Metamucil is the most popular fiber supplement in the U.S. The brand's website claims that their products can "support your digestive health" and cause users to "feel lighter & more energetic."
But is Metamucil really the healthiest fiber option on the market? Are the ingredients which create its distinctive orange color natural or artificial? How does Metamucil compare to other popular fiber supplements like Benefiber? And does it cause side effects?
In this article we’ll answer these questions as we review the ingredients in Metamucil's most popular products: Metamucil Sugar-Free Fiber Powder, Metamucil Premium Blend Fiber Powder, Metamucil Gummies, and Metamucil Fiber Thins. We'll also highlight a report of lead contamination related to one of Metamucil's products and share a real user review of their fiber powder.
Metamucil Sugar-Free Fiber Powder Review
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 medical research shows 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.
Citric acid is a preservative and flavor enhancing compound that was shown in a 2018 medical review to cause systemic inflammation in a small percentage of patients.
Natural and artificial orange flavor is another questionable ingredient choice from a health perspective. A medical study published in the Food Technology & Biotechnology journal found synthetic orange flavoring to cause acute toxicity in animal studies.
Aspartame is an artificial sweetener. A medical review published in the Environmental Health journal found that this ingredient is carcinogenic (cancer-causing) in animal studies.
Yellow 6 is an artificial food dye which has been found in medical research to be contaminated in some cases with carcinogens (cancer-causing chemicals). We recommend avoiding all artificial food dyes.
Overall we do not recommend this product and consider it the worst formulation of any fiber product we've reviewed 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 of fiber daily would likely benefit many Americans, but we'd recommend getting the fiber without all of the questionable additive ingredients.
One of the YouTube reviews of Metamucil fiber that appears unsponsored is only 3 minutes long and includes a taste test:
Lead Contamination Issues
Metamucil 4-in-1 Fiber powder Orange flavor was found to contain relatively high levels of lead in testing conducted by an independent third-party organization called ConsumerLab.
ConsumerLab found up to 14.6 micrograms (mcg) of lead per serving of this product.
While some consumer products contain a small amount of lead due to environmental contamination according to the Centers for Disease Control (CDC), this lead level documented by ConsumerLab is concerning in our opinion. As reported above, the testing also found "12 insect fragments" per 25 g of Metamucil fiber powder.
These test results are enough for us to recommend consumers avoid Metamucil products entirely. A medical review documented that lead is a highly poisonous metal that negatively affects all organ systems, and minimizing its ingestion as much as possible is prudent.
Metamucil Side Effects
Consumers are often curious about whether Metamucil is likely to cause side effects.
Any fiber supplement (or high-fiber food) may cause digestive discomfort in patients used to a low-fiber diet, which is why it's important to gradually increase fiber intake over the course of days and weeks.
The specific type of fiber in Metamucil called psyllium husk fiber may have a greater risk of side effects than other types according to a YouTube video published by a channel called "Heme Review" that's achieved nearly 1 million views at the time of updating this article.
The creator is an adjunct professor at the University of Illinois and appears knowledgable about this topic:
Metamucil Gummies Review
Metamucil sells fiber gummies.
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 we consider to be significantly healthier than added sugar when used in small doses, and doesn’t appear to confer any of the metabolic health risks of added sugar.
A medical review of xylitol’s health benefits published in the Applied Microbiology and Biotechnology journal found that xylitol benefited blood sugar and weight, and also 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 used in the fiber powder reviewed above. 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 don't recommend Metamucil Fiber Gummies due to the additive ingredients, but we do consider this product to be healthier than Metamucil Sugar-Free Fiber Powder which we reviewed above.
Benefiber Vs. Metamucil
Consumers are often curious about whether Benefiber or Metamucil is healthier, given that these are two of the most popular fiber supplements on the market.
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.
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. There are no questionable additive ingredients like artificial dye or artificial sweeteners.
In this section we’re only referring to the formulation of original Benefiber powder and not any of their other products.
Our Fiber Supplement Recommendation
The fiber supplement we recommend is Supergut Fiber Mix. This supplement provides 8 g of fiber per serving and contains no questionable additive ingredients. The only ingredients are a blend of fiber powders including green banana powder resistant starch and resistant potato starch. There is no psyllium husk fiber in Supergut.
A medical review published in the Advances in Nutrition journal analyzed data from various clinical trials and concluded that resistant starch intake was associated with improved gut health, weight loss in overweight and obese individuals, and improved insulin resistance.
Interested consumers can check out Supergut Fiber Mix at this link.
Metamucil Premium Blend Fiber Powder Review
Metamucil sells a “Premium Blend” of fiber powder, with more natural 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" because this broad descriptor fails to detail what actual flavoring agents are used.
Metamucil Premium Blend contains stevia as a natural sweetener rather than aspartame, which we find to be a healthier option. Stevia is shown in 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.
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 one of Metamucil's fiber powders, we believe this is the best option.
Metamucil Fiber Thins Review
Metamucil sells a food product called Fiber Thins that provides 4-5 g of fiber per serving. The ingredients list above is from the "Cinnamon Spice" flavor.
This product contains 7 g of sugar, and 6 g of added sugar per serving. We recommend avoiding added sugar entirely.
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 also don't believe that functional high-fiber foods really make sense as a product category, since it's so simple and convenient to just add a fiber powder to water or any other liquid.
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, and there may be health risks associated with its long-term use.
Will Metamucil Cause Weight Loss?
Metamucil may cause weight loss in overweight and obese individuals, but that's due to the fiber content and not anything unique to Metamucil's formulations.
A meta-study found that fiber intake is associated with weight loss. The study authors found that an additional 14 g per day of fiber intake was associated with a 10% decrease in calories consumed from diet.
Fiber is zero-calorie plant material that takes up space in the stomach, so it causes individuals to feel full faster and can therefore be a natural, effective weight loss aid.
Any fiber powder can have this effect when consumed at the appropriate dose.