Answered questions
Gut & microbiome
72 answered questions · 492 studies
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Which fermented products have the greatest effect on gut health?
Yoghurt and kefir have the most human evidence supporting a beneficial effect on gut health; for kimchi, kombucha and tempeh,…
Yes · Moderate evidence
Is fermented food good for your health and your microbiome?
Fermented food, and kefir and yoghurt in particular, likely has beneficial effects on gut flora and several health markers,…
Yes · Moderate evidence
Does long-term antibiotic use weaken your immune system?
Antibiotics disrupt the gut microbiota in ways that indirectly weaken your immune system; use them only when truly necessary…
Yes · Moderate evidence
Is there a link between oral bacteria and the development of Alzheimer's disease?
There is a consistent association between oral bacteria and Alzheimer's disease, but a proven cause-and-effect relationship in…
Moderate evidence
How does your microbiome affect your health and longevity?
Your microbiome is associated with how healthily you age, but whether you can deliberately steer it to live longer has not yet…
Preliminary evidence
What does a disrupted gut barrier do to the rest of your body?
A leaky gut barrier is associated with chronic inflammation and a range of diseases, from diabetes and joint complaints to…
Yes · Moderate evidence
Do probiotics help with irritable bowel syndrome itself, or only when taken alongside antibiotics?
Probiotics reduce irritable bowel symptoms without antibiotics, with Bacillus coagulans and Bifidobacterium strains having the…
Yes · Moderate evidence
Can you permanently change your gut microbiome through diet?
Diet does indeed change your gut microbiome, but lasting change requires lasting adjustment of your dietary pattern; a…
Moderate evidence
How much probiotic do you need per day?
There is no universal daily dose for probiotics: how much you need depends strongly on the bacterial strain, the application,…
Moderate evidence
Can probiotics improve your health in later life?
Probiotics may offer specific benefits for older adults, such as a better immune response and less constipation, but which…
Moderate evidence
Does eating a varied diet help your gut bacteria?
Fermented products have the strongest evidence base for increasing gut bacterial diversity. Eating broadly varied meals also…
Yes · Moderate evidence
Is fibre-maxxing (eating as much fibre as possible) healthy?
Eating more fibre is a good idea for most people in the West, but fibre-maxxing as an extreme principle offers no additional…
Yes · Moderate evidence
Can you strengthen your immune system by eating more fibre?
Eating more fibre has a clear biological mechanism, but in healthy people it does not automatically lead to a measurably…
Moderate evidence
What does the transition or menopause do to your gut microbiome?
Menopause is accompanied by measurable shifts in the gut microbiome, but how large these are and what they mean in practice…
Can you improve your gut microbiome by picking up bacteria while playing outside?
Playing outside exposes your child to more bacteria, and one small study observed a change in gut microbiome, but whether that…
Preliminary evidence
Can you see how fast you are ageing from your stool?
Your microbiome does change with age and is associated with health risks, but a reliable ageing test based on stool does not…
Moderate evidence
Are the gut bacteria of children different from those of adults?
Yes, the gut bacteria of children differ fundamentally from those of adults, with consequences for allergy and asthma risk. If…
Can an unhealthy gut contribute to skin problems such as acne or eczema?
A disrupted gut microbiome is associated with acne and eczema, although that association has not yet been proven to be cause…
Does chewing slowly really help with better digestion?
Chewing well certainly helps form a smooth food bolus and increases saliva production, but whether it actually leads to better…
Preliminary evidence
What does drinking coffee every day do to your gut bacteria?
Drinking coffee in moderation every day (up to 4 cups) is associated with a more favourable composition and greater diversity…
Can your gut microbiome affect your memory and concentration?
Your gut microbiome can influence your memory and concentration through several routes, but most of the evidence still comes…
What is the role of bile acids in healthy digestion?
Bile acids are indispensable for proper fat digestion and the absorption of fat-soluble vitamins. If you suffer from greasy…
What does smoking do to your gut and gut microbiome?
Smoking disrupts your gut microbiome and increases the risk of intestinal inflammation, gastrointestinal complaints and…
Does bone broth help your gut health?
The individual components of bone broth, such as certain amino acids, show favourable effects on the intestinal wall in…
Preliminary evidence
Can your gut microbiome influence inflammation in your body?
Your gut microbiome can influence inflammatory processes throughout your body via the gut wall. Eating more fibre and…
Does your gut microbiome affect how well you sleep?
Your gut microbiome and your sleep mutually influence each other, but how to practically steer that through probiotics or…
Are the gut bacteria of lean people different from those of heavier people?
The gut bacteria of people with excess weight differ measurably from those of lean people, but whether those bacteria are the…
What does a high-fat diet do to your gut microbiome?
A high-fat diet noticeably disrupts the gut microbiome: less bacterial diversity, more harmful species and a leaky gut wall…
Can you improve your gut bacteria by spending more time in nature?
Whether spending more time in nature improves your gut bacteria is a question the available studies cannot answer; if you want…
Preliminary evidence
Can certain fungi or bacteria in your gut influence your cellular ageing?
Certain gut bacteria produce substances that accelerate cellular ageing, while a diverse microbiome rich in fibre-fermenting…
Does drinking apple cider vinegar help your digestion?
There is no research whatsoever showing that apple cider vinegar improves digestion. If you want to use apple cider vinegar…
No · Preliminary evidence
Can your gut microbiome control your appetite and hunger?
Yes, your gut microbiome can influence your hunger and eating behaviour via a direct connection to your brain. Eating more…
What does eating too much sugar do to your gut health?
Eating a lot of sugar probably disrupts your gut microbiome and makes the gut wall more permeable, but it is the combination…
Does a healthy gut microbiome lead to better skin?
There are several indications that a healthy gut microbiome is beneficial for your skin, but how best to achieve that and…
Yes · Moderate evidence
Does eating flaxseed help your gut?
Through its fibre and lignans, flaxseed has a plausible positive effect on the gut, but for the gut as a specific target the…
Yes · Moderate evidence
Can your gut microbiome influence your risk of heart disease?
Your gut microbiome influences your heart health through metabolic by-products that can promote arterial hardening, high blood…
Yes · Moderate evidence
Can your microbiome reveal how old you are biologically?
Your microbiome does send signals about how you are ageing, but a reliable clinical test to measure your biological age with…
Is the appendix actually useful for your gut microbiome?
The appendix most likely does have a function: as a reservoir for healthy gut bacteria and as an immune organ. If you have…
What does fasting one day a week do to your gut microbiome?
Intermittent fasting demonstrably changes your gut microbiome, but the effects are likely temporary if you stop; for healthy…
Can your gut microbiome affect your cholesterol?
Your gut microbiome influences your cholesterol through bile acid conversion and the fermentation of fibres. Eating more fibre…
Does eating gluten-free help if you don't have coeliac disease?
For healthy people without coeliac disease or gluten sensitivity, eating gluten-free offers nothing and even carries a risk of…
No · Preliminary evidence
What do polyphenols, such as those found in berries and red wine, do to your gut bacteria?
Polyphenols from berries and red wine have a positive influence on your gut bacteria, but the human studies are still small;…
Are plant-based diets better for your gut than mixed diets?
A plant-based diet appears to be beneficial for your gut bacteria, but fermented foods perform at least as well in a direct…
Moderate evidence
Does fermented food like kimchi boost your immune system?
Kimchi and other fermented products can improve your gut microbiome and lower inflammatory markers, but whether that actually…
Preliminary evidence
Can exercise improve your gut microbiome?
Moderate regular exercise demonstrably improves your gut microbiome, but you need to keep exercising because the effect…
Yes · Moderate evidence
What are the signs that your gut flora is out of balance?
There are several recognisable signals, of which abdominal complaints such as persistent pain, diarrhoea, or constipation are…
Does green tea help your gut health?
Green tea extract showed measurable improvements in gut wall integrity and gut inflammation in a randomised trial; the signals…
Yes · Moderate evidence
How does your gut microbiome influence your hormone balance?
Your gut microbiome drives multiple hormones through enzymes, fermentation products and bile acids, ranging from oestrogen to…
What does too little sleep do to your gut?
Sleep deprivation may disrupt your gut microbiome, but we do not yet know with certainty how large that effect is in humans.…
Are abdominal pain and bloating signs of an unhealthy gut?
Abdominal pain and bloating usually do not indicate a damaged gut, but rather a functional condition such as IBS. If warning…
What does alcohol do to your gut microbiome?
Chronic heavy drinking demonstrably disrupts the gut microbiome, with consequences for the heart and liver. Moderate drinking…
Does intermittent fasting help your gut health?
For healthy people and people with metabolic syndrome there is reasonably consistent evidence that intermittent fasting has a…
Yes · Moderate evidence
Can stress really make your gut sick?
Stress really can make your gut sick: from abdominal pain and altered bowel habits to an increased risk of IBS and stomach…
What is the difference between probiotics and postbiotics?
Probiotics contain living bacteria; postbiotics contain inactivated variants or their building blocks. Postbiotics are safer…
Does eating garlic help your gut health?
There are preliminary indications that garlic is beneficial for gut health, with the strongest evidence being a randomised…
Yes · Moderate evidence
What does eating red meat do to your gut in the long term?
Eating a lot of red and processed meat measurably increases your risk of colorectal cancer, although for most people the…
What does alcohol do to your immune system?
Heavy or prolonged alcohol use clearly weakens your immune system and increases the risk of serious infections and liver…
Can your gut microbiome influence how long you live?
There are clear associations between a healthy, diverse gut microbiome and older age, but whether that microbiome promotes…
Preliminary evidence
Is my gut flora linked to being overweight?
Your gut microbiome is probably linked to excess weight through multiple mechanisms, but a proven causal relationship in…
Does eating a high-fibre diet help against constipation as you get older?
Eating more fibre helps against constipation in older adults, but the overall dietary pattern counts at least as much as fibre…
Yes · Moderate evidence
Does my gut microbiome change as I get older, and does it matter?
Yes, your gut microbiome changes measurably with age, but whether that matters depends strongly on your diet and lifestyle. A…
Yes · Strong evidence
Does leaky gut actually exist?
Leaky gut is a recognised biological phenomenon that is associated with various diseases, but whether it also causes those…
Do prebiotics, the fibres that feed your good bacteria, work just as well as probiotics?
Prebiotics alone are less effective than probiotics in the best-studied situations. For diarrhoea or immune support,…
No · Moderate evidence
What do artificial sweeteners do to your gut microbiome?
Whether artificial sweeteners truly disrupt your gut microbiome is not yet clear: studies contradict one another. Until there…
Can you restore your gut microbiome after a course of antibiotics?
Your gut microbiome partially recovers after a course of antibiotics, but a full return to its original state is rarely…
Moderate evidence
Can a disrupted gut microbiome weaken your immune system?
A disrupted gut microbiome demonstrably dysregulates your immune system and increases the risk of chronic inflammation. Eating…
Yes · Moderate evidence
Is there a real connection between your gut microbiome and your mood or brain?
There is a biologically plausible and, in animal research, robustly supported connection between your gut microbiome and your…
Does fermented food such as yoghurt, kefir and sauerkraut help your gut microbiome?
Fermented foods, and kefir and yoghurt in particular, have the strongest clinical support for a positive effect on the gut…
Yes · Moderate evidence
What does eating fibre do to your gut microbiome and your long-term health?
Fibre demonstrably feeds your gut bacteria, improves stool consistency and protects the gut wall. But how your microbiome and…
Do probiotic pills really help your gut?
Probiotics demonstrably work for acute diarrhoea, but for most other gut complaints it depends on which strain you take and…
Moderate evidence
Are fermented foods and probiotics good for your gut?
Fermented foods, particularly yoghurt and kefir, show positive indications for gut health; for most other products such as…
Yes · Moderate evidence
Are at-home microbiome tests worthwhile?
Commercial at-home microbiome tests are not clinically useful at this time: the advice is premature, the methods are not…
No · Moderate evidence