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* The importance of fermentation for increasing the bioavailability of active substances in plants (extracts) *

Food fermentation has existed for thousands of years and was used in the past for the preservation and better digestibility of plants.

There are still populations worldwide that put fermented foods such as Japanese miso, tempeh and Korean kimchi on the menu daily.  Unfortunately, fermented foods have largely disappeared from the Western diet.  For a long time, the wrong idea existed that all bacteria would be dangerous to health, and of course this is not the case, because for the fermentation process only the "good" microorganisms are used, such as Lactobacillus.  Consequently, the "bad" pathogens are supplanted and the process of fermenting food is an extremely safe technology.

Chemically, fermentation is a simple reaction.  During the fermentation process, microorganisms, such as yeast and bacteria, are used to convert carbohydrates into alcohol and carbon dioxide or organic acids.  Yeast fermentation is usually used to make alcoholic drinks such as wine and beer.  Lactobacillus varieties are used to make foods such as yogurt and sauerkraut.  In addition to the unique flavors produced by lacto-fermentation, the fermented food also has a probiotic gut benefit conferred by the Lactobacillus genus itself.

In addition to the preservative and probiotic properties that fermentation can bring to foods, recent scientific studies have confirmed that fermented foods offer many other nutritional and health benefits.

Pre-digestion of Complex Foods:

  • Fermentation pre-digests the food and breaks down proteins and carbohydrates into more easily absorbable amino acids and simpler sugars.  Certain foods can contain a lot of nutritional value, but are difficult to digest for humans.
  • Cereal grasses are a good example of this.  Cereal grasses are defined as the young grass stage of the wheat, barley, alfalfa or oat plant and are much more nutrient dense than the adult plant which contains many times more B vitamins, minerals, chlorophyll and antioxidants.  However, the nutrients are encapsulated in cellulose containing plant cells and humans cannot digest cellulose.
  • Grain grass fermentation is an excellent way to break down cellulose.  This is exactly what happens in the "second stomach" of cows and other ruminants.  The grasses have been made more digestible because during the prolonged fermentation process that takes place in the stomach chamber, cellulase produces enzymes that break down the cellulose with the help of beneficial bacteria.

Improving Nutrient Levels and Their Bio-accessibility:

  • Bioaccessibility is described as the amount of nutrients released from the food matrix that are potentially available for absorption.
  • Many peoples fermented grains, and studies have also shown that the fermentation of grains increases the levels of B vitamins. (1,2,3,4,5)  For example, wheat contains several essential nutrients including the group of B vitamins.  The B group vitamins, which are normally present in grain products, are easily removed or destroyed during grinding, processing or cooking.  Certain strains of lactic acid bacteria have the ability to synthesize water-soluble vitamins such as B vitamins. (3)  Fermentation also improves the amino acid and vitamin composition 2.5 and the bio-accessibility of minerals such as zinc. (4,5,6)  Many grains (wheat, rice, barley and oats) are low in lysine and are therefore not a complete protein source.  Fermentation appears to increase the available lysine levels in these grains by 5.7 making it almost a "complete" protein source.

Improving Phytonutrient Content and Absorption:

  • The antioxidant power of phytonutrients can also be enhanced through fermentation.  Polyphenols, a specific category of phytonutrients, are naturally found in fruits, vegetables, nuts, seeds, leaves, rhizomes, flowers and barks of plants.  A study in which legumes were subjected to natural fermentation resulted in a significant increase in the content of freely soluble polyphenols in the legume mixture.  The bound phenol content of the legumes had decreased considerably.  The free soluble polyphenols have both a higher reducing power and the ability to remove free radicals than bound polyphenols, as well as an increased inhibition of lipid peroxidation.  The study concluded that fermentation enhances the antioxidant activity of the legumes. (8)
  • Spontaneous garlic fermentation also resulted in an increased antioxidant activity of the extract, in particular a 13-fold increase in superoxide dismutase (SOD) -like activity and a 10-fold increase in free radical activity against hydrogen peroxide compared to that of the control garlic extract.  In addition, the polyphenol content of the fermented garlic extract has increased sevenfold.  The color of the garlic turns black due to fermentation, and the black color is probably derived from anthocyanins, which is the reason for the increased levels of polyphenols.
  • The effect of fermentation on Pu-Erh tea was investigated by inoculating fresh tea leaves with individual strains of isolated microorganisms.  The results showed that the antioxidant activity was increased, as well as the statin content, the total polyphenol content and the GABA content of the fermented tea. (10)
  • Turmeric contains the phenolic antioxidant curcumin.  However, due to poor water solubility, poor permeability and / or poor stability, there is minimal absorption of curcumin in the gut.  A fermented drink containing Lactobacillus, made from turmeric rhizomes, increased the antioxidant effect in vitro.  Absorption of the encapsulated fermented turmeric drink in rats was measured in terms of plasma antioxidant activity.  The plasma antioxidant concentration was higher in rats administered the fermented turmeric than the non-fermented version, (11) supporting the theory that fermentation of turmeric increases its bioavailability.
  • In some cases, fermentation even creates different phytonutrients that are not present in the raw material.  An example of this is the production of glucosinolate derivatives that occur in fermented charcoal. (12)  Another example is the transformation of ginsenosides during fermentation of ginseng.  The fermented ginseng extract actually mimics the fermentation environment in the colon and Compound K is formed, a new metabolite.  Study shows that Compound K is the most bioavailable metabolite of ginseng. (13) Fermented ginseng extracts containing Compound K have also been shown to have significantly higher and faster absorption in humans compared to non-fermented ginseng. (14)  Fermented ginseng extracts also have powerful adaptogenic properties such as a strong antioxidant capacity, (15) anti-stress, (16) liver protective, (17) anti-allergic and anti-inflammatory (18) activities as well as support for blood sugar and lipid regulation. (19)

Reduction of Anti-nutrients:

Fermentation can also eliminate "anti-nutrients" such as phytic acid, a compound found in cereal grains that prevents mineral absorption, (5,20,21,22) and lectins, toxins that affect digestion.  The production of kimchi has also been shown to degrade pesticides during the fermentation process. (24)


(1).  Capozzi V, et al. Biotechnological production of vitamin B2-enriched bread and pasta. J Agric Food Chem. 2011;59(14):8013-20.

(2).  Chavan JK, et al. Nutritional improvement of cereals by fermentation. Crit Rev Food Sci Nutr. 1989;28(5):349-400.

(3).  Capozzi V, et al. Lactic acid bacteria producing B-group vitamins: a great potential for functional cereals products. Appl Microbiol Biotechnol 2012; 96:1383–1394.

(4).  Hemalatha S, et al. Influence of germination and fermentation on bioaccessibility of zinc and iron from food grains. Eur J Clin Nutr. 2007;61(3):342-8.

(5).  Haard N, et al. Fermented Cereals. A Global Perspective. FAO Agricultural Services Bulletin No. 138. 1999.

(6).  Famularo G, et al. Probiotic lactobacilli: an innovative tool to correct the malabsorption syndrome of vegetarians? Med Hypotheses. 2005;65(6):1132-5.

(7).  Hamad AM, et al. Evaluation of the protein quality and available lysine of germinated and fermented cereal. J. Food Sci. 1976; 44(2):456-459.

(8).  Oboh, G et al. Changes in Polyphenols Distribution and Antioxidant Activity During Fermentation of Some Underutilized Legume. Food Science and Technology International. 2009;15: 41-46.

(9).  Sato E. et al. Increased anti-oxidative potency of garlic by spontaneous short-term fermentation. Plant Foods Hum Nutr. 2006;61(4):157-60.

(10).  Jeng KC, et al. Effect of microbial fermentation on content of statin, GABA, and polyphenols in Pu-Erh tea. J Agric Food Chem. 2007;55(21):8787-92.

(11).  Pianpumepong P, et al. Study on enhanced absorption of phenolic compounds of Lactobacillus-fermented turmeric (Curcuma longa Linn.) beverages in rats International Journal of Food Science & Technology. 2012;47(11): 2380–2387.

(12).  Ciska E, et al. Glucosinolate derivatives in stored fermented cabbage. J Agric Food Chem. 2004;52(26):7938-43.

(13).  Hasagawa H. Proof of mysterious efficacy of ginseng: basic and clinical trials: Metabolic activation of ginsenoside: Deglycosylation by intestinal bacteria and esterification with fatty acid. Journal of Pharmacological Sciences. 2004; 95:153-157.

(14).  Jin H, et al. Pharmacokinetic comparison of ginsenoside metabolite IH-901 from fermented and non-fermented ginseng in healthy Korean volunteers. Journal of Ethnopharmacology. 2012; 139 (2012) 664– 667.

(15).  Ramesh T, et al. Effect of fermented Panax ginseng extract (GINST) on oxidative stress and antioxidant activities in major organs of aged rats. Exp Gerontol. 2012. 47(1):77-84.

(16).  Kitaoka K et al. Fermented Ginseng Improves the First-Night Effect in Humans’ Sleep. 2009;32(3):413-421.

(17).  Lee HU, et al. Hepatoprotective effect of ginsenoside Rb1 and compound K on tert-butyl hydroperoxide-induced liver injury. Liver International. 2005;25: 1069–1073.

(18).  Yang CS, et al. Compound K (CK) Rich Fractions from Korean Red Ginseng Inhibit Toll-like Receptor (TLR) 4- or TLR9-mediated Mitogen-activated Protein Kinases Activation and Pro-inflammatory Responses in Murine Macrophages. Journal of Ginseng Research. 2007; 31(4): 181-190.

(19).  Yuan HD, et al. Beneficial effects of IH-901 on glucose and lipid metabolisms via activating adenosine monophosphate–activated protein kinase and phosphatidylinositol-3 kinase pathways. Metabolism Clinical and Experimental. 2011;60: 43–51.

(20).  Reale A, et al. The importance of lactic acid bacteria for phytate degradation during cereal dough fermentation J Agric Food Chem. 2007;55(8):2993-7.

(21).  Leenhardt F, et al. Moderate Decrease of pH by Sourdough Fermentation Is Sufficient to Reduce Phytate Content of Whole Wheat Flour through Endogenous Phytase Activity. J. Agric. Food Chem. 2005; 53 (1):98–102.

(22).  Reddy NR. Reduction in antinutritional and toxic components in plant foods by fermentation. Food Research International. 1994;27(3):281–290.

(23).  Hamad AM, et al. Evaluation of the protein quality and available lysine of germinated and fermented cereal. J. Food Sci.1976; 44(2):456-459,

(24).  Cho KM, et al. Biodegradation of chlorpyrifos by lactic acid bacteria during kimchi fermentation. J Agric Food Chem. 2009;57(5):1882-9.

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