If there were one nutrient we could all benefit from eating more of, it’s likely fiber—there are some obvious signs when you need more of it. Still, it can be tricky to get enough from your diet, which is why many people turn to fiber supplements—especially if they are trying to improve their digestive health. But what is the best time to take fiber supplements for digestion?
“Fiber works by doing three main things, which are feeding your gut microbiome, improving stool consistency, and supporting blood sugar and appetite regulation,” says Anar Allidina, M.P.H., R.D., a registered dietitian based in Toronto. “You may want to consider a fiber supplement if you have constipation or irregular bowel movements, if you have bloating after meals, high blood sugar [or] cholesterol, or if you have a low-fiber diet.”
Meet the experts: Anar Allidina, M.P.H., R.D., a registered dietitian based in Toronto; Vicki Koenig, R.D., C.D.N., a masters-level registered dietitian based in New Paltz, NY.
If you fit into one of those categories, read on to find out the best time to take a fiber supplement, plus what you should and shouldn’t take it with and your best options to support your gut health.
When is the best time to take a fiber supplement?
“The best time to take a fiber supplement is between meals to help digestion,” says Allidina. For people who are taking a fiber supplement to ease constipation or combat irregular bowel movements, timing it between meals may help make sure things are continuously moving. “You want to take it at the same time every day since your gut loves rhythm,” Allidina adds. If your aim is blood sugar management or increasing feelings of fullness to help with weight loss, Allidina suggests taking your fiber supplement before a meal. In one study published in the journal Nutrition, people with prediabetes who took 15 grams of fiber daily before meals saw significant reductions in fasting blood sugar levels and post-meal blood sugar and insulin levels after six months.
Besides timing and verifying that the supplement you’re taking is legit, “the most important thing to remember when taking a fiber supplement is that it should be taken with plenty of water,” says Vicki Koenig, R.D., C.D.N., a masters-level registered dietitian based in New Paltz, NY. “Without enough water, it can cause a bowel or esophageal obstruction. Most labels on fiber supplements encourage at least 8 ounces of water per serving. More is always a good idea.”
Fiber supplement interactions to know
If you take any prescription medications, make sure to leave at least a two-hour window between your meds and your fiber supplement, says Koenig. “Dietary fiber can reduce or block absorption of many drugs,” she explains. “At least two hours of separation is suggested, but you should check with your pharmacist to be sure.”
You should also avoid taking a fiber supplement before bed, suggests Allidina, as it may disrupt your sleep, or during episodes of gas or bloating, as it may worsen your existing GI distress.
The best fiber supplements to support digestion
When selecting a fiber supplement to support your digestion, you’ll be met with a host of options. If you’re looking to make your bowel movements more regular or to support healthy cholesterol or blood sugar levels, both Allidina and Koenig suggest psyllium husk as a smart first option. A 2025 study published in Food Bioscience found that psyllium husk helps relieve and reduce constipation and nourish the gut microbiome. “Psyllium comes in the form of capsules or powder,” says Koenig. “Again, it’s important to take it with a lot of water.” Always consult your healthcare provider before adding a supplement to your routine.
From there, you have different ones to choose from. “Acacia fiber is very gentle and great for those with sensitive tummies,” says Allidina. “Inulin is a powerful prebiotic, but it can cause gas if introduced too quickly.” She adds that when you’re just starting a fiber supplement, begin with the recommended dose and then gradually increase over the next week and see what feels best for you. “Make sure you are well hydrated and be consistent,” Allidina stresses.
While fiber is completely natural and a necessary part of a healthy diet, getting it from sources besides whole foods does qualify as supplementation. For this reason, Koenig says it’s smart to consult with a registered dietitian or physician to determine the form and amount that is best for you and will best help you reach your goals.
Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing. Also, be careful about giving supplements to a child, unless recommended by their healthcare provider.
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