The Health Benefits and Uses of Miso

By Claire Jones
Published on April 3, 2019
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Photo by Adobe Stock/jedi-master

Analyzed in health communities,treasured for its fifth-taste flavor, and at times incorporated into recipes without knowing its entire potential, miso — a salty, slightly sweet brown paste of fermented pulses — is a food steadily garnering attention. It originated in China and was adopted by Japanese cooks hundreds of years ago, where dozens of different varieties are now produced in various regions, in ways similar to how other cultures produce regional wines or cheeses.

Most miso is made from soybeans, which are cooked, mashed, and fermented with grains of rice or barley that have been impregnated with the Aspergillus oryzae culture. These grains are known as koji and are the basis of several Japanese ingredients, including traditional soy sauce. The savory flavor produced by the culture is known as “umami,” or “the fifth taste.” A highly sought-after component of Asian cuisine, umami is created by the formation of glutamate during the fermentation process.

Different types of miso are made by varying ingredient proportions and fermentation times. The types can be split roughly into two categories: stronger-tasting, darker misos and lighter, sweeter ones. The richer misos are used to flavor soups and stews, while the paler, less powerful misos are ideal for dips, dressings, and lighter broths.

Miso for Health

Miso’s flavor isn’t the only attractive thing about this paste; it’s also believed to have a number of health benefits. Unpasteurized miso (miso that hasn’t been heat-treated) contains a mixture of probiotics and enzymes that promote beneficial microorganisms in the gut.

This effect may, in turn, strengthen the immune system, since around 70 percent of it resides in the gut.

Though some of it is still developing, research continues into the health benefits of miso. It has been found to contain antioxidants, which help promote cellular health and may reduce the inflammation that can be a root cause of many health problems. One study found that miso’s antioxidants scavenged free radicals, the unstable molecules found in our bodies that can damage cell membranes.

Although miso is salty, it’s not believed to have the same negative effect on blood pressure as ordinary table salt. Studies have reported measured blood pressure in mammals to be lower when they’ve consumed salt through miso rather than eating salt on its own.

A study in Japan, reported in the Journal of the National Cancer Institute in 2003, found that women consuming at least three bowls of miso soup daily showed a lower incidence rate for breast cancer compared with those who didn’t consume the soup as regularly. Isoflavone genistein, which inhibits the

growth of some colon, cervical, brain, and prostate cancer cells, is found in miso. Tests have also found that miso may protect against radiation sickness when eaten regularly.

Making Miso

Often, most commercially available miso is pasteurized to allow for longer storage. The easiest way to ensure your miso contains the health-enhancing enzymes and live probiotics found in unpasteurized forms is to make the superfood yourself.

Paler, sweeter misos, such as rice miso made with soybeans and rice koji, are usually fermented for a fairly short period, from around 8 to 12 weeks, meaning less wait time until they can be sampled. As such, they are ideal if you are making your first homemade miso.

Darker, stronger-flavored misos, such as hatcho (soybean mash fermented with soybean koji), barley, or brown rice misos, have a lower proportion of koji but contain more salt. Fermentation must take place over several months, which should include the warmer summer period. It can be left for as long as two years. These darker, long-aged misos are believed to be more powerful in protecting from radiation exposure and fighting colon, lung, and stomach cancer cells. Shortaged misos are thought to contain higher levels of probiotics.

There are dozens of ways to make miso, so it’s worth experimenting with varying amounts of beans and koji, as well as using other legumes such as garbanzo beans, adzuki beans, pinto beans, or dried peas. Other kojis can also be found, including wheat, soybean, and rye. Try making a light rice miso to start, and once that’s underway, make up a darker miso that can be left to ferment over a number of months while you enjoy the quicker, lighter version .

When making miso, organic ingredients always work best, as they will be free of any chemical residue that may hinder fermentation. Similarly, untreated sea salt is better than ordinary table salt. Koji is available from some whole food and Asian shops, as well as online.

Using Miso

It’s important when using miso to avoid heating it for too long. It should never be boiled, as this will destroy the beneficial bacteria and enzymes. To add it to soups, stews, or dressings, put the miso in a cup with some warm water and mix them together until smooth. This mixture can then be added right at the end of any cooking process, just before serving.

The umami taste is incredibly versatile, making miso a useful seasoning for dips, marinades, sauces, and casseroles, where it can be used in place of salt as a deeper, more satisfying flavoring. In places where miso is eaten on a daily basis, the paste is often incorporated in a light, nourishing, and warming broth.

With its flavorful versatility, as well as its potential advantages to health, adding miso to the diet is an easy and tasty way to help your body achieve balance and maintain well-being.


Claire Jones is a freelance writer specializing in natural health and sustainability. She is a vegetarian, grows her own fruits and vegetables, and likes experimenting with fermentation.

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