What’s the Deal With Collagen?

By Aadam | May 19, 2022

This post is taken from Physiqonomics Weekly. Every Thursday I drop some knowledge bombs on your face to help you get to your goals quicker while avoiding all the bullshit.

Collagen protein is the most abundant protein in the human body and is a major component of bone, muscle, tendons, ligaments, and cartilage. Considering the key role collagen plays in the human body, you’d be forgiven for thinking collagen can be a valid protein source for muscle gain––especially with the marketing hype surrounding it. 

The problem, however, is collagen has a pretty terrible amino acid profile; it’s rich in non-essential amino acids like proline and glycine but low in essential amino acids like methionine and leucine, and completely lacks tryptophan. For example, collagen has a Digestible Indispensable Amino Acid Score (DIAAS)–– a method used to rank the quality of different protein sources––of zero. Compare this to whey protein which has a DIAAS of 1.09. 

Note: there are 20 amino acids. 11 of these are “non-essential”, meaning the body can produce them. 9 of these are “essential”, meaning the body can’t produce these, and they need to be provided through the diet. To create new muscle protein, all the amino acids must be present in adequate amounts (especially the essential amino acids). In the case of collagen, it lacks the essential amino acid tryptophan, hence the DIAAS score of zero.

Despite the poor amino acid profile of collagen, some studies have found that collagen supplementation can increase muscle and strength compared with a placebo. 1 2 3

This shouldn’t be that surprising. If one group receives protein while the other doesn’t, you can expect the protein group to gain muscle.

Though, one of these studies 1 has been questioned by other researchers, noting the muscle gain reported in the study exceeded that of another study where participants were taking steroids. 4

Another study that directly measured muscle growth noted the increase in fat-free mass observed in the collagen group was likely due to an increase in connective tissue (not muscle tissue). 2

Ok, let’s put nitpicking aside for a moment and assume that collagen protein might increase fat-free mass compared to a placebo. But to truly determine if collagen has any anabolic properties, we need a study that compares collagen protein to a high-quality protein source like whey. 

Well, that’s exactly what a group of researchers decided to do in a recent study. The researchers wanted to investigate the effects of whey and collagen protein supplementation on muscle size during a 10-week resistance training program in young adults. This was an important study because, unlike previous research that compared collagen to a placebo, this study directly compared collagen to whey protein (a high-quality protein source). Let’s see what they did and what they found.

What did the researchers do?

Originally there were 36 participants but 14 were lost to follow up, so 22 participants completed the study (16 males, 6 females). The participants were matched according to sex and strength and then randomly assigned to one of two groups.

1- Whey Protein: Participants consumed 35g of whey protein isolate containing 3g of leucine in addition to the protein they were consuming from their regular diet (around 1.4g/kg or 0.6g/lb)

2- Leucine-matched Collagen Protein: Participants consumed 35g of hydrolyzed collagen peptide containing 1g of leucine and received an extra 2 g of leucine to match the total amount of leucine (3 g) of the whey protein group. Like the previous group, the collagen protein was supplemented in addition to the protein they were getting from their regular diet (1.5g/kg or ~0.7g/lb).

The participants resistance-trained 3x/week, consisting of three sets of 8-12 reps with 90-120 secs rest between sets and exercises. Training loads were increased weekly to ensure progressive overload. 

Dietary intake records were completed 3 days a week (a training day, an off-day, and a weekend day) at baseline and weeks 3, 7, and 10 of the study.

The main outcomes the researchers were interested in were muscle hypertrophy of the vastus lateralis and biceps brachii (assessed via ultrasound), isokinetic strength and power of elbow flexors, and peak power of the lower body (assessed via countermovement jump).

The researcher’s used Cohen’s d effect size to quantify the change from pre– to post-training. An effect size of <0.19 was considered trivial, 0.20–0.49 was considered small, 0.50–0.70 was considered moderate, and 0.80 was a large effect size.

What did the researchers find?

The whey protein group experienced a significantly larger increase in muscle thickness (a moderate effect size of 0.68 for vastus lateralis and 0.61 for biceps brachii) compared to the collagen group (a small effect size of 0.38 for vastus lateralis and 0.35 for biceps brachii). In terms of percentage change, the whey protein group saw an 8.4% increase in vastus lateralis and a 10.1% increase in biceps brachii compared to 5.6% and 6% in the collagen group. 

Muscle thickness of the vastus lateralis and biceps brachii in the WP (n = 11) and CP (n = 11) groups before and after the 10-week RT program. The box plot shows the median (line) and mean (+), interquartile range (box), and the maximum and minimum values (whiskers).
“a” p < .05 compared with pretraining values for both groups (ANOVA; time effect).
“b” p < .05 compared with CP group (ANOVA; Group × Time interaction).

There were no significant differences between groups for all other measures (training load, lower-body peak power, or isokinetic elbow flexor strength or power).

Practical applications

The researchers hypothesised that leucine-matched collagen protein supplementation would result in similar muscle hypertrophy as whey protein supplementation. Despite similar gains in muscle strength and power, the whey protein group outperformed the collagen protein group in muscle gain.

When I get asked about collagen protein, my advice is to either not count it towards your total protein intake or increase your protein intake to account for the grams of collagen you’ve consumed. Take a look at the table below, and I’ll explain why.

As you can see, the whey protein group consumed around ~1.9g/kg of protein per day (1.4g/kg/d from food and 0.5g/kg from supplementation) throughout the study barring Week 3, where protein intake dropped to 1.6g/kg/d. On the other hand, the collagen group’s protein intake dropped from 2g/kg/d to 1.6g/kg/d but was still consuming enough protein overall (≥ 1.6g/kg/d or ≥ 0.7g/lb). And yet, the whey protein group outperformed the collagen group in muscle growth. The researchers noted this was likely due to the lower essential amino acid content of the collagen protein (7.7g versus whey protein’s ~14g), which “wasn’t sufficient to reach the threshold of essential amino acids to maximally stimulate MPS (~8.6g).”

If you were feeling particularly pugnacious, you might argue collagen has benefits on joint health and skin ageing. And I may acquiesce and say you have a point, but we can’t say for sure. A 2018 consensus statement by a group of leading sports nutrition researchers on supplements notes that: 5

Few data [are] available, but increased collagen production and decreased pain seem possible. Functional benefits, recovery from injury, and effects in elite athletes are not known.

A recent meta-analysis found that collagen may improve joint function and reduce joint pain. 6 While another meta-analysis found collagen supplementation improved skin hydration, elasticity, and wrinkles. 7

However, all the studies that have looked at collagen’s effect on joint pain and skin health have either used collagen protein on its own or compared with a placebo, and more research is needed before we can conclude whether collagen protein alone could have benefits that extend beyond muscle growth, especially when an individual is already consuming enough high-quality protein. For instance, one study found no difference in muscle collagen protein synthesis between collagen and whey protein. While this is just one study, it may be the case that total protein intake (and a higher quality amino acid profile) is more important for collagen protein synthesis than collagen alone. 8

It’s also worth pointing out many collagen studies have been funded by supplement companies. This doesn’t mean we can’t trust a study because it’s had industry funding but it pays to be sceptical until we have more independently funded research.

In sum, if the goal is muscle hypertrophy, then high-quality protein sources should be your go-to option. As for the other purported benefits of collagen, well, we can’t say for sure at the moment. But my pragmatic advice would be this: If you find a difference when you take collagen, then by all means continue taking it. Just be mindful you’re not replacing a large portion of high-quality proteins with low-quality proteins like collagen. 


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