PGX Investigation

Shopping for health or diet supplements is often an uphill task for consumers. The market is flooded with dangerous or ineffective products, sold by disreputable or dishonest companies that tend to look legitimate at first glance. Visitors to will face one of the most interesting and convincing pitches for a diet supplement out there; a product that seemingly has wide support in the scientific community, with numerous studies providing evidence that it really works.

A closer examination once again reveals the less-encouraging truth, giving us as consumers another reason to be cynical when shopping for diet and health supplements.

What is PGX? is the outlet that sells the PGX super fibre supplement and its associated range of products. The domain and product are owned by a Canadian company called Inovo Biologic, which has sold a range of supplement ingredients and softgels to trade since 2002. Inovo Biologic have also registered PGX as a registered trademark and have put forward numerous patents to protect the formula. The same PGX products are also available through Natural Factors, which seems to be the primary distributing company.


PGX works in the same way as Glucomannan and other fibre-heavy diet supplements. When eaten with a meal, PGX expands in the stomach over an approximate 30 minute period. It then creates a false feeling of fullness and satiety by absorbing water and slowing the digestive process. This process is claimed to have a number of benefits, including preventing hunger cravings, lowering cholesterol, and balancing blood sugar levels. offers a number of ways for consumers to add PGX to their diet. Consumers can buy softgel tablets, protein bars or drink mixes, all of which contains PGX as a key ingredient and often mixed with something else (such as whey or vegan-friendly protein, Mulberry, or purified coconut oil). PGX can even be purchased in a single-serve granule format, designed to be sprinkled over cereals, yoghurts or into drinks as a flavourless addition.

The website also offers a specially-designed PGX program which gives dieters a plan for how to take PGX as part of an all-round diet plan. The information contained in the PGX program is all free and can be sent to consumers on request, although the program itself should not be considered free given the amount of PGX that would need to be ordered regularly.

What does PGX claim to do?

PGX (PolyGlycopleX) is a patented super fibre complex made up of natural, highly viscous polysaccharides. When consumed, it expands in the stomach, absorbing water to fill the stomach. This is said to reduce one’s appetite and slows digestion down. This has two effects; delaying the time until the consumer is hungry again, and slowing the absorption of carbohydrates from the intestines into the blood stream. This helps to lower blood glucose levels, and also regulates blood sugar levels, helping to prevent the sugar spikes and crashes that cause cravings and sudden pangs of hunger between meals.

The Science Behind PGX

One thing that helps PGX to stand out from the crowd is the relatively strong levels of support it seemingly enjoys from the scientific community. The section explaining the science of PGX on the webiste is clearly written by an experienced hand, displaying a thorough knowledge of the chemistry behind the creation of PGX and the properties of the product that make it effective. Compared to other products seen on the market, these descriptions seem relatively free from the kind of baseless rambling that one sees all too often in marketing copy.

More impressively, the claims made on the website are backed up by 15 clinical studies, all of which are cited fully on the website itself and which appear in legitimate scientific and nutritional journals. Overall, the clinic studies seem to confirm every claim made about PGX by the website: that PGX reduces postprandial glycaemia, decreases cardiovascular risk factors, and ultimately, helps overweight and obese patients to lose weight.

However, a more thorough investigation reveals that not all is not what it seems. When examining the authors of the 15 different studies, one will notice that some names appear and reappear with suspicious frequency. Although the research teams are different each time, almost all feature one or both of two repeat researchers: Michael Lyon and Rolan Gahler.

Dr Lyon’s and Dr Gahler’s interest in PGX is not coincidental. Both men have authored and submitted all of the patents and legal ownership forms over PGX via the Inviro Biologic company, meaning that the pair invented the formula and now enjoy the sole rights and benefits of selling it. Their direct involvement in 15 clinical studies on the formula should thus be treated with scepticism, especially given that all studies are unanimous in their praise and that a number of studies declare financial support from Inviro Biologic.

The possibility of outright misleading or fraud is further raised when one starts to look at studies of PGX that were NOT written by the group that sells it. A more recent 2015 study conducted by Onakpoya and Heneghan analysed all the existing trials on PGX, discounting those that drew incorrect conclusions from small sample sizes and poor techniques. This study found that although PGX may cause reductions in cholesterol, “the evidence from available RCTs does not indicate that PGX intake causes reductions in body weight.” Onakpoya/Heneghan’s study also makes direct reference to the 15 Lyon/Gahler studies that came before it, and is unequivocal in its condemnation:

Few trials examining the effects of PGX have been conducted; they are characterized by small sample sizes, deficiencies in reporting quality, and are funded by a single manufacturer. Future clinical trials evaluating its effect should be adequately powered and better reported.

Unfortunately, the obvious potential for bias in almost all of the studies on PGX brings all positive claims about it into question. It is particularly troubling that the most comprehensive unbiased report that was not funded directly by the manufacturer found no connection with PGX and weight loss at all, and directly alluded to incompetence or dishonesty on the part of the manufacturer-funded trials.

What do people think of PGX?

PGX has had relatively strong independent reviews on Amazon, and people generally report that the product works as advertised. Many users seem to have bought PGX supplements to lower their blood sugar levels as part of a treatment for diabetes; although many customers report satisfaction with the effects, those considering trying this should obviously consult with their doctor first.

Reports on weight loss success are a little more mixed, although much of this is related to the nature of PGX itself (it primarily acts to make you feel full, and thus doesn’t lead to weight loss automatically). Most users seem satisfied, although a range of side effects have been reported. Users of PGX should expect a degree of bloating, discomfort, diarrhoea, gas and constipation, and the evidence suggest that the benefits of PGX do not apply to everyone.

One point that is often raised is the relative high dose recommended by the packaging and by the PGX program. Users taking the softgel capsules alone are expected to take 3-6 capsules 3 times a day on the third week of their program (a staggering 18 capsules in a day). Given that the capsules themselves are up to an inch long (as is typical with glucomannan-related products), this has resulted in a degree of discomfort for some customers. In general, the high intake of PGX recommended would cost observant customers a fortune no matter the product type, with a $25-30 capsule tub lasting around 2 weeks and other forms even less.

PGX is available on Amazon and from a number of health stores across North America. Although some retailers may have their own policies, there is no money back guarantee on the product itself. Caution should be taken before purchasing PGX, as it may be difficult or impossible to return the product.


PGX is a product that enjoys generally good customer reviews, and is related to a glucomannan-based approach that is generally thought to yield the advertised results. It is disappointing then that the science behind this particular formula is so tied up with issues of dishonesty and misrepresentation. Ultimately, we would argue that the body of scientific evidence backing PGX is almost entirely tainted, with all of it directly funded by the manufacturer, conducted by the scientists that patented the formula itself, and using sample sizes and techniques that were carefully designed to yield the needed results. Independent studies have failed to find the same results, and have been sharp in their criticism of these practices.

With little else to speak for it, PGX becomes merely another version of a glucomannan-based product, albeit one that is far more expensive. Consumers can find a more tried and true formula for a fraction of the price elsewhere, and should generally aim to shop for products that are based on real evidence and strong customer feedback. We do not recommend PGX!

Disclaimer: Our reviews and investigations are based on extensive research from the information publicly available to us and consumers at the time of first publishing the post. Information is based on our personal opinion and whilst we endeavour to ensure information is up-to-date, manufacturers do from time to time change their products and future research may disagree with our findings. If you feel any of the information is inaccurate, please contact us and we will review the information provided.

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