Eating Satan's footprints

What can the onion and garlic diet do for you? Ask, rather, what you can do for Macedonia.


Susan McCarthy
October 29, 1999 8:00PM (UTC)

The news was good, but delivered with a smirk. "Of Onions and Osteoporosis," the press release was headed. In a brief communication to the journal Nature, Swiss researchers reported a possible inexpensive, natural treatment for osteoporosis, the thinning of bones that may occur with advancing age. Experiments with rats indicated that "a variety of salads, herbs and cooked vegetables ... can alter bone metabolism."

Rats that ate a gram of dried onion daily had stronger bones (around 15 percent stronger) in just four weeks. Actually there were good results with 14 different vegetables, including arugula, cucumber, dill, lettuce, parsley and tomato. Because osteoporosis is a particular concern in women after menopause, the researchers created quasi-menopausal rats (by removing their ovaries), and plied them with onions -- Lo! the onion inhibited bone loss. It didn't stop it, but reduced it by about a quarter. And the more onions they ate, the stronger the effect.

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"However, what with garlic for the heart and onions for the bones, postmenopausal women may live to be sprightly centenarians but may end up with few close friends," snickered the press release.

Some things always seem to get a laugh. Cartoonists know that any body part is funnier with a band-aid on it. Accordions are funny, tubas are funny, Kenneth Starr falling in a mud puddle is funny. Onions and garlic are funny. They are members of the Allium genus, along with leeks and so forth, and it's hard to do a dignified survey of Allium therapies. You keep tripping on the stink jokes.

Note that other vegetables were also involved in the Swiss study, but the onions get the ink. Dill, for example, could use a publicist. As onions and their close relative garlic would tell you, any publicity is good publicity. At least, that's what their PR firm tells them. But would Dan "Potatoe" Quayle agree?

There's some evidence that a steady diet of onions and garlic is good for your heart and circulatory system, lowers your chance of getting certain kinds of cancer and may even discourage parasites. There's also some evidence that these medical benefits are largely imaginary, and that what onions and garlic are really good for is lowering stress by making food taste better. But -- insert obligatory joke about the reek here -- some say typecasting may be a problem. The authors of "Garlic, Cancer and Heart Disease," Dr. Orville Green III and Nicholas Polydoris, worry that "It is possible that modern society has shunned this history of therapeutic effectiveness because of the odor associated with ingestion of fresh garlic."

Onions and garlic are old hands at the I-don't-care-what-they-say-about-me-as-long-as-they-spell-my- name-right game. A Turkish legend says that when Satan left the Garden of Eden after the Fall, onions grew from the spot where he set his right foot and garlic from where he set his left foot. Following Satan, I'm going to discuss onions and garlic together, as if they were just two different footprints of the same fallen angel, since they have many of the same active ingredients.

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Sumerian records as far back as 2400 BCE mention onion patches. Later, the Sumerian Code of Hammurabi ordered that the poor should receive a monthly ration of bread and onions.

When Moses led the Jews into the desert, one of the complaints he had to handle was the lack of onions and garlic. The exiles also mentioned missing fish, cucumbers, and melons, but I have nothing in my files from the Cucumber Growers Association or the Melon Council, so once again it's onions and garlic in the starring roles.

In the fifth century BCE, Herodotus noted that there was a sign on the Great Pyramid at Giza promoting the vast sums spent on feeding the workers who built it: 1600 silver talents were blown on onions, garlic and radishes to keep the people piling rock on rock. (Take note, root-crop growers: Why not use this as a basis for your "Got Radishes?" campaign?)

The long history of onions and garlic is not only culinary but medical. In around 1500 BCE an Egyptian medical work, the Ebers Codex, prescribed garlic for tumors, worms, arthritis and heart disorders as well as providing tasty recipes.

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Alexander the Great of Macedonia (356-323 BCE) is said to have fed vast amounts of onions to his soldiers on the theory that they restored courage. (If it were up to me, I would prefer to lay off the onions, no matter how tasty, and stay home in Macedonia rather than rampaging through Asia Minor with Alex.)

Onions and garlic have many uses in folk medicine, including the power to ward off the evil eye. (You might think this means vampires, but couldn't it apply equally well to recruiters from the Macedonian army?) They have been used as anticoagulants, vermifuges, antiseptics, poultices and hair restorers. (You know that last one is wishful thinking or we'd all be trying to get in on the IPO of the Onion Club for Men.) They're prescribed by herbalists for everything from colds to cancer.

Gen. Ulysses S. Grant esteemed onions highly, for reasons I haven't been able to pin down. During the Civil War he sent a message to the War Department, snarling, "I will not move my army without onions." They sent him three wagonloads. It may have been to ward off dysentery, or it may have been an antiseptic to treat wounds. Or maybe Grant subscribed to the Macedonian theory that onions give courage.

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Other miscellaneous garlic prescriptions from purveyors of herbal remedies include the appalling news that "A Garlic and Catnip enema is a popular remedy" for back pain. So prissy humans draw back in horror and cats follow you down the street, purring lasciviously? It's never going to be "popular" with my clique.

A persistent tradition about garlic and onions had been that they kill parasites. Indeed, it has always been my custom to celebrate its powers by screaming, "Die parasites!" whenever I taste some particularly garlicky delicacy.

There seems to be a grain of truth in this. The sulfur compounds that make garlic and onions so refreshingly fragrant probably evolved to repel insect pests. On the other hand, say what you will about the human race, we're not insect pests. Almost every herb or spice we like to eat evolved to disgust insect pests. But where an aphid or weevil might stagger away gagging and frantically wiping its mouth parts, humans grin and ask for more. May I have some more pepper? More cinnamon? Gimme another jalapeqo. More garlic, please.

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Garlic and onions also have anti-bacterial, anti-fungal and anti-protozoal activity in the test tube and perhaps even in the body. But before you back up the garlic truck to the pharmacy, consider that one study of garlic's powers concluded that it had 1 percent of the strength of penicillin against certain bacteria. Apparently a lot of bacteria already know how to deal with garlic.

The pest-repellent qualities of onions and garlic have traditionally been employed in vegetable gardens, where they are planted not only for their own sweet sakes, but as bodyguards for fragile and tasty celebrity plants. One is advised to grow garlic around lettuce to repel aphids, for example.

But some insect pests have fine, cultured palates and are as likely to gnaw on garlic as lettuce. As Marian Coonse, author of "Onions, Leeks and Garlic: A Handbook for Gardeners," writes, "with the fine reputation the onion family has for protecting other plants against insect invasion, you would think they'd be immune to any such problems of their own. Not so."

Coonse is chillingly specific. She writes of the thrips, the onion maggot (which is the onion fly in its youth), the cutworm, the wireworm and the woolly worm. She mentions the spider mite, the leaf miner and the bulb mite. She harps on root knot nematodes and stem and bulb nematodes.

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If you bring up fungus, she is right back at you with downy mildew, white rot and purple blotch. Open your mouth and she will hit you with pink root, neck rot and basal rot. Close it again -- it's no use -- she's on to the smuts: onion smut, black mold and smudge.

As for bacterial woes, don't get her started on soft rot, sour skin, yellow dwarf and aster yellows -- which last are carried by the six-spotted leafhopper.

It's a wonder there are any onions at all. But if they can't protect themselves, how can they protect us? Personally, my hygiene routine has protected me so far from aster yellows and onion smut.

If onions and garlic can't shield us from sour skin and are only slightly discouraging to bacteria, what of their vaunted powers to lower blood pressure and lower cholesterol? Alas, the juries are out.

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Garlic, in large doses (or one of its active ingredients, allicin), is said to lower blood pressure. One doctor describes its effects as "modest but measurable." An herbal medicine Web site says that garlic "gently" lowers blood pressure. (When you hear that a substance does something "gently," do the math -- often it means that the effects are laughably small.) Some studies show garlic lowering blood pressure by small amounts. Other studies show nothing of the kind. Several meta-analyses have looked at garlic and blood pressure, some finding a small but significant reduction on both systolic and diastolic blood pressures. Others find nothing. "Increased amount of garlic and onions have not been found to affect blood pressure," sighs the National Heart, Lung & Blood Institute. Everyone agrees it would be nice to do a few more studies with more people and better controls.

Garlic is often suggested for lowering cholesterol, and dozens of studies are said to show that around one clove of the raw stuff per day (or 600-900 grams of the processed stuff) can lower cholesterol. Gently. By about 10 percent. But one recent study at the University of Bonn found no improvement at all in 25 people with high cholesterol who ate the equivalent of three to four cloves of garlic a day for six months. (They took the garlic in pills containing garlic oil. This is why I never sign up for these studies. They're always about the extract or the pill or the powder or the puree -- never about the french-fried onion topping or the garlic mashed potatoes.) Critics say the study was too small and the pills were the wrong kind -- steam distilled! They argue that the process could destroy the allicin.

British researchers gave dried garlic pills (or placebos) to 115 patients with high blood pressure and found no effect on cholesterol levels. They then did a meta-analysis of previous studies, which gave a modest drop in cholesterol levels -- but they discredited even this, saying that the earlier studies weren't good enough to be meaningful. Once again, they used a form of garlic supplement that others find suspect. Once again, more and better studies are called for.

Both onions and garlic are said to "clear the blood," a mystifying phrase beloved of amateur herbalists. Sometimes they say "thin the blood." This is woo-woo talk for increasing clotting time, a thing that is usually considered good for cardiac health. You might not want to schedule your surgery right after competing in a garlic- eating contest, however. This is one of the effects of onions and garlic that is not in dispute.

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The evidence that garlic and onions decrease the incidence of stomach and colon cancer also looks pretty good. (It seems to have no effect on the incidence of breast cancer and lung cancer.) Most of these studies looked at thousands of people in Iowa, the Netherlands or China, asked people how much garlic they ate, and they compared stomach and colon cancer rates in people who ate lots of garlic or onions and people who didn't. The Iowa study, which looked at 40,000 women, found a 35 percent lower risk of colon cancer in those who ate garlic at least once a week.

At one meeting an Italian researcher also reported that people who cooked with lots of garlic in the area where he lives, around Genoa, have lower stomach cancer rates, specifically praising pesto. (God, I want to believe him.) And a Dutch study found that those who ate half an onion a day had half the risk of stomach cancer, ascribing this to an antioxidant called quercetin, found in onions, especially red and yellow onions.

Some enthusiasts happily declare that garlic has no side effects -- then they make jokes about the smell. Which I can see I'm going to have to discuss. The active ingredients in onions and garlic are mostly sulfur compounds, to which our noses are quite sensitive. Odorless garlic preparations, many authorities suggest, are useless garlic preparations. But then, they all disagree about whether you should eat raw or cooked onions, and whether garlic should be eaten raw, cooked, fresh, aged or in a capsule.

In one study, researchers made a fresh garlic extract by whirling about 40 cloves in a blender, and filtering the sludge -- but the resulting extract was so powerful that it caused nausea and burning sensations in the throat.

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Many sources recommend chewing parsley after eating garlic or onions, to freshen the breath. I suspect it's propaganda from the Parsley Board.

A recent German study that claimed powerful garlic pills could not only reduce the rate of plaque formation in arteries, but actually make existing plaque go away, has been criticized on several counts. The Berlin university where the principal researcher works is investigating the allegation that the study (which was commissioned by the makers of a powerful garlic pill) uses suspicious photos purporting to show the inside of a carotid artery before and after four years of garlic therapy, but which in fact look as if they were taken at the same time.

Another complaint is that the statistical analysis ignored the fact that many patients quit the study because they couldn't stand the ferocious reek of the high-dose pills.

While onions and garlic may not be the answer to every medical problem, they are beneficial as well as enjoyable, providing you stay away from zealots with blenders. The only things to watch out for in your pursuit of the allium vegetables are people who are just trying to fortify you for building pyramids, defending Shiloh or conquering Asia Minor.

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Susan McCarthy

Susan McCarthy is a San Francisco freelance writer and the author, with Jeffrey Masson, of "When Elephants Weep: The Emotional Lives of Animals."

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