Fructooligosaccharides (FOS) are short chain prebiotic fibers taken from plants like onions, garlic, and bananas. The supplement feeds helpful bacteria in your gut. This selective feeding can encourage more regular bowel movements and firmer stool consistency.
Many people use FOS to tend their gut microbiome, particularly when whole food fiber consumption dips. Some take it to enhance the body’s uptake of calcium and magnesium, though the data backing this use is thinner.
FOS usually comes as a powder you stir into water or food once or twice a day. Start with a small amount and raise it slowly over several days to ease into things. Jumping in too fast often triggers gas and bloating.
Key cautions: Large or rapid doses can cause gas, bloating, or cramping. Anyone with irritable bowel syndrome (IBS) or trouble absorbing fructose should proceed carefully. No serious drug interactions are well documented, but like any fiber, FOS might shift the absorption timing of medications. Separate it from other drugs if that worries you.