# Is collagen a complete protein?

Source: https://www.healthnews24.co.za/answers/is-collagen-a-complete-protein/
Publisher: Healthnews24 (South Africa's supplement answer desk)
Updated: 2026-10-27

> No. Collagen is an incomplete protein because it contains almost no tryptophan, an essential amino acid, and it is low in leucine. As a sole protein source its quality score is effectively zero. In South Africa, use collagen for connective-tissue goals if you wish, but rely on whey, eggs, meat, dairy or soya for muscle protein.

Key facts:
- Collagen contains almost no tryptophan and is low in leucine, so it is an incomplete protein with an effectively zero quality score as a sole protein.
- Whey is about 10 to 11% leucine and scores highest among common proteins on DIAAS (Mathai 2017).
- October 2026 powder prices per 100 g: ATP collagen about R104, ATP unflavoured whey concentrate R80, Primal Whey Isolate R93.33.
- ISSN recommends 1.4 to 2.0 g/kg/day of protein for people who train, mostly from complete sources.

## Why is collagen incomplete?

A complete protein supplies all nine essential amino acids in useful amounts. Collagen is rich in **glycine, proline and hydroxyproline**, which suit connective tissue, but it has essentially **no tryptophan** and is low in leucine, the amino acid that most strongly switches on muscle protein synthesis. Protein-quality scores such as PDCAAS and DIAAS are effectively zero for collagen when it is the only protein. Whey, by contrast, is one of the highest-scoring proteins; Mathai and colleagues (2017) found whey and milk protein highest on DIAAS, ahead of soy and pea.

| | Collagen peptides | Whey protein |
|---|---|---|
| Tryptophan | Almost none | Present |
| Leucine (share of protein) | Low | About 10 to 11% |
| Protein quality (DIAAS) | Effectively zero as sole protein | Highest of common sources |
| Best use | Connective-tissue goals (emerging evidence) | Muscle building, daily protein targets |

## Does a collagen scoop count towards my protein target?

It adds nitrogen and calories, but it should not be counted as a full-quality serving. If you are aiming for 1.4 to 2.0 g of protein per kg a day (the ISSN range for people who train), get the bulk from complete sources and treat collagen as a small bonus. The per-meal target of roughly 0.25 to 0.4 g/kg with 2 to 3 g leucine cannot be met with collagen alone; see [whey isolate vs concentrate](/answers/whey-isolate-vs-concentrate-south-africa/) for the complete-protein options.

## Can I combine collagen with whey?

Yes. They do different jobs. A shake with 25 g of whey and 10 g of collagen gives a complete protein plus connective-tissue amino acids, but the whey is doing the muscle work. Do not replace whey with collagen to save money: per gram of powder, collagen is not cheaper. As of October 2026, ATP Fitness Hydrolysed Collagen costs about R104 per 100 g (910 g for R950, ATP shop), while ATP's Unflavoured Whey Protein Concentrate is R80 per 100 g (1 kg for R800) and Primal Whey Isolate is R93.33 per 100 g (750 g for R700, Dis-Chem Living Fit). ATP does not publish protein per serving, so we compare price per 100 g of powder only.

## Why do labels sometimes say "protein"?

Collagen products often list 9 to 15 g of "protein" per serving by nitrogen content (for example, Biogen Peptan lists 9.0 g and The Harvest Table Bovine lists 15 g per serving). That figure is correct as grams of protein but says nothing about quality. South African testing has found label overstatement in some protein supplements: Schönfeldt and colleagues (2019) found 5 of 70 products had 42% to 80% less protein than claimed. If you buy a "protein" product containing collagen, check the amino acid profile.

## Where does collagen fit?

- **Useful for:** skin, joint and tendon goals, with emerging evidence ([how much collagen per day](/answers/how-much-collagen-per-day/)). AIS classes it as Group B.
- **Not useful for:** muscle gain, recovery or replacing protein meals.

For muscle, see our [best whey protein](/best/best-whey-protein-south-africa/) and [best whey isolate](/best/best-whey-isolate-south-africa/) comparisons. Anyone with kidney disease, pregnant women, under-18s and people on regular medication should follow their doctor or dietitian's advice before adding protein powders, and anyone allergic to beef or fish should avoid the matching collagen.

## Products mentioned

| Product | Size | Price (source, date) | Servings | R per 10 g | R per 100 g powder | Sweeteners |
|---|---|---|---|---|---|---|
| ATP Fitness Hydrolysed Collagen | 910 g | R950 (ATP Fitness shop, 2026-10) | 91 | R10.44 | — | None |
| ATP Fitness Unflavoured Whey Protein Concentrate | 1 kg | R800 (ATP Fitness shop, 2026-10) | — | — | R80.00 | None |
| Primal Whey Isolate (750 g) | 750 g | R700 (Dis-Chem Living Fit, 2026-10) | — | — | R93.33 | sucralose |
| ATP Fitness Unflavoured Whey Protein Isolate | 800 g | R900 (ATP Fitness shop, 2026-10) | — | — | R112.50 | None |

Disclosure: ATP Fitness is a commercial partner of Healthnews24 and its products are featured on this site. Rankings follow our published method, and every pick, including ATP Fitness, shows its price maths and trade-offs.

## Sources

- [Mathai JK, Liu Y & Stein HH (2017) DIAAS values for dairy and plant proteins vs PDCAAS. Br J Nutr](https://agris.fao.org/search/en/records/65de3cca0f3e94b9e5cc4b98)
- [Jäger R et al. (2017) ISSN position stand: protein and exercise. JISSN](https://pubmed.ncbi.nlm.nih.gov/28642676/)
- [Australian Institute of Sport Supplement Framework: Group B (emerging evidence)](https://www.ausport.gov.au/ais/nutrition/supplements/group_b)
- [Schönfeldt HC, Hall N & Pretorius B (2019) High protein sports supplements: protein quality and label compliance. J Food Compos Anal 83:103293](https://repository.up.ac.za/handle/2263/74902)
- [Iwai K et al. (2005) Identification of food-derived collagen peptides in human blood after oral ingestion of gelatin hydrolysates. J Agric Food Chem](https://pubmed.ncbi.nlm.nih.gov/16076145/)