Quick Hit Summary
Most experts recommend consuming high glycemic carbohydrates as part of a post workout shake. These rapidly absorbed carbohydrates stimulate the release of the anabolic hormone insulin while limiting secretion of the catabolic hormone cortisol. Many supplement manufacturers claim that waxy maize starch is the best source of carbohydrates to accomplish this task, even better than maltodextrin. However, recent research clearly indicates that maltodextrin is absorbed faster into the bloodsteam, leading to a more rapid rise in insulin.
Waxy Maize Starch
Figure 1 Glucose Metabolism. As represented by the red arrows, the major carbohydrates in ones diet includes monosaccharides (glucose, fructose, galactose) disaccharides (maltose, sucrose, lactose) and polysaccarides (starches, maltodextrin). These are stored as glycogen in both the liver and muscle tissue.5
Update – Since originally writing this article a few years back, I have slightly changed my stance on Waxy Maize – I still don’t believe it to be a “fast” CHO as the science on that hasn’t changed… However, towards the start of 2012, I started playing around with the idea of adding waxy maize to post-workout shake due to it being absorbed slower than maltodextrin and potentially less fat storage as well. Will keep you posted as I continue to fine tune things.
As I’ve stressed in some of my more recent articles, the ingestion of high glycemic carbohydrates are advised as part of the post-workout meal/shake. Compared to carbohydrates with low glycemic indexes (GI), high GI foods are quickly absorbed into the bloodstream, stimulating the release of the anabolic hormone insulin. Elevated blood insulin levels facilitate muscle growth and glycogen recovery. Furthermore, quickly absorbed carbohydrates decrease circulating levels of the catabolic hormone cortisol12.
For many strength and endurance athletes, high GI foods, such as fresh fruit or maltodextin, have been a staple stir-in for post workout shakes due to its rapid absorption. However, within the past few years, a new supplement, waxy maize starch (WM), has been touted as the supreme champion of post workout carbohydrate sources. After reading various claims made by websites promoting WM, one has to wonder how he/she ever survived without this product in their post workout shake. Rather than leave you pondering about all the gains you could have made if you had only heard of this product sooner, I’ll let you in on a little secret…. With respect to its rapid absorption capabilities, The Great Waxy Maize Starch is nothing but a myth!
Waxy Maize Starch vs. Maltodextrin
In a recent study conducted by Sands et al., investigators compared the effects that 50 grams of various carbohydrate sources had on blood glucose levels and the ensuing insulin response3. The study involved a total of 12 healthy, physically active participants (6 men- mean age 21; 6 women- mean age 25). At three separate trials, participants took 50 grams of WM, a mixture of maltodextrin & sucrose (MS), white bread (B) or glucose control following a 10 hour fast. Maltodextrin made up 38.2 grams (78%) of the MS, while sucrose made up 11g (22%) of the mixture. After 4 hours of observation, it was recorded that WM had the lowest GI at both the 2 hr and 4 hr mark. In fact, the GI of MS was almost 250% greater than the WM at 2 hours post ingestion and 200% greater at 4 hours. Furthermore, insulin (225%) and glucose (195%) levels were significantly higher over the four hour time period following MS ingestion in comparison to WM. This was especially apparent during the first hour following ingestion. Please see Figures 2 & 3 Thus, researchers concluded that WM was a slower absorbed carbohydrate that led to a “more steady supply and release of energy over a period, compared to the rapidly digesting starch maltodextrin.” In other words, if your goal is rapid absorption and you have these three products in front of you, take the maltodextrin.
Table 1 “Values are means ± SEM (median). Values within a row with a different superscript letter differ (P < .05). Glycemic index was calculated over both a 2- and 4-hour period, using the equation as follows: GI = [(postprandial incremental AUC of the test treatment/postprandial incremental AUC of the white bread control) × 100]/1.4. The correction factor 1.4 was used because of the use of white bread as a control rather than glucose”1.
| Glycemic Index (GI) Time Period | Glucose Control | White Bread | Maltodextrin-Sucrose Mix | Waxy Maize |
| Gl (2 hr) | 100±0 a (100) | 71±0 a (71) | 163±37 a (106) | 63±11 b (58) |
| Gl (4 hr) | 100±0 a (100) | 71±0 a (71) | 127±27 a (89) | 60±11 b (64) |
Figure 2 Insulin response to different carbohydrate sources over the cost of 60 minutes following ingestion. Maltodextrin (8.61 nmol/L) led to a significantly greater insulin response than the Waxy Maize (2.44 nmol/L) during this time period.3
Figure 3 Glucose response to different carbohydrate sources over the cost of 60 minutes following ingestion. Maltodextrin (78 mmol/L) led to a significantly greater glucose response than the Waxy Maize (25 mmol/L) during this time period.3
As the above figures and tables indicate, maltodextrin had a much more favorable effect on GI, plasma insulin and plasma glucose responses in comparison to waxy maize.
Where did the Great Waxy Maize Starch Myth Originate?
I can’t say with 100% certainty where this myth all started. As I’ve mentioned previously, I do not make conclusions based off 1 study alone. Rather I try to find a collection of studies to support the inclusion/exclusion of a specific theory in my training and nutrition arsenal. Thus, I performed multiple searches trying to find other research articles that may lend support to using WM as a post-workout supplement. Despite numerous searches, the only study that somewhat provided evidence for the use of WM was a research experiment conducted by Piehl Aulin et al4. According to many WM manufacturers and distributers, this study serves as one of the primary proofs that WM is a superior glycogen replenishing supplement. In their study, Piehl Aulin et al. compared how carbohydrates of different molecular weights (high molecular (HM) and low molecular (LM)) affected muscle glycogen recovery following 2 separate exhaustive workouts. Each glycogen depleting workout lasted 2 hours and the different carbohydrate drinks were taken soon after completing each workout. It was found that the HM carbohydrate led to significantly greater muscle glycogen content after 2 hours. Since WM is considered a HM carbohydrate and carbohydrates like maltodextrin are of LM, product manufactures started to proclaim that WM was far superior at supporting anabolism (tissue growth) and replenishing glycogen stores.
The study by Piehl Aulin et al. sounds pretty great doesn’t it? However, if you look closer at the study, you can see that there are some MAJOR limitations. First off, they didn’t even use WM as the source of carbohydrate in the study. Rather, they used a potato starch and the article fails to mention if it’s from a “waxy” variety or not. Second, the total muscle glycogen content between the HM and LM carbohydrates was only significant when measured at 2 hours. When muscle samples were taken at 4 hours, there was no significant difference between the muscle glycogen content following the ingestion of the HM compared to the LM carbohydrate.
Bottom Line
Supplement distributors & manufactures have greatly misled consumers by claiming that waxy maize starch is an unrivaled post workout carbohydrate source. Does this mean that waxy maize is a bad supplement? Of course not; it just means that there are better times of the day to take it than following a workout. In fact, due to its lower GI, Sands et al. hypothesized that it would be a useful pre-workout supplement since it could provide a slow sustained release of carbohydrates into the bloodstream1. Thus, the body could partially preserve its own glycogen stores, while relying on this dietary glucose as a source of energy.
In conclusion, waxy maize starch is not the best source of carbohydrates post workout. Rather, it may be more advantageous to consume them prior to an endurance event due to it’s ability to provide a slow, steady source of energy.
Reference
1 Tarpenning KM, Wiswell RA, Hawkins SA, Marcell TJ. Influence of weight training exercise and modification of hormonal response on skeletal muscle growth. J Sci Med Sport. 2001 Dec;4(4):431-46.
2 Venkatraman JT, Pendergast DR. Effect of dietary intake on immune function in athletes. Sports Med. 2002;32(5):323-37.
3 Sands AL, Leidy HJ, Hamaker BR, Maguire P, Campbell WW. Consumption of the slow-digesting waxy maize starch leads to blunted plasma glucose and insulin response but does not influence energy expenditure or appetite in humans. Nutr Res. 2009 Jun;29(6):383-90.
4 Piehl Aulin K, Söderlund K, Hultman E. Muscle glycogen resynthesis rate in humans after supplementation of drinks containing carbohydrates with low and high molecular masses. Eur J Appl Physiol. 2000 Mar;81(4):346-51.
5 Created by Mikael Häggström. Accessed June 14, 2010 from: http://commons.wikimedia.org/wiki/File:Glucose_metabolism.svg