Could collagen supplementation improve bodily functions?

Peer reviewed / Manuscript (original) submitted: February 9, 2023 / Revision accepted: July 18, 2023

Physiological aspects of collagen supplementation: a narrative review

Introduction

Collagens
Collagens are structural proteins consisting of 662–3152 amino acids, with glycine, lysine and proline forming the largest percentage of these in quantitative terms [1]. Collagens play an important role wherever there are solid body structures, such as skin, bones, teeth, cartilage, intervertebral discs and ligaments. The human body synthesizes collagen through endogenous collagen synthesis. The capacity for synthesis decreases with increasing age [1]. There are 28 types of collagen, all of which share a triple helix as their common structure. This structure is also known as the collagenous domain. The molecular structure also includes non-collagenous domains. These either have structural functions or are biologically active. Examples include von Willebrand factor domains, Kunitz domains, fibronectin [2], and thrombospondins [3].

Collagens occur naturally in foods such as meat and fish. They are a component of both human and animal body structures and are necessary for their construction [1]. Gelatin is purified collagen with a collagen content of up to 85%. Foods with a high gelatin content, such as aspic and gummy bears, contain between 4 and 8 g of collagen per 100 g [4]. Native collagens and collagen hydrolysates are also available in the form of nutritional supplements. Collagen hydrolysates are formed under the action of heat together with acids and alkalis to produce collagen peptides. Their water solubility is said to facilitate absorption [5]. Furthermore, adequate vitamin C supply is essential for the maintenance of normal endogenous collagen synthesis [6]. ...

Abstract

The possible beneficial effects of collagen supplementation, for example in osteoarthritis, skin aging, and certain inflammatory diseases, is currently a subject of discussion. To date, no mechanisms through which collagens mediate their effects have been clearly identified. Possible mechanisms of action have been little investigated as a whole, so the efficacy of collagen on the physiological level cannot yet be substantiated. Using an exploratory literature search and narrative review, this article aims to review physiological explanatory approaches and mechanisms of action that may be associated with collagen supplementation. Statements on the systemic bioactivity of collagen peptides, which appear to be able to cross the gastrointestinal barrier and exhibit relative stability in the bloodstream, mostly refer to modulation of endogenous collagen synthesis, immunological mechanisms, or influence on cell proliferation. These statements are largely based on in vitro or animal studies and also often have low evidence, which means that they cannot be easily extrapolated to the human body. Systematizing research approaches and conducting targeted studies to address unanswered questions would strengthen the physiological perspective and could yield scientific evidence that would enable well-founded statements to be made.

Keywords: collagen, supplementation, collagen peptides, osteoarthritis, skin aging, cell proliferation, collagen synthesis, availability, physiology

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