Submitted by hodlboo t3_110kc20 in askscience
Genetic markers, gut bacteria, inoculation level exposure, exercise, diet… What does the science say is the biggest factor that makes one person’s immune system stronger than another? Most interested to know the role of genetics and epigenetics.
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I think this is a difficult question to answer. The immune system isn't like a muscle, where it really only does one job. You've eliminated the primary defense from your question (skin, cilia, mucus), but the secondary, innate system and the tertiary, adaptive system, all have a large number of roles.
Your immune system's ability do deal with any of those things has a lot of variables (nutrition and genetics to some extent). Your innate system will use different cells for each of those pathogens. Your adaptive response will vary to a large degree as well.
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In that case I’m most interested in what determines the health / effectiveness of each of those distinct systems
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With no context, no one can really answer this question without just referring you to a textbook.
Immune systems are not "strong" in the sense of a muscle. Good immunity is a balanced response to appropriate stimulation. Any over-response typically either results in morbidity, e.g. eczema, Crohn's, or mortality, e.g. cytokine storm.
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The most outward symptoms of being sick are induced by your own immune system. Fevers, chills, congestion, body aches, etc, are triggered when your immune system reacts to an infection. People who “don’t get sick often” usually just have a weaker response to infection. People who do get sick often (myself included) have immune systems that tend to overreact. A “good”, or preferable, immune system is one that doesn’t overreact to minor illness. That is, if your body is infected with a common cold virus, a healthy immune system can eliminate the virus without causing congestion and fevers.
A good case study for this is the original H1N1 flu that killed young adults more than people who are generally more susceptible to illness. Their healthy immune systems reacted too strongly (something called a “cytokine storm”), that the response was far more lethal than the virus itself.
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Wouldn’t a strong immune system be one that responds appropriately in the 5 ways you listed?
Sure, that makes sense. That’s what I’m interested in—not outward symptoms of being sick but the immune system’s effectiveness against viruses and bacteria.
The problem is, if it's too "strong", it starts going after things that it shouldn't, which is why we have autoimmune disorders like:
Addison's disease - where your immune system attacks your adrenal glands, and ruins your cortisol production
Celiac Disease - or gluten allergies (or any allergies for that matter)
Myasthenia Gravis - Where your immune system attacks the bridge between your nerves and muscles, and gives you paralysis when trying to use your muscles repeatedly
Edit: I see that you mightve replied to the wrong reply, and I also just re-explained what PHealthy already did.
I would use the word "Effective/healthy" instead of "strong", and the main ways that people say you can support an effective and healthy immune system are essentially as follows.
Sleep / Hydration / avoiding serious diseases by things like vaccination, as your immune system cant tell the difference between the original thing we vaccinate against, and the vaccine (most of the time, usually natural infection gives a stronger CD8 T-cell response, which is what tells infected cells to lock themselves down and self-destruct without leaking anything out.)
Everyone has a unique „library“ of cells that fight viruses and bacteria. Which „books“ you have in your library is dependent on your parentage and the epidemiological history of your ancestors. A person can have a great variety of books fighting a specific disease, but only a few for another. So the effectiveness of someone’s immune system is not some absolute thing, but a mosaic of strengths and weaknesses.
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This is helpful, and makes it sound like genetics have the greatest impact on the effectiveness of an immune system in context…
That's a normal immune system. People are living to 90 with all those nasty germs out there. These are people who don't even take vitamin C, prevagen, Zinc, Boost, or have regular spinal alignments and colonic irrigations! Like Toches says, do you want to turn it immune system into a caged rabid weasel that will attack anything that moves? Actually that is what some cancer immune therapies do, but they can have unpleasant to devastating toxicity. Makes sense if you need to do it to fight a fatal cancer, but not a bad head cold.
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As a geneticist with a little (very little) background in immunology I’m going to say, idk, maybe? Maybe not. Genes always matter, so sure. But there’s a pretty big stochastic factor with the immune system, a whole lot of environmental factors, and a ton we don’t understand. Starting with the definition of “strong immune system” - and if you can’t define that you can’t answer (or meaningfully ask) the question.
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So would people who “don’t get sick” often be more likely to die from certain things where their under reactive immune systems are a problem? And if so, what kinds of things?
But not all immune systems are alike or normal, so what makes for those that are less effective, in the sense that the person gets actually sick more often? (Again, other variables like diet and exercise and sleep and age being equalized if possible - looking for info from scientific studies)
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Everything that you mentioned plays a role the immune system. Genetics is an important variable. Some people genetically have stronger immune responses that protect them from infection. Some people have genetic variations that cause them to be more prone to autoimmune diseases. There is a scientific journal titled Genes and Immunity that focuses on this topic.
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The immune system is better thought of as being good if it's balanced rather than strong.There's also still a lot we don't know about what makes the immune system stay in balance and react in the best way possible for the organism, but generally maintaning optimal health and homeostasis in the organism is probably the best answer.
So yeah, like you said we know being sedentary, being overweight, having a poor gut microbiome, poor sleep, drug/alcohol intake etc lead to poor health and also an unbalanced and poorer immune system. As most of us know now being obese was one of the most significant risk factors for Covid 19 mortality for example.
We also know that woman of fertile age have a more active immune system as they have to interact with and protect a fetus, meaning they might get sick less often but they also as a group suffer more auto-immune disease as a side effect.
TLDR: Good health and balance in the organism -> optimally balanced immune system.
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Lets simplify this greatly.
The immune system is a very complex interplay of just about everything in our lives. We have components that just are, and dynamic components which react to stimuli.
It is very unlikely for two healthy people where one gets sicker than the other to have a truly pinpointable problem, unless they have an undiagnosed biochemical/immunological problem.
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Thank you, that’s helpful. It sounds like it’s too complex and individualized for us to have answers beyond generalizations at this stage of scientific knowledge.
Jane rides the crowded train to work taking orders at subway. Bill works alone at home. Jane gets a lot of colds Bill doesn't. Does bill have a better immune system? After 30 head colds over 4 years, Jane has a variety of antibodies to rhinoviruses. She doesn't get sick as often as the new hire. Does she have have a better immune system? Or a normal immune system with more training? Asthmatic smoker Jim gets COVID and dies. Healthy Joe gets it and is under the weather for four days. Is that the immune systems fault for Jim?
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Not really - we know the immune system quite well, you just can’t point to any one problem based on the question you are asking.
Almost 60-70% of medicine comes down to the immune system in some form… either too proactive (lupus, MS, Myasthenia Gravis… etc.) or not good enough (cancer, infection… etc.)
But that’s just it, we can’t answer the question about the biggest factor that makes an immune system most effective in its specific context. For example an immune system that very effectively fights off viruses and bacteria so that the human is not often sick, but also does not overreact and create auto immune disorders.
I would love to get pointed towards scientific studies or knowledge about which factors have the largest impact, for example between two healthy people, and by healthy I mean in terms of lifestyle, can specific colonizations of good bacteria cause disparities in how their immune system fight off viruses and bacteria? Can this have an impact that is statistically notable among other variables? Or are there genetic markers that make certain immune systems more effective across the board, meaning a person doesn’t get sick often, doesn’t have auto immune diseases, and also doesn’t get cancer?
The data to answer such questions would ideally control for demographic factors like age, poverty level, etc. and self-reported behaviors related to a healthy lifestyle. I recognize this is a pipe dream in terms of scientifically validated data but I am looking for any evidence that attempts to answer this question.
Your question is too broad.
That is what I am telling you.
This can be eventually boiled down to nature vs nurture (this is the crux of your question), which is largely an unanswerable question.
We know that good genetics on its own does not stand to be a perfect scenario, we also know that perfect health doesn’t work either. What I am saying is it is both in unison to provide success, and not one or the other - hence the question of which provides the largest benefit is more or less is not a useful question.
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Your immune system is not one thing. You have your innate immune system, which includes your primary defenses to bodily insults and injury such as coagulation and inflammation. Then there is the adaptive immune system, which is a large, interwoven, almost indescribably complex framework of different cells and tissues that respond to specific threats in a myriad of ways. Many of them are dependent on each other, but some are more removed from others.
In practical terms, a strong immune system is the result of good self care, especially adequate restful sleep. Your body replenishes its stock of circulating immune cells during sleep. Sleep deprivation induces a state of temporary immunodeficiency, which is why people who don't sleep much or sleep poorly will get sick more often and stay sick longer. It does not matter how healthy you eat or how much you exercise - sleep is the foundation of good health and without enough of it your health will crumble.
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Thank you, this makes sense to me both in terms of what I understand about the body and also in terms of my own experience. I’d be curious to see data from large scale studies that link sleep to health and sickness.
What makes a person's immune system stronger than another? Many factors. Genes play a fundamental role, to an extent. The genetic makeup a person has may lead them to require certain nutrients or higher/lower levels of nutrients, both of which may be implicated in their propensity towards a disease. The rest is up to your environment, behaviour, lifestyle, etc.
If you are born with a genetic predisposition, that gene may not be expressed until it encounters an environmental factor that signals it (including social and familial influences, and lifestyle choices). So if the environment signals the gene - that is epigenetics.
However, this also includes the mental environment. Mental and emotional stress is one of the greatest taxes on the immune system. Sympathetic nervous system overdrive causes adrenal fatigue, which takes energy from other bodily functions (such as the immune system, digestive system, etc.) to produce cortisol. In this case, our constant experience becomes our habitual environment, which stimulates an emotion (anger, frustration, depression, etc.). Therefore, if the environment signals the gene, then to an extent a gene's expression can be influenced by the mind/emotions.
In conclusion, many things make up the strength of someone's innate immune system. Nutrition, activity, neurochemical balance, gut flora (which affects mental health), toxic habits, thought patterns, genetics, environment etc. all play an essential role. Generally, in most 'standard' individuals in first world countries, low immune system function is caused by poor health choices and mineral/vitamin deficiency. That in turn affects mental health, creating chemical imbalances in the brain, as the brain needs sufficient micronutrients to function optimally (therefore, for the other bodily systems to function optimally).
There's also the factor of initial viral load.
Jack gets covid, has no symptoms, and only notices because his work did a random screen.
Jane gets covid and dies from lung failure.
Maybe Jack got a single viral particle and his body had plenty of time to ramp up is response but Jane got coughed on by someone chock full o virus and by the time she started producing antibodies her lungs were already saturated.
[deleted] t1_j89xmvq wrote
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