It's tough to keep garlic a secret. If you use fresh garlic, the telltale sign lingers on your breath. If you are using garlic dietary supplement products, chances are a friend will discover them on a shelf in the kitchen or bathroom. Garlic breath was once a measure of bad breath. Now, as baby boomers come of age, whether it be adopting a love for gourmet Italian food or haute cuisine vegetarian, garlic is a must ingredient. The aging baby boomers are also the population segment most likely to buy garlic dietary supplement products. Sales of one garlic product in Germany top $40 million per year. Garlic is one of the two best-selling herbal dietary supplement products in the mass market in the United States, and is the second-best-selling herbal dietary supplement in the health food market (second to Echinacea). In 1995, the United States imported more than 5.3 million kilograms of dehydrated garlic valued at over $2.9 million. In the same year, the U.S. exported nearly 3.6 million kilograms of dehydrated garlic worth over $8.5 million. Figures are not available for the most recent year on fresh garlic sales, but top $80 million a year.
The spice of life is garlic. The bulbs of this familiar member of the lily family have been cultivated for thousands of years for use as a flavoring as well as a medicinal herb. The health benefits of garlic are varied and many. Nature has ingeniously packaged a chemical factory in garlic. It contains a collection of sulfur and selenium aroma compounds that probably developed in the plant to protect it from predators such as animals or even soil-born organisms. It is these chemicals, released upon cutting or crushing garlic, that provide its health-giving benefits.
The 1990s have been the heyday of garlic research, with perhaps as many scientific papers on garlic published in this decade alone as in the previous 80 years of this century. There are now well over 2,200 credible scientific papers on all aspects of garlic, including its chemistry, pharmacology, and clinical applications. Research on garlic is beginning to catch-up with at least 70 centuries of human experience with this important herb.
Garlic's historical use is recorded by the great herbalists and physicians of the ancient world. "Garlic has powerful properties, and is of great benefit against changes of water and of residence . . ," wrote Pliny the Elder, the first century Roman naturalist (23-79 AD). He recommended garlic as an antidote for the poisonous bites of shrews and snakes, as well as poisoning from aconite and henbane. Like the ancient Chinese, he noted its use in the treatment of asthma, as a cough suppressant, and to expel intestinal parasites. Pliny regarded the freshly crushed seeds of coriander, mixed with garlic in neat wine, as an aphrodisiac. But there was a down side. According to Pliny, excessive use of garlic may dull the sight, causing flatulence, injure the stomach, and cause thirst.
The herb was also surrounded in superstition. According to Maude Grieve in her Modern Herbal (1931), in some parts of Europe, men running a race would chew a small piece of the bulb, because it was believed that this would prevent competitors from getting ahead of them. William Coles in his Art of Simpling (1657) wrote, "Cocks having eaten Garlick, are most stout to fight and so are horses."
Through the ages, herbalists have considered garlick a good carminative for digestive problems. An excellent treatment for diarrhea, and a treatment for bacterial, fungal and viral infections. In many cultures garlic has been used to treat intestinal parasites. In the first world war, garlic was widely used as an antiseptic. In short garlic has been used for about every human ailment. Writing in his Materia Medica, Therapeutics and Pharmacognosy, Finely Ellingwood (1902) says, "As an antiseptic and preventer of disease it has not equals."
Much modern research on garlic has focused on garlic's value as a "preventer of disease."
Garlic has become recognized for its great value in the prevention of arteriosclerosis. Its ability to lower high serum cholesterol and triglyceride levels is well-researched and widely recognized. It has a hypotensive effect, helping to lower blood pressure. Its cancer preventing effects have been the subject of a number of studies. Some researchers have focused on its antidiabetic activity, by virtue of its ability to lessen moderately elevated blood sugar levels. It has also been shown to inhibit thrombocyte aggregation (acting as a blood thinner) and activate fibrinolysis. If there's one herb sold as a dietary supplement on the American market today that has stood the test of time, and been accepted by the medical community because of the quality and quantity of research, it is certainly garlic. No other herb comes close.
One of the best-researched areas of garlic is its effects on the heart and circulatory systems. Garlic has been used since ancient times in India and China for a beneficial effect on the heart and circulation. A number of papers from the 1920s to the 1950s focused on the possible health benefits of garlic on circulation. Research in the late 1960s laid the ground work for a modern understanding of how garlic can benefit the heart and circulation. Its positive effects on circulation are not the result of any one single pharmacological mechanism, rather they combine a number of well-researched effects working in concert to produce benefits. Garlic has been shown to protect blood vessels from the deleterious effects of free radicals. This antioxidant activity has also been linked to its blood cholesterol-lowering action and its ability to decrease deposits of cholesterol on the walls of blood vessels. By lowering lipids in the blood (such as cholesterol and triglycerides) it benefits the heart. It not only lowers low-density lipoprotein in the blood, buts shifts the ratio of low-density lipoproteins in favor of high-density lipoproteins - so called good cholesterol, which helps the liver metabolize fat substances in the blood, rather than allow them to be deposited in tissue. It also increases flow of blood to the capillaries, helping to reduce blood pressure. In addition garlic reduces thrombocyte adhesiveness and aggregation. In other words, it helps reduce the stickiness of blood platelets and their ability to aggregate (or produce blockage). It also enhances a process known a fibrinolysis, which results in speeding up the dissipation of coagulated blood, plaque and clots.
There's no question that garlic is good for you. But which kind? The biggest problem with garlic from a social as well as a manufacturing perspective is the characteristic odor that garlic leaves on the breath. This perception of garlic breath as "bad breath" is not new to modern dietary supplements or modern consumers. The Roman poet Horace (65-8 BC), detested the smell of garlic and consider it a sign of vulgarity. A 16th century German botanist and physician, Jacobus Theodorus Tabernaemontanus (1520-1590) wrote an herbal published in 1588 called Neww Kreuterbuch. In his herbal he recommended using parsley as an odor blocking substance for masking the smell of garlic. Later authors suggesting strong-smelling essential oils such as those of peppermint and thyme to mask the odor.
New manufacturing procedures have produced "odorless" or "odor minimized" garlic products. The odor of garlic in powdered garlic products comes from two sources. Allyl sulfides found in the powder are produced from compounds called thiosulfinates when garlic is cut or crushed prior to drying. Freeze-drying will eliminate the fragrance of these compounds. Binding garlic powder in tablets that resist stomach acid and pass the stomach, disintegrating in the intestines, is yet another means of keeping garlic off the breath.
Another type of garlic odor is produced in the intestines themselves. Allicin, a well-known compound in garlic preparations, can be transformed into the intestines into a highly fragrant compound called allyl mercaptan, some of which is absorbed into the blood stream, which makes it ways to the lungs, producing garlic breath. Other odor-affecting manufacturing procedures include various types of extracts or aging of garlic which can also produce less odiferous products.
Different types of garlic preparations may also produce different compounds, hence there are different groups of active components in various product forms. For example garlic oils produced by soaking garlic in oil, steam-distilled type products and aged garlic extracts have chemical transformation products that do not mirror the chemical constituents of fresh garlic. Other types of preparations, including most powdered garlic products (tablets and capsules), attempt to mirror the chemical profile of fresh garlic in a stabilized form. While most studies have involved the latter, form, studies have also been conducted on aged garlic extracts and other products.
Ultimately, deciding how much garlic to take depends on the product form you choose to use. Generally, speaking you should follow the instructions on product labels. According to the 1988 German therapeutic monograph on garlic, the daily dose is equivalent to 4 g of fresh garlic cloves, which is about the size of one average clove of garlic. For the twenty-first century, the old adage about an apple a day, should be recited "a clove a day keeps the doctor away."
Foster, S. 1996. Garlic - Allium sativum. Botanical Series, No. 311. 2nd. ed. Austin, Texas: American Botanical Council.
Koch, H. P. and L. D. Lawson, (eds.).Garlic - The Science and Therapeutic Application of Allium sativum L. and Related Species, 2nd ed. Baltimore: Williams & Wilkins, 1995.
Reuter, H.D. 1995. Allium sativum and Allium ursinum: Part 2 Pharmacology and Medicinal Application. Phytomedicine 2(1):73-91.