BCAA’s and Glutamine useful even when protein intake is high

Something that we hear a lot from mainstream nutritionists and even some ardent bodybuilders is that BCAA and Glutamine supplements are useful only to the extent that your dietary protein intake contains insufficient amounts of these amino acids. This school of thought proposes that by consuming plenty of meat, milk, fish and whey protein you will naturally provide your body with a very high level of BCAA and Glutamine making the supplementation of more a costly exercise in futility. Better to spend the money on more food or so the argument goes.

Objective: Colker et.al studied the effect on body mass, body composition and athletic performance of supplemental whey protein with or without additional L-Glutamine and BCAA’s to see whether or not the whey protein (naturally high in both BCAA’s and Glutamine) would be sufficient to provide the subjects’ bodies with the benefits associated with BCAA supplements.

Methods: Sixteen healthy, athletic males were divided into two groups. Group 1 received 40g whey per day (which would contain just over 6g of BCAA’s typically). The second group received the same 40g dose of whey protein along with 5g of L-Glutamine and 3G of branched chain amino acids. Both groups were given diet plans that provided protein at a level of 1.6g/kg of bodyweight.  Both groups also engaged in bodybuilding exercise and underwent performance and body composition testing at weeks 5 and 10.

Ingredients Group 1 Group 2
Whey Protein Concentrate 30.0 30.0
Whey Protein Isolate 10.0 10.0
L-Glutamine None 5.0
Branched-Chain Amino Acids    
Leucine None 1.5
Isoleucine None 0.75
Valine None 0.75

Results: Compared to their performance at the start of the study (baseline) Group 1 who supplemented with 40g whey on top of their 1.6g of protein per kg of bodyweight ended up losing bodyweight slightly although they did average a 0.5kg increase in lean mass. They dropped from an average body fat of 9.6kg to 8.8kg while they added an average 2 reps to the bench press and 5 reps to the leg press. Impressive results for whey protein you may say.

When we look at the second group who received the BCAA/Glutamine cocktail we see a massive surge in performance compared to the whey only group. They added 9 reps to their leg press and 8 reps to their bench press and this despite starting from a higher start point. They added nearly 2kg of lean mass although they only increased body mass by 1.2kg due to a 0.7kg drop in body fat.

Measure Baseline Week 10 Mean Change
Body Mass (kg)

Group 1

Group 2







Percentage Body Fat

Group 1

Group 2







Fat-Free Mass (kg)

Group 1

Group 2







Bench Press (repetitions)

Group 1

Group 2







Leg Press (repetitions)

Group 1

Group 2







Our Take: This study addressed two points which those who argue against supplemental BCAA’s make frequently. One, it provided a level of protein at 1.6g/kg of bodyweight that most dieticians would regard as being sufficient given the preponderance of studies in the past suggesting this as an upper limit for protein needs and in providing an additional 40g of whey protein on top of this few would argue their protein intake at this point which would be 2g/kg for a 100kg individual is not enough to meet their needs. Secondly, by providing a good amount of BCAA/Glutamine in the diet plus in the whey of group 1 the traditional argument that additional BCAA/Glutamine supplementation is wastefully unnecessary is one that can now be countered forcefully. The huge disparity in results between the group taking supplemental amino acids versus just whey certainly provides some justification for athletes’ long term belief in the benefits of standalone BCAA and Glutamine supplementation.

In an ideal world this study would have been split into two additional BCAA only, and Glutamine only groups to assess the relative effects of these two in isolation but for now the evidence as to the benefits this combination provides is clearly illustrated.

View our range of glutamine supplements

View our BCAA supplements


Effects of supplemental proteins on body composition and muscular strength in healthy athletic adult males Colker et.al (2000)

© 2012 – 2014, Reggie Johal. All rights reserved.

About Reggie Johal

Reggie Johal is a former Great Britain American Football player and the founder of Predator Nutrition. He has a strong background in strength and fitness coaching with articles published in Flex and other leading online and print magazines.

One thought on “BCAA’s and Glutamine useful even when protein intake is high

  1. Pingback: Adding leucine to your post workout shake can increase muscle growth « Predator Nutrition

Leave a Reply

Your email address will not be published. Required fields are marked *