Collagen Peptides vs. Whey Protein for Muscle Growth

It is well understood that protein is beneficial for muscle growth, however, it is one molecule in particular that is crucial. Leucine is a key molecule for muscle growth, and some proteins contain more leucine than others. 

We interview Stu Phillips to share the details of his research taking collagen and whey protein head-to-head for muscle growth.

I have been with McMaster University now for 23 years, and my research focuses on skeletal muscle. We consider age with younger people and older people, then consider what happens in muscle with resistance exercise (loading), or with immobilisation or bed rest (unloading).

Outside of work, my true passion is rugby. I don’t play any more, but I love watching it! I also love staying fit. 

A PhD student of mine, now Dr Sara Oikawa, did a great job comparing collagen peptides with whey protein to show the impact on muscle protein synthesis at baseline and with resistance exercise^[1].

The study had subjects consume isonitrogenous quantities of whey or collagen, meaning the protein content was the same;  however, there was a big difference in the quality of the two protein supplements.

In whey protein, the leucine content is much higher. Leucine is the key amino acid to stimulate muscle growth and this was shown in the outcomes. When stimulated with exercise, whey is significantly more effective.

We used a new testing method which shows muscle synthesis over days, and the chronic 5-day muscle growth was significantly higher with whey protein than with collagen supplementation. In line with our hypothesis, proteins that contain higher leucine like whey are superior in stimulating muscle protein synthesis.

Of late, collagen has enjoyed somewhat of a renaissance for its potential bioactivity. We wanted a head to head comparison. Collagen is lower in leucine, therefore is not as effective at stimulating muscle growth. It is an incomplete protein as it doesn’t contain tryptophan unless its added.

With those features it becomes hard to reconcile how collagen could support muscle protein synthesis. Perhaps supporting other tissues could be a proposition for collagen peptides, however, it would have a dilutive impact on protein quality measures.

The most correct statement is that for muscle, protein quality is linked directly with leucine content and essential amino acid profile. A protein will always be superior for muscle growth when it has a full essential amino acid profile and higher leucine levels.

Considering that, you can’t do a lot better than whey protein. Like a light switch, rapidly digesting whey stimulates anabolism, then the rest of the essential amino acids provided are the supporting cast to enable muscle growth to continue .

There are a number of studies using crystalline leucine as a top-up to compensate for poorer quality proteins.

These studies convincingly show you can make the protein perform better, however I think the major stumbling point is that leucine has one of the most bitter profiles that you could imagine of all twenty, having tasted them all!

There’s actually very little evidence that that a combination of branched chain amino acids would do anything superior to leucine alone. In reality, you need leucine and all of the other essential amino acids to make things work.

There needs to be a consideration for product compliance as a key element for future success. Lower doses of whey protein are more effective and taste much better in products whilst still supporting muscle growth .

In general, we see that young men and young women are similar in terms of their response to stimulus in creating new muscle. Beyond puberty with the associated hormonal changes, men and women’s muscles are stimulated in very similar ways.

Where things diverge is after menopause where women’s hormones change significantly. Bone is known as the key tissue which undergoes change with hormonal fluctuations, but we see evidence that post-menopause there are also muscular problems.

Much of the existing protein and muscle mass-related research has been done in men and we wanted to take into account the hormonal impact of menopause and determine if that was able to be overcome with certain proteins. We see in this study that with proteins of high quality, you can overcome the anabolic resistance typically seen in older women. 

We now are happy to have good proof of concept of superiority of whey protein compared to collagen peptides for muscle synthesis. The holy grail of geriatric care is to look to physical outputs – such as improvements in the 6 min walk test, sit to stand or functional outcome; that would be a great step forward if we could show whey to be effective in this regard.

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