Dukan Diet

The meager increase in glucose disposal observed in the study at hand is not likely to do anything, but be good for another confusing graph on the label of the licensees first OpunDia powered supplements.

Against the background that insulin still has a pretty bad rep, it is actually quite funny that its fiercest enemies and most loyal followers of low-carb diets are usually the guys and girls who spent tons of money on 100% useless "insulin mimetics". Insulin mimetics like the cactus extract thats at the heart of a recent study by Louise Deldicque, Karen Van Proeyen, Monique Ramaekers, Ivo Pischel, Hartwig Sievers and Peter Hespel? Or could it be possible that Opuntia Ficus-Indica is the infamous exception that proves the rule?

To answer this question, it is obviously necessary that we take a closer look at the corresponding paper in the Journal of the International Society of Sports Nutrition (ISSN). I mean, it is not impossible that this is finally the "next big thing" weve all been waiting for, right?

Leucine + Herb = Win?

Before we dig further into the methods and results of the study, it it probably suitable for me to tell you about the meaningful letters "™" behind the word OpunDia and the openly declared competing interests of Ivo Pischel and Hartwig Sievers.
Enough of the foreplay , though, lets finally take a look at the design and the results of this human trial that was conducted by the Exercise Physiology Research Group at the Department of Kinesiology of KU Leuven in Belgium (Deldicque. 2013).

There were 11 male subjects who participated in the study. All were physically active and the mean age was 21.1 ± 0.9 years. With a body weight of of 74.5 ± 4.2 kg and a VO2 max (~fitness level) of 65 ± 4 ml·min/kg), they are probably representative of the average, but not necessarily the extra-extraordinaire trainee.

After the usual pre-testing procedures, the guys were randomized to receive either

• 1,000 mg LUVOS Heilerde serving as placebo (PL),
• 1,000 mg OpunDia™ (OFI), 
• 3,000 mg of old-fassioned leucine (LEU), or 
• 1,000 mg OpunDia™ + 3,000 mg leucine (OFI+LEU).

After each of the four randomized cross-over testing session that involved 30min of rather casual cycling at 70% of the predetermined VO2 max (90-100 rpm) the subjects received capsules containing one of the above formulations and the 75g of glucose that were used for the oral glucose tolerance tst.. Needless to say that all capsules had identical appearance and the number of capsules ingested was the same for each condition.

It works, but what does that tell us?

In a previous trial, Van Proeyen et al. had already observed that the ingestion of an identical supplement stimulates the peripheral disposal of oral glucose before and after exercise in healthy men. If you will, you may thus call the study at hand a follow up, which did - what a surprise (!) - confirm the effects of OFI and a certain, but not exactly impressive synergism between the plant extract and everyones favorite amino acid leucine, one of the branched chain amino acids and, as SuppVersity readers know, likewise highly pro-insulinogenic (learn more about leucine).

Figure 1: Glucose and insulin iAUC after oral glucose test performed subsequent to the ingestion of PL, OFI, LEU or LEU + OFI supplement and 30min of "cardio" at 70% of the VO2max (left); glucose levels in the 2h after the OGGT (Deldicque. 2013)

A cursory glance at the data in Figure 1 should suffice to see two things: (1) There was the expected / hoped for synergistic effect of leucine and OFI, but (2) only the OFI-only trial, and not the combination treatment led to significant reductions in the area under the glucose curve.

Is this even an improvement?

Remember that chromium picolinate can worsen the insulin sensitivity in  healthy non-diabetic, non-obese individuals by up to 25% | learn more

"Add Leucine and get more insulin, but a lower rate of glucose disposal"... I dont know what youd say, but for me this sounds much like insulin resistance or lets rather say no improvement over the provision of OFI alone. The first take-home message is thus that the addition of leucine to OFI may produce a synergistic effect on insulin, the effect we are actually looking for, namely the increase in blood glucose uptake and glycogen synthesis is however absent. And whats more, neither I nor the researchers have an real clue as to what it is that triggers the short-lived increase in insulin production thats brought about by the ingestion of 1,000mg Opuntia Ficus-Indica extract.

Accordingly, it is very difficult to give any prognosis whether more would help more, or the whether wed see similar detrimental effects as with chromium upon dose escalation.
References:

• Manders RJ, Little JP, Forbes SC, Candow DG. Insulinotropic and muscle protein synthetic effects of branched-chain amino acids: potential therapy for type 2 diabetes and sarcopenia. Nutrients2012. 4:1664–1678.
• Van Loon LJ, Saris WH, Kruijshoop M, Wagenmakers AJ. Maximizing postexercise muscle glycogen synthesis: carbohydrate supplementation and the application of amino acid or protein hydrolysate mixtures. Am J Clin Nutr. 2000,72:106–111.
• Van Loon LJ, Kruijshoop M, Verhagen H, Saris WH, Wagenmakers AJ. Ingestion of protein hydrolysate and amino acid-carbohydrate mixtures increases postexercise plasma insulin responses in men. J Nutr. 2000, 130:2508–2513.
• Van Proeyen K, Ramaekers M, Pischel I, Hespel P. Opuntia ficus-indica ingestion stimulates peripheral disposal of oral glucose before and after exercise in healthy men.Int J Sport Nutr Exerc Metab 2012,22:284–291
• Wiese J, McPherson S, Odden MC, Shlipak MG. Effect of Opuntia ficus indica on symptoms of the alcohol hangover. Arch Intern Med. 2004 Jun 28;164(12):1334-40.