Clinical Trials - PGX^® Studies

 

PGX^® has been the subject of 15 clinical trials, 8 of which were conducted in Australia at The University of Sydney with Professor Brand-Miller and Curtin University with Professors Pal and Solah. This work covers glycaemic testing, satiety, glucose and lipid studies, with some of these studies conducted over 365 days. Below are summaries of a few of these studies, all of which have been published in peer reviewed international journals. 

Effects of PGX^®, a novel functional fibre, on acute and delayed postprandial glycaemia.¹

Abstract: Viscous fibre in food has established health benefits but few functional fibre preparations are both effective and palatable. The authors’ objective was to determine the most effective dose, formulation and timing of consumption of a novel fibre supplement (PGX^®) in reducing postprandial glycaemia.

Method: Three trials were undertaken, each with 10 subjects – from a pool of 16 (8M: 8F, age 24.4 ± 2.6 y). Granular PGX^® was tested at 4 doses (0, 2.5, 5 and 7.5 g) with breakfast (study 1). Granular and softgel forms of the supplement were given in a single dose (5 g for granules and 4.5 g in softgels) at -60, -45, -30, -15, 0 before and +15 min after a bread meal (study 2). Softgels at increasing doses (1.5, 3, 4.5 and 6 g) were consumed with the evening meal to determine effects on glucose tolerance at breakfast (study 3). Incremental area under the blood glucose curve was determined. 

Results: Granular PGX^® at breakfast time at doses of 2.5, 5 and 7.5 g reduced the iAUC by up to 50% in a linear dose-response fashion (p < 0.001). The granular form of PGX^® (5 g) but not the softgel, reduced glycaemia by up to 28% when consumed from -45 to +15 min (p < 0.001). Capsules containing 3, 4.5 and 6 g PGX^® consumed with the evening meal reduced glycaemia at breakfast by up to 28% (p < 0.001).

Conclusion: The authors concluded that PGX^® has biologically important, dose-related effects on acute and delayed (second meal) postprandial glycaemia. 

Effects of added PGX^®, a novel functional fibre, on the glycaemic index of starchy foods.²

Abstract: The development of lower-glycaemic index (GI) foods requires simple, palatable and healthy strategies. The objective of this study was to determine the most effective dose of a novel viscous fibre supplement (PGX) to be added to starchy foods to reduce their GI.

Method: Healthy subjects (n 10) consumed glucose sugar (50 g in water × 3) and six starchy foods with a range of GI values (52-72) along with 0 (inert fibre), 2.5 or 5 g granular PGX^® dissolved in 250 ml water. GI testing according to ISO Standard 26642-2010 was used to determine the reduction in GI.

Results: PGX^® significantly reduced the GI of all six foods (P < 0.001), with an average reduction of 19 % for the 2.5 g dose and 30 % for the 5g dose, equivalent to a reducing the GI by 7 and 15 units, respectively. Consuming small quantities of the novel functional fibre PGX^®, mixed with water at the start of a meal, is therefore an effective strategy to reduce the GI of common foods.

Conclusion: It was concluded that PGX^® significantly reduced the GI of all six foods (P < 0.001), with an average reduction of 19% for the 2.5 g dose and 30% for the 5 g dose, equivalent to reducing the GI by 7 and 15 units, respectively. As a popular fibre, Inulin was used as the inert fibre and was found to have had no effect on lowering the GI of the foods. 

Dose-response effect of a novel functional fibre, PolyGlycopleX, PGX^®, on satiety.³

Abstract: The objective of this research was to determine the dose-response effects of a palatable, viscous and gel forming fibre, PolyGlycopleX (PGX^®), on satiety and to gain insight into the underlying mechanisms that lead to appetite inhibition.

Method: Healthy subjects consumed PGX^®, in granular form at 0, 2.5, 5 and 7.5 g with a standard breakfast.

Results: As examples at the low and high dose (2.5 and 7.5 g) of the novel functional fibre PGX^® mixed with water at the start of a meal was associated with increasing satiety (iAUC of 140.0 and 157.7 and P = 0.025 and 0.001 respectively).

Conclusion: When included as part of a breakfast meal, PGX^® resulted in increased fullness, iAUC and provided an improved satiety effect compared to breakfast without PGX^®. The findings provide further evidence that satiety and postprandial glycaemia response are connected and both may be dictated by viscosity and the effect of blood glucose on satiety seems likely. PGX^® has a very strong effect on satiety especially at the 7.5 g dose and delays the postprandial glycaemia.

N.B. Data used in this paper were derived from the same study by Brand-Miller et al. was derived from the same study as in no.1 above. 

Effects of a viscous-fibre supplemented evening meal and the following unsupplemented breakfast on post-prandial satiety responses in healthy women.⁴

Abstract: The post-prandial satiety response and “second-meal effect” of a viscous fibre supplement PolyGlycopleX (PGX^®) as a softgel was evaluated in a single-blind, randomised controlled crossover study of 14 healthy adult women.

Method: The two-hour post-prandial satiety response, expressed as the area under the curve (AUC) of perceived hunger/ fullness score versus post-prandial time, of a standardised evening meal with concurrent intake of either PGX^® softgel or rice flour softgel (control) was determined. On the following morning, after an overnight fast, the four-hour satiety response to a standardised breakfast with no softgel supplementation was assessed. 

Results: A significantly higher satiety response (AUC) to the standard dinner for the PGX-supplemented dinner compared with the control dinner (p = 0.001) was found. No significant difference (p = 0.09) was observed in the satiety response (AUC) of the breakfast regardless of which supplemented dinner had been consumed prior, however the p value indicated a trend towards a higher response to the breakfast following the PGX-supplemented dinner. The fullness scores of the breakfast following the PGX-supplemented dinner at 15, 30, 90, 120, 150, 180, 210 and 240 min post-prandial were significantly higher than those for the breakfast following the control dinner (p = <0.001, 0.007, 0.009, 0.009, 0.049, 0.03, 0.003 and <0.001 respectively).

Conclusion: PGX^® supplementation at dinner increased the satiety effects of both the dinner itself and the subsequent un-supplemented breakfast; a “second-meal effect” indicting the potential for PGX^® supplementation to induce extended satiety. 

Consumption of the soluble dietary fibre complex PolyGlycopleX^® reduces glycaemia and increases satiety of a standard meal postprandially.⁵

Abstract: The effect of consumption of PGX^® was compared to wheat dextrin (WD), a popular soluble fibre, in combination with a standard meal on postprandial satiety and glycaemia. This study was a double-blind, randomised crossover trial of 14 healthy subjects that had been trained as a satiety panel. At each of six two-hour satiety sessions, subjects consumed one of three different test meals on two separate occasions. 

Method: Fourteen healthy adults (2 male and 12 female); age 21.9 ± 4.0 years (range 19–32 years) and body mass index 23.2 ± 4.3 kg/m2 (range 19–32 kg/m2) were recruited. The study was a randomised, crossover trial with the PGX^® and WD arm double-blinded. The third arm, PGX^® softgel was randomised and single-blinded. Subjects participated in six breakfast and two-hour postprandial sessions, held fortnightly. At each session, subjects consumed one of three different test meals on occasions: a standard meal (1205 kJ) plus 5 g PGX^®; the standard meal plus 4.5 g of PGX^® as six softgels (each containing 750 mg PGX^® and 600 mg medium chain triglycerides) and the standard meal (1205 kJ) plus 5 g WD. On each test morning, subjects arrived after having fasted for 10 h overnight and consuming only ad libitum water. Blood was taken by finger-prick followed by occupation of individual sensory booths where the breakfast test meals were served. Subjects rated their feeling of hunger and fullness at baseline (before eating commenced) using a visual scale. They were then provided with the test meal which consisted of the standard breakfast meal, a 500 mL bottle of water and a small plastic cup containing either 5 g of WD, 5 g of PGX^® or 4.5 g of PGX^® in the form of six softgels. Subjects sprinkled the product onto the meal prior to eating or swallowed the softgels and consumed the entire test meals including 500 mL of water within 12 min. After consumption of the test meal, subjects moved to a different room (where they were not allowed to eat or drink but were allowed to use a computer or read) to rate their sensation of fullness using the visual scale at 15, 30, 45, 60, 90 and 120 min after commencement of eating. Immediately after each satiety time point, subjects moved to the clinic room where finger-prick blood samples were taken and tested for blood glucose levels. 

Results: For satiety, the mean fullness score peaked at 15 min and then dropped over the time period of 30 to 120 min for all groups. The mean fullness score of the PGX^® softgel meal for all time points was significantly higher than that of the WD meal (all p < 0.01). The mean fullness score for the PGX^® (granules) meal was also significantly higher at time points 15, 30, 45 and 60 min than for the WD meal (all p < 0.01) and showed a strong trend towards being higher at 90 min (p = 0.051). Mean fullness scores at each time point from the PGX^® group did not differ significantly from those of the PGX^® softgel group. The area under the curve (AUC) for postprandial satiety (subjective hunger/fullness score vs time) for PGX^® meal and PGX^® softgel meal were significantly higher than for the WD meal (both p < 0.001). There was no significant difference in the AUC of satiety between the PGX^® and the PGX^® softgel meal groups (p = 0.81). Only the granular form of PGX^® was used for postprandial glucose (PPG) response measurement. The time to peak blood glucose level for both PGX^® and WD was 30 min. At 15, 30, 45 and 60 min after meal consumption, the blood glucose mean values for the PGX meal were significantly lower than those for the WD meal (p < 0.05). At 120 min, the effect reversed and the mean blood glucose level was slightly but significantly higher for the PGX^® than the WD meal (p=0.008). The mean AUC for postprandial blood glucose levels was significantly lower for the PGX^® meal than for the WD meal. 

Conclusion: The participants in this study found that when PGX^® as granules and as softgels were consumed with a high carbohydrate breakfast, satiety was increased compared to WD. It was also determined that PGX^® in granular form provided significant reductions in the postprandial glucose (PPG) response (the softgels were not evaluated in this test). This postprandial comparison of PGX^® and WD has provided additional knowledge on the connection between postprandial satiety and glycaemia responses due to fibre consumption and viscosity. The potential role of consumption of PGX^® in assisting the prevention of obesity and development of type 2 diabetes has been strengthened by the findings of this study. Controlling satiety is an important factor in weight loss and its management. PGX^® has been shown in this study to be an excellent method of controlling satiety and hence helping with reducing caloric intake. The management and prevention of impaired glucose tolerance and type 2 diabetes requires the avoidance of postprandial “spikes” and a more gradual drop of blood glucose over time, thus the postprandial response for PGX^® indicates its potential benefits in relation to type 2 diabetes prevention and its management. 

References:

1) Brand-Miller JC, Atkinson FS, Gahler RJ, Kacinik V, Lyon MR and Wood S. Effects of PGX^®, a novel functional fibre, on acute and delayed postprandial glycaemia. European Journal of Clinical Nutrition 2010;64.

2) Brand-Miller JC, Atkinson FS, Gahler RJ, Kacinik V, Lyon MR, Wood S. Effects of added PGX^®, a novel functional fibre, on the glycaemic index of starchy foods. British Journal of Nutrition 2011;108.

3) Solah VA, Brand-Miller JC, Atkinson FS, Gahler RJ, Kacinik V, Lyon MR and Wood S. Dose-response effect of a novel functional fibre, PolyGlycopleX^®, PGX^®, on satiety. Apetite 2014;77C:74-78. 

4) Yong MK, Solah VA, Johnson SK, Meng X, Kerr DA, James AP, Fenton HK, Gahler RJ, Wood S. Effects of a viscous-fibre supplemented evening meal and the following un-supplemented breakfast on post-prandial satiety responses in healthy women. Physiology & Behavior 2016;154:34-39. 

5) Solah VA, O’Mara-Wallace B, Meng X, Gahler R J, Kerr D A, James A P, Fenton H K, Johnson S K and Wood S. Consumption of the Soluble Dietary Fibre Complex PolyGlycopleX^® Reduces Glycaemia and Increases Satiety of a Standard Meal Postprandially. Nutrients 2016;8:268.