The study was recently published in the journal Public Health Nutrition.

It’s well known that fish is a nutritious food, thanks to its omega-3 fatty acids, proteins, and vitamins, and eating entire small fish is even more beneficial than eating filets of larger ones, according to the study.

“Previous studies have revealed the protective effect of fish intake on health outcomes, including mortality risks. However, few studies have focused on the effect of the intake of small fish specifically on health outcomes,” lead researcher Chinatsu Kasahara, a doctoral student and associate professor at Nagoya University Graduate School of Medicine in Japan, said in a university statement.

“Nutrients and physiologically active substances unique to small fish could contribute to maintaining good health.”

Just 1 to 3 Times per Month

The university investigators used a food frequency questionnaire to measure how frequently the participants ate whole small fish. During nine years of follow-up, 2,482 people in the study died, approximately 60 percent of them from cancer.

The women who reported eating small fish even just one to three times per month were less likely to die of cancer—and of all other causes—than were those women who rarely ate small fish.

In the male subjects, the reduced risk of all-cause and cancer mortality was similar to the risk among women, but it did not reach statistical significance, the researchers reported. They suggested this may have been due to the smaller number of male subjects (34,555, as opposed to 46,247 women) or other factors not measured in the study, such as fish portion sizes and sex-specific cancer types.

Other factors were linked to how often people ate small fish. Those who did so more frequently were more likely to be older (the mean age of study subjects was 54.7 years), non-lean, nonsmokers, current drinkers (among the men), and physically active and have hypertension.

Small Fish, Big Nutrition

“Small fish offer a unique advantage in that they can be consumed as a whole,” the researchers wrote, unlike large fish, which are typically processed to remove the bones and organs, leaving only the filet.

When eaten whole, the bones and organs in small fish make them “a good source of micronutrients such as [calcium], vitamins and fatty acids,” they said.

A 2021 study published in the journal Clinical Nutrition found that people with prediabetes who ate two cans of sardines each week significantly lowered their insulin resistance, their blood pressure, and their risk of developing Type 2 diabetes.

Another benefit to smaller fish: They accumulate fewer toxins such as mercury in their bodies than larger fish do.

Who Eats Small Fish?

Fish preferences are, in part, a cultural phenomenon. Eating small fish is much more common in Japan and Europe, for instance, than it tends to be in the United States. In Japan, whitebait, Atlantic capelin, Japanese smelt, and small dried sardines are popular, and so are small horse mackerel and young sweetfish, according to the researchers. The Japanese eat them raw or prepare them by marinating them in vinegar, simmering them in soy sauce, or deep-frying or drying them, they wrote.

“I was interested in this topic because I have had the habit of eating small fish since childhood,” lead researcher Chinatsu Kasahara noted in the university statement. “I now feed my children these.”

She noted that all cultures can benefit from her research.

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

However, in many parts of the world, people prefer to eat larger species of fish prepared as filets after the bones and organs have been removed. Although eating larger species whole may also be beneficial, filets are easier to ship and store, making them a more practical choice for producers and consumers, according to the Global Seafood Alliance. So in inland areas with less access to fresh fish, eating whole fish often means eating smaller fish that has been canned, or “tinned,” as it’s termed in some areas.

In Europe, demand for tinned fish, particularly tuna, rose during the COVID-19 lockdowns, according to a 2021 report by the Dutch CBI Ministry for Foreign Affairs. Sales of sardines and mackerel were trending upward as well. Canned fish are a familiar part of the European diet, the report states, and “shelf-stable [fish] products are the most consumed by Europeans, followed by frozen and chilled products.”

Tinned fish began to rise in popularity in the United States in 2022, according to food trend watchers, and market research company IndustryARC released a report in 2021 predicting that the global canned fish market would reach $11.3 billion by 2027.