Garlic: clove at first sight?

Garlic. Other than warding off vampires and helping make a mean pesto, is it good for anything? The garlic-supplement industry would have you believe so.

It will happily sell you any number of pricey tablets and capsules that may be no better than the garlic you can buy at your local supermarket.

The bottom line: It wouldn't hurt you to eat more garlic or take garlic supplements...and it might even make you healthier. But the benefits are far from proven. (For our test of the most popular garlic supplements, see p. 5.)

LOWERING CHOLESTEROL

Just imagine. Use garlic regularly and your cholesterol could drop from 300 to less than 275.

At least that's what could happen if Stephen Warshafsky and his colleagues at the New York Medical College in Valhalla, New York, are right. In 1993, after they combined the results of four separate studies, they concluded that the equivalent of one-half to one clove of garlic a day "decreased total serum cholesterol levels by about nine percent."(1)

And when scientists in England and Australia combined the results of 16 studies, they calculated that garlic supplements could cut high cholesterol levels by 12 percent.(2)

A simple way to lower the risk of heart disease? Maybe. Maybe not.

"The studies have been so poorly designed and carried out that it seems to us simply a hypothesis about which there's not adequate evidence," concludes cholesterol expert Stephen Hulley of the University of California at San Francisco.

And, recently, researchers from Yale University didn't see cholesterol levels drop in 30 people who were taking a popular garlic supplement for six months.

"Preliminary data have failed to show a significant effect of garlic powder supplements on cholesterol," says Yale University cardiologist Marvin Moser, who was one of the investigators.

Until the study is published, however, it's hard to know whether it will settle the controversy.

So what does Moser tell his patients? "That garlic can't hurt you. That it's very tasty. That you should put all you want in your food, unless you're allergic or sensitive to it. And that maybe, maybe, in some people, it might lower cholesterol."

PREVENTING CANCER

"There is growing evidence that garlic or its derivatives may be able to prevent the development of at least six different cancers," says John Pinto of the Memorial Sloan-Kettering Cancer Center in New York.

He's talking cancers of the breast, colon, esophagus, prostate, skin, and stomach.

But don't rush off and invest in garlic futures. At least not yet. Nearly all of the evidence is based on work in test tubes and experimental animals--not humans.

Even so, the research is intriguing.

"Feeding rats large amounts of garlic compounds for two weeks before and two weeks after exposing them to a powerful carcinogen [cancer-causing chemical] delayed the appearance of breast cancer and reduced the total number of tumors by 27 to 73 percent, depending on the amount of powder," says John Milner of Pennsylvania State University.

And when mice were given large quantities of a component of garlic known as S-allyl cysteine (SAC) before being exposed to a carcinogen, the incidence of colon tumors was cut in half, says Michael Wargovich of the University of Texas M. D. Anderson Cancer Center in Houston. SAC is found in many garlic supplements (see test results on p. 5).

"What may be happening here," explains Pinto, "is that something in garlic is stimulating one of the body's natural defenses, glutathione-S-transferase, which is an enzyme that helps detoxify and dispose of unwanted chemicals."

All well and good. But rats are rats and mice are mice. What does garlic do to people, who don't get cancer from one massive dose of a chemical carcinogen?

Few studies have looked at cancer rates in people who happen to eat garlic. One, on women in Iowa, found less colon cancer in garlic-eaters. But it needs to be confirmed. Most other studies have been done on stomach cancer in countries like China, where it's common.

In fact, the first human experiment to see if taking garlic supplements can prevent (stomach) cancer is scheduled to begin this fall in China.

One potential problem: the amounts of garlic compounds that had to be fed to animals to block cancer were so enormous that it's not clear whether humans could ever get enough to see the same benefit. Mice and rats, for example, were typically given the equivalent of hundreds--and sometimes tens of thousands--of garlic capsules or tablets a day.

Here's how cancer researcher John Milner sums up the evidence: "I certainly don't think that garlic is a magic bullet that's going to eliminate all tumors. It's part of a healthy diet, not the healthy diet."

OTHER HEALTH BENEFITS

If you think the evidence on garlic's ability to lower cholesterol or prevent cancer is iffy, wait until you see what's known about its other health benefits:

* Blood pressure. When researchers combined the results of eight different studies, they concluded that people with hypertension who took garlic powder supplements every day for one month to one year lowered their systolic blood pressure (the higher number) by an impressive eight points and their diastolic blood pressure (the lower number) by an average of five points.(3)

But the studies "didn't protect against bias when measuring blood pressure," says epidemiologist Jeffrey Cutler of the National Heart, Lung and Blood Institute. "While at first the results might seem impressive," he adds, "we need to rely on better-designed studies."

Unfortunately, at least one of those studies has come up empty.

"Blood pressure was not lowered to a significant degree in garlic-powder-takers," says Yale University's Marvin Moser, who monitored volunteers' pressure as part of a six-month study that looked at whether garlic could also lower cholesterol levels (it didn't).

* Sticky blood. One reason people get heart attacks or strokes is that their blood becomes "sticky." That means their platelets tend to clump together. And clumpy platelets can develop into clots. Could garlic make clumping less likely, or even break up clots once they start to form?

A compound derived from garlic called ajoene (AH-hoe-een) has "quite a strong effect on preventing blood clotting in test tubes," says researcher Eric Block of the State University of New York at Albany. "But the stomach may inactivate ajoene," he adds, "so it's uncertain if it will work in humans when swallowed."

Other results are just as murky. For example, the blood of 12 healthy Italians was less likely to clot after they took a popular garlic supplement for just two weeks.(4) But six months of taking the same supplement didn't appear to affect clotting in the volunteers in Marvin Moser's not-yet-published U.S. study.

* Strengthening the immune system. Can garlic curb cold symptoms and help fight off infections, as some of its boosters claim?

"There hasn't been enough good research to establish that garlic is helpful with the immune system," says Ranjit Chandra of the University of Newfoundland, who is a recognized authority on nutrition and immunity.

(1)Annals of Internal Medicine 119: 599, 1993.

(2)Journal of the Royal College of Physicians at London 28: 39, 1994.

(3)Journal of Hypertension 12: 463, 1994.

(4)Arzeneimittelforschung 43: 119, 1993.

RELATED ARTICLE: POWDER WISE...

Americans buy more garlic pills than any other herbal supplement. Yet few people know that some brands are much more potent than others, and that the best are often the least expensive.

"Let the buyer beware," cautions garlic researcher Eric Block of the State University of New York at Albany, "because there are people out there making lots of claims--and substantial amounts of money--with little to back them up."

While more research is needed, there is some promising evidence that garlic is good for you. And if you want to take a garlic supplement, you ought to know what you're getting.

That's why we sent samples of nine of the top-selling garlic supplements--plus a popular garlic powder seasoning--to an independent laboratory. We bought at least three different "lots" of each brand in Los Angeles, Chicago, and Washington, D.C. The lab analyzed a "composite," or mixture, of each brand for:

* Allicin. It's not allicin, but what this sulfur-containing compound turns into when garlic is minced, crushed, swallowed, or digested, that may lower cholesterol, blood pressure, and the risk of cancer, say most experts. You can also thank allicin for garlic's smell.

* SAC. S-allyl cysteine is one of garlic's many compounds. In animal studies, it seems to prevent some cancers.

OUR RESULTS

"We don't know exactly how much of which garlic compounds are able to do what," says John Erdman, director of Nutritional Sciences at the University of Illinois. "So it makes sense to choose products with the greatest variety of compounds that are found in whole, fresh garlic."

That's how we ranked the supplements (see "Garlic vs. Garlic"). Since allicin is considered the "parent" of most of garlic's beneficial compounds, we calculated how many tablets or capsules of each brand's regular-potency formula would give you 5,000 micrograms (mcg) of allicin. That's about how much you get in one large clove of fresh garlic. The results:

1. Fresh Garlic. It's your best choice, say most researchers. (We didn't test it.) Some tips: 1) The more finely divided, the more allicin. So minicing is better than slicing. 2) Cooking may destroy some compounds. Light cooking may be better than none, though, because raw garlic irritates some peoples' mouths and stomachs.

2. Garlic Powder. The best--and cheapest--garlic supplement may be sitting on your spice shelf. It takes just a third of a teaspoon of McCormick (Schilling) Garlic Powder to give you 5,000 mcg of allicin. The cost: about a nickel.

3. The Best-Buy Pills.

KAL Beyond Garlic offers the biggest bang for your buck and your gulp. Garlique, Garlicin, and Nature's Way also require only one to three tablets at a reasonable cost.

Most experts say that you're better off with an "enteric coated" supplement (like KAL, Garlique, or Garlicin). Enteric coating keeps the allicin from being released before it reaches your small intestine. Some researchers argue against coating, though, because all that allicin might irritate your small intestine.

But Yale University gastroenterologist Gary Abrams isn't worried about irritation. "I search the literature regularly, since I have to inform the patients in my garlic studies about any potential side effects," he explains.

4. Mid-Range Pills. Researchers don't know if it helps to spread out six to nine pills over a day. But that's what you'd have to take to get 5,000 mcg of allicin from Kwai or Quintessence.

5. Least Acceptable. Seventeen pills a day? GNC's Natural Brand hardly seems worth it. And no one's going to take the 44 pills you'd need if you go with P. Leiner--which makes "private label" garlic supplements that carry the names of drugstores and other chains. (How to identify Leiner products: most say "Release Assured" on their labels.)

"We're changing our specifications to the new higher-potency allicin," said a Leiner spokesperson after being told of our test results. "We're looking into it and we'll make whatever changes need to be made," said GNC.

Kyolic, the best-selling garlic supplement, contains no allicin. Instead, it "offers standardized levels" of SAC. Kyolic's manufacturer, Wakunaga of America, won't say exactly how much SAC it contains.

Now we know. Our test results show that four Kyolic capsules have about 1,000 mcg of SAC. But all of the other supplements we tested--including garlic powder seasoning--also contain SAC.

And what if Kyolic is wrong? What if it's not just SAC, but allicin and the compounds it turns into, that are also beneficial? It makes no sense to put all your eggs in the SAC basket.

RELATED ARTICLE: GARLIC VS. GARLIC

Here are the results of our tests of nine leading regular-potency garlic supplements plus garlic powder seasoning. With the exception of the powder (which doesn't come in tablets), supplements are ranked from least to most number of tablets necessary to get closest to 5,000 micrograms (mcg) of allicin, the parent compound of most of garlic's good stuff.

Garlic                         No. of     Cost(1)   Allicin   SAC
                               tablets               (mcg)   (mcg)
McCormick (Schilling) Garlic
Powder(2)                      1/3 tsp.    6[cts.]   5,660     590
KAL Beyond Garlic(3)               1      18[cts.]   4,800     270
Garlique(3)                        1      33[cts.]   3,840     130
Garlicin(3)                        2      35[cts.]   4,330     290
Nature's Way                       3      24[cts.]   4,580     420
Kwai                               6      66[cts.]   4,880     340
Quintessence                       9      81[cts.]   4,810   1,640
Natural Brand (GNC)               17         $1.70   5,050     730
P. Leiner (private label)         44         $1.99   5,020   2,020
Kyolic                             4(4)   42[cts.]       0   1,010

(1)Based on the list price when available or the average price we paid.

(2)Other garlic powder seasonings--but not garlic salt--may yield similar numbers.

(3)enteric coated.

(4)Kyolic contains no allicin, so we used the suggested daily dose.

* The use of information from this chart is prohibited without written permission from CSPI.