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 for blood sugar control in diabetes, discuss this with your doctor, as good evidence is also lacking for healthy people.
No single study in the available literature has directly examined whether drinking apple cider vinegar improves digestion. The widespread feeling among so many people that it helps has therefore not been scientifically confirmed. There is simply no evidence that apple cider vinegar makes your gut work better, settles your stomach, or improves the digestion of food.
What has been studied are the effects on blood sugar. An analysis of nine randomised studies shows that apple cider vinegar lowers fasting blood sugar by an average of nearly 8 mg/dL, and a measure of long-term blood sugar control (HbA1c) by 0.5 units. That effect was most pronounced in people with type 2 diabetes and with use of more than eight weeks. In healthy people, blood sugar appeared to rise slightly instead. Total cholesterol fell modestly, but there was no effect on 'bad' LDL cholesterol or insulin.
Fermentation of apples can improve the absorption of certain plant compounds in the laboratory, but this has not yet been demonstrated in humans and says nothing about a concrete digestive benefit.
One safety point deserves attention. Apple cider vinegar tablets are not reliable: research into eight brands found large differences in acidity and labelling, and it was sometimes even unclear whether the tablets actually contained apple cider vinegar. There is also a report of oesophageal damage following use of such tablets. The health claims on packaging were unsubstantiated. Liquid apple cider vinegar is highly acidic and can erode tooth enamel with regular use; diluting it in water is therefore advisable.
Based on two primary sources (PMID 15983536, 38251987, 34187442). The question about digestion is explicitly unanswered in the literature. The blood sugar findings come from a meta-analysis with high heterogeneity (I2 high), which limits their reliability.
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 digestion in healthy people has not been demonstrated. Take your time with it, but do not expect a major health benefit if you already eat normally.
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 evidence in humans is still limited. If you want to take concrete action, opt for at least 30 grams of ground flaxseed per day.
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 beneficial effect on gut bacteria and inflammation markers. If you have a chronic bowel disease, discuss fasting with your doctor first, as evidence in that group is still lacking.
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 stools or have had a liver disease or intestinal surgery, discuss this with your doctor, as a bile acid deficiency may be the underlying cause.
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 antibiotic-associated diarrhoea and irritable bowel syndrome; for Crohn's disease, they demonstrably do not work.
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 was not examined in these studies, but the mechanisms identified provide a clear picture of how harm arises.