People who have the habit of eating fish live longer!

Compiled by: Gong Zixin

The Japanese are used to eating small fish, including whitebait, Atlantic capelin, small sweetfish and small dried sardines. Importantly, they usually eat the whole small fish, including the head, bones and organs.

Recently, a new Japanese study found that eating whole small fish was associated with a lower risk of all-cause and cancer mortality. The study highlights the potential longevity benefits of habitually eating small fish. The findings were published in the journal Public Health Nutrition.

Small fish are one of the important sources of micronutrients such as calcium, magnesium and vitamins A and D, which, when consumed with bones and offal, help prevent non-communicable diseases, including cardiovascular disease and cancer, through their anti-hypertensive, anti-atherosclerotic and anti-tumor effects. The bones, eyes and offal of fish are reservoirs of most micronutrients, including calcium and vitamin A. Unlike large fish, whose bones and organs are often discarded, small fish have a unique advantage as they can be consumed as a whole.

"Previous studies have revealed protective health effects of fish intake, but few studies have focused on the effects of small fish intake on health outcomes," said lead researcher Dr. Kasahara of the Graduate School of Medicine at Nagoya University in Japan. "I was interested in this topic because I have been eating small fish since I was a child and now feed it to my children."

The research team investigated the relationship between small fish intake and mortality risk in the Japanese population. The study included 80,802 participants (34,555 men and 46,247 women) aged 35 to 69 years across Japan.

The frequency of the participants' small fish intake was assessed using a questionnaire at baseline, and the researchers followed them for an average of nine years. During the follow-up period, there were 2,482 deaths among the study subjects, about 60% of which were related to cancer.

One of the most striking findings of this study is that women who habitually ate small fish had significantly lower all-cause and cancer mortality rates. Compared with women who seldom ate small fish, women who ate small fish 1-3 times per month, 1-2 times per week, or 3 times per week or more had 0.68, 0.72, and 0.69 times the risk of all-cause mortality, and 0.72, 0.71, and 0.64 times the risk of cancer mortality, respectively.

After controlling for factors that could affect mortality risk, such as the participants' age, smoking and drinking habits, body mass index, 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 incorporating small fish into a daily diet may be a simple and effective strategy to reduce women's risk of mortality.

Trends in all-cause and cancer mortality risk in men were similar to those in women, although the differences were not statistically significant. The reason for the lack of significance in men is unclear, but the researchers suggest that the limited number of male participants or other factors not measured in the study, such as portion size of small fish, may also have an effect. According to the researchers, differences between the sexes in the types of cancers that contribute to cancer mortality may be related to sex-specific associations.

Multivariable-adjusted HRs (95% CI) for all-cause, cancer, cardiovascular disease, and other-cause mortality by sex, according to frequency of small fish consumption
Dr. Kasahara believes that "although our findings are specific to Japanese people, they may also be important for people in other countries."

Indeed, previous studies have highlighted that affordable small fish are a potentially important source of nutrition, particularly in developing countries where nutrient deficiencies are severe. This study adds to the growing body of evidence supporting the health benefits of a diet that includes eating small fish.

Dr. Kasahara explained: "Small fish are easily accessible to everyone and can be eaten whole. Small fish contain nutrients and physiologically active substances that help maintain good health. The inverse relationship between small fish intake and mortality risk in women emphasizes the importance of these nutrient-rich foods in people's diets."

The researchers noted that the habit of eating small fish is usually found in coastal or maritime countries, however, consuming small fish anywhere may be a way to extend lifespan, and further evidence is needed to clarify the potential role of small fish intake in mortality risk.

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