Choosing an appropriate garlic supplement can be a confusing process. Actually, there are four choices:

1. heat distilled garlic oil in softgels,
2. heat dehydrated garlic seasoning powder in capsules/tablets,
3. garlic oil macerates and
4. Kyolic^® odorless Aged Garlic Extract^™.

All garlic supplements have some nutritional value. However, powders and oils contain little or no water-soluble compounds which may be essential to obtain some of the key benefits of garlic. Garlic powders and oils contain some beneficial oil-soluble sulfur compounds. However, these compounds also have a pungent garlic odor as well as harsh, oxidizing side effects. Even though these products may claim to be deodorized, the garlic odor is just masked by chemical or sugar coatings. When the capsules or tablets dissolve, garlic body odor results.

Kyolic odorless Aged Garlic Extract, on the other hand, is truly the only odorless garlic supplement. The exclusive aging process eliminates garlic odor and harsh side effects. Moreover, Kyolic contains various antioxidant properties and is the only antioxidant garlic supplement available.

Kyolic is also standardized with SAC (S-Allyl Cysteine), a beneficial water-soluble sulfur containing compound which is characteristic of Aged Garlic Extract.

“Allicin Potential” of Questionable Value. Intestinal Conditions Hinder the Generation of Allicin.
Allicin production in the body (from naturally occurring alliin and alliinase in garlic) is inhibited by various body fluids. Most supplements can only produce allicin in water but not in the body. Stomach fluids have been shown to destroy the enzyme, alliinase, in raw garlic powders which is necessary to generate allicin.

What About Enteric Coatings?

Enteric-coated supplements can potentially produce allicin in the intestinal tract, but….
— much of the allicin production is inhibited by intestinal fluids (only 60% of the amount produced in water can be produced in intestinal fluids).
— the remaining allicin may destroy not only bad, but also good bacteria. Allicin is a harsh oxidizing agent and high amounts have been shown to aggravate the intestinal lining as well as the stomach.
— if the allicin is absorbed by the liver in small amounts, it is completely metabolized or detoxified, however, absorbed in large amounts it may damage liver tissue.
— if it makes it past the liver to the blood, it may oxidize red blood cells.

Allicin Is Not Bioavailable:
No allicin found in the body following oral intake. Allicin is not biologically active inside of the body Allicin has not been conclusively proven to be responsible for garlic’s known health benefits. Allicin was not found in the blood or urine after consumption of approximately 90,000 mcg (roughly 10 cloves). It is lost en route and therefore is unlikely to be the active compound in garlic.

Other Compounds Must Be Responsible for the Benefits of Garlic

Allicin: Not Found in Top Garlic Products

For years, allicin has been deemed as the compound responsible for the benefits of garlic. It has shown an ability to kill bacteria and fungus in test tubes and topically crushed raw garlic has been used in wars to fight infections. However, no clinical trials have been performed with allicin and it has not become a commercial product, mainly because of its chemical instability but also because of its pungent odor and irritating nature.

Allicin is produced by an enzymatic reaction when raw garlic is either crushed or somehow injured. The enzyme, alliinase, combines with a compound called alliin in raw garlic and produces allicin. Because allicin is so unstable, once it is generated it readily changes into other compounds. Thus cooking, aging, crushing and otherwise processing garlic causes the allicin to be decomposed into other compounds. According to two studies of garlic preparations, allicin decreased to nondetectable amounts within one to six days (20-144 hours) This could explain why a study of various products on the market showed that they all contained an undetectable amount (<1 ppm) of allicin.

“Allicin Potential” of Questionable Value

To prevent the typical loss of allicin, some manufacturers have attempted to stabilize alliin and alliinase so that these compounds would not come together until after they enter the body in hopes of producing allicin inside of the body. Such “allicin potential” is measured by adding water to garlic products which contain both alliin and alliinase to determine how much allicin can be produced. However, the actual production of allicin inside the body is not the same as that produced in a test tube for the following reasons:

Intestinal Conditions Hinder the Generation of Allicin:

— Stomach acid destroys alliinase, preventing allicin production.
— Intestinal fluids further diminish the amount of allicin that can be produced.

Simulated stomach fluids and simulated intestinal fluids have commonly been used to determine the effects of typical digestion on nutrients or chemicals in question. Interestingly, alliinase, the enzyme which catalyzes the conversion of alliin to allicin, has been shown to be irreversibly deactivated at pH 3 or below, an acidic environment typically found in the stomach.Further, a 99% loss in allicin production was observed following consecutive exposure to simulated stomach fluids and simulated intestinal fluids which would occur when one takes a garlic powder orally.Therefore, it appears that unless a garlic powder bypasses the stomach, the amount of allicin produced is negligible.

What About Enteric Coatings?

Some manufacturers have enteric-coated their garlic powder so that it would bypass the stomach. Assuming the best, that a high quality garlic powder is used initially (one that is not exposed to high temperatures which can deactivate alliinase), this form of garlic could potentially deliver alliin and alliinase to the intestinal tract. However, simulated intestinal fluids have been shown to inhibit 40% of the allicin production. The remaining allicin may exert anti-microbial effects on bad bacteria, however, it may also destroy friendly bacteria. Both allicin and raw garlic preparations which contain allicin have been shown to decrease the bacteria flora. Further, being a strong oxidizing agent allicin may irritate the sensitive cells which line the intestinal tract as it has been shown to irritate the cells lining the stomach. Finally, if organically grown garlic is not used as a starting material, enteric-coatings may assist in delivering pesticides and other contaminants in the garlic directly into the intestinal tract for absorption.

Allicin Is Not Bioavailable:

No allicin found in the body following oral intake.

A study in which participants consumed a large amount of allicin (approximately 90,000 mcg) via crushed raw garlic (25 grams; roughly 10 cloves) revealed that neither allicin nor 16 of its daughter compounds could be detected in blood or urine from one to 24 hours after consumption. Due to its high reactivity allicin was shown to be completely metabolized in the liver. If allicin could even make it to the blood (to be delivered throughout the body), studies have shown that it changes into other compounds within five minutes and in the process may oxidize the blood cells causing them to lose their ability to carry oxygen.

“Allicin is not biologically active inside of the body”

Yukihiro Kodera, at the Designer Foods III Symposium: Research Update on Phytochemicals in Garlic, Soy and Licorice held in May, 1994 in Washington, D.C. found the following:

“Under simulated digestive conditions, little allicin was released from a garlic powder which contained both alliin and alliinase. When allicin was mixed with blood, it disappeared very rapidly, and the formation of trace amounts of allylmercaptan and diallyl disulfide were observed. Allicin also converted the hemoglobin in red blood cells to methemoglobin. Furthermore, allicin has been shown to disappear upon contact with the liver; no allicin could be detected in the effluent when allicin was perfused into an isolated liver.”

“Though allicin was considered to be a key compound in garlic in the past, recent scientific findings, including the pharmacokinetics and metabolism of organosulfur compounds in garlic, have revealed that allicin is not biologically active inside of the body…”

Allicin has not been conclusively proven to be responsible for garlic’s known health benefits.

Following are some conclusions drawn about allicin from garlic scientists at the “First World Congress on the Health Significance of Garlic and Garlic Constituents” held in August 1990 in Washington, D.C.:

Contrary to the popular myth that a garlic product must contain allicin to be beneficial, allicin has not been conclusively proven to be responsible for garlic’s known health benefits. Most of the garlic or garlic products that have been based to demonstrate garlic health effects do not contain significant amounts of allicin. (Allicin is an odorous and transient garlic compound.)

Equally untrue is the myth that if garlic or a garlic product does not have a garlic odor it does not provide benefits. A major part of the data on the benefits of garlic is derived from studies of cooked garlic, pickled garlic, aged garlic, and Aged Garlic Extract^™. All of them have little typical garlic odor.

Other Compounds Must Be Responsible for the Benefits of Garlic

Various forms of garlic, which contain no allicin (e.g., cooked, steamed, microwaved and aged garlic extract), have demonstrated an array of benefits in studies. Therefore, it is logical that compounds other than allicin are responsible for such benefits. To date, well over 100 compounds have been identified in garlic preparations. Presently, S-allyl cysteine appears to be a very promising compound with good absorption. Again, according the research of Kodera et al:

“The pharmacokinetic studies of S-allyl cysteine demonstrated rapid absorption and almost 100% bioavailability after oral administration. In addition, since both the safety and effectiveness of S-allyl cysteine have been reported, this compound appears to play an important role in garlic’s medicinal effects.”

Though individual compounds, such as S-allyl cysteine, have shown activity in studies and are absorbed by the body, it is likely that a synergism of various compounds provide the benefits of garlic. This is in agreement with Dr. Koch, a renowned Austrian scientist who stated that the activity of various sulfur compounds could not alone be responsible for the benefits of garlic and fixation on a single group of components can lead to mistakes and wrong conclusions.

1. What type of current research is being done with Aged Garlic Extract?
2. Why have researchers focused on Aged Garlic Extract in their research?
3. Many garlic products describe themselves as being standardized. What are the differences between those products?
4. What about products that claim allicin is their active ingredient?
5. How should consumers choose a garlic supplement?

Q: What type of current research is being done with Aged Garlic Extract^™?

A: Aged Garlic Extract is used in several university research projects annually. These studies have focused on aspects such as cholesterol, high blood pressure, homocysteine levels, immune stimulation, cognitive effects, and liver function effects. The results are published in peer-reviewed scientific journals. Some of the institutions involved are Loma Linda University, Brown University, Penn State University, Rutgers University, Cornell, the National, Cancer Institute and the National Institute of Health.

Q: Why have researchers focused on Aged Garlic Extract in their research?

A: Consistency is very important for scientific research. Aged Garlic Extract is manufactured with an extraction process that offers consistent amounts of effective compounds. Simple dehydrated powders used in other garlic pills not only lack consistency but are standardized with non-active compounds that actually are not present in the products you take. This lack of true standardization and inconsistency render these products far less acceptable than Aged Garlic Extract for research and therapeutic purposes.

Q: Many garlic products describe themselves as being standardized? What are the differences between those products?

A: As you can see from the table below, Kyolic® is standardized with S-allylcysteine (SAC). This compound was chosen because it has been proven effective, safe and bioavailable. Various other products are standardized with compounds that are not bioavailable, not present in the product, or are not even effective. It makes no scientific sense to market any botanical based on a marker compound that is not a chemical constituent of the garlic supplement or biologically active in the body. The SAC in Kyolic is both biologically active and present in the supplement itself. This very important difference separates Kyolic from all other garlic brands.

Q: What about products that claim allicin is their active ingredient?

A: Strangely, not one of these products actually contain allicin or delivers allicin to the blood or liver where garlic actives are measured. Obviously, if it can’t be found in the body, it can’t be an active ingredient. These products are the subject of recent negative media reports that should not be confused with the positive reports on Aged Garlic Extract.

Q: How should consumers choose a garlic supplement?

A: To be fully safe and effective, a garlic supplement should be an antioxidant and manufactured through an aged extraction process. Consumers should always be sure the product is standardized with SAC and manufactured under current Good Manufacturing Practices (GMP) established by the World Health Organization (WHO) as an international standard. Kyolic Aged Garlic Extract fits all of these guidelines.

Sulfur-containing compounds

Recently, researchers have been focusing on the benefits of a variety of sulfur-containing compounds in garlic instead of allicin. These are classified as oil- and water-soluble compounds. Oil-soluble compounds include sulfides, such as diallyl sulfide (DAS), diallyl disulfide (DADS), diallyl trisulfide and allyl methyl trisulfide, dithiins, and ajoene. Water-soluble compounds include cysteine derivatives, such as S-allyl cysteine (SAC), S-allyl mercaptocysteine (SAMC) and S-methyl cysteine, and gamma-glutamyl cysteine derivatives. Oil-soluble sulfur compounds are odorous, whereas water-soluble compounds are odorless. Moreover, water-soluble compounds are more stable and safer than oil-soluble compounds (1).

Non-sulfur compounds

Garlic was also found to contain unique non-sulfur compounds, such as allixin and saponins and recent studies have revealed the important contribution of these compounds to garlic’s health benefits (2-4).

Garlic Powders: Chemically, there is almost no difference between the garlic flavoring powders sold at grocery stores and the garlic supplements made of garlic powder and then sold at health food stores. Often these manufacturers claim that their products deliver allicin into the body. Though no garlic supplement can contain allicin due to its instability and high reactivity, some garlic powder products contain alliin and the enzyme, alliinase, and, therefore, can produce allicin with the addition of water in a test tube (the so-called “allicin potential”). However, allicin potential is an empty promise. The environments in a test tube and in our body are totally different and there is no scientific evidence to support the idea that allicin can be produced in the stomach. Furthermore, garlic powder contains only a residual amount of the alliin found in raw garlic, i.e., more than half of the alliin is lost during the manufacturing process.

Garlic Oil Macerates: There are two types of oil macerate products on the market and both are packaged in soft gel capsules. One is made by simply mixing a garlic flavoring powder with vegetable oil. It’s constituents are almost the same as the capsule and tablet forms of garlic powder. Another one is made by grounding raw garlic in vegetable oils. Since this type of product contains oil-soluble compounds (allicin break down products) and leftover alliin, it has a strong garlic odor. Both products are rich in fat -the major component being vegetable oil. Thus, they are not suitable for use as daily supplements.

KYOLIC^® Aged Garlic Extract^™: KYOLIC begins with only organically grown garlic bulbs. This is essential for growing naturally balanced garlic because organic fertilizers produce an ideal ratio of essential nutrients in the raw garlic without any contamination by harmful chemicals including herbicides and pesticides. Then KYOLIC is gently aged to convert the harsh and irritating compounds in raw garlic to mild, stable and beneficial compounds. KYOLIC Aged Garlic Extract, is a totally balanced garlic supplement containing large amounts of essential water-soluble compounds and small amounts of oil-soluble compounds. KYOLIC is a sociable garlic and its safety and benefits have been confirmed by over 600 scientific studies. Furthermore, the bioavailability of its key compound, S-allyl cysteine, has been substantiated.

Historical and Traditional Use of Garlic

Condiment/flavoring preparations: With little effort, you can find numerous recipes calling for garlic as a condiment/flavoring. Most of these recipes require some method of processing and/or cooking. Boiling and baking, and also very simple processes, such as slicing, chopping, or grinding raw garlic, initiate many chemical reactions within the garlic and result in completely different chemical constituents compared to those originally found in the whole raw garlic cloves. Salubrious/Salutary preparations Preparation of garlic for beneficial use can be classified into the following two categories: 1.   Topical/external use: Ground or sliced raw garlic cloves applied directly onto wounds or injuries. Used in this way, allicin, produced enzymatically from alliin, may play an important role in killing bacteria to prevent infections. However, allicin may also destroy tissues on contact, as previously mentioned, thus limiting the utility of its anti-bacterial properties and making it inappropriate for internal consumption. 2.   Internal use: A number of recipes for the preparation of garlic for internal use are shown in the historical herbal books published in Europe, China and India. All of these recipes include some type of processing, such as boiling, baking, pickling or aging of raw garlic. In the Orient, aging is the unique and traditional method used to increase the benefits of herbs and to decrease or eliminate any toxicity. Hundreds of sulfur-containing compounds and unique amino acid derivatives formed through chemical and biological reactions, in addition to the non-sulfur compounds, contribute to the benefits of the internal use of garlic.

Recent scientific findings

Recent scientific findings have given validity to these traditional methods for preparing garlic. It is well-known that garlic cloves contain alliin and the enzyme, alliinase. Cutting or crushing garlic cloves activates alliinase, which catalyzes the reaction that converts alliin to allicin. However, allicin is an odorous, highly unstable and reactive/oxidative compound which readily decomposes to other sulfur-containing compounds (5, 6). Therefore, raw garlic and related preparations are chemically unstable and have been known to cause side effects, such as stomach disorders and allergic reactions when taken internally (7, 8). Thus, such preparations would be of limited application. Furthermore, since lack of bioavailability of allicin has been shown, garlic preparations containing allicin can be useful only for external application. On the other hand, processed garlic is rich in a variety of sulfur-containing compounds which may act synergistically or antagonistically to provide the benefits of garlic. Since these preparations contain little or none of the harsh and irritating compounds in raw garlic, they would cause less undesirable effects when consumed internally.

Aged Garlic Extract

A garlic extract, called Aged Garlic Extract, has been developed based on the traditional usage of garlic. Instead of using heat, Aged Garlic Extract is aged naturally for 20 months. The unique natural aging process adds greatly to the value of garlic:

1. the harsh and irritating compounds are significantly reduced
2. the pungent odor of garlic is also reduced
3. sulfur-containing compounds, such as alliin and allicin, are converted to many other sulfur-containing compounds, which are mainly water-soluble. Aged Garlic Extract has been studied extensively and shown to have almost all known garlic benefits.

Natural Aging-Bioconversion Pathway: This pathway leads both water- and oil-soluble sulfur compounds, mainly water-soluble. During the natural aging, the harsh and irritating compounds in raw garlic are converted mild, stable, safe and beneficial compounds.

Cell Rupture-Allicin Decomposition Pathway: When garlic is cut or crushed, alliin is enzymatically converted into allicin. Allicin is highly unstable and rapidly decomposes under uncontrollable chemical reactions to produce odorous oil-soluble sulfur compounds.

Furthermore, it has been shown that after ingestion of 25 g of raw garlic containing a significant amount of allicin, neither allicin nor sixteen of its common transformation products were detected in either the serum or urine from 1 to 24 hours after ingestion (6).

These data suggest that allicin taken orally may not be delivered to the organs and tissues, and that it does not appear to be a biologically beneficial compound in garlic.

Fig. 1 The color of red blood cells changes to black when mixed with allicin (right test tube). Physiological saline as a control was added to the left test tube.	Fig. 2 The red line shows the spectrophotometry profile of hemoglobin prepared from the control blood. The brown line shows the formation of methemoglobin when blood was mixed with allicin. (The appearance of the third peak is characteristic of methemoglobin).