Fermentation gives beer and many cheeses their appealingly sour taste, but fermented foods may offer more than just great flavor and the possibility of a hangover or food baby: Research suggests that these foods may help improve blood sugar and lower the risk of conditions ranging from high blood pressure to eczema in children who’s mothers’ ate fermented foods while pregnant. One study even proposes that fermented foods benefit eaters’ mental health.
Products like yogurt, kimchi and a notorious Japanese dish called natto contain probiotics—living microorganisms (such as yeast or bacteria) that cause fermentation. Fermentation preserves foods, and provides multiple health benefits to eaters.
“Fermented foods are ‘pre-digested,’” explains Kristi L. King, MPH, RDN, CNSC, LD, senior dietitian at Texas Children’s Hospital and national representative for the Academy of Nutrition & Dietetics. These foods “allow for better protein digestibility as well as provide probiotics to the gut. There are quite a few studies that show probiotics can help with weight loss, depression, vaginal health and inflammatory conditions.”
Derek Dellinger ate only fermented foods, including rotten shark meat, for a year, and he thinks his health benefited. “I felt like I had more energy,” says Dellinger, who chronicled his experiment in The Fermented Man: A Year on the Front Lines of a Food Revolution. “I never got sick during that year, and saw my blood pressure go down.”
King recommends a serving a day of fermented foods. However, “if your system is not used to fermented products, it may cause GI symptoms for a bit.” So start small with some of these foods and ingredients, and work your way up.
1. Black Teas and Kombucha
Tea leaves ferment—and turn black—when they’re exposed to air. Unlike most of the foods listed here, black tea doesn’t contain lactic acid, according to King, which is produced by probiotics and gives many fermented foods their sour tang. Instead, it’s the tea’s plentiful antioxidants, which help neutralize the effects of cell-damaging free radicals that provide protection against cardiovascular disease and cancer.
Kombucha (pictured above) is a mildly sweet fermented beverage, and some studies suggest it might help prevent infectious diseases and lower cholesterol (when tested on rats). But human studies are lacking, and there have been cases of suspected kombucha toxicity, so don’t overdo it.
2. Kefir
Kefir is a fermented milk drink with a slightly fizzy texture and the sour taste of yogurt. A review of multiple studies found that kefir may prevent or even help treat cancers. And in a small study of young men, fermented milk products helped soothe muscle soreness and improved glucose metabolism (the process by which sugar from foods is turned into energy) after vigorous exercise.
At just under 200 calories, one cup of whole milk kefir supplies about 30 percent of most adults’ recommended dietary allowance for calcium. Put a cup in a blender with a handful of fresh or frozen berries for a post-workout pick-me-up.
3. Kimchi
This garlicky fermented cabbage, which gets its heat from spices like ginger and chili, is ubiquitous throughout Korea, where it’s so important that there’s even a government-affiliated World Institute of Kimchi. A recent study of Korean adults found that people who ate more kimchi were less likely to have asthma, though researchers aren’t sure why this is. Kimchi makes an excellent condiment (a whole cup has just 22 calories and 2.5 grams of fiber), and is available at stores like Costco and Whole Foods, as well as online.
4. Natto
Natto is fermented soybean, and this Japanese staple has a sticky, slimy, stringy texture as well as what Dellinger terms a “bitter” flavor and an “ammonia-like” smell. Of course, that won’t convince you to try it, but this might: One cup of natto contains almost 34 grams of protein; it’s also an excellent source of iron and vitamin K. A 2016 study links a high intake of natto with a lower risk of death from cardiovascular disease. Dried natto is available online via Amazon and independent vendors; try it over rice for a super-healthy, savory breakfast.
5. Fermented Fish
Fermented fish and fish pastes are particularly popular in Asia. Fermented fish can be “so inherently pungent that they will retain much of their essential flavor (for better or worse) after aging,” Dellinger notes. One Korean study found that eczema was less common in people who ate a lot of fermented foods, including seafood.
Research suggests that fermentation causes fish protein to break down, making antioxidants available; these could help lower blood pressure, stimulate the immune system and control blood sugar, too. If you’re tempted, Asian markets are your best bet, though Amazon sells fermented fish powder and cubes. But like natto, fermented fish is quite salty, so people watching their sodium intake should tread carefully.
6. Sourdough Bread
Finally! An excuse to eat carbs! In a small study, people with higher-than-normal blood sugar levels who ate sourdough bread had better blood sugar and insulin levels than those who ate bread leavened with baker’s yeast. “My favorite is to eat it with olive oil or for a sandwich,” says King. “You can also use sourdough bread to make stuffing, which is quite tasty!”
Elizabeth Michaelson Monaghan is a NYC-based freelance health writer and editor.