Saturday, January 14, 2012

Waxy Maize Reloaded: Hydroxypropyl-Distarch Phosphate (HdP) from Waxy Maize Starch Could Help You Burn Fat While Replenishing Your Glycogen Stores

Image 1: By adding some hydroxypropyl-distarch phosphate from waxy maize starch to your pancakes you can turn it into a fat burning superfood... well, sort of ;-)
Sometimes I miss studies, sometimes I file them in my candidates folder and forget about them, but most often I simply discard them. The latter also happened to a study on the effects of hydroxypropyl-distarch phosphate from waxy maize starch that was published in the British Journal of Nutrition (actually one of my favorites) in February of 2011 (Shimotoyodome. 2011). Due to the unjustified hype that has surrounded its introduction to the supplement market the word(s) "waxy maize starch" had become a red rag to me and the main finding of the study, i.e. the observation of a "lower postprandial glucose-dependent insulinotropic polypeptide response" only seemed to confirm my conviction that waxy maize is yet another industry scam.

Waxy maize a natural cheaper Vitargo? I don't think so!

A few months later, on November, 17, 2011, to be precise, the whole topic resurfaced on the Mind and Muscle forums, which are part of my usual morning read. Apparently a supplement company, which shall not be named, here because otherwise I would have to rail against its hilarious name, had released a product that contained this "new" form of waxy maize. Totally contrary to the common practice, the respective thread, as well as the web-page the company rep was referring to lacked the bragging and exaggerations that usually accompany the launch of a (unique) new product and listed references as well as graphs from real studies - not the ones where the patent holder takes ten bros from the gym and asks them how they liked the product.

Image 2: Even the logo on the website with the "product information" (which by the way lacks a link to a source to by the HDP WM) is somewhat extraordinary. Where is the brawny bodybuilder? Where the fitness chick? Where are the abs and the 20" arms? No "hardcore", no "incredible pumps", no "steroid like gains"... instead references to real studies, graphs and a brief rundown on the science - strange.
About 2 weeks ago, a brief email which contained no more than the question "What do you think about HDP WM?" brought the whole story back onto my radar. The email came from Anthony Roberts, whom I consider to be one of the few real innovators among the countless "experts" and plagiarists, ah... I mean "supplement designers" out there. And since he answered my question if he would mind if I cover the subject on the SuppVersity or whether he was coming up with an article of his own by stating that he preferred to keep to the sidelines, these days, I finally filed the study into my aforementioned "candidates" folder and took a few notes in preparation for this blogpost. But hey, I guess that is enough gossip for today, after all we are here for the facts, so let's go ahead and tackle those.

Heavy carbohydrates = better carbohydrates?

The idea that "not all fats are created equal" should by now have settled on your minds. That "not all carbohydrates" are created equal is yet about to be buried in oblivion with the whole low-to-no-carb craze of the last months (or has it been years, already?). Tough luck, especially for those supplement companies who still have "carby" post-workout products in their line-up the Joes and Janes from the gym refuse to buy, because they are afraid that the "simple sugars" in those products will whiz past the glycogen stores in their muscles and settle right on their hips and bellies.
Muscle glycogen resynthesis 0-2h and 2-4h after ingestion of 4x75g of carbs from either high molecular weight or low molecular weight starch sources at 0, 30, 60 and 90min after a standardized 120min exercise protocol (data adapted from Piehl. 2000)
What is the molecular mass / weight? If you isolated one molecule (i.e. structure build of atoms, like 2xhydrogen + oxygen for water) and put it onto a tiny, tiny scale, the latter would show you the "molecular mass", i.e. the specific weight of the molecule in u (unified atomic mass units). The molecular weight on the other hand is the same quantity, but expressed in 1/12 of the mass of carbon-12. Now with "more mass per molecule" you can pack the same amount of carbohydrates into 1L of water by using a lower number of molecules. And with the latter being one of the main determinents of how fast the solution will empty from the stomach, the high molecular mass, low osmolality starch has a head-start over its low molecular weight cousin.

That this does actually have real-world implications becomes evident when we take a look at the muscle glycogen resynthesis at 0-2h and 2-4h after the consumption of either a high molecular weight, low osmolality or a low molecular weight, high osmolality carbohydrate drink that was ingested in 75g boluses immediately, 30min, 60min and 90min after a standardized exercise protocol consisting of 90 min running on a treadmill (or outdoors), another 60 minutes of a submaximal cycling exercise and a series of short sprints to exhaustion.
In spite of that even bodybuilders, fitness and figure athletes acknowledge the necessity or at least usefulness to "carb load" at least periodically to keep their muscles full and their performance up (I know the low carb faction will now argue that this ain't necessary, but this would be the topic of another blogpost ;-). In this regard, they are yet facing a problem:
  • on the one hand, they want to replenish their glycogen stores as fast as possible, i.e. preferably within the first 1-2h after a workout, where the exercise-induced increase in GLUT-4 glucose transporter expression on the muscle facilitates glucose uptake
  • on the other hand, though, any glucose that does not get stored within the muscle will initially trigger an insulin response, which would compromise the exercise-induced "nutrient partitioning effect" - in other words, the glucose that is not directly taken up by the muscle will be converted to triglycerides and stored within their adipose tissue
Against that background, the idea that the ingestion of a "super-fast carbohydrate", which the waxy maize myth tells you the latter would be, appears to be a double-edged sword. On the one hand, you would obviously get a fast delivery of glucose to the bloodstream, on the other hand, you would run the same risk as with dextrose or any other "regular fast carb" that all the glucose that is not taken up by your muscle will be stored in your adipose tissue.
What is ameliopectin? Ameliopectin and amylose are the two forms of starch you will find in plants, while molecules which belong to the latter group are quite compact, the former are highly branched and thusly (theoretically) more susceptible to enzymatic breakdown, so that the glucose subunits will hit the bloodstream faster. The high number of branches is also responsible for the increased weight of the molecule (cf. red box above), so that ameliopectin starches are about 10^3-10^4-times "heavier" than their less branched cousins.
Interestingly, the real-world results people who switch from dextrose or maltose to waxy maize as their post-workout carbohydrate source, almost always report less bloating, less water retention and lower fat gains from the same amount of carbohydrates. Contrary to what the myth says, the reason for this slight, but recognizable advantage of waxy maize over the more common post-workout carbs dextrose or maltose is not that the glucose is hitting your blood stream so fast that you make "optimal use of the post-workout window of opportunity", but rather the opposite.

The truth about "regular" waxy maize

Even a cursory search of the literature will return dozens of results which show quite conclusively that waxy maize or "waxy corn starch", as it is also referred to, is by no means the "turbo-charged" glycogen replenisher the industry tried to make people believe. Studies such as Goodpaster (1996), Anderson (2002), or Sands (2008) rank waxy maize under the "slower digestible carbs" with a tendency to lower glucose in exercise- and non-exercise scenarios. 

What is quite ironic now is that the "waxy maize scam" could long have become at least a mediocre success, if people had realized that the blunted blood glucose and insulin response could be an advantage not only for bodybuilders and physique competitors and average Joes and Janes trying to build a men's health or shape cover-model physique, but also - and this may come as a surprise - for endurance athletes.

HdP WM - Leaning out with waxy maize 2.0

Now, if a slightly blunted glucose and insulin response, as with regular waxy maize can prevent the obesogenic side effects of high insulin levels (and the ups and downs in blood sugar which compromise the performance of endurance athletes), it appears to be only logical that a starch with a similarly high molecular weight should deliver the glycogen to the muscle at an even lower risk of fat storage.
Figure 1: Blood glucose, triglycerides, insulin and NEFA levels (left) and body weight, liver weight and and total white adipose tissue weight (right) of mice after 24 weeks on regular control or high fat diets with either regular starch (HFD, control), hydroxypropylated distarch phosphate waxy corn starch (HdPWCS) or high-amylose corn starch (data adapted from Shimotoyodome. 2009)
Compelling evidence that this is could be the case from the initially mentioned study from the February 2011 issue of the British Journal of Nutrition (Shimotoyodome. 2011). Based on previous observations in rodents, in which the scientists had compared the effects of high fat diets the carbohydrate component of which contained either unmodified starch, hydroxypropylated distarch phosphate (RS4), or high-amylose corns starch on the development of diet-induced obesity in mice (results cf. figure 1), Shimotoyodome and his colleagues had speculated that a the inclusion of RS4 into a regular meal could induce similarly beneficial effects on the hepatic fatty acid oxidation capacity and energy homeostasis in humans, as it did in mice (cf. figure 2).
Figure 2: Hepatic fatty acid oxidation capacity, medium-chain acyl-CoA (MCAD) dehydrogenase and acyl-CoA oxidase (ACO) activity (left, arbitrary units) and average oxygen consumption (VO2), respiratory exchange ratio (RER), 78h energy expenditure and fat oxidation (right, expressed relative to high-amylose starch group) of mice after 24 weeks on a high fat diet with either hydroxypropylated distarch phosphate waxy corn starch (HdPWCS) or high-amylose corn starch (data adapted from Shimotoyodome. 2009)
And while the increase in energy expenditure in the HdP waxy maize group did not reach statistical significance (p = 0.064), the upregulation of the fatty acid oxidation capacity, medium-chain acyl-CoA (MCAD) dehydrogenase and acyl-CoA oxidase (ACO) activity in the liver of the mice, as well as the subsequent absolute and relative increase in 78h fat utilization (+13%, cf. figure 2, right) would probably be very welcome "side-effects" for any of the afore-mentioned potential customers.

Hydroxypropylated distarch phosphate waxy corn starch pancakes, anyone?

In order to test their hypothesis Shimotoyodome et al. came up with the world's first dydroxypropylated distarch phosphate waxy corn starch pancake and fed the latter, as well as an identical pancake with regular waxy maize (this makes the study particularly interesting for us, after all we will see how WM 2.0 and WM 1.0 compare) to ten healthy male volunteers (age 35.2y; BMI 23.6 kg/m) - each one on seperate occasions, of course.
Figure 3: Composition of the test meals (left) and postprandial changes (min vs. max) in blood glucose, insulin, glucose-dependent insulinotropic polypeptide (GIP), TAG and NEFA concentrations (data calculated based on Shimotoyodome. 2011)
The subjects had to report to the lab fasted after having ingested a standardized meal on the evening before the experiment took place. Before and up to 180min after the ingestion of the 1673.6kJ test meals, their resting energy expenditure (REE) and blood concentrations of various biomarkers were measured and the results suggest that mice and men react similar to the ingestion of HdP waxy maize: The maximal glucose, insulin and GIP levels in glucose-dependent insulinotropic polypeptide (GIP) levels were blunted in the HdP compared to the regular waxy maize group.
Figure 4: Time-course of the changes in blood glucose (left) and insulin (right) after ingestion of waxy maize or HdP waxy maize pancakes (data adapted from Shimotoyodome. 2011)
If we take a closer look at the time course of the insulin and glucose responses in figure 4 the ameliorative effect of the replacement of regular waxy maize (which, as you will remember already is a "slow(er)" carbohydrate source) with its HdP cousin, is particularly pronounced and statistically significant in the early part of the post-prandial window.
Figure 5: Area under the curve for glucose, insulin and GIP in mice after administration of 2mg/g highly gelatinized regular or HdP waxy maize starch to mice in the presence of 0.4, 1 or 2mg/g of the saturated fatty acid triolein (data adapted from supplementary material to Shimotoyodome. 2011)
From the supplementary material to the study, we also know that this effect (at least in rodents) is even more pronounced, when the amount of fat (in the experiment the scientists co-administered triolien, an unsaturated form of oleic-acid) in the meal is reduced - as it would probably be when you ingested the HdP WM post workout.
Figure 5: Insulin response of mice after administration of 2mg/g highly gelatinized regular (left) or HdP waxy maize starch (right) in the presence of 0.4, 1 or 2mg/g of the saturated fatty acid triolein (data adapted from supplementary material to Shimotoyodome. 2011)
And with the exercise induced increase in GLUT-4 receptor expression the moderate increase in glucose and - most importantly - the quasi non-existent rise in insulin (cf. figure 6), I would venture the guess that the statistically significant increases in fatty acid oxidation the scientists observed in their non-exercised (but fasted) subjects subsequent to the ingestion of the HdP waxy maize pancakes, would have been even more pronounced if this "experimental junk food" had not contained 10.8g of fat, 7.5g of sucrose (table sugar), 15.3g of maltodextrin and 1.8g of other carbohydrates.
Figure 6: Changes in ppostprandial energy expenditure (left) and fatty acid oxidation (right) after the ingestion of regular and HdP pancakes (data adapted from Shimotoyodome. 2011)
But let's not be greedy ;-) I mean, after all, we still have an average +250kJ/d increase in postprandial fatty acid oxidation in the 180min postprandial period and that not over the regular WM pancake, which produced an average reduction of -1108kj/d, but over baseline (just to make this 100% clear the subjects burned more fat after they ingested the HdP pancake than they did in the fasted state!). And that would be a big plus for physique competitors and regular dieters, alike... even if the total effect size is not earth shattering, a meal replacement shake with HdP waxy maize as the sole carb source could in fact revive a part of the supplement market which is virtually dead, ever since the original MetRx shakes have disappeared from the scene.

Implications:Whatever the future of this fast absorbing (into the intestine), slow digesting, high molecular weight, resistant starch which supplies your body with a likewise nourishing as fatty acid oxidation triggering influx of short chain fatty acids and undisclosed, but comparatively minimal amounts of glucose may be. Functional food, meal replacement, or post-workout supplement, I guess you know that the SuppVersity is the place to go if you want to keep up with the news ;-)