A study conducted by Dr. Chinatsu Kasahara alongside Associate Professor Takashi Tamura and Professor Kenji Wakai at the Nagoya University Graduate School of Medicine in Japan has uncovered compelling evidence that links the consumption of small fish, eaten whole, with a notable reduction in mortality from all causes and cancer, particularly in Japanese women. The research, published in Public Health Nutrition, explores the life-extending benefits of regularly consuming small fish such as whitebait, Atlantic capelin, Japanese smelt, and small dried sardines. These fish are typically eaten whole, including their heads, bones, and organs, providing a rich source of micronutrients like calcium and vitamin A.
Dr. Kasahara, the study’s lead researcher, mentioned that the protective effects of fish consumption on health and mortality risks are well-documented. Yet, few studies have focused explicitly on the impact of small fish consumption on health outcomes. Driven by a lifelong personal practice of eating small fish—a habit she now passes on to her children—Dr. Kasahara was mainly motivated to investigate this area further.
The study encompassed a large cohort of 80,802 Japanese individuals, comprising 34,555 men and 46,247 women aged between 35 and 69, from various regions across Japan. At the study’s outset, participants’ frequency of small fish consumption was meticulously gauged using a food frequency questionnaire. Over an average follow-up period of nine years, the researchers recorded 2,482 deaths, of which around 60% (1,495 deaths) were attributed to cancer.
Among the study’s key findings was the significant decrease in all-cause and cancer-related mortality observed among women who regularly consumed small fish. Women who ate small fish once to three times a month, one to two times a week, or three times or more per week experienced 0.68, 0.72, and 0.69 times the risk of all-cause mortality, respectively, and 0.72, 0.71, and 0.64 times the risk of cancer mortality compared to those who seldom ate small fish.
After adjusting for potential confounding factors such as age, smoking and alcohol habits, BMI, and other dietary nutrients and foods, it became clear that women who frequently consumed small fish had a lower likelihood of dying from any cause. These findings advocate for integrating small fish into daily diets as a straightforward yet potent strategy to enhance longevity in women.
Conversely, while a similar trend was observed in men, the results were not statistically significant. The researchers speculated that this could be due to a smaller sample size among men or other unmeasured factors, such as the portion sizes of small fish consumed. They also considered that differences in the types of cancer-causing mortality between the sexes might reflect a gender-specific association.
Despite these promising results being specific to the Japanese population, Dr. Kasahara believes these findings have broader implications. She expressed enthusiasm about the potential relevance of their findings to other nationalities. She highlighted the need for further research to explore the mechanisms underlying these associations and to validate these findings in different populations.
Furthermore, the study reiterates the importance of small fish as an affordable and nutrient-rich food source, particularly in developing countries where nutrient deficiencies are prevalent. Dr Kasahara emphasised the unique nutrients and physiologically active substances found in small fish that could be crucial in maintaining health, underscoring the inverse relationship between small fish intake and mortality risk in women.
Associate Professor Tamura noted that while eating small fish is generally limited to coastal or maritime nations like Japan, there is a growing suspicion that it could universally extend life expectancy. However, additional evidence is needed to fully understand the potential role of small fish intake in reducing mortality risk.
More information: Chinatsu Kasahara et al, Association between consumption of small fish and all-cause mortality among Japanese: the Japan Multi-Institutional Collaborative Cohort Study, Public Health Nutrition. DOI: 10.1017/S1368980024000831
Journal information: Public Health Nutrition Provided by Nagoya University
