Metamucil’s active ingredient is psyllium husk, a plant-based soluble fiber derived from the seeds of the Plantago ovata plant. That single ingredient does the heavy lifting, but the full ingredient list varies quite a bit depending on which version you buy. Powders, capsules, and gummies each contain different inactive ingredients, sweeteners, and additives worth knowing about.
Psyllium Husk: The Active Ingredient
Every serving of Metamucil powder contains about 3.4 grams of psyllium husk fiber. Psyllium is a natural soluble fiber that absorbs water and forms a thick gel in your digestive tract. Unlike many other fibers, it isn’t broken down or fermented by gut bacteria. It stays intact as it moves through you.
That gel does a few things. In the small intestine, it thickens the contents of your gut, which slows down how quickly your body absorbs sugars and fats. This is why psyllium can help with cholesterol levels and blood sugar management, not just regularity. In the large intestine, the gel adds bulk and moisture to stool, making it easier to pass. It’s the same active ingredient whether you buy the orange powder, the capsules, or the unflavored version.
What’s in the Powder Besides Fiber
The powdered versions of Metamucil come in several formulations, and the inactive ingredients differ significantly between them. The biggest distinction is between the “Real Sugar” and “Sugar-Free” products.
The Real Sugar version uses sucrose (table sugar) as its sweetener, which adds calories and carbohydrates per serving. The Sugar-Free Orange Smooth version replaces sugar with aspartame, an artificial sweetener. This is why the label carries a warning for people with phenylketonuria (PKU), a genetic condition that makes it dangerous to consume phenylalanine, a component of aspartame. Each teaspoon contains about 25 mg of phenylalanine.
If you want to avoid both real sugar and aspartame, the Premium Blend Sugar-Free line uses stevia as its sweetener and is made with natural flavors. Beyond sweeteners, the flavored powders typically contain citric acid for tartness, natural and artificial flavoring, and coloring agents like Yellow 6 (in the orange varieties). The unflavored version strips all of this away and contains only psyllium husk.
What’s in the Capsules
Metamucil capsules contain psyllium husk fiber packed inside a gelatin shell. According to the product’s DailyMed listing, the inactive ingredients are caramel color, gelatin, polysorbate 80 (an emulsifier), shellac (used as a coating), and brown iron oxide (a coloring agent). There are no sweeteners, flavors, or sugars.
Because the capsule shells are made from gelatin, they aren’t suitable for vegetarians or vegans. The capsules also deliver less fiber per serving than the powder. You typically need to take five capsules to get roughly 2.6 grams of fiber, compared to about 3.4 grams from a single scoop of powder. This makes the powder more efficient if your goal is maximizing fiber intake.
What’s in the Gummies
Metamucil’s gummy products are a notable exception to the rest of the lineup because they don’t actually contain psyllium husk. Instead, the gummies use a plant-based fiber blend that includes Fibersol, a soluble corn fiber. This is a completely different type of fiber from psyllium. It still counts toward your daily fiber intake, but it won’t form the same thick gel in your gut, which means the digestive effects can feel different. If you specifically want psyllium’s gel-forming properties for cholesterol or blood sugar benefits, the gummies aren’t a direct substitute for the powder or capsules.
Lead and Heavy Metals in Psyllium
One ingredient concern that doesn’t appear on any label is lead. Psyllium husk, regardless of brand, contains trace amounts of heavy metals because the plant absorbs them from the soil where it grows (primarily in India). Independent testing by ConsumerLab.com has found that lead levels in psyllium products vary widely. Some products contained as much as 8.5 micrograms of lead per 4 grams of fiber, which would exceed California’s warning threshold many times over at a full daily dose. Other brands tested much lower. The amounts are small enough that most regulatory bodies don’t flag them, but people who take psyllium daily for years may want to be aware that not all products are equal in this regard.
Choosing the Right Version
Your choice comes down to what you want to avoid. Here’s a quick comparison:
- Unflavored powder: Psyllium husk only. No sweeteners, colors, or flavors.
- Real Sugar powder: Psyllium plus sucrose, flavoring, and coloring. Higher in calories.
- Sugar-Free powder: Psyllium plus aspartame. Very low calorie but contains phenylalanine.
- Premium Blend Sugar-Free: Psyllium plus stevia and natural flavors. No artificial sweeteners.
- Capsules: Psyllium in a gelatin shell. No sweeteners, but lower fiber per serving and not vegetarian.
- Gummies: Soluble corn fiber, not psyllium. Different mechanism of action.
If your only goal is getting more fiber with the fewest additives, the unflavored powder is the simplest option. If taste matters and you want to avoid artificial sweeteners, the stevia-sweetened Premium Blend is the cleanest flavored version. And if you’re specifically looking for the cholesterol and blood sugar benefits studied in clinical research, stick with a psyllium-based product rather than the gummies.