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Metamucil Review: Is It The Healthiest Fiber Brand?

Metamucil Review: Is It The Healthiest Fiber Brand?

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Read our Editorial Guidelines to learn more about what makes our site the premier resource for online health information.

Read our Editorial Guidelines to learn more about what makes our site the premier resource for online health information.

Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s). We recommend that patients follow their doctor’s guidance in regard to dietary fiber intake.

Metamucil is the most popular fiber supplement in the U.S. It’s so popular that many consumers use the brand as a generic term for fiber. But is Metamucil really the healthiest fiber option on the market? Are the ingredients which create its distinctive orange color natural or artificial?

In this article we’ll review the ingredients in some of Metamucil’s most popular formulations like their 4-in-1 fiber powder and their fiber gummies based on published medical research to give our determination on whether they’re healthy or whether there are better options.

Metamucil Sugar-Free Fiber Powder Review

Metamucil Sugar-Free Orange Powder ingredients

Metamucil’s most popular products are their fiber powders, which can be added to water or drinks to increase dietary fiber intake throughout the day. The ingredients list above is from Metamucil’s Sugar-Free Orange Smooth Powder.

While it’s proven in medical research that increasing fiber intake can have a range of health benefits such as decreased blood pressure, improved gut function and even weight loss, this product contains several ingredients we’d recommend avoiding.

The first is aspartame which is an artificial sweetener that has been shown in an in vitro (test tube) study to disrupt gut barrier function. This type of research is less conclusive than research with human participants, but we still find these results concerning.

A meta-review published in the Nature journal analyzed the results of both human and animal studies on artificial sweeteners, and concluded that they may cause impaired blood sugar function. We recommend avoiding artificial sweeteners entirely.

We find the inclusion of aspartame especially strange in the context of a fiber product, considering many consumers of this product may be using it mainly to improve gut function.

The Orange Smooth Powder also contains artificial food colorant Yellow 6 which has been found in medical research in some cases to be contaminated with carcinogens (cancer-causing chemicals). We always recommend avoiding all artificial food dyes out of an abundance of caution.

Another ingredient in this fiber powder we find questionable is Natural and Artificial Orange Flavor. A medical study published in the Food Technology & Biotechnology journal found synthetic orange flavoring to cause acute toxicity in animal studies. The artificial flavoring agents used to create Metamucil’s flavor may be different than those used in the study, and the dosage is probably lower, but we recommend avoiding artificial flavor altogether.

Metamucil also contains citric acid, which is a multi-purpose additive originally derived from citrus fruits, however the vast majority of the world’s production of this ingredient comes from a fungus called Aspergillus niger, as documented by this medical review of citric acid.

The above-linked study details how manufactured citric acid may cause systemic inflammation in a small proportion of patients, which is why we recommend avoiding it considering it has no nutritive value.

Overall this is the worst fiber product we’ve reviewed to date on Illuminate Health, which is unfortunate because of how popular it is.

We have no issue with the actual fiber source psyllium husk or its dosage of 6 grams (g) per serving. An additional 6 g fiber daily would likely benefit many Americans. 

However we do not recommend this product due to all of the additive ingredients we consider questionable.

Metamucil Premium Blend Fiber Powder Review

Metamucil Premium ingredients

Metamucil sells a “Premium Blend” of fiber powder, with different additive ingredients. This product contains paprika extract and turmeric as natural colorants, which we believe to be much healthier choices than Yellow 6.

The Premium product only contains natural orange flavor and not the synthetic orange flavor which we strongly recommended avoiding in the previous section. We still recommend avoiding health products containing "natural flavor" as this term fails to describe the specific chemical compounds used. 

As we discussed in our BodyArmor reviews article, it seems illogical to consume a health supplement with an essentially undefined ingredient. We urge manufacturers to publish the specific flavoring agents used because that information would be valuable to consumers.

Metamucil Premium Blend contains stevia as a natural sweetener rather than aspartame, which we find to be a healthier option. Stevia actually appears based on medical studies to have a hypoglycemic (blood sugar lowering) and anti-inflammatory effect, and a much better safety profile in our opinion than aspartame.

Metamucil Premium does contain citric acid.

The fiber dosage of this product is 5 g.

Overall this is a much healthier formulation than Metamucil Sugar-Free. We wouldn’t recommend it due to the natural flavor and citric acid combination, but for consumers set on purchasing Metamucil products we’d definitely recommend the Premium Blend over the Sugar-Free Powder.

Metamucil Gummies Review

Metamucil Gummies ingredients

Metamucil sells a fiber gummy product in addition to their fiber powders. This is a somewhat novel product category as all of the fiber products we’ve previously reviewed have been powder blends.

As we detailed in our review of Goli Ashwagandha Gummies, we typically don’t recommend gummy “health” products because they almost always contain added sugar which can negate potential health benefits from other ingredients.

In Metamucil’s case though, the gummies contain xylitol as a natural alternative sweetener. Xylitol is a sugar alcohol that appears based on medical research to be significantly healthier than processed sugar when used in small doses, and doesn’t appear to confer any of the metabolic health risks of sugar.

A medical review of xylitol’s health benefits published in the Applied Microbiology and Biotechnology journal found that xylitol benefited blood sugar and obesity control, and had a significant benefit to the teeth and gums: it reduced plaque and gingival inflammation.

Metamucil gummies contain 5 g of fiber per serving which is an impressive amount for a gummy product. They contain the ingredient annatto as a natural coloring agent, and this is a much better choice than the Yellow 6 in their sugar-free powder. Annatto is derived from a plant called Bixa orellana and has been found in medical studies to be non-toxic.

Like their other products, Metamucil’s gummies contain natural orange flavor and citric acid.

We wouldn’t recommend this product due to these additive ingredients, but we do believe this is a pretty decent formulation for a gummy product. It’s one of the healthiest gummy formulations we’ve reviewed to date.

Metamucil Fiber Thins Review

Metamucil Fiber Thins ingredients

Metamucil sells a food product called Fiber Thins that contain 4-5 g fiber per serving. The ingredients list above is from the "Cinnamon Spice" flavor.

This product contains 7 g sugar, and 6 g added sugar per serving, which is only 100 calories. We consider it to be unhealthy for this reason alone.

The only questionable additive of note in this formulation is natural and artificial flavors. The remaining ingredients are mostly whole foods ingredients or spices such as oat hull fiber, nutmeg and wheat flour, all of which we would consider nutritious.

We cannot recommend this product due to the artificial flavors and added sugar. We believe that unsweetened fiber powder is the healthiest option for consumers seeking supplemental fiber.

Lead Contamination in Third-Party Testing

Metamucil failed third-party testing

ConsumerLab is an independent research firm that performs laboratory tests on popular consumer products. Their findings on Metamucil 4-in-1 fiber are seen above.

They gave Metamucil’s 4-in-1 Sugar-Free Fiber Powder a failing grade due to relatively high levels of lead, finding up to 14.6 micrograms (mcg) per serving.

While some consumer products contain a small amount of lead due to environmental contamination according to the Centers for Disease Control (CDC), this level documented by ConsumerLab is concerning in our opinion.

This test result is enough of a sign for us to recommend avoiding Metamucil entirely, and we hope that Metamucil puts in place whatever quality controls may be necessary to improve their test results in the next round of independent testing.

Benefiber Vs. Metamucil

We receive a lot of questions from consumers about whether Benefiber or Metamucil is healthier. Benefiber is another popular fiber supplement available at many retailers like CVS and Target.

We believe that Benefiber is the clearly superior option from a nutritional perspective, because it only contains one ingredient: wheat dextrin. This is a soluble fiber processed from wheat grain. Based on this formulation we would generally recommend Benefiber to people seeking fiber powder.

The lack of questionable filler ingredients makes Benefiber the better option, and for patients with no gluten sensitivity, Benefiber may be one of the best fiber formulations on the market due to its clean, simple and non-toxic formulation.

In this section we’re only referring to the formulation of original Benefiber powder and not any of their other products.

Metamucil Vs. Miralax

Miralax is an over-the-counter (OTC) product used to treat constipation. Because fiber can also cause a bowel movement, consumers are often curious which product is more effective for treating constipation.

We believe that Miralax is more likely to be effective for treating constipation than Metamucil because it's formulated for that outcome. The active ingredient in Miralax is polyethylene glycol which is proven in a medical review to be effective for the treatment and management of constipation.

While we consider Miralax the better option for treating acute constipation, we would not recommend it overall as an alternative to Metamucil. It's used for a specific medical circumstance; not as a fiber replacement.

Metamucil Side Effects

Consumers are often curious about whether Metamucil is likely to cause side effects. Our take is that their products may cause digestive discomfort in some patients, but that's because of the fiber content and is not unique to Metamucil's formulation or due to any of their additive ingredients.

Many Americans consume a diet high in processed foods and low in fiber. People who are not used to consuming fiber can experience digestive symptoms like gas, bloating and pain when significantly increasing fiber intake.

For this reason, it's a good idea for patients to speak with their doctor or nutritionist prior to using a fiber supplement. There are no health risks to fiber supplementation but a medical expert can help schedule a plan for slowly increasing dosage to minimize any digestive discomfort.

Better Fiber Alternative

We generally recommend psyllium husk fiber supplements because of their demonstrated superiority over other types of fiber supplements in medical research.

An extensive medical review of fiber supplements published in the Nutrition Today journal compared the clinically-proven benefits of different types of fiber.

Only psyllium had demonstrated benefits for cholesterol, blood sugar control, sense of fullness, weight loss, constipation, diarrhea and Irritable Bowel Syndrome (IBS).

We recommend Yerba Prima fiber powder for two reasons: first, it only contains psyllium husk powder and no additive ingredients.

Second, the brand had the lowest lead levels in the ConsumerLab testing referenced earlier that failed Metamucil.

We have no commercial partnership with Yerba Prima and receive no compensation for recommending this product.

Stay up-to-date on our research reviews


We don’t recommend any Metamucil fiber products and we hope that in the near future, brands with superior formulations overtake them as the leading fiber supplement in the U.S. 

Not only did one of Metamucil’s products fail independent testing for lead, but all of their products contain filler ingredients that we recommend avoiding.

Metamucil’s gummies have a decent formulation relative to other gummy brands, but we can’t recommend any products from a brand with a failed heavy metals test by ConsumerLab.

We recommend Yerba Prima as a fiber powder supplement, and find that Benefiber is also a decent option for consumers who are non-celiac.

Getting adequate fiber from healthy whole foods like fresh fruits and vegetables should always be the first option, but Yerba Prima is a good backup option for consumers who want the convenience of mixing a powder into water to increase their fiber intake, given that it has a clean formulation and the lowest toxin levels of any brand tested by ConsumerLab.

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