A new study has found evidence that the intake of small fish, eaten whole, is associated with a reduced risk of all-cause and cancer mortality in Japanese women. The research, conducted by Dr. Chinatsu Kasahara, Associate Professor Takashi Tamura and Professor Kenji Wakai at the Nagoya University Graduate School of Medicine in Japan, highlights the potential life-extending benefits of regularly eating small fish. The findings were published in the journal Public health and nutrition.
Japanese people usually eat small fish, such as whitefish, Atlantic capelin, Japanese smelt and small dried sardines. Importantly, it is customary to eat small fish whole, including the head, bones and organs, which are rich in micronutrients, such as calcium and vitamin A.
“Previous studies have revealed the protective effect of fish consumption on health outcomes, including mortality risk. However, few studies have specifically focused on the effect of small fish intake on health outcomes,” said lead researcher Dr. Kasahara. “I was interested in this topic because I have had the habit of eating small fish since I was a child. I now feed my children these foods.”
The research team investigated the association between small fish intake and mortality risk among Japanese people. The study included 80,802 participants (34,555 men and 46,247 women) aged 35 to 69 years across Japan. The frequency of small fish intake among participants was assessed using a food frequency questionnaire at baseline. The researchers followed them for an average of nine years. During the follow-up period, 2,482 deaths of people participating in the study were recorded, of which approximately 60% (1,495 deaths) were cancer-related.
One of the most striking findings of the study was the significant reduction in total and cancer mortality among women who habitually ate small fish. Women who ate small fish 1-3 times per month, 1-2 times per week, or 3 or more times per week had 0.68, 0.72, and 0.69 times the risk of total mortality and 0.72, 0.71, and 0.64 times the risk of cancer mortality, respectively, compared with women who rarely ate small fish.
After adjusting for factors that may influence mortality risk, such as participants' age, smoking and alcohol consumption habits, BMI, and intake of various nutrients and foods, the researchers found that women in the study who regularly ate small fish were less likely to die from any cause. These findings suggest that including small fish in their daily diet could be a simple but effective strategy for reducing mortality risk among women.
The risk of total and cancer mortality in men showed a similar trend as in women, although it was not statistically significant. The reasons for the lack of significance in men remain unclear, but the researchers speculate that the limited number of male subjects or other factors not measured in the study, such as portion size of small fish, may also be important. According to the researchers, the difference in the type of cancer that causes cancer death between the sexes may be related to a sex-specific association.
While she acknowledges the need for additional research in other populations and a deeper understanding of the mechanisms involved, Dr. Kasahara is excited about the results. “Although our findings were only among Japanese, they should be important for other nationalities as well,” she said.
In fact, previous studies have shown that affordable small fish are a potentially important source of nutrients, particularly in developing countries that suffer from severe nutrient deficiencies. This study adds to the growing evidence supporting the health benefits of diets that include small fish. As Dr. Kasahara explained, “Small fish are easy for everyone to eat and can be eaten whole, including the head, bones, and organs. Nutrients and physiologically active compounds unique to small fish may help maintain good health. The inverse relationship between small fish intake and mortality risk in women underscores the importance of these nutrient-rich foods in the human diet.”
“The habit of eating small fish is usually limited to several coastal or maritime countries, such as Japan,” said Associate Professor Tamura. “However, we suspect that the intake of small fish may be revealed everywhere as a way to extend life expectancy. More evidence is needed to clarify the potential role of small fish intake in mortality risk.”
