IMO, if you have a reasonably normal diet and have no medical conditions, vitamin supplements are a waste of time and money. The one concession to that is vitamin D for over 50s that don't get a couple of hours of sunlight. (might apply to one or two keyboard warriors on here, locked in their bedrooms telling the rest how to think and behave?) Personally I take it during the Winter months - mainly because it is so cheap, so why not.
Most people would benefit from more fibre in their diets. In particular, soluble fibre is highly beneficial to general health and particularly mental health and wellbeing. (read up about microbiome and gut health - not from product suppliers, but from health advisory sources) You do get soluble fibre from food but it is very difficult to get enough, even on a very high fibre diet. Therefore I also take a fibre supplement every day.
Most dietary fibre is absorbed in the stomach and small intestine, soluble fibre is not and passes straight through to the colon where it feeds your gut microbiome. The microbiome produces numerous digestive enzymes and amino acids that attack harmful bacteria and pathogens in the gut, fights off diseases and cancers and generally strengthens the immune system. It also produces higher levels of short chain fatty acids, which is good for muscle function. If you can only take one supplement, my advice would be to take a multi fibre capsule that includes at least 30g of soluble fibre.
PS. soluble fibre is known as 'prebiotic'. This is completely different to 'probiotic' which you'll see splashed over much of the stuff on supermarket shelfs. Probiotic is 'live culture', which is supposed to build up your gut microbiome. i.e. yoghurt drinks and so on. Now, yoghurt drinks are good for you - they are nutritious etc. - but the good research says there is no evidence that they 'build' your gut microbiome, because 'live' cultures can't survive the stomach acid.
