Glutamine for Athletes: Boost Immunity & Recovery?

observational-study PMID: 38193521

Quick Summary: A recent study found that L-glutamine supplements helped combat sport athletes by boosting their immune systems, improving hormone balance, and potentially reducing the risk of getting sick after intense training.

What The Research Found

This study looked at how L-glutamine affects combat sport athletes. The results showed that taking L-glutamine for three weeks:

Strengthened Immunity: Increased levels of important immune factors in saliva, which helps fight off infections.

Improved Hormones: Helped maintain healthy testosterone levels and reduced cortisol (a stress hormone), leading to a better hormone balance.

Reduced Illness: Athletes taking glutamine were less likely to get upper respiratory infections (like colds).

Study Details

Who was studied: 21 combat sport athletes.

How long: 3 weeks.

What they took: Athletes took either L-glutamine powder (0.3 grams per kilogram of body weight) or a placebo (a harmless substance) mixed with water, once a day.

What This Means For You

If you're a combat sport athlete, this research suggests that L-glutamine might help:

Stay Healthy: Reduce your chances of getting sick after tough workouts.

Recover Faster: Improve your hormone balance, which is important for muscle recovery.

Boost Performance: By staying healthy and recovering better, you may be able to train harder and perform better.

Important Note: Always talk to your doctor or a qualified healthcare professional before starting any new supplements.

Study Limitations

Small Group: The study only included a small number of athletes, so more research is needed to confirm these findings.

Short Time: The study lasted only three weeks. We don't know if the benefits would last longer.

Specific Athletes: The study focused on combat sport athletes. The results may not be the same for other types of athletes or people who don't exercise.

Subjective Data: The study relied on self-reported data for illness and well-being, which can be less reliable.

Key Findings

This 2024 study found that 3 weeks of L-glutamine supplementation (0.3 g/kg body weight/day) in combat-sport athletes significantly increased salivary immunoglobulin A (IgA) and nitric oxide (NO) concentrations, reduced upper respiratory tract infection (URTI) incidence, and improved the testosterone-to-cortisol (T/C) ratio compared to a maltodextrin placebo. However, the placebo group reported higher mood scores on the Hooper’s Index questionnaire, suggesting mixed effects on subjective well-being.

Study Design

The study was a randomized, controlled observational trial involving 21 combat-sport athletes (age, sex, and sport unspecified) from the National Taiwan University of Sport. Participants were divided into an L-glutamine group (GLU, n=10) and a maltodextrin placebo group (PLA, n=11). Saliva samples and wellness questionnaires were collected pre- and post-intervention to assess immune markers (IgA, NO), hormonal status (testosterone, cortisol), and URTI rates during intensive training.

Dosage & Administration

The GLU group received 0.3 g/kg body weight/day of L-glutamine powder dissolved in water, while the PLA group consumed an equivalent dose of maltodextrin. Supplements were taken daily at the same time for 3 weeks post-training.

Results & Efficacy

Immune Function: GLU increased salivary IgA (p<0.05) and NO levels (p<0.05), indicating enhanced mucosal immunity. URTI incidence was significantly lower in GLU (no exact rate provided).
Hormonal Status: The PLA group showed decreased testosterone (T) and increased cortisol (C), lowering the T/C ratio (p<0.05). GLU maintained T levels and reduced C, improving the T/C ratio (p<0.05).
Wellness: GLU reported better overall well-being per the Hooper’s Index, but PLA had higher mood scores (p<0.05).

Limitations

Small Sample Size: Only 21 participants (10 GLU, 11 PLA) limit statistical power and generalizability.
Short Duration: 3 weeks may not capture long-term effects or sustainability of benefits.
Population Specificity: Results apply only to combat-sport athletes; no data on other athlete types or non-athletes.
Self-Reported Outcomes: URTI incidence and Hooper’s Index rely on subjective reporting, risking bias.
Unspecified Baseline Data: Demographics (age, sex) and training intensity were not detailed.
Contradictory Wellness Results: Improved hormonal status in GLU conflicts with higher mood scores in PLA, requiring clarification.

Clinical Relevance

For combat-sport athletes undergoing intensive training, L-glutamine (0.3 g/kg/day) may support immune function and hormonal balance, potentially reducing URTI risk and aiding recovery. However, the lack of detailed statistical metrics (e.g., effect sizes, confidence intervals) and mixed well-being outcomes suggest cautious interpretation. Larger, longer trials in diverse athletic populations are needed to confirm these effects and determine optimal dosing. Athletes should consider individual variability and consult healthcare professionals before supplementation.

Note: The study’s classification as an observational study conflicts with its randomized, placebo-controlled design, which aligns more with a clinical trial. This discrepancy may affect the perceived strength of evidence.

Glutamine for Athletes: Boost Immunity & Recovery?