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Post-Workout High Isoleucine AA+CHO Decreases Glucose Spikes, But Impairs Musclular Glyocogen Resynthesis - Reason Enough to Skip Amino Acids?

If you put any faith into the promises of the supplement industry, amino acid supplements are the solution to all your problems - including those you havent even known about, yet. Against that background its always interesting if scientists study the real world effects of amino acid supplements in a realistic scenario like after strenuous exercise.

In their latest study Wang and colleagues from the University of Texas at Austin and the Shanghai Research Institute of Sports Science did just that: They studied the effects isoleucine and four additional amino acids, on blood glucose homeostasis and glycogen synthesis after strenuous exercise.
As the scientists point out, the results of their study "could provide a practical and safe means of increasing the rate of muscle glycogen synthesis after exercise and enhancing the rate of recovery" (Wang. 2015).

Table 1:  Subjects’ characteristics (Wang. 2015).

Ten healthy active adults volunteered for the study. All subjects were accustomed to cycling for prolonged periods of 3–5 h during an exercise session. The ,aximum oxygen uptake (VO2max) was measured in all subjects on a cycle ergometer by using a TrueOne 2400 metabolic measurement system (ParvoMedics, Sandy, Utah) to verify adequate aerobic fitness levels (results see Table 1).

Figure 1: Basically the AA supplement contained almost exclusively isoleucine. It was administered in the dosage shown above and at twice that amount in the LAA and HAA trials (Wang. 2015)

"Two to three days after the VO2max test, the subjects reported to the laboratory to perform a practice ride to familiarize them with the laboratory environment and the experimental protocol. The practice ride was also used to adjust and verify appropriate workloads for the experimental trials. The practice rides simulated the protocol ride but without blood samples or muscle biopsies being taken. The ride consisted of cycling at 70 % VO2max for 2 h, which was followed by five 1-min sprints at 85 % VO2max. The sprints were separated by 1 min cycling at 45 % VO2max. During the first 15 min of each hour, oxygen uptake was measured for 5 min to verify workload.

Water (250 mL) was provided every 20 min of exercise. Heart rate (HR) was monitored and ratings of perceived exertion (RPE) on a Borg-scale (ranging from 6 to 20) were collected every 30 min of exercise. The practice ride and each of the following three experimental trials were separated by a minimum of 7 days and maximum of 12 days" (Wang. 2015).

The actual tests consisted of cycling on an ergometer to deplete muscle glycogen. Blood sampling and a muscle biopsy were performed immediately on cessation of exercise. After the muscle biopsy, subjects were given the first of two supplement doses. More specifically they received either...

• 1.2 g carbohydrate/kg body weight (CHO), 1.2 g carbohydrate/kg body weight plus 6.5 g AA (CHO/LAA) or 
• the same carbohydrate supplement plus 6.5g (CHO/LAA) or 13 g AA (CHO/HAA) 

immediately after the first muscle biopsy and at 120 min of recovery. The carbohydrate base consisted of simple dextrose dissolved at a ratio of 100g/296 mL in an orange flavored drink (SUN-DEX, Fisher Healthcare, Houston, Texas). The additional amino acids contained 0.046 g cystine 2HCl, 0.023 g methionine, 0.045 g valine, 6.342 g Isoleucine, and 0.044 g leucine per person, or twice that amount in the CHO/HAA trial. The amino acids were simply added to the dextrose drink.

Why would you even believe that there may be benefits from AA supplementation?

As Wang et al. point out, "this amino acid mixture was selected as it was previously reported to be more effective in lowering the blood glucose response to a glucose challenge than isoleucine alone" (Wang. 2015) by Bernard et al. (2011).

Figure 2: Blood glucose AUC during the oral glucose tolerance test (OGTT). Sprague-Dawley rats were gavaged with either glucose (CHO), glucose plus a 5-amino acid mixture (CHO-AA-1), glucose plus a 5-amino acid mixture with increased leucine concentration (CHO-AA-2), or placebo (PLA). Blood was taken from the tail immediately before the gavage and 15, 30, 60, and 120 min afterward (Bernard. 2011).

The three test beverages were similar in color, taste, and texture to allow a double-blinded and counter-balanced study design. All test drinks were randomly assigned and dispensed by a laboratory technician who was not involved in the data collection.

Figure 3: Blood glucose postexercise and during the 4-h recovery. Treatments were with CHO (circle), CHO/LAA (triangle), and CHO/HAA (filled circle) supplements provided immediately after and 2 h after exercise. Values are mean ± SE. CHO/HAA vs. CHO (*p < 0.05). CHO/LAA vs. CHO (# p < 0.05) - left; Blood glucose area under the curve (AUC) during the 4-h recovery. Treatments were CHO, CHO/LAA, and CHO/HAA supplements provided immediately after and 2 h after exercise. AUC was calculated with baseline (pre). Values are mean ± SE. CHO/HAA vs. CHO (*p < 0.05). CHO/LAA vs. CHO (# p < 0.05) - right (Wang. 2015).

As the data in Figure 3 indicates,There was a similar effect in humans as it has previously been observed in rodents. An effect of which you as a SuppVersity reader know that it is probably mostly ascribable to isoleucine (see "The Glucose-Repartitioning Effects of Isoleucine" | more).

Figure 4: Total muscle glycogen storage in the vastus lateralis during the 4-h recovery from intense cycling. Treatments were CHO, CHO/LAA, and CHO/HAA supplements provided immediately after and 2 h after exercise. Values are mean ± SE. CHO/HAA vs. CHO (*p < 0.05 | Wang. 2015)

What is a bit disappointing is the fact that the decrease in blood glucose did not come with an increase in glycogen storage.

As the data in Figure 4 shows, the exact opposite was the case. After 4h of recovery the muscle glycogen levels were not higher, but lower in the amino acid supplemented trials.

For diabetics this wouldnt be a problem. For athletes its yet clearly a disadvantage that the 4-g recovery glycogen levels were lower and significantly lower in the low and high dose amino acid supplement trials.

Eventually this result is surprising because specifically in the high amino acid group (a) the insulin levels, (b) the AS160, a protein that controls insulin mediated glucose uptake, (c) the mTOR & p-AKT levels, (d) the "exercise hormon" levels of serum irisin  and (e) the levels of glycogen synthase which stores carbs in forms of glycogen in the high dose AA trials were significantly elevated.
References:

• Armstrong, Jane L., et al. "Regulation of glycogen synthesis by amino acids in cultured human muscle cells." Journal of biological Chemistry 276.2 (2001): 952-956.
• Bernard, Jeffrey R., et al. "An amino acid mixture improves glucose tolerance and insulin signaling in Sprague-Dawley rats." American Journal of Physiology-Endocrinology and Metabolism 300.4 (2011): E752-E760.
• Doi, Masako, et al. "Isoleucine, a potent plasma glucose-lowering amino acid, stimulates glucose uptake in C2C12 myotubes." Biochemical and biophysical research communications 312.4 (2003): 1111-1117. 
• Ivy, John L., et al. "Early postexercise muscle glycogen recovery is enhanced with a carbohydrate-protein supplement." Journal of Applied Physiology 93.4 (2002): 1337-1344.
• Ivy, J. L., et al. "Post exercise carbohydrate–protein supplementation: phosphorylation of muscle proteins involved in glycogen synthesis and protein translation." Amino acids 35.1 (2008): 89-97.
• Morifuji, Masashi, et al. "Dietary whey protein increases liver and skeletal muscle glycogen levels in exercise-trained rats." British journal of nutrition 93.04 (2005): 439-445.
• Morifuji, Masashi, et al. "Post-exercise carbohydrate plus whey protein hydrolysates supplementation increases skeletal muscle glycogen level in rats." Amino acids 38.4 (2010): 1109-1115.
• Wang, Bei, et al. "Amino acid mixture acutely improves the glucose tolerance of healthy overweight adults." Nutrition Research 32.1 (2012): 30-38.
• Zawadzki, K. M., B. B. Yaspelkis, and J. L. Ivy. "Carbohydrate-protein complex increases the rate of muscle glycogen storage after exercise." J Appl Physiol 72.5 (1992): 1854-9.

Does her hair hold the secret to her fitness body? Actually thats unlikely, but it appears possible that a hair analysis could reveals whats keeping you back from a similarly amazing physique.

Hair mineral analyses have been discredited by certain snake oil vendors who use them to sell their "oils" in form of an endless list of "essential" supplements youd have to take if you dont want to end up as dead as the hair they used to produce the analysis. Still, they share one big strength with the more expensive RBC or other cell tests: They give you an idea of your actual calcium, magnesium, sodium and potassium balance.

Much in contrast to serum levels, by the way. If those are off, its either due to an acute event (like diarrhea, for example ;-) or you have a real reason to be concerned. There is after all a really good reason these minerals are also called "electrolytes": They are heavily involved in the ion and thus charge-exchange that keeps your heart beating!
Before we get to the actual hair mineral analysis data, lets briefly have a look at another set of striking and not so striking differences between the "normal" subjects and those with established metabolic syndrome:

Figure 1: Serum mineral concentrations, visceral (VAT) and subcutaneous body fat and smoking status in subjects w/ and w/out metabolic syndrome (Choi. 2014)

If you take a closer look at the data in Figure 1 you will see that - aside from marginal, but statistically non-significant differences in serum phosphor - the often-checked total Ca, Mg, K, Na & Ph concentrations did not differ between the two groups.
Moverover, visceral fat was a much more reliable parameter to distinguish the healthy and unhealthy subjects than subcutaneous fat and... a bit to my surprise: Smoking appears to be associated with a lower metabolic risk than non-smoking.

Lets take a look at the hair analysis, now

Much in contrast to the serum levels, the hair mineral analysis did reveal significant inter-group differences and corresponding correlations:
Of all potentially toxic molecules the researchers measured only the levels of arsenic and lead differed significantly between the two groups. The concentrations of cadmium, mercury, and aluminum were not different between the two groups, on the other hand, did not.
References:

• Choi, Whan-Seok, Se-Hong Kim, and Ju-Hye Chung. "Relationships of Hair Mineral Concentrations with Insulin Resistance in Metabolic Syndrome." Biological Trace Element Research (2014): 1-7.
• Rowe, John W., et al. "Effect of experimental potassium deficiency on glucose and insulin metabolism." Metabolism 29.6 (1980): 498-502.

Blueberries and other foods w/ tons of polyphenols are GSH boosters (Moskaug. 2005) and make supplements obsolete.

If you have been interested in dietary supplements for some time, I am pretty sure that you will have heard about oral glutathione ob(GSH) supplements in one of the "snake oil warnings" on various websites. The "master antioxidant" as it is called is after all believed by many to be not bioavailable - at least not orally. Studies in animal models, however, have already shown that oral GSH, administered either in the diet or by gavage, has the ability to increase plasma and tissue GSH levels ( Loven. 1986; Aw. 1991; Favilli. 1997; Kariya. 2007). It would thus be more appropriate to say that the efficacy of oral glutathione in humans has not yet been tested in peer-reviewed studies.
Now, the absence of human studies should definitely ring an alarm bell in the head of every healthily skeptic supplement user, what it should not do, though is mislead you to believe that GSH supplements dont work in human beings.

Now this is where John P. Richie Jr. and his colleagues from the Penn State Cancer Institute, the Department of Microbiology and Immunology at the Penn State University College of Medicine and the Orentreich Foundation for the Advancement of Science, come into play. As the scientist state, their "objective was to determine the long-term effectiveness of oral GSH supplementation on body stores of GSH in healthy adults." (Richie. 2014)
To this end, they conducted a 6-month randomized, double-blinded,placebo-controlled trial in the course of which the subjects, 41 women and 13 men (6 dropouts not included) with a normal BMI and no known health issues, consumed either ...

• an oral GSH supplement dosed at 250mg/day,
• an oral GSH supplement dosed at 1,000mg/day, or
• an identically looking placebo.

The main study outcomes were obviously analyses of the GSH levels in (a) blood, (b) erythrocytes, (c) plasma, (d) lymphocytes and (e) exfoliated buccal mucosal cells (the effects on a battery of immune markers was tested only in a handful of subjects).

Figure 1: Effects of 6 months GSH supplementation on ratio of oxidized to reduced GSH and natural killer cell cytotoxicity in healthy men and women aged 28-72y (Richie. 2014)

As the data in Figure 1 already suggests, there was a dose-dependent increase in GSH levels. With the high dose (1,000mg/day) producing GSH increases of 30–35 % in erythrocytes, plasma and lymphocytes and 260 % in buccal cells (P<0.05) and increases of 17 and 29 % in blood and erythrocytes, respectively, in the low-dose group (P<0.05 - data not shown in Figure 1).

These improvements had beneficial downstream effects on the overall status of the subjects antioxidant defense system. A fact you can conclude based on the decreased ratio of oxidized (used) to reduced (fresh) glutathione in whole blood the scientists observed in their subjects after 6 months. These benefits came hand in hand with an increase in natural killer cytotoxicity (+100%), another potentially highly desirable health benefit.

References:

• Aw, Tak Yee, Grazyna Wierzbicka, and Dean P. Jones. "Oral glutathione increases tissue glutathione in vivo." Chemico-biological interactions 80.1 (1991): 89-97.
• Favilli, Fabio, et al. "Effect of orally administered glutathione on glutathione levels in some organs of rats: role of specific transporters." British journal of nutrition 78.02 (1997): 293-300.
• Kariya, Chirag, et al. "A role for CFTR in the elevation of glutathione levels in the lung by oral glutathione administration." American Journal of Physiology-Lung Cellular and Molecular Physiology 37.6 (2007): L1590.
• Loven, Dean, et al. "Effect of insulin and oral glutathione on glutathione levels and superoxide dismutase activities in organs of rats with streptozocin-induced diabetes." Diabetes 35.5 (1986): 503-507.
• Moskaug, Jan Ø., et al. "Polyphenols and glutathione synthesis regulation." The American journal of clinical nutrition 81.1 (2005): 277S-283S.
• Richie Jr, John P., et al. "Randomized controlled trial of oral glutathione supplementation on body stores of glutathione." European journal of nutrition (2014): 1-13.