Fermented vs fermentable food: There's a difference!
by Steven Sandberg-Lewis, ND, DHANP
Many of us, including some healthcare professionals, are confused about the difference between foods with high fermentation potential and fermented foods.
My patients have often told me that they were avoiding all fermented foods because they believed the fermented food will make their IBS, SIBO, yeast overgrowth or other digestive problem worse. It is true that some highly sensitive people do react to fermented food, which may be due to histamine sensitivity - the fermentation and aging process may produce histamine. Others might react to acids (acetic, butyric, etc.) or traces of yeast, alcohol, or some other fermentation byproduct. But unless a person experiences such an individual response, there seems no reason to remove fermented foods from the diets of patients with bacterial and yeast overgrowth.
Highly fermentable foods
Researchers and clinicians such as Sydney Haas, Elaine Gottschall, Natasha Campbell-McBride, and, more recently, Mark Pimentel, Allison Siebecker, Nirala Jacobi and Norm Robillard have developed the modern dietary concepts underlying low fermentation diets. These diets organize common foods into various degrees of fermentation potential, allowing patients to follow a diet that reduces the fermentation of carbohydrates into gas and alcohol. Some of our patients can partially or completely control their IBS or IBD symptoms by using one of these low fermentation diets. It is unlikely that these approaches cure bacterial overgrowth (although this has not been studied), but can effectively control the fermentation of carbohydrates and the symptoms caused by the byproducts of this process – painful distention of the GI lining, stool frequency and consistency changes, abdominal bloating, reflux, nausea, etc.
Humans cannot digest the more highly fermentable carbohydrates. In contrast, bacteria, archaea, and yeast living in the human gut ferment these carbohydrates into hydrogen, methane, hydrogen sulfide, and carbon dioxide gas (F. Scaldaferri, 2013). In addition, acids such as acetic, lactic, and butyric as well as ethanol are common metabolites – byproducts - of these processes. Indigestible carbohydrates include fructans, oligosaccharides, disaccharides, monosaccharides (opinions vary on this one) and most sugar alcohols (E. Altobelli, 2017). All of these fall into the general categories of prebiotics/fiber.
Fermented foods
The same biochemistry applies to fermented foods, but the big and essential difference is that the fermentation process occurs outside the body. Although the same gases and metabolites are produced, the gases escape into the environment. Fermentation locks, airlocks or water-sealed crocks are used to keep contaminants and oxygen out of the mix and allow the gases to escape during the process of fermentation in vitro. Unless the patient is sensitive to some other metabolite, the usual problems induced by gas pressure and chemistry are not an issue with fermented food. All the health benefits of fermentation – organic acids, anti-microbial agents, bioactive peptides, probiotics, and nutrients (M. Derrien, 2015) – can be ingested without the issues of internal gas accumulation.
Types of Fermented Foods
The common list includes beer, wine, yogurt, kefir, cheese, sourdough, fermented meat (salami, etc.), pickles, olives, sauerkraut, kimchi, fish sauce, tempeh, miso, soy sauce and kombucha (fermented tea). Cocoa and various ethnic foods may also be fermented.
Health Benefits of Fermented foods
Although it is believed that the probiotic organisms in fermented foods are “just passing through” and not creating an ecological niche in the gut flora, there is plenty of evidence of their benefits. It is thought that they do not persist in the gut for more than a few days. Frequent consumption of fermented foods leads to a “transient microbiome”. They are thought to positively influence the diversity and function of the gut microflora (D. Zhang, 2016). Common organisms include various species of Lactobacillus. Leuconostoc, Streptococcus and Bifidobacteria. Even if the bacteria are not viable, there can be significant benefit from their presence. Probiotics and their salutary effects include:
Fermented dairy and metabolic syndrome (N. Babio, 2015)
Fermented soy and Type 2 diabetes mellitus (V. Akbari, 2016) and hypertension (The Japan Public Health Center-Based Prospective Study. Sept 2017)
Probiotics and body weight and blood lipids in obese individuals (M. Kim, 2017)
Yogurt and bladder cancer incidence (S.C. Larrson, 2008)
Yogurt and body weight (D. Mozaffarian, 2011)
Probiotics and infantile eczema (M. Zhao, 2018)
Probiotics and asthma prevention in the womb and during the first month of life (X. Du, 2019)
Yogurt and the prevention of lactose intolerance (DA. Savaiano, 2014)
Probiotics and antioxidant protection in colitis (SA. Ballal, 2015)
Probiotics and prevention of antibiotic associated diarrhea in children (H. Szajewska, 2016)
Additional benefits are improved mineral absorption (D. Cizeikiene, 2015), increased polyphenol production in beer (A. Capese, 2018) and antimicrobial compounds in fermented milk (M.D.S.F. de Lima, 2018).
Some so-called fermented products are “fake” in that they are not truly fermented. Instead, they are processed with lye, salt, or vinegar. This includes some pickles, olives, and sauerkraut. These are not expected to have the same health-promoting effects as true fermented foods.
I am not a microbiologist and certainly do not consider myself an expert on probiotics. I wrote this post to take a closer look at this common misconception and hope that you find it useful.
References
1. Intestinal gas production and gastrointestinal symptoms: from pathogenesis to clinical implication. F. Scaldaferri. 17, 2013, Eur Rev Med Pharmacol Sci. , pp. Suppl 2:2-10.
2. Low-FODMAP Diet Improves Irritable Bowel Syndrome Symptoms: A Meta-Analysis. E. Altobelli. 9, Aug 26, 2017, Nutrients. , Vol. 9, p. pii. E940.
3. Fate, activity, and impact of ingested bacteria within the human gut microbiota. M. Derrien. June 23, 2015, Trends Microbiol., Vol. 6, pp. 354-66.
4. Changes in the diversity and composition of gut microbiota of weaned piglets after oral administration of Lactobacillus or an antibiotic. D. Zhang, 23, Dec 2016, Appl Microbiol Biotechnol. , Vol. 100, pp. 10081-10093.
5. Consumption of Yogurt, Low-Fat Milk, and Other Low-Fat Dairy Products Is Associated with Lower Risk of Metabolic Syndrome Incidence in an Elderly Mediterranean Population. N. Babio. 10, Oct 2015, J Nutr. , Vol. 145, pp. 2308-16.
6. Effects of probiotic supplementation in patients with type 2 diabetes: systematic review and meta-analysis. V. Akbari. 12, Dec 2016, Nutr Rev. , Vol. 74, pp. 774-784.
7. Fermented Soy Product Intake Is Inversely Associated with the Development of High Blood Pressure: The Japan Public Health Center-Based Prospective Study. 9, Sept 2017, J Nutr. 2017 Sep;147(9):., Vol. 147, pp. 1749-1756.
8. Effects of weight loss using supplementation with Lactobacillus strains on body fat and medium-chain acylcarnitines in overweight individuals. M. Kim. 1, Jan 25, 2017, Food Funct., Vol. 8, pp. 250-261.
9. Cultured milk, yogurt, and dairy intake in relation to bladder cancer risk in a prospective study of Swedish women and men. S.C. Larrson. 4, Oct 2008, Am J Clin Nutr. 2008 Oct;88(4):., Vol. 88, pp. 1083-7.
10. Changes in diet and lifestyle and long-term weight gain in women and men. D. Mozaffarian. 25, Jun 23, 2011, N Engl J Med., Vol. 64, pp. 2392-404.
11. Treatment efficacy of probiotics on atopic dermatitis, zooming in on infants: a systematic review and meta-analysis. M. Zhao. 6, Jun 2018, Int J Dermatol. , Vol. 57, pp. 635-641.
12. Efficacy of probiotic supplementary therapy for asthma, allergic rhinitis, and wheeze: a meta-analysis of randomized controlled trials. X. Du. 4, Jul 1, 2019, Allergy Asthma Proc. , Vol. 40, pp. 250-260.
13. Lactose digestion from yogurt: mechanism and relevance. DA. Savaiano. 5, May 2014, Vol. 99, pp. 1251S-5S.
14. Host lysozyme-mediated lysis of Lactococcus lactis facilitates delivery of colitis-attenuating superoxide dismutase to inflamed colons. SA. Ballal. 25, Jun 23, 2015, Proc Natl Acad Sci U S A. , Vol. 112, pp. 7803-8.
15. Probiotics for the Prevention of Antibiotic-Associated Diarrhea in Children. H. Szajewska et al, ESPGHAN Working Group for Probiotics and Prebiotics. J Pediatr Gastroenterol Nutr. 2016 Mar;62(3):495-506.
16. Phytase activity of lactic acid bacteria and their impact on the solubility of minerals from wholemeal wheat bread. D. Cizeikiene. 7, 2015, Int J Food Sci Nutr. , Vol. 66, pp. 736-42.
17. Use of Saccharomyces cerevisiae var. boulardii in co-fermentations with S. cerevisiae for the production of craft beers with potential healthy value-added. A. Capese. Nov 2, 2018, Int J Food Microbiol. 2018 Nov 2;284:22-30., Vol. 284, pp. 22-30.
18. Brazilian Kefir-Fermented Sheep's Milk, a Source of Antimicrobial and Antioxidant Peptides. M.D.S.F. de Lima. 3, Sept 2018, Probiotics Antimicrob Proteins. 2018 Sep;10(3):446-455, Vol. 10, pp. 446-455.
Steven Sandberg-Lewis, ND, DHANP, has been in clinical practice since his 1978 graduation from NUNM. He has been a professor since 1985, teaching a variety of courses but primarily focusing on gastroenterology and GI physical medicine.
Hive Mind Medicine blog posts are for educational purposes only and are not intended as medical advice. Please consult with your health care practitioner for personalized guidance.