likely to experience increased levels of inflammation as their hormones wobble all over the show which can (not always) trigger auto-immune responses.

And then we hit chicken and egg - which one came first ? And from who/where/when ? Hello rabbit hole!

I appreciate this is the debate section but am surprised at the lack of intellectual curiosty - there seems to be a lot of focus on trashing individuals and/or articles bought to the site and sometime a seeming lack of awareness of ourselves being triggered in some way and bringing it here instead. This isnt specific to this subject on this part of the board, just a general observation across the wider board.

Microbiom is part of the body and so it has an impact - will we ever understand it enough to be able to neatly apply some sort of rule like our old friend "1200 calories a day or welcome nutritional deficiency" ?

Of course not - because we are individuals at a physically as well as emotionally.

Should we poo-poo (sorry, couldnt help myself) articles because they arent 'scientific enough' when there is plenty of bobbins shared on this site by those linking some webiste a self appointed nutrtionist / influencer has offloaded on. But thats ok, because we like them ?!

We can all find something on the Internet to back up / slag off someones 'here's something to read / look at' post. I fear we are missing the point once thats the priority.

As an example, I did a quick Google on FMT in the UK and came up with this:

https://wwwf.imperial.ac.uk/blog/imperial-medicine/2018/11/07/going-with-our-guts-to-find-new-treatments-faecal-microbiota-transplantation-at-imperial/

Not an academic reference in sight - and I would guess thats because the perceived audience is not academic. Someone at this highly rated hospital has tried to make this article accessible.

So how can we tell the difference between bobbins and accessible science stuff or even views shared on MFP ?

I would suggest do your own research, use your own brain and dont let anyone here tell you what to think, say or do.

Ask for the views if you need to, listen to it - but you decide whats next.

Wishing everyone well !

Still trying to figure out what the topic of debate is, since the OP had presented no arguments, just posted random web links.

We have had placed before us a number of links which provide information detailing the beneficial nature of our microbiome. The last one by Dr. Chris Kresser, educated in both eastern and western medicine, lays out everything neatly, how the body can be susceptible to issues within our microbiome.

I put it to you John, particularly, the debate is framed in the links. These links provide information on the ways to improve one's biome and why in various instances it could be helpful. As a younger person able to eat and drink what ever you choose seemingly without health issues have no wish to increase your knowledge - true this is news relating our microbiome will be new to many a Western Medical adviser don't we owe it to ourselves to look after ourselves to the best we can so as not to become an impediment to our families or societies?

Kindly do us a favour and set out your objections to the concept of the microbiome being beneficial. Enlighten us as to why any talk of a healthy microbiome is totally floored.

What was the date of this graphic. Who id this Bacult.

GaleHawkins wrote: »

magnusthenerd wrote: »

WinoGelato wrote: »

GaleHawkins wrote: »

try2again wrote: »

GaleHawkins wrote: »

One thing I try to keep in my mind is research is not the final answer because our understanding of gut microbiome impact on health and fitness will continue to evolve so an open mind is required for my own health and fitness.

Since no one has the final answer on the subject I will work to read and understand each research paper I can find on the subject regardless of the authors stated or unstated objectives.

As the author of this paper about reading research papers points out the more we read on any subject the better our BS detector works.

Isn't that like calibrating an instrument according to a faulty standard?

While I feel like this topic is a promising area of research, what you describe as "keeping an open mind" seems more akin to gullibility. While we may not need concrete evidence for every health choice we make, I wouldn't want to make changes based on every hypothesis that comes along.

In my case to I just shifted my calorie sources when shopping at Walmart and Krogers to enhance my health so there is no need to dive in the deep end of the pool is one is going swimming for the first time.

I just wanted to know how eating low carb in my case for the past 5 years has fixed or improved 40 years of serious health issues. Understanding cravings can come from one's own gut microbiome was exciting news in my seeking the WHY. That covers why Willpower is not a factor in weight loss often.

As has been pointed out to you time and again, you do not know, and cannot possibly know, if the health improvements you realize were from the change to low carb or the weight loss itself. Now you want to throw gut biome into the mix as a possible source?

When you hear hoofbeats, why look for unicorns or zebras rather than horses?

We need Gale to start loading up on the oils to gain 40 pounds but remain low carb, n=1 demands it.

As you well know I have been doing exactly that for nearly 5 years in my n=1 trail to see if it is calories or type of calories that impact my weigh the most and so far I have learned I can eat to stay stuffed as long as I keep carbs under 50 grams daily. Bumping up the carbs is the only easy and fast way to bump up my weight.

I found that to be puzzling until I learned about the gut microbiome and how it can demand binging to get more carbs in some cases. Science is a wonderful thing to get past dieting myths that are false.

You have no way of determining the causal effects.

But I suspect you know that already

GaleHawkins wrote: »

https://chriskresser.com/how-the-gut-microbiome-influences-everything-about-your-health/

I looked up Chris Kresser, and I'm genuinely curious how an acupuncturist and "functional medicine practitioner" (which is not highly thought of per anything I can find) knows more about the gut microbiome than leading researchers who state clearly the research has really only begun in that field.

GaleHawkins wrote: »

johnslater461 wrote: »

GaleHawkins wrote: »

magnusthenerd wrote: »

WinoGelato wrote: »

GaleHawkins wrote: »

try2again wrote: »

GaleHawkins wrote: »

One thing I try to keep in my mind is research is not the final answer because our understanding of gut microbiome impact on health and fitness will continue to evolve so an open mind is required for my own health and fitness.

Since no one has the final answer on the subject I will work to read and understand each research paper I can find on the subject regardless of the authors stated or unstated objectives.

As the author of this paper about reading research papers points out the more we read on any subject the better our BS detector works.

Isn't that like calibrating an instrument according to a faulty standard?

While I feel like this topic is a promising area of research, what you describe as "keeping an open mind" seems more akin to gullibility. While we may not need concrete evidence for every health choice we make, I wouldn't want to make changes based on every hypothesis that comes along.

In my case to I just shifted my calorie sources when shopping at Walmart and Krogers to enhance my health so there is no need to dive in the deep end of the pool is one is going swimming for the first time.

I just wanted to know how eating low carb in my case for the past 5 years has fixed or improved 40 years of serious health issues. Understanding cravings can come from one's own gut microbiome was exciting news in my seeking the WHY. That covers why Willpower is not a factor in weight loss often.

As has been pointed out to you time and again, you do not know, and cannot possibly know, if the health improvements you realize were from the change to low carb or the weight loss itself. Now you want to throw gut biome into the mix as a possible source?

When you hear hoofbeats, why look for unicorns or zebras rather than horses?

We need Gale to start loading up on the oils to gain 40 pounds but remain low carb, n=1 demands it.

As you well know I have been doing exactly that for nearly 5 years in my n=1 trail to see if it is calories or type of calories that impact my weigh the most and so far I have learned I can eat to stay stuffed as long as I keep carbs under 50 grams daily. Bumping up the carbs is the only easy and fast way to bump up my weight.

I found that to be puzzling until I learned about the gut microbiome and how it can demand binging to get more carbs in some cases. Science is a wonderful thing to get past dieting myths that are false.

You have no way of determining the causal effects.

But I suspect you know that already

Thankfully you will never support your point of debate.

Pot, kettle, black.

The burden of proof falls on the person making the claims (hint, that's you)

Not only have your links failed to do so, but many of them have stated exactly what others have been stating. Namely that very little is known about the gut microbiome, and any claims regarding its causative effects are premature.

Chris Kresser, is qualified in both Eastern and Western medicine, if you read his history he became ill during his gap year, tried to recover his health through conventional medicine and failed. He did his own research as many of us, more often more mature persons, he achieved a better quality of life and went on to train in both Western and Eastern medicine. His academic qualification are much higher than many in higher medical circles. I hold the work of qualified persons who follow the detail of how the body actually works in high esteem. He and others like him implement treatments which achieve relief for their many patients who are failed by the hypocrisy of many medical systems which assumes if you do not fit their boxes it is you which is at fault rather than the system you are trying to access for relief of being seriously ill.

One could set out his work and that of other Functional Practitioners as balancing the body's systems. General Western Medicine has divided the systems of our bodies into unrelated systems where as it should be likened to a drive system which runs several interrelated systems in synchronicity where everything works supporting a well functioning body.

Before I return to our microbiome - the oft disregarded thyroid gland shows difficulties when the adrenals, pituitary, liver, and pancreas, the pineal gland as well, I believe, do not function to the optimum for comfortable contented life. The past medical literature states the reasons why the thyroid is indicating issues should be addressed before treating the symptoms because this amplifies any issue.

Many unread persons scoff at the idea of "cleanses" as hokum. Functional Medicine believes each of the endocrine glands should work well and by using treatments including foods, herbs etc to facilitate better function provide relief for their patients. Regrettably the diet industry have taken this treatment and popularised them in order to earn a fast buck or for me shilling, degrading the efficacy of functional medicine and the successful treatments achieved each year. Most of the successfully treated persons on achieving good health again shun the modern western diet which is the cause of most chronic illness. Most members of the general public will not receive benefits from "cleanses" but those who have significant health problems could if the option used was related to their "actual health" problems.

As had been stated in many of the links offered, medication provided by western medicine causes the digestive biome to degrade. Principally the use of antibiotics which not only removes the problem for which it is prescribed but also the more beneficial bacteria which enables us to absorb our vitamins and minerals. Many other medications are harmful to our gut bacteria. Vitamin and mineral deficiencies lead to a persons body being less able to make the numerous enzymes and hormones which are essential for our bodies to function well.

Women are at a greater disadvantage, use of the contraceptive pill has a double hit, it over-rides the natural reproductive cycle but also changes other essential factors on an individual unrecognised level. Copper is frequently used in contraception - if you stop and think, door handles made from copper will reduce transfer of flue and other similar problems, its not surprising it does more harm to women it is introduced into. True copper is present in many foods, nuts and similar the balancing mineral is zinc primarily available in meat which is why vegetarians can have more copper related issues. Women are also more likely to react badly to ER use of cardiac prescriptions because of the difference in symptoms women experience with circulatory problems. My common denominator to all this is. When the woman's already declared complicated system is over ridden by the use of contraceptives it can produce a back lash from the endocrine system, in that the digestive motility decreases which impedes the life of beneficial microbes which contributes to a domino effect.

There are many pharmacological research papers which give the subject cohort as being male because, women's cycles complicate understanding and could deplete the observations. Not to mention women are less able to inoculate their children with beneficial bacteria at birth than our ancestors were. Children born by C section are at more risk of digestive related issues because of their compromised biome, fortunately there are products to help because the role of our digestive biome is better understood.

If the endocrine system et al, is in good health there would be fewer cancer diagnosis, fewer respiratory/ circulatory problems, fewer reproductive issues of species and cells, fewer chronic illnesses, fewer people with mental health problems, not least there could be fewer autistic person with disrupted digestions because of too few beneficial microbes and a good functioning endocrine system depends on the nutrition it receives and that comes down to the healthy balance of the microbiome in our guts.

Back in 1946, in Britain the soil association was formed because farmers were realising their soils were being degraded by previous farming practices. The microbiome which held their crops together was degrading and the farmers were being intreated to rely on petrochemical based firtilisers in preferance to the methods used for milenia. The upshot is our foods are less healthy than that our earlier populations, were they wealthy enough had access too, those crops provided greater numbers of beneficial microbes. We are not better than our ancestors we have fallen fowl of the idea that hygene is all, when not all microbes are unhellpful. Our populations health has not improved with the Clean Air Acts of the 1950 (UK) because beneficial microbes are less available.

In my view and those of others who prefer the functional perspective is, we disregard our digestive biome balance at too great a cost, we are doing ourselves an injustice.



Its commonly known, many with Autism can be helped to be more comfortable by supporting their digestion with microbes, none of this will change there personalities it will only facilitate a more comfortable body. I love my 3rd gradson dearly, i would not change his personality only stop his tummy area discomfort. For other reasons I have used products to help me digest salicylate and casein, my product was only availabe because families of autistic children asked their doctors to help the children with their digestive issues. I am greatful to those parents, its all part of my being fitter as i see 70 at the end of the year, than i was when i was 35 or 40 thanks to my use of antibiotics in my childhood but we did not know as much as we do now.

I have a tendency to be inappropriately receptive to new studies. I’m glad to have a community that cautions us that we need to wait for repeat studies before we can come to any conclusions.

I would love for these discussions to be more respectful, but that’s a two-way street. IMO posters should be careful not to make causal connections when none have been proven. @lemurcat12 received no woos when she posted upthread about diverse diets and diverse microbiome (an area that has caught my attention recently too) because she acknowledged that it’s just emerging.

This is interesting stuff for people who are into emerging science and nutrition - and I agree that MFP has a mob mentality about a lot of subjects. Go against the grain at your own risk in many subjects that just don't have support one way or the other. There is little room for personal experience here. "We are all the same!" is the battle cry.

Anyone who has ever worked in the restaurant or greocery business knows when it comes to food, no, we are not all the same.

With that said, some posters on MFP do tend to miss the point of the research all together.

lukejoycePT wrote: »

i see a hell of a lot of negative comments on here and not many thanks. At least Gale bothers to try and help others. Even him posting studies with links isn't enough for you lot. You are all too set in your ways and are in danger of not seeing the forest for the trees. Don't be so quick to call BS on something just because it isn't proven, it's well known that the medical industry is 10 years behind itself, especially when it comes to nutrition and gut health. If it isn't doing you any harm then surely its better to be safe than sorry?

I'm too scared to post on here now as i've already had two warnings. But there is definitely no room for outliers on here. You either agree with the consensus or get shot down. Keep doing what you are doing Gale, I find your posts informative and interesting. I appreciate your efforts.

I'm going to point something out to you regarding outliers and the necessity for proven, vetted and peer reviewed research and acknowledgement of what we know vs budding theories.
I'm using the post above yours as an example.

Fuzzipeg wrote: »

Its commonly known, many with Autism can be helped to be more comfortable by supporting their digestion with microbes, none of this will change there personalities it will only facilitate a more comfortable body. I love my 3rd gradson dearly, i would not change his personality only stop his tummy area discomfort. For other reasons I have used products to help me digest salicylate and casein, my product was only availabe because families of autistic children asked their doctors to help the children with their digestive issues. I am greatful to those parents, its all part of my being fitter as i see 70 at the end of the year, than i was when i was 35 or 40 thanks to my use of antibiotics in my childhood but we did not know as much as we do now.

I have an autistic family member who suffers with severe food issues running the gamut from digestive problems when she does eat all the way to refusing food altogether which usually results in hospitalization. My brother and his wife have spent everything they have and then some getting her to as many of the top specialists in the field for years now. NOTHING in the way of physical treatment has worked other than running a feeding tube into her belly. All of her progress has come from therapies geared towards helping her to see and understand the world around her and how she responds to it, and her place in the world and her bodies needs.

So when someone makes a bold claim such as "It's commonly known" as above, that needs to be backed up with some serious evidence. Other than the above that I used for an example I'm not going to call out names here, but blindly quoting people with questionable qualifications and posting links to questionable sources are going to be, should be, called out.

No one, not one "naysayer" as they're called, has stated that there is nothing to microbiome research or it's importance. Not one. What everyone is doing is rejecting what's questionable and demanding something empirical if possible, or realistic without bold claims that have no scientific backing yet.

Some of us reading here, while not scientists or doctors, have a personal stake in these fields discussed in this forum.

"I did this for 4 years and am great now" is NOT a valid source of evidence.

I'm deeply sorry for the family who has not benefited from the products I referred to. I know it is difficult and not everyone has the same cause for disorders and some may not responds to digestive microbes and digestive enzymes in the same way. All I can say is, living in the UK products from Huston are imported from the US and some families are able to have them prescribed, there is even a charity which helps some to pay for the things. So among this particular community it is commonly known. When I started on this path getting on for 7 years ago, my life was so impacted, my diet so restricted not least because I prefer a vegetarian diet so when you have 10 may be vegies you can eat because my salicylate load was too great, my liver etc could not make enough enzymes to eliminate the stuff, life is not fun. I did mention my 3rd grandson. Also if I hear one of the kids needs antibiotics I give them the product. The eldest ggs, I have 2, reacted to his first injections, I provided an infant product for him. I never want anyone to endure the difficulties and restrictions I have endured.

I've seen more than adequate scientific verification for there being validation of the microbiome having a broad sphere of application maintaining an efficient microbiome. Using pre and pro biotics designed to be taken with antibiotics, things changed with the first application but I still repeat them often. They changed my life, the more trivial things they have helped with was my chemical sensitivity. I'm no longer house bound by the smells from Lush, a mile away as the crow flies, when the wind is in the wrong direction or the neighbour has freshly washed laundry on the line, or there has been a light fall of rain on a hot day and the ground stinks, once upon a time I could not go near the laundry isle in the store for fear of throwing up or passing out. I still need to be careful near petrochemicals, car fumes, and paraben preservatives and perfumes. There were places in our conurbation I could not visit because of the breadth of my symptoms. I have not yet had the confidence to book a ticket for a BSO concert I would hate to have to leave having paid so much because I could not control a hacking cough, I did not have before I entered the concert hall. For me my issues were mostly about unhelpful microbes but I, thanks to helpful microbes more in balance I have my life back.

How the body works is complicated no two people are exactly the same, when I am expected to take the graph repeated 3 or 4 times above as fact, when it is written by some student who has no real interest in diet against the references of Chris Kresser and the many other Functional Practitioners, I am afraid I see red because if this is the best nay Sayers can find! That has no credibility. I can say the sky is black all I like. Empty vessels make most noise. BTW the medical cohort at some of our universities are taking a very strong interest in the microbiome. I think it started at Warwick.

As I have said many times, as a very much older person, my body has been through more than most of yours. I hope no one lives to regret not at least considering taking on board the science of the microbiome.

I have just seen a communication re - The Candida Diet - Lisa Richards - science backed people lead

associating poor gut health to, arthritis, asthma, autism, type 2 diabetes, heart disease metabolic syndrome, mood disorders, fatty liver disease and Parkinson's.

Ceiswyn, its day time here, should have said, green, giggle.

LukejoycePT. I see no reason here for you to be referred or censored. all the very best.

kimny72 wrote: »

@Fuzzipeg I don't think anyone is making the point that gut bacteria doesn't affect health. The point we're trying to make is that the study of the gut microbiome is too new to make specific claims about it, and what we do know suggests it's at least highly variable from person to person.

The problem with personal anecdotes is that we are all susceptible to believing an improvement was caused by the change we are excited about, while not noticing other possible causes. One of the toughest parts of scientific inquiry is separating out all the different variables to determine which one actually made the difference. Assuming one individual is capable of seeing every variable in their life, and narrowing down how that variable affected each part of their health and well-being, is a leap.

The point of this OP seems at least to me to suggest that the gut microbiome is the answer to obesity and the cause of a wide ranging litany of health problems. All the replies are saying is that there is a ton of "jumping to conclusions" in these posts and some of the links put forward as "sources".

I'm glad you're finding relief, and I have no doubt that some people will find the same by addressing their gut health. However, it is simply not true to suggest that any of this is well-understood or definitive.

As usual, @kimny72 said it far better than I ever could have.

kimny72 wrote: »

The point we're trying to make is that the study of the gut microbiome is too new to make specific claims about it, and what we do know suggests it's at least highly variable from person to person.

^^^^ This....