Collagen is a protein. But is a collagen bar a protein bar?

Walk into an urban pharmacy and browse the protein bar aisle, and you’ll increasingly find products built around collagen, marketed as easy ways to boost your protein intake. Some prominently display their protein content alongside claims about improving skin, hair, joints or muscle recovery.

For consumers trying to eat more protein, the message seems straightforward: collagen is protein, so a collagen bar must be a protein bar. But while collagen is indeed a protein, it is not nutritionally interchangeable with the proteins found in foods such as eggs, dairy, soy, or meat.

The difference comes down to what each type of protein actually does in the body, and the amino acids it provides.

An incomplete protein

When we consume protein, our digestive system breaks it down into amino acids, which the body uses to build and repair proteins. Of the 20 amino acids used by the body, nine are considered essential because we cannot make them ourselves and must obtain them from food.

Collagen is the body's major structural protein and is abundant in skin, bones, cartilage, tendons and ligaments. A ‘complete’ protein contains all nine essential amino acids in adequate amounts. Collagen is an incomplete protein since its amino acid profile is mainly composed of glycine, proline and hydroxyproline, all of which are non-essential amino acids. It contains no tryptophan, an essential amino acid which regulates sleep, mood and muscle synthesis; and very little methionine and leucine, which aid in the growth and repair of muscles and tissues.

While collagen is indeed a protein, it is not nutritionally interchangeable with the proteins found in foods such as eggs, dairy, soy, or meat.

That makes collagen an unusual, if impractical protein supplement. For starters, collagen is found naturally only in tougher cuts of red meat and the bones and skin of fish like tilapia and salmon. Its molecules (whether from whole foods or supplements) are also too large and tightly bound to be absorbed directly into the body. The gut breaks it down into individual amino acids and short chains of amino acids called peptides. This means that even though products may be marketed as collagen ‘supplements’ or ‘boosters,’ our bodies don’t preserve these distinctions and utilise them as is. The amino acids from a collagen supplement may be routed to wherever our bodies deem necessary at the moment—perhaps for cartilage or bone integrity, or for the keratin in our hair.

Another significant reason why this protein is not the most nutritionally efficient supplement, is because a large share of its amino acids are ones the body can produce itself. Simultaneously, it is deficient in amino acids that the body cannot make and must obtain from food. So although collagen contributes to the total number of grams of protein consumed, those grams are not nutritionally equivalent to the same amount of a protein rich in indispensable amino acids.

A large share of its amino acids are ones the body can produce itself.

This distinction matters especially when collagen is used as the main protein in a supplement or food marketed to people trying to increase their protein intake. Ten grams of collagen still count as ten grams of protein on a nutrition label. But they do not deliver the same amino-acid package as ten grams of a complete protein like whey, milk, egg or soy.

Also read: The human body needs collagen. Does it need collagen supplements?

How does collagen fare on nutritional scales?

The Protein Digestibility Corrected Amino Acid Score (PDCAAS) is one standard method used to measure protein quality. It first compares the amount of each essential amino acid in a protein, such as collagen, with what the body needs, and identifies the amino acid which is most deficient. This gives the protein its amino acid score, which is then combined with the protein’s digestibility percentage to give the PDCAAS score. This score, expressed as a number between 0 and 1, signifies the quality of any protein consumed after factoring in its amino acid profile and digestibility.

Since the score is ultimately determined by the most deficient essential amino acid, the absence of tryptophan in collagen drives its PDCAAS score to zero. This does not mean it contains zero protein or that the body simply ignores it. But if collagen were your only protein source, its amino-acid profile would be inadequate to meet your body's requirements.

If collagen were your only protein source, its amino-acid profile would be inadequate to meet your body's requirements.

If a collagen bar claims to ‘boost’ protein (especially for people building muscle), it is important to consider how much of that protein comes from collagen alone and whether it is complemented by other protein sources. If a collagen supplement’s primary selling point is that it boosts protein intake, the promise deserves a closer look: the number on the label does not tell you the quality of the protein behind it.

For someone simply looking to eat more protein, foods such as dairy, eggs, soy, pulses, fish and meat provide a broader mix of indispensable amino acids. Collagen may have a place of value for other reasons, but as a protein supplement, its appeal should not rest on the word ‘protein’ alone.

Also read: Protein’s seen and unseen benefits: How it affects metabolism, muscle repair