Protein derived from fish has not only nutritional properties but also health-promoting properties. Few studies have examined the effect of dietary Alaska pollock protein (APP) on the anticolitis effect reported to be associated with metabolic syndrome (MetS). This study investigated the effect of APP intake on colitis symptoms, gut microbiota, and its metabolites in the experimental colitis mouse model induced by dextran sulfate sodium (DSS). Male C57BL/6J mice were divided into three groups: (1) DSS-untreated mice fed an American Institute of Nutrition (AIN) 93G diet (protein source is casein), (2) DSS-treated mice fed an AIN93G diet, and (3) DSS-treated mice fed an APP diet. After the mice were fed the diets for 21 days, experimental colitis was induced by three cycles of 2% DSS administration for 5 days followed by washouts over the course of 5 days. APP-reduced body weight loss increased the disease activity index, and elevated spleen weight and alleviated colon length shortening and colonic tissue damage. Furthermore, APP altered the structure and composition of the microbiota and short-chain fatty acids in feces. Since APP intake alleviates experimental colitis induced by DSS administration through alterations in the gut microbiota and its metabolites, we deduced that APP would inhibit MetS progression via colitis suppression.

The discarded internal organs of the Japanese giant scallop (Patinopecten yessoensis) are abundant resources rich in n-3 polyunsaturated fatty acids (PUFA), such as eicosapentaenoic acid and docosahexaenoic acid. However, they have not been utilized due to contamination with toxic substances such as cadmium (Cd) and the occurrence of diarrhetic shellfish toxins (DST). We have successfully prepared a high-quality scallop oil (SCO) from its internal organs with negligible contamination with Cd and DST. The scallop internal organs were obtained from two different scallop processing areas, Mutsu and Uchiura bays, Japan, and referred to as SCO-M and SCO-U, respectively. To evaluate the safeties of SCO-M and SCO-U as food ingredients and n-3 PUFA supplements, repeated 28-day and 13-week dose oral toxicity studies in rats were conducted. Rats were fed diets containing 1% and 5% of SCO-M and SCO-U, respectively, in the repeated 28-day dose oral toxicity study and 5% SCO-M or SCO-U in the repeated 13-week dose oral toxicity study (limit test). No adverse toxicological effects were observed when rats were fed diets containing SCO-M and/or SCO-U at up to 5% for 28 days and 13 weeks. These results suggest that SCO-M and SCO-U are safe products in terms of subacute toxicity under these experimental conditions.

This study aimed to investigate the effects of scallop oil (SCO) on atopic dermatitis (AD)-like symptoms induced by mite allergens in the dorsal and ear skins of NC/Nga mice compared to those of refined corn oil and krill oil (KO). SCO, rich in n-3 polyunsaturated fatty acids and phospholipids, was prepared from the internal organs of Japanese giant scallop, an underutilized fishery resource in Japan. Results showed that SCO intake improved AD-like symptoms, including ear edema, ear thickness, and transepidermal water loss of dorsal skin, and tended to decrease the scratching behavior, whereas KO intake did not. Further, SCO intake decreased the degranulated mast cell count and increased the tight junction protein claudin-1 expression, which is important for the barrier function, in the dorsal skin compared to refined corn oil intake. SCO improved the AD-like symptoms by suppressing mast cell degranulation and strengthening the barrier function of dorsal skin in NC/Nga mice.