What do whole anchovies, sardines, smelt, and herring offer that you can't get from a filet of sole? Bones, head, organs, and other internal treasures that contain micronutrients such as zinc, selenium, and magnesium, as well as a good dose of calcium and vitamins B12, D, and niacin.

Sardines, for example, also deliver almost 25 grams of protein in every 3 ounces.

And then there's the omega-3s they contain, which help protect your heart and tamp down body-wide inflammation — the culprit in many chronic diseases.

But the benefits of these little fish are even more far-reaching.

A nine-year study of around 80,000 Japanese people, who often eat small fish whole, was published in the journal Public Health Nutrition. It found that women who enjoy whole small fish regularly reduced their risk of developing cancer by 25% to 30%, and death from all causes significantly.

The study didn't find the same benefit for men, either because of the gender-specific cancers that were prevented or the need for people with greater body mass to eat larger portions than most men did. But we're betting guys should dig in too.

How much do you need to eat to gain protection? Eating whole small fish one to three times a month offers measurable benefits, and aiming for once or twice a week may be the smartest option.