Loading ...- Miso is typically considered to be a high-sodium food, since one teaspoon of miso often contains 200-300 milligrams of sodium. However, recent research has shown that in spite of its high-sodium content, miso does not appear to affect our cardiovascular system in the way that other high-sodium foods sometimes can. In recent animal studies, for example, identical concentrations of salt (sodium chloride) obtained from miso versus table salt were discovered to have very different impacts on blood pressure. High-salt diets that derived their high salt level from table salt raised blood pressure in these animal studies, but high-salt diets that derived their high salt from miso did not. Recent human studies on miso intake among Japanese adults have also shown that miso-containing diets tend to lower risk of cardiovascular problems, despite the high-salt content of miso. Reasons for this unique relationship between miso and our cardiovascular system are not yet clear. However, some researchers have speculated that the unique soy protein composition of miso (including peptide building-blocks of protein that get formed from soy proteins when the beans are fermented) is one of the key reasons for the cardiovascular support provided by miso. Since miso is seldom eaten alone, other cardio-supportive foods in miso soups and miso stir-fries might also play an important role in these research findings.
- Some of the health benefits provided by soy foods depend on the ability of bacteria or other micro-organisms to break down two of the soy’s isoflavones – daidzein and genistein—into related compounds (for example, equol). Interestingly, recent research has shown that many different strains of the fungus Aspergillus oryzae—by far the most widely-used fungus in the fermentation of miso—are capable of breaking down both daidzein and genistein. This finding is great news for anyone who already enjoys miso, or is considering adding miso to their diet. If micro-organisms used in miso fermentation don’t break down some of the daidzein and genistein into other compounds like equol, it’s up to the micro-organisms in our digestive tract to do so. While it is fantastic when we have the right balance of micro-organisms in our digestive tract to help us get optimal nourishment and health benefits from our food, those conditions don’t always hold true. So it can be very helpful when a miso-fermenting fungus like Aspergillus oryzae helps breaks down the daidzein and genistein before the miso ever reaches our digestive tract!
- The list of research-documented antioxidants in miso is growing! In addition to conventional antioxidants like the minerals zinc and manganese, miso is now known to contain phytonutrient antioxidants including phenolic acids like ferulic, coumaric, syringic, vanillic, and kojic acid. Particularly interesting are new additions to the list of miso antioxidants that are related to its fermentation. In several recent studies, the amount of some specific antioxidants in miso appears to increase when fermentation is carried out for a longer period of time. DDPH (2,2,-diphenyl-1-picrylhydrazyl) antioxidants appear to be one category of miso antioxidants that increases with prolonged fermentation. These particular free radical scavengers may be more plentiful in miso that has been fermented for many months—or even several years—in comparison to miso that has only been fermented for one to three months. While the jury is still out on the overall antioxidant benefits of miso pastes with varying lengths of fermentation time, the jury is not out on the impressive antioxidant benefits that are provided by this widely enjoyed food.
What’s New and Beneficial About Miso
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