Raw versus fermented garlic–what’s the difference?

Kerey asks “Does fermented garlic have the same anti-viral benefits as raw garlic? Also, why does eating raw garlic cloves give me an upset stomach and headache.”

Thank you for your question. The short answer to the first question is ‘no’, but to understand why and what fermented garlic does provide, I’ll need to draw on nutritional biochemistry. I will also explain why it may cause some side effects as well.

What is the garlic constituent that has anti-viral actions?Is the antiviral constituent, ajeone, inactivated in lacto-fermentation?What garlic constituents are associated with upset stomach and headache, does lacto-fermentation help reduce them?

I. Many of the bioactive compounds attributed to garlic’s (Allium sativum) activity have long been associated with garlic oil. The strong smelling, sulfur containing liquid is called allicin. This is not present in intact fresh garlic but is the product of a natural enzymatic reaction when the pulp is damaged. When the garlic clove is crushed separate cellular compartments release the precursor, alliin (S-allyl-l-cysteine sulfoxide) and an enzyme, allinase, which then produces allicin (diallyl thiosulfinate). As allicin is metabolized, the molecule ajeone is produced. It has been demonstrated in vitro that ajoene exerts both anti-microbial (bacteria, yeast and fungi) and anti-viral activity.The breaking of this sulfur (disulfide) bond is the mechanism of action for the anti-microbial and anti-viral action so always crush your garlic to get the most out of it. Remember this, all of the above are oil-soluble compounds. The water soluble compounds of garlic are odorless and more stable than the oil-soluble fraction. These water-soluble compounds provide other health benefits and include allixin and saponins.

II. Lacto-fermentation is the controlled process where bacteria convert glucose and other 6-carbon sugars to lactic acid to preserve foods. Minimally, lacto-fermentation harnesses the bacteria, Lactobacillis bulgaricus and Streptococcus thermophiles (probiotic strains). As mentioned above, the active anti-microbial and anti-viral compounds are oil soluble molecules and these are not consumed in lacto-fermentation of garlic. That said, the ajeone molecule is not stable and breaking of the bond requires a pH higher than 8. Where, most lacto-fermentation is complete when the production of lactic acid makes the product pH 4, therefore there is a low likelihood that ajeone is still present in the fermented garlic product. Further, most recipes for fermentation of garlic advise the use of intact cloves, not crushed. Therefore the enzymatic process to produce ajeone may not have been initiated, and present lower quantities than in fresh crushed clove extracts. Keep in mind that the water soluble compounds remain intact and are not consumed by fermentation.

III. If you experience stomach ache when you eat foods containing garlic or onion, you may be sensitive to fructans. These are fructose polymers (6-carbon sugars) that are 2-9 units in length, oligofructose are inulins which are > 10 units in length. Foods containing high amounts of fructans include onions, garlic, shallots, barley, cabbage, pistachio, artichoke, chicory root and asparagus. The good news is that the fructan sugars are consumed during lacto-fermentation. Therefore fermented garlic is a great way to get the water-soluble nutrients from garlic.

Further, garlic is considered one of many dietary triggers for migraines. I have found no specific reference to lacto-fermentation ameliorating this, however it is worth trying if the stomach ache is resolved. I have provided some references below.

Park KY, Jeong JK, Lee YE, Daily JW 3rd. Health benefits of kimchi (Korean fermented vegetables) as a probiotic food. J Med Food. 2014 Jan;17(1):6-20. doi: 10.1089/jmf.2013.3083.Harunobu Amagase; Clarifying the Real Bioactive Constituents of Garlic, The Journal of Nutrition, Volume 136, Issue 3, 1 March 2006, Pages 716S–725S, https://doi.org/10.1093/jn/136.3.716SGarlic & Headaches | LIVESTRONG.COM How To Ferment Garlic & Its Health Benefits

Judith Fox Smith, MS, is the founder of Foxsmyth Herbal, in Stoneham, MA. Judy is a biological research scientist and clinical herbalist. She is the founder and past president of the Eastern PA chapter of American Herbalist Guild, the Herb Gatherers of Lansdale, PA and past Vice President of San Antonio Herb Society. She combines her knowledge of biology and botany with her passion to provide practical herbal and lifestyle recommendations for a holistic balance in today’s techno-driven world.