Sports Ingredients: Going the Distance

Pedaling on stationary bicycles, lifting dumbbells, and pushing leg presses-it’s time for Nutritional Outlook’ssports ingredient coverage. Like in any other year, private- and public-funded studies are putting average Americans to the test in clinical trials to see which dietary ingredients truly support athletic performance. Here’s a look at some ingredients making moves in the sports market.

L-Glutamine

L-glutamine is the most abundant amino acid in the human body, and its relationship with exercise is substantial. A great body of science suggests that L-glutamine plasma levels drop during prolonged exercise. While science is still needed to fill some holes in our knowledge of this amino acid, published studies suggest that L-glutamine can increase hydration, which may be notable considering scientists have stated that dehydration levels of as little as 2% can impact physical performance. Other results believed to come from L-glutamine are improved immune response after exercise and increases of human growth hormone, which may increase lean body mass and help injury resistance.

As research continues on this significant nutrient, absorption has become a significant discussion. As it turns out, L-glutamine uptake may be aided by other amino acids. In 2008, Kyowa Hakko (New York City) began marketing an ingredient called Sustamine, which science suggests results in accessible L-glutamine levels superior to L-glutamine alone.

Sustamine is a dipeptide of L-glutamine and L-alanine, and scientists believe the combination of these two amino acids greatly increases the efficiency of ion transporters in the intestine, where L-glutamine is absorbed.

A study published in February’s Journal of International Sports Nutritionmeasured the effects of Sustamine on 10 athletic, college-aged males. The intention was to determine Sustamine’s effect on time to exhaustion after prolonged exercise (in this case, cycling up to 75%
VO2_maxon an ergometer). Blood samples were drawn at subject baseline before exercise, immediately before the same exercise with Sustamine, immediately after exercise with Sustamine, and after a 24-hour resting period. Subjects received 0.05 g or 0.20 g of Sustamine per kg body weight.

After exercise, glutamine plasma levels were recorded as significantly greater with the higher dosage, but not with the lower dosage. Even so, time to exhaustion significantly increased with both groups, supporting previous study findings that L-glutamine can improve time to exhaustion after exercise.

The study was funded by Kyowa Hakko and performed by independent researchers.

Kyowa Hakko’s Sustamine isn’t the only L-glutamine ingredient being tested on today’s market. FrieslandCampina Domo (Paramus, NJ) has an older alternative in Glutamine Peption, which launched back in 1998. Glutamine Peption is a peptide comprised of many amino acids. Beyond that, it’s rich in protein. Glutamine Peption is actually sourced from wheat protein, offering 78% protein.

Both Sustamine and Glutamine Peption have received Generally Recognized as Safe (GRAS) status and are available for formulation in a variety of food and beverages.

One thing that may be certain is L-glutamine’s safety profile. L-glutamine is considered safe when taken in dosages as indicated. In one study, athletes supplemented with 28 g of glutamine every day for 14 days, and no adverse health events were reported.

Arginine

The list of sports-aiding aminos goes on with arginine. In a study published in the March issue of the Journal of the International Society of Sports Nutrition, arginine showed positive effects on exercise. In a double-blind, placebo-controlled, two-arm study, 16 cyclists over 60 years old were given placebo or an arginine-and-antioxidants supplement. Cyclists performed an exercise protocol on cycle ergometers, and breath-by-breath analysis was conducted at baseline, week one, and week three. Results in the arginine group showed striking improvements compared to placebo. Increases in anaerobic threshold were noted in the arginine group by an average of 16.7% (week one) and 14.2% (week three). No significant change of anaerobic threshold was detected in the placebo group. The study’s researchers noted that every single subject in the supplemented group showed increases in anaerobic threshold.

A partial explanation of the results of the previous study may be suggested by another study, published in April in the Journal of Strength and Conditioning Research. Seventeen subjects were assigned to an exercise protocol. Before the exercise protocol, two minutes immediately after, and one hour after recovery, subjects’ blood samples were taken. Various hormone levels were analyzed for changes, and growth hormone was found to increase in those supplementing with arginine. Previously published clinical science has linked growth hormone to increased lean mass and increased bone density, among other effects.

Carnitine

L-carnitine, the amino acid commonly regarded as a benefactor of heart health, continues to show potential in the field of exercise recovery. In a double-blind, placebo-controlled, crossover trial published in the journal Metabolism: Clinical and Experimental, researchers at the University of Connecticut tested the effects of 2 g of L-carnitine or placebo on 18 healthy men and women after they exercised.

Supplementation occurred for three weeks and three days followed by a one-week washout period and the second half of the counterbalanced treatment. During each supplementation period, subjects performed four sets of 15 repetitions of squat and presses.

Researchers analyzed blood samples of subjects for physical stress biomarkers at baseline before exercise; at 0, 15, 30, and 120 min post-exercise; and during four days of recovery. After both treatments, researchers concluded that supplementation significantly reduced levels of xanthin oxidase and hypoxanthine (commonly used markers of exercise-induced oxidative stress), and myoglobin and creatine kinase (markers of muscle tissue disruption).

L-carnitine was provided for the study by Lonza (Basel, Switzerland). 

“These findings support our previous findings of L-carnitine in younger people that such supplementation can reduce chemical damage to tissues after exercise and optimize the processes of muscle tissue repair and remodeling,” wrote the study’s author.

Phospholipids

Phospholipids are essential to the human body, as they make up the membranes of all of our cells. One type of phospholipid is called phosphatidylserine (PS), and science indicates it could very well have an impact on exercise recovery.

PS can be obtained through the diet from animal meat, and, to a much lesser degree, from some non-meat foods like vegetables. As a dietary supplement, it’s perhaps best known for cognitive function in aging humans. PS currently has two qualified FDA health claims that are characterized as having “very limited and preliminary” research: “Consumption of [PS] may reduce the risk of dementia in the elderly” and “Consumption of [PS] may reduce the risk of cognitive dysfunction in the elderly.”

Over the past couple of decades, PS has been emerging as a potential candidate for athletic supplementation. Studies indicate that PS can lower natural levels of cortisol, a hormone released when the body is under physical and psychological stress. Too much cortisol could mean serious health imbalances, like rapid conversion of proteins to energy, a weakened immune system, and even lowered testosterone.

Chase Hagerman, business development and marketing manager at Chemi Nutra (White Bear Lake, MN), says the road for PS as a viable athletic ingredient looks promising-which is why Chemi Nutra continues to offer its patent-pending SerinAid brand PS.

Published studies on PS are continuing to move forward. Adding to the already sizeable list of PS studies, the Journal of the International Society of Sports Nutritionpublished a PS study in 2008. In this double-blind, placebo-controlled, crossover study, 10 non-vegetarian males were assigned to 600 mg of PS or placebo daily, for 10 days. Blood samples were taken at baseline, after exercise (five three-minute stages on a cycle ergometer from 65% VO2_maxto 85% VO2_max), and during a 65-minute recovery session. Blood was measured for cortisol, testosterone, and testosterone-to-cortisol ratios, among other markers.

Blood recordings indicated cortisol levels were significantly lower in the PS group (which supports previous research). PS also increased testosterone and testosterone-to-cortisol levels, but the differences compared to placebo were not deemed significant. The study’s researchers noted that some results of their study conflict with previous studies and that this may be related to differences in the intensity of exercise used and the PS dosing levels used.

While studies suggest that PS inhibits cortisol release, the theory that cortisol negatively impacts physical recovery continues to strengthen. Most recently, Spanish researchers analyzed the blood serum of 21 male skiers before and after a two-day race. In their analysis, cortisol was shown to have a negative association to total energy; protein; fat intake; vitamins C, B1, and B2; and niacin. This study was published in the June issue Journal of Sports Science & Medicine.

Read our creatine update here.

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