Consumption of small whole fish could reduce all-cause mortality and cancer risks in women, research finds

25 Jun 2024 --- The intake of small fish may reduce the risk of all-cause cancer and cancer mortality, according to a recent study conducted on Japanese women. The research underscores the potential life-extending health benefits of habitually eating whole, small fish.

The researchers highlight that Japanese people often consume small fish, such as Atlantic capelin, Japanese smelt, dried sardines and whitebait. Moreover, in Japan, it is common to eat whole fish, including the organs, bones and head, which are rich in micronutrients such as vitamin A and calcium.

“Previous studies have revealed the protective effect of fish intake on health outcomes, including mortality risks,” says Dr. Chinatsu Kasahara, lead author of the study. “However, few studies have focused on the effect of the intake of small fish specifically on health outcomes.”

“Small fish are easy for everyone to eat, and they can be consumed whole, including the head, bones and organs. Nutrients and physiologically active substances unique to small fish could contribute to maintaining good health. The inverse relationship between the intake of small fish and the mortality risk in women underscores the importance of these nutrient-dense foods in people’s diets.” 

Boosting women’s health
Published in Public Health Nutrition, the study included 34,555 men and 46,247 women — 80,802 participants in total — ranging in age from 35 to 69 years across the country. The frequency of the participants’ small fish consumption was assessed using a food frequency questionnaire at baseline.

The researchers followed each participant for an average of nine years. During the follow-up period, 2,482 deaths from people included in the study were recorded and approximately 1,495 deaths were cancer-related.

The significant finding of the study was the reduction in all-cause and cancer mortality among female participants. Women who eat small fish one to three times a month, one to two times a week or three times or more a week had lower rates of all-cause mortality along with a lower risk of cancer mortality, compared to those who rarely eat small fish. 

Stable results
According to the research team, these results were apparent even after controlling for factors such as age, habits like smoking and alcohol consumption, body mass index and the intake of other foods and nutrients.

“The habit of eating small fish is usually limited to several coastal or maritime countries, such as Japan,” explains Dr. Takashi Tamura, second author of the study and associate professor at Nagoya University Graduate School of Medicine, Japan. “However, we suspect that the intake of small fish anywhere may be revealed as a way to prolong life expectancy.”The research found that consuming whole white fish reduced all-cause mortality and cancer risks in women.

“Further evidence is necessary to elucidate the potential role of the intake of small fish in mortality risk.”

Differences in male participants
Though the risk of all-cause and cancer mortality in men showed a similar trend, it was not found to be statistically significant when compared to the women participants. The research team highlighted that reasons for the lack of significance in men remain unclear.

However, it may have been affected by the limited number of male participants or even by other factors not measured in the study. Additionally, the difference in results could be sex-specific.

Kasahara points out that the results show a need for additional research to better understand the mechanisms involved and to test if the results are different in other populations.

“While our findings were only among Japanese people, they should also be important for other nationalities,” Kasahara concludes.