Fish protein, particularly when derived from fish such as salmon, sardines, and mackerel, is recognized for containing not only high-quality amino acids but also bioactive peptides and associated nutrients like omega-3 fatty acids. While omega-3s are more frequently cited in the literature for their antioxidant and anti-inflammatory properties, fish protein itself has demonstrated some capacity to mitigate free radical damage through several mechanisms.

Scientific studies indicate that certain peptides isolated from fish protein hydrolysates can enhance the body's antioxidant defenses. These peptides may act by upregulating endogenous antioxidant enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase, or by directly scavenging free radicals. Several in vitro and animal studies have reported that fish protein hydrolysates reduce oxidative stress markers and lipid peroxidation. For example, research published in Food Chemistry and Journal of Functional Foods has shown that fish-derived peptides can protect cells from oxidative damage and reduce overall oxidative stress in animal models.

However, while the laboratory and animal model evidence is promising, robust clinical trials in humans are relatively limited. Most human evidence focuses on the broader health benefits of fish intake, which includes but does not isolate the contribution of fish protein against free radical damage. Therefore, while there is a scientific basis for the use of fish protein to support antioxidant defenses and combat free radical damage, the evidence level is best rated as moderate (3/5) due to the need for more large-scale, well-controlled clinical studies.