Answered questions
Gut & microbiome
77 answered questions · 558 studies
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Are emulsifiers and sweeteners harmful?
There are serious indications that widely used emulsifiers and artificial sweeteners can disrupt the gut microbiome and may be…
Preliminary evidence
Can intermittent fasting cause constipation?
Intermittent fasting can temporarily cause constipation, but in people who already suffer from constipation as a bowel…
Preliminary evidence
Can magnesium glycinate cause diarrhoea or gastrointestinal complaints?
At normal doses (around 5 mg per kilogram of body weight per day) gastrointestinal complaints are not to be expected, but at…
Preliminary evidence
Does eating an avocado every day improve the diversity of your gut microbiome?
Eating an avocado every day likely increases the diversity of your gut bacteria, although the evidence comes primarily from…
Yes · Moderate evidence
Which fermented foods are the healthiest?
Yoghurt has the strongest support: regular consumption is linked to a lower risk of diabetes and heart and vascular disease.…
Moderate evidence
Which fermented products help most for your gut health?
Yoghurt and kefir have the most human evidence supporting a beneficial effect on gut health; for kimchi, kombucha and tempeh,…
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?
Prolonged antibiotic use disrupts gut bacteria, and that disruption can influence your immune system, but how strongly this is…
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…
How does your microbiome influence your health and longevity?
Your gut flora changes over the years and is associated with inflammatory processes, immune function and possibly how long you…
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…
Do probiotics help with irritable bowel syndrome itself, or only when taken alongside antibiotics?
Probiotics reduce IBS symptoms even without antibiotics, with Bacillus coagulans and Bifidobacterium strains having the…
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 many probiotics do you need per day?
For irritable bowel syndrome, 1 to 4 billion live bacteria per day, maintained for at least four to eight weeks, has been…
Preliminary evidence
Can probiotics improve your health in later life?
Probiotics can make a modest contribution in later life, but which product works best depends on what you want to improve. For…
Yes · 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 fibermaxxing (eating as much fibre as possible) healthy?
Eating more fibre is well supported as healthy for most people, but overdoing it causes gastrointestinal complaints and no…
Yes · Strong 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 menopause do to your gut bacteria?
During the menopause, specific bacterial species in your gut shift and your gut bacteria process oestrogen less actively.…
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 flora of children differs markedly from that of adults, both in composition and in maturity. These differences…
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 daily is associated with higher levels of beneficial gut bacteria such as Bifidobacterium and Bacteroides, but…
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 influences your sleep through substances it sends to your brain, and poor sleep in turn disrupts your gut…
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
Do your gut bacteria influence how fast your cells age?
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?
The bacteria in your gut change in recognisable ways with age and are linked to how healthily you grow old. The early evidence…
Is the appendix actually useful for your gut microbiome?
The appendix appears to play a real but modest role as a reservoir organ for gut bacteria, particularly in recovery after…
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 an established condition, there is no evidence that eating gluten-free provides any benefit, and it…
No · Moderate 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 has shown measurable positive effects on gut bacteria and the gut wall in small studies, but the studies are too…
Preliminary 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?
Research shows that too little sleep harms the diversity and composition of your gut bacteria. The trends in people are…
Are abdominal pain and bloating signs of an unhealthy gut?
Abdominal pain and bloating are a sign that your gut needs attention, but on their own they say little about how "unhealthy"…
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 can really make your gut sick, from abdominal pain and unpredictable bowel movements to stomach complaints. If you have…
What is the difference between probiotics and postbiotics?
Probiotics contain live bacteria; postbiotics work with inactivated micro-organisms or their building blocks. Postbiotics are…
Does eating garlic help your gut health?
Garlic shows some signs of improving gut function in people, although the evidence is limited. The best-supported finding is…
Preliminary 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?
Chronic excessive alcohol use weakens your immune system on multiple fronts simultaneously and increases the risk of serious…
Can your gut microbiome influence how long you live?
There are clear indications that the composition of your gut microbiome is associated with how long and how healthily you age,…
Moderate 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 with constipation in older adults, but the overall dietary pattern matters at least as much as fibre…
Yes · Moderate evidence
Does my gut microbiome change as I get older, and does it matter?
Your gut microbiome certainly changes as you get older, but whether that is harmful depends strongly on which direction that…
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 work just as well as probiotics?
Prebiotics and probiotics are comparably effective for constipation; for depression and blood sugar, probiotics have a slight…
Preliminary 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 throws your immune system off balance and increases the risk of chronic inflammation.…
Yes · Moderate evidence
Is there a link between your gut microbiome and your mood?
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 do fibres do to your gut microbiome?
Fibre demonstrably feeds your gut bacteria, improves stool consistency and protects the gut wall. But how your microbiome and…
Do probiotic pills actually help your gut?
Probiotics genuinely help, but not for everything and not equally with every pill. The evidence is strongest for…
Yes · 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