Recommendation: Try different fermented foods until you find a few you like. If you currently eat a balanced diet, try to trade-out a few servings of non-fermented foods for servings of fermented foods in the same food group. For example, substitute 1 serving of spinach for 1 serving of kimchi per week, instead of just adding a serving of kimchi to your diet. This will incorporate fermented foods without causing an imbalance between food groups. Common and effective options include yogurt (with live cultures), kimchi, sauerkraut, natto, and kefir. Cheeses may work, but more research needs to be done to know which types are best. Avoid or seek a physician’s guidance before using probiotic supplements (concentrated pill-form probiotics) if you are immunocompromised or have been diagnosed with ‘leaky gut’.
Quick Disclaimer
After decades of neglect this is a hot topic in research, so there’s way more theory than proof at the moment. I wasn’t able to find many clinical studies showing healthy adults who benefited from a serving or two per day of fermented foods. However, we see the relative health of populations which consume these foods (a.k.a. epidemiological study). Since that’s the whole purpose of this article, I want to make it clear that the behavior of probiotics in the clinical studies (usually in vitro) may be different in our bodies (in vivo); that’s not to say it would be less effective, though. It could be that when probiotics are part of the food we eat, they are even more effective.
Furthermore, there are many different strains of bacteria from this ‘probiotic’ family, and the brand you buy won’t label the non-researched types. Compounding the issue, the amount of bacteria consumed in these few clinical studies isn’t easily converted into a number of servings of fermented food, which would help us know we were eating enough to make a difference. As of 2013, different ‘fermented food’ associations require fermented foods to contain 10-100 million “viable cultures” (bacteria) per gram to be recognized as “probiotic” food. ((Emergence of a Quality Assurance…)) But I can’t be certain I’m consuming that much in one serving of the yogurt I buy, nor can I be sure all those bacteria make it to my intestine and do what they’re supposed to. With all this in mind, we’re left to trust our gut–we must assume the type of yogurt we buy contains the right bacteria, in the right amount per serving, and that the bacteria will behave similarly to the way it did in rats and petri dishes when studied. I recommend it because the alternative is missing out on the potential incredible health benefits of these foods.
One last note: as research continues, we learn that different foods may be more/less effective than others at delivering the bacteria to our gut. In one study, cheddar cheese was found to be significantly better than yogurt at protecting/transporting a specific species during digestion. ((Evaluation of Cheddar Cheese as a Food Carrier…)) In fact, “various cheese varieties including Cheddar, Gouda, cottage, white-brined, caprine, and Crescenza cheeses have been assessed as carriers for both probiotic Lactobacillus and Bifidobacterium strains”. ((Probiotics in Dairy Foods…)) It should go without saying that the less-processed the better, especially when it comes to cheese (Velveeta’s effectiveness as a probiotic food is suspect, at best). In the end, these are still nutritious foods and they don’t seem to have common side-effects, so even if the probiotics in them do nothing, they’re still pretty healthy (except for Velveeta, again due to the fact that it isn’t actually food).
What are fermented foods?
“Food fermentations can be classified in a number of ways: by categories: alcoholic beverages fermented by yeasts, vinegars fermented with Acetubacter, milks fermented with lactobacilli, pickles fermented with lactobacilli, fish or meat fermented with lactobacilli and plant proteins fermented with molds with or without lactobacilli and yeasts; or by classes: beverages, cereal products, dairy products, fish products, fruit and vegetable products, legumes and meat products.” ((Classification of fermented foods))
Basically, they contain edible microorganisms whose enzymes change carbs, proteins and fats to beneficial products. If the products of enzyme activity have unpleasant odors or flavors or the products are harmful, the foods are described as spoiled. Lactic acid fermentations are most common, and include:
– sauerkraut – Korean kimchi – cucumber/pickles
– olives – milks/kefir – yogurts
– cheeses – Sudanese kisra – Philippine puto
– Indian idli – Ethiopian enjera – sour-dough bread
– yogurt/wheat mixtures: Egyptian kishk and Greek trahanas
– boiled rice/raw shrimp/raw fish mixtures: Philippine balao balao, burong dalag
Also, alcoholic fermentations include grape wines, Mexican pulque, honey wines, South American Indian chicha and beers, palm and jackfruit wines in India, sugar cane wines, Japanese sake, Indonesian tape, Chinese lao-chao and Thai rice wine. A non-alcoholic option from Europe is Kombucha, a tea fermented using acetic acid fermentation, and alkaline fermentation is used to make Japanese “natto”.
What can probiotics do for us?
The term ‘probiotic’ (for life) relates to both supplements and to foods containing beneficial bacteria. This article will focus on what benefits can be gained strictly from probiotics in fermented foods. I am much more interested in finding great tasting food to incorporate into my diet than spending money on pills, IF that method is still effective. Also, there are different bacteria used in supplements, so I don’t want to give fermented foods credit for their benefits, nor assume that eating foods with the same bacteria are equally effective (or ineffective). The bacteria I’m most concerned with are those found in kefir, yogurt, cheeses, sauerkraut, and kimchi, which are easy to find and all undergo lactic-acid fermentation. These are the Lactobacillus, Streptococus, and Bifidobacterium types (they’re usually abbreviated and written as ‘L. Acidophilus’, for example, meaning ‘Lactobacillus Acidophilus’). In vitro, these guys are capable of everything from inhibiting Salmonella and E-coli ((Probiotics inhibit…)) to increasing the amount of almost all B vitamins in starches and dairy. ((Chemical and Biological Evaluation…)) ((Nutritional and Health…)) What about when consumed? Among other things, they reduce the pH in the gut, making it a harsh environment for harmful bacteria, which helps us avoid illness. ((Microorganisms With Claimed Probiotic…)) Another important result shown multiple times is the ability of Lactobacilli to reduce intestinal distress associated with antibiotics. ((Probiotics for the Prevention and Treatment…)) The best-supported health claim of lactic acid probiotics I found was that we should consume them if we’re on antibiotics or travelling; no other claim had more research supporting it.
Interesting non-digestive benefits of probiotics found in these foods have been seen as well, though not as convincingly. L. Rhamnosus, specifically, was found to reduce lung damage due to respiratory viruses by modulating the immune response. ((Immunobiotic lactobacilli reduce…)) Also, a 51% reduction in recurring urinary tract infections was seen in 127 women given a Lactobacillus probiotic, though they concluded the sample was too small to be definitive. ((Lactobacillus for preventing…)) Bifidobacteria (e.g. B. Lactis) has been found to alleviate eczema in infants, in addition to helping with general gastrointestinal distress along with other probiotics in adults. ((Probiotics in the Management of…)) There is also research showing a benefit to patients with Chron’s/Ulcerative Colitis. One report stated, “The combination of Lactobacillus, Bifidobacterium, Saccharomyces boulardi and the treatment with Escherichia coli Nissle were found beneficial in inducing and maintaining remission of disease activity of gut inflammation and moderately severe ulcerative colitis.” ((Probiotics in the Mechanism of Protection…))
Reduction in cholesterol has been seen in rats ((Serum Cholesterol Levels in Rats…)) and in humans fed large quantities of dairy containing lactobacilli (both clinically and in specific populations) ((Manufacturing Yogurt and Fermented…)). This idea came up several times, and is perhaps the #1 or #2 most exciting claim along with the cancer-fighting properties of probiotics. However, I was unable to find the gold standard–a double-blind placebo-controlled study of humans–to prove that eating a few servings/week will lower cholesterol.
Regarding cancer, Lactobacillus Lactis appears to have anti-cancer potential. ((Different effects of two…)) ((Cell Cycle Dysregulation Induced…)) We even have an idea what the mechanism for this is with certain species, but again, before we start printing this claim on bottles of kefir, much more research is needed.
It is also suggested that allergies may be able to be treated/prevented by Lactobacilli, though we again don’t have conclusive results. ((Microorganisms With Claimed Probiotic Properties…)) We have, however, found correlation between food allergies in children and an imbalance of good/bad gut bacteria–termed “gut dysbiosis”–so the idea is that regaining the balance with probiotics would be effective at treating or preventing these allergies.
Conclusion
To me, fermented foods are like vegetables in many ways–some types are healthier than others, we should eat a variety of them every day, and there’s a bunch of research in labs showing what the chemicals inside them might do for us if we eat them. Like fermented foods, we know that people who eat a bunch of veggies are usually healthier than those who don’t, but we have a hard time proving clinically that a specific amount of a specific type of veggie per day will provide a specific benefit. Because of the huge amount of research–“imperfect” as it is–I recommend introducing fermented foods into a diet. They’re generally affordable, safe, and convenient to find and use. Sure, kefir is disgusting–but that’s just another problem for chocolate to solve…