The microbiome and fermented foods

The microbiome

The role of microorganisms in supporting the health of humans, livestock and ecosystems is among the hottest health science topics. Special attention has been given to the human microbiome, which is the sum of the bacteria, yeasts and molds that live in and on the human body.¹ The microbiome is 100 trillion microbes, which is 10-times more than all human cells.² The gut microbiome is considered to have a profound influence on immunity, cognition, nutritional status, and general health. It influences health so much that it's best described as an "externalized organ".³

The purpose of this post is to explore the potential benefits of traditional fermented foods in supporting a healthy microbiome. This reflects a health approach that emphasizes harmony with nature and microbes as opposed to today's overly sanitized and germophobic society. Research states that modern, city lifestyles mean lower exposure to beneficial microbes, low microbiome diversity, greater immune dysregulation, and increases in inflammatory and allergic disorders.⁴ The idea is that a healthy microbiome makes a healthy gut and that a healthy gut makes you resistant to chronic and infectious disease. This perspective focuses on influences of food, medicine (especially antibiotics), toxicants, the environment, and even stress and psychological factors on the microbiome and overall health.   

$3 kraut with eggs, avocado, 
and cooled sweet potatoes

Benefits of fermentation

Culture, culinary art, biology and medicine intersect at traditional fermented food. Traditional fermentation employs bacteria, yeast and fungi in converting carbohydrates into acids and alcohols.² Also, a food that has been processed with bacteria, yeast, or mold (or their enzymes) for preservation, safety, palatability, appearance or nutrition is fermented.⁵ This is different from putrefaction, which involves protein breakdown and production of off odors.² Fermentation is the oldest food biotechnology.⁵ It is low-energy and essential where other food processing technologies such as canning and freezing are not available. The benefits of this time-tested technology include the following:^2,5,6 

• Reduction in anti-nutrients including protease inhibitors and lectins in legumes and phytates in cereal grains.
• Cruciferous vegetables are considered healthy, though they contain naturally occurring toxic compounds and goitrogens that may lower thyroid function when consumed in excess.  Crucifers include broccoli, cabbage, collard greens, kale, radishes, and watercress. In fermentation these potentially harmful chemicals are converted into cancer fighting  and liver detoxification supporting chemicals (i.e., isothiocyanates, indole-3-carbinol, and sulforaphane)
• Soybean isoflavones are changed into antioxidant glycones, which may help reduce hypertension, cardiovascular disease, and cancer.
• Increase of B vitamins (bioenrichment) and stabilization of vitamin C.

The buzz about fermented foods has a lot to do with the beneficial bacteria found in them. These bacteria are considered probiotic, which means "life promoting". Pasteurized and canned fermented foods are not probiotic because probiotics are killed in high heat processing. Fermented foods may be the best way to get probiotics considering that they can be made cheaply and provide vitamins, minerals, antioxidants, and fiber.⁷ Making them can be fun and educational too.

As with many nutrition topics, there is debate over the healthiness of fermented foods for certain health conditions. For example, some holistic health experts advise patients with gut candidiasis (yeast overgrowth) to avoid fermented foods.⁸ Still, others recommend at least a couple servings of fermented veggies daily, stating that they generally improve gut health and reduce inflammation. I say that you may have to start slow and pay attention to how your digestion responds. Whether increasing exercise, fiber, or fermented foods, you may experience temporary discomfort followed by a benefit. It's up to you. This isn't medical advice.

Fermented vegetables
 

Make kraut with onions, garlic, carrots,
 beets, curry, or peppers. Be creative. 

Sauerkraut is a German word for sour cabbage. Interestingly, history credits China as the birthplace of fermented cabbage-- and it took about 1000 years before it arrived in Europe with Mongolian ruler Genghis Khan.⁹ The fermentation method described here, the sauerkraut method, may be used with any suitable raw vegetable: carrots, radishes, cauliflower, turnips, onions, garlic, etc. The method utilizes lactic acid bacteria (LAB) found naturally on the surface of vegetables. LAB consume sugars and produce lactic acid to prevent growth of bad bacteria.¹⁰ Fermentation methods are as diverse as the world's cultures.

The sauerkraut method is simple, though you have to pay attention to salt concentration, temperature, moisture, and fermentation vessel. Rinse cabbage and remove outermost leaves. Use a knife, box grater, food processor or mandolin to cut into 1/4 inch strips. Place shredded cabbage in a container with salt and pound or massage to release sugars and nutrients essential to LAB.

A 2% by weight salt concentration is recommended in sauerkraut production.¹¹ That's about 2-3 teaspoons of sea salt per 1 quart jar of shredded vegetables, which is basically salt to taste. It is important to press out air pockets when packing vegetables into fermentation vessels and to keep them submerged to inhibit growth of aerobic (air-loving) spoilage microbes including mold. Leave a little head space for expansion. If using a plain mason jar, you'll have to open it to relieve pressure. Fermentation is complete in 1 to 4 weeks,¹¹ though there are recipes that call for only 3 to 7 days of fermentation.

Another salting method is dry salting. Use 2-3% salt by weight . A 1-inch layer of shredded vegetables and part of the salt is applied; this layering continues until the container is three quarters full.¹¹ The vegetables are covered with plastic and compressed with weights to promote brine (salt water) formation. Fermentation starts as soon as brine forms and is evidenced by bubbling, which is CO2. Most LAB work best at 64 to 72°F.¹¹ Lower temperatures slow fermentation and higher temperatures can cause spoilage. Room temperature is fine in my experience.

Sea salt, pickling salt, and kosher salt are recommended due to their purity and absence of additives. Impurities and additives including non-caking material, iodine, lime, iron and magnesium cause problems; don't use common table salt.²

Common fermentation vessels for the home scale include mason jars, ceramic crocks with moats, and proprietary anaerobic (no oxygen) fermentation vessels with air-locks. Crocks with moats or air-lock lids let CO2 out and don't let oxygen in. There are special mason jar lids that do this too.

Fermentation crock

There is debate on whether an anaerobic vessel is necessary. Some say you'll get a moldy product without an anaerobic vessel, even though the mold may not be apparent-- others say they aren't necessary and a plain mason jar is fine. I've made kraut with a plain mason jar and it was tasty, though I don't have lab testing to confirm it was optimal. Also, the lid I used might have contained the toxin BPA, which I aim to avoid. Good news is that probiotics in ferments may help us detoxify BPA. Mercola.com has an interesting mason jar lid. Ceramic crocks make sense if you're that committed.

Unfortunately, government and academic information on traditional fermentation is rare or zero. For example, the Michigan State University Extension says that "for many popular products there are not yet any science-based guidelines for safe production. For this reason ... [they recommend] trying recipes outlined by reliable sources such as the USDA, the National Center for Home Food Preservation and University of Wisconsin Extension".¹² But even these leads require high heat processing and canning, which destroy probiotics. So, the public must either search high and low to develop research-based recipes, or trust the safety of non-scholarly sources.

In conclusion, I think it's reasonable to (1) shred cabbage or other vegetables; (2) salt to taste and pound briefly with a potato masher or massage to expel juices;(3) seal in a glass jar, leave at room temperature for days or weeks, and relieve pressure as needed; (4) refrigerate and enjoy your fermented food for weeks or months. It's pretty simple. 

Be wholesome,
Joe Zastawny 


References

1. Blaser M. The microbiome revolution. Journal Of Clinical Investigation [serial online]. October 2014;124(10):4162-4165 4p. Available from: CINAHL Plus with Full Text, Ipswich, MA. Accessed April 19, 2016.

2. Battcock M, Azam Ali S. Fermented Fruits and Vegetables: A Global Perspective. Rome, Italy: Food and Agriculture Organization of the United Nations; 1998:1-6.
3. Lu K, Mahbub R, Fox J. Xenobiotics: Interaction with the Intestinal Microflora. ILAR Journal /National Research Council, Institute Of Laboratory Animal Resources [serial online]. 2015;56(2):218-227. Available from: MEDLINE with Full Text, Ipswich, MA. Accessed April 19, 2016.
4. Thornton C, Macfarlane T, Holt P. The Hygiene Hypothesis Revisited: Role of Materno-Fetal Interactions. Current Allergy & Asthma Reports [serial online]. November 2010;10(6):444-452. Available from: Food Science Source, Ipswich, MA. Accessed April 23, 2016.
5. Nout R, Sarkar P, Beuchat L. Indigenous fermented foods. In Doyle M, Beuchat L, eds. FoodMicrobiology: Fundamentals and Frontier. 3rd ed. Washington DC: ASM Press; 2007:817-835.
6. Tolonen M, Taipale M, Viander B, Pihlava J, Korhonen H, Ryhanen E. Plant-derived biomolecules in fermented cabbage. Journal Of Agricultural And Food Chemistry [serial online]. n.d.;50(23):6798-6803. Available from: Science.
7. Meyer M, Romotsky S. Going with your gut. The Integrative RDN. 2014;17(2):25-26.
8. Myers A. 10 signs you have candida overgrowth & how to eliminate it. Amy Myers MD website. http://www.amymyersmd.com/2015/11/10-signs-you-have-candida-overgrowth-and-what-to-doabout-it. November 6, 2015. Accessed April 30, 2016.  
9. Haas S. Fermented &flavorful Sauerkraut: Natural fermentation adds goof-for-you bacteria tosome of your favorite foods. Food & Nutrition; July/August, 2015:26-27.  
10. Breidt F, McFeeters, Diaz-Muniz I. Fermented vegetables. In Doyle M, Beuchat L, eds. Food Microbiology: Fundamentals and Frontier. 3rd ed. Washington DC: ASM Press; 2007:783-793.
11. Battcock M, Azam Ali S. Fermented Fruits and Vegetables: A Global Perspective. Rome, Italy:Food and Agriculture Organization of the United Nations; 1998:43-56. Cowan MK, Microbiology: A Systems Approach. 4th ed. New York, NY: McGraw-Hill; 2015:396,458.
12. Jarvie, M. Interested in making your own fermented foods? Michigan State University Extension.April 3, 2014. http://msue.anr.msu.edu/news/interested_in_making_your_own_home_fermented_foods. Accessed April 23, 2016.