Two prominent researchers have accused Mannatech, Inc. of making unwarranted claims for its “glyconutrient” products. For many years, the company has claimed that certain sugars may be lacking in people’s diet and that supplementation with these sugars—using its Ambrotose® products—can enhance people’s health. To support its claims, the company maintains a Web site that cites research from legitimate journals along with reports from other sources.
In August 2008, the journal Glycobiology published an analysis of these claims authored by Ronald L. Schnaar, Ph.D. (a prominent pharmacologist) and Hudson H. Freeze, Ph.D. (a prominent glycobiology researcher). Their article notes:
Mannatech describes “eight sugars” that they claim enhance health. . . .
However, except for rare patients with certain types of congenital disorders of glycosylation (CDG). . . , the inference that humans can benefit clinically from ingesting these monosaccharides is unsupported by controlled clinical trials. Furthermore, the relationship between Mannatech’s flagship product, Ambrotose Complex, and vertebrate glycans is tenuous. . . . Claims of health benefits of ingesting Ambrotose Complex, or its components, remain untested in controlled human trials, or have been disproved in such trials, depending on the indication. Despite this . . . the glyconutrient industry and its salespeople infer that ingesting their products is required for “optimal health,” or cures disease. . . .
A wealth of data connects glycans to human health and disease, and many valid publications support the conclusion that glycans are key components in human physiology. The relevant question for consideration of glyconutrients is: What is the relationship between the impressive body of biomedical glycobiology data in the peer-reviewed literature and the value to human health of ingesting glycans – particularly the plant polysaccharides larch bark arabinogalactan, aloe vera glucomannan, and plant gums? 
In their detailed analysis, Schnaar and Freeze point out:
- Some of the studies are legitimate but have no relevance to Mannatech’s health claims.
- Larch bark arabinogalactan supplements have shown no measurable health effects in the few human studies in which they have been tested.
- No credible data support claims of health or therapeutic benefits from oral administration of aloe glucomannan in humans.
- The emulsifier gums included in Ambrotose Complex have not been the subject of any PubMed-indexed human clinical trials for any indication in the past 25 years.
- Thus there is no convincing support for human therapeutic or health claims of Ambrotose Complex or its components.
In 2007, the Texas Attorney General accused Mannatech of violating the Texas Deceptive Practices Act by encouraging and allowing their distributors to make claims that mislead consumers into believing that the supplements dramatically cure or treat serious illnesses [2,3].
In 2017, Schnaar and Freeze published an update that included analyses of five studies published since their 2008 statement and concluded:
Tthere remains insufficient evidence to conclude that “glyconutrients” diagnose, treat, cure or prevent any disease. Further, we have not found convincing evidence to indicate that, except as a source of indigestible fiber, Ambrotose enhances health or quality of life..
- Schnaar RL, Freeze HH. A “glyconutrient sham.” Glycobiology 18:652-657, 2008.
- Texas Attorney General charges Mannatech with unlawful, misleading sales practices: Illegal scheme markets supplements as cure for cancer, improved health. News rrelease, July 5, 2005.
- State of Texas vs. Mannatech Incorporated, Manna Relief Industries, The Fisher Institute, Samuel L. Caster, and Reginald McDaniel. District Court of Travis County, Cause No. D-1-GV-07-001386, filed July 5, 2007.
- A “glyconutrient sham” and the Jenner Glycobiology and Medicine Symposium. Glycobiology 27:383-384, 2018.
This article was revised on November 20, 2018.