The Best Fiber Supplement
Fiber supplements boast health claims that range from normalizing blood sugar to improving digestion, but these promises aren't always well-researched. The best fiber supplement should be clinically proven to deliver on its claims. After speaking with dietitians and nutritional researchers and reviewing the scientific literature, one type of fiber came out on top: psyllium fiber. Our top picks — two psyllium powders and one capsule — keep additives to a minimum, were more palatable than other formulas, and have ample research to support their benefits.
Contains nothing but finely ground psyllium husk. Like all fiber powders, it must be mixed with water or another liquid before consuming, forming a gel-like texture our testers weren't wild about. But we found Yerba Prima smoother and easier to swallow than other formulas.
A flavored powder that reminded us of an orange smoothie once mixed with water. The tradeoff? It has more sugar (8 grams) than fiber (3 grams) per serving.
Yerba Prima Psyllium Husks Caps
A capsule alternative to powders. Because fiber is bulky, just know you'll have to swallow a lot of pills for an effective dose.
The Best Fiber Supplement
The average American only consumes about 15 grams of fiber per day, falling well short of the commonly recommended daily fiber intake of 25 grams for women and 38 grams for men. A serious dietary workhorse, fiber is responsible for keeping you full after eating and bringing a certain digestive regularity to your day. But if you’re planning to add a fiber supplement to your diet, it’s important to be aware that fiber can come from many sources — and some are more beneficial than others. Psyllium stood out time and again as the best fiber supplement on the market.
Yerba Prima Psyllium Husks Powder was our overall top pick. Easy to dissolve and relatively palatable, this product consists of nothing but pure psyllium husk, ground to a consistency that’s a little smoother and easier to swallow than the other powders we tried. For something a little tastier, try Metamucil MultiHealth Fiber Powder — an orange-flavored powder that we found surprisingly delicious. Unfortunately, the tastiness comes at a cost: Each serving delivers more sugar than fiber, with over 2 grams of sugar for every gram of fiber. If you can’t stomach a liquid formula at all, you can also try Yerba Prima Psyllium Husks Caps, which contain nothing but powdered psyllium fiber in a gelatin casing. To hit widely recommended fiber supplement dosages, however, you’ll need to down 18 capsules a day.
How We Found the Best Fiber Supplement
One walk down the supplements aisle at Walgreens presents a dizzying number of choices. Soluble or insoluble? Inulin, dextrin, methylcellulose, psyllium, bran, oat, or barley? In all, we considered 134 fiber supplements, each readily available from retailers like Amazon and GNC.
We focused on types of fiber first — and psyllium is best.
Here’s where it gets tricky. Our supplements fell into two broad categories: soluble and insoluble fiber.
- Insoluble fiber includes fiber from sources like wheat bran. This type doesn’t fully dissolve when you swallow it. It passes through your body intact, bulking up stool and preventing constipation.
- Soluble fiber includes fiber like inulin (from chicory root), methylcellulose (aka wood pulp), and beta-glucan (from oats and bran). This type does dissolve, and it comes with a slew of health claims that range from lowering cholesterol to increasing satiety and regulating blood sugar, although we learned the science behind these promises is often spotty.
As we dug into clinical studies, we found that if you want a source of fiber proven to deliver on all of the above promises, you have only one real option: psyllium fiber, which comes from a small plant native to Asia, whose seed and husk are ground into powder.
According to nutritional researcher Dr. John McRorie, psyllium stands out because of what happens when it’s mixed with water: It gels, and stays gel-like even as it passes through your body. A researcher for Metamucil manufacturer Procter & Gamble, McRorie explained, “Fiber must be highly viscous to get the metabolic properties and health benefits shown in research studies.”
The gel formed by psyllium allows it to do things like trap “bad” cholesterol (LDL) molecules in the bloodstream so that your body can remove them as waste, lowering your odds of cardiovascular disease.
Many fiber sources don’t gel, or else gel but lose their stickiness as they travel through the intestines. Take inulin, wheat dextrin, and a class of fiber products known as oligosaccharides (all common fiber sources in gummy formulations): These ferment in the digestive tract rather than retain their gel-like properties. This fermentation is responsible for much of the bloating and flatulence for which fiber is notorious.
In other words, psyllium is less likely to give you gas and more likely to prevent cardiovascular disease. But that’s not all. Like insoluble fiber, psyllium also promotes bowel regularity. Research has found that psyllium holds onto water in the intestines as it gels, helping to relieve constipation by bulking up the contents of the intestines. Because psyllium absorbs water, it’s also used to help relieve diarrhea. And did we mention that it reduces blood sugar levels in individuals with Type 2 diabetes and is proven to help you feel full longer?
In short, psyllium is the whole package: an all-around digestive normalizer that reduces cholesterol, increases satiety, and regulates blood sugar. Needless to say, we cut supplements sourced from other types of fiber.
Then we taste-tested 13 finalists.
This left us with 29 psyllium supplements, many of which were variants from the same brand. (Metamucil, for instance, occupied six of those slots.) So we selected one to two products from each brand, giving priority to formulas with as much fiber and as few additives as possible. We also cut a couple of brands entirely, including Hydrocil, whose Instant Dietary Fiber Supplement contained polyethylene glycol, a common laxative that seemed unnecessary — and Nature’s Way Psyllium Husk, whose capsules had such a low amount of fiber that we would’ve needed to take a whopping 30 pills a day to hit the 10-gram supplemental serving commonly recommended by fiber research.
We mixed, stirred, and gulped our way through 13 finalists: 10 powders and three capsules, looking for formulas that were easy to measure and free of off-putting odors, textures, smells, and flavors.
The powders all had to be mixed with some type of liquid (we used water), and a few were dismissed entirely by testers at this point. Simple Truth Whole Psyllium Husk and Organic India Whole Husk Psyllium were both rated poorly for the texture of the plumped psyllium husks once mixed with water, while the powdered seed-plus-husk formula of Sonne’s No. 9 Intestinal Cleanser produced floating debris that no one wanted to drink.
After testing all 13 products, we feel safe in saying fiber supplements just aren’t palatable: the same gelling capabilities that allow psyllium to do its work mean that no one’s going to drink Metamucil for fun. But our top picks stood out as being easier to swallow than average.
Our Picks for Best Fiber Supplement
This straightforward, one-ingredient supplement supports heart health, satiety, blood sugar regulation, and digestive benefits, with a texture testers preferred over the other powdered mixes we tried. Inside the plastic jar, you’ll find finely ground psyllium husk, a fluffy brown powder that testers said smelled like “oatmeal” and “hay.” There’s nothing else on the ingredient list: no fillers, no additives — just pure psyllium powder.
One heaping teaspoon delivers 4.5 grams of fiber. Just be aware that once mixed with water, the powder immediately begins to gel — and becomes more viscous the longer it sits. After three minutes, the texture reminded us of runny applesauce, and our main takeaway post-testing was that you should drink it quickly. That said, Yerba Prima gave us a wider drinkability window than some contenders. Species Fiberlyze turned into a solid mass within 30 seconds of mixing, with one tester reporting that it resembled cement — and turned the glass upside down to prove it.
Yerba Prima’s applesauce-like texture (left) was more appealing to us than the thicker, grainier texture of other contenders, like Species Fiberlyze (right).
Most of our testers also preferred the texture of Yerba Prima’s ground psyllium husks over “whole husk” products like Colon Cleanse Everyday Fiber, which had a grainy texture we found off-putting in a beverage. Yerba Prima doesn’t taste like much — it has faintly herbal undertones that none of our testers took issue with. Like most psyllium powders, you can also mix it with more than just water. The packaging suggests trying juice, milk, soy, or rice drink, and we could also see psyllium powder being an easy addition to a smoothie. A 12-ounce bottle retails for $9.
Others to Consider
If you need a spoonful (or three) of sugar to make your fiber go down, Metamucil MultiHealth Fiber received one of the highest scores on our taste-test. It’s an orange-flavored powder that looks like fruit punch mix and has a texture reminiscent of a smoothie once you add water. The end result was also surprisingly tasty, with one tester reporting, “This reminds me of Tang.”
But we were unable to give Metamucil MultiHealth our top spot due to the sheer amount of sugar it contains. Sucrose appears first on the ingredient list, meaning this supplement has more sugar than fiber. A 1-tablespoon serving gives you 3 grams of dietary fiber — and 8 grams of sugar. (An Oreo has about 4.7 grams of sugar, by comparison.)
All that being said, if the only way you’re going to keep taking a fiber supplement is if it tastes better, then Metamucil MultiHealth Fiber is our pick. A 48-ounce tub retails for about $17.
If you have strong objections to a thick, goopy texture, you can also try fiber capsules. The drawback? Fiber is bulky, and there’s only so much you can fit in a single capsule. If you’re aiming for the widely recommended 10-gram dose, be prepared to swallow a lot of pills.
Yerba Prima Psyllium Husks Caps stood out because they had a slightly higher psyllium content than the other capsules we tested, at roughly 0.55 gram per pill, versus the 0.4 gram offered by Metamucil’s MultiHealth Capsules, or Thompson Psyllium Husks’ 0.5 gram. It’s a slight increase, but if you’re aiming for 10 grams a day, it will save you from swallowing an additional three to seven pills. (Although you’ll still need to swallow eighteen to hit that recommended dosage.) You get 180 capsules per $8 bottle.
We also appreciated the transparency of Yerba Prima’s label, which spells out exactly how many grams of soluble and insoluble fiber you’re getting, in addition to calling out trace elements like calcium and potassium. Thompson Psyllium Husk’s label, by contrast, includes no information except milligrams of psyllium.
Did You Know?
Getting your fiber from food is still best.
The National Fiber Council recommends that consumers rely on food-based fiber sources whenever possible. Our experts agreed. “I recommend people get their fiber from food first because along with the fiber, they also get vitamins, minerals, powerful plant compounds, water, and electrolytes,” said registered dietitian Elaine Magee, MPH, RD, a wellness corporate dietitian for Albertsons Companies. “Sometimes with certain health conditions or living situations, people just can’t get all the fiber they need from food. This is when a fiber supplement may be helpful.”
If you want to make changes to your diet, but you’re not sure where to start, Magee offered these guidelines: “By eating about 3 cups of veggies and 2 cups of fruit a day, you’ll consume roughly 15 grams of fiber. A handful of nuts will add 3.5 grams. Three servings of whole grains a day adds approximately 9-15 grams.”
If you’re looking for specific recommendations, the Mayo Clinic suggests artichokes, green peas, and broccoli as good vegetable-based fiber sources, and raspberries, pears, and apples if you prefer fruits. Lentils and beans of all varieties are also chock-full of fiber.
Fiber in baked goods might not be as potent.
Many baked goods, like breads, snack bars, and even some fiber supplements — like Metamucil’s Multi-Grain Fiber Wafers — use beta-glucan from oats as a fiber source. Beta-glucan offers many of the same health benefits as psyllium (though clinical research suggests it lacks the ability to normalize bowel movements). But notably, research suggests beta-glucan is more fragile than psyllium: Its ability to lower cholesterol may be reduced when it’s baked or exposed to high heat and pressure. The jury is still out on exactly how much the cooking process impacts oat fiber, but it’s one more point in favor of psyllium in the meantime.
The health claims that fiber supplements are allowed to make are changing.
The Food and Drug Administration is beginning to scrutinize less-effective fiber sources. A rule change to the Nutritional Labeling and Education Act (NLEA) issued in 2016 will require fiber supplement manufacturers to prove the health benefits of their sources of fiber in order to print health claims on labels. That rule is likely to affect much of the market, including well-known brands with “fiber” in their name, such as Benefiber, that use non-psyllium formulas but still make broad claims about the efficacy of their products. “By July 2018, these fiber types have to prove their health benefits,” McRorie told us.