Echinacea: still out in the cold.

It's been the best-selling herb in health food stores for several years. Now you're just as likely to see it at Wal-Mart or your local pharmacy.

What's the evidence that the herb with the hard-to-pronounce name--echinacea (ECK-in-AY-shuh)--"promotes well-being in cold and flu season" or "cuts the time you'll suffer from the symptoms of the flu or colds," as some manufacturers promise?

So far, the research is too skimpy and inconsistent to support those kinds of claims.

"Echinacea is an herb that's been so commonly used historically that it just kind of rolled into modern herbal therapy without adequate scientific scrutiny," says Donald Brown, a naturopathic physician and industry consultant in Seattle.

"There are surprisingly few well-controlled human trials," says botanical expert Steven Foster of Fayetteville, Arkansas.

Plant Power

Echinacea is a family of nine flowering plants indigenous to North America. Three of the nine--E. purpurea, E. angustifolia, and E. pallida--are used in dietary supplements.

"The best scientific evidence that echinacea works comes from studies in which extracts are injected into animals or people," says immunologist Tim Lee of Dalhousie University in Halifax, Canada. "When given that way, it's exceptionally good at stimulating the immune system to fight bacteria."

But just because something is effective when it's injected doesn't mean that it works when swallowed. Take insulin by mouth, for example, and it's destroyed in the intestinal tract.

Only a handful of studies have looked at whether echinacea supplements can help people prevent or fight off a cold or the flu. The results are iffy, to say the least.

Can echinacea prevent colds?

Not according to the only study to look.

German researchers tested 108 men and women who had suffered at least three common colds or respiratory infections like laryngitis, bronchitis, or ear infections the previous winter. Those who were given about 1 1/2 teaspoons of the popular supplement EchinaGuard each day for eight weeks were just as likely to report getting sick as those who got a (looka-like but echinacea-free) placebo.[1] EchinaGuard contains E. purpurea.

Can echinacea shorten the duration of colds?

Maybe ... maybe not.

In 1997, 60 Swedish factory workers reported that their colds ended after an average of six days when they took EchinaGuard at the first sniffle (1/2 tsp. every two hours the first day, then 1/2 tsp. three times a day until the colds ended).[2] That was four days shorter than the colds of 60 workers who were given a placebo.

But in a similar study in Germany using about the same amount of EchinaGuard, colds lasted an average of seven days, whether the volunteers took echinacea or a placebo.[1]

And in a Canadian study not yet published, 750 mg a day of E. angustifolia didn't shorten the colds of 106 university students compared with those of 84 students who were given a placebo.

Can echinacea lessen cold or flu symptoms?

In two studies it did; in two it didn't

In the work most often cited by echinacea-backers, German researchers tested two different doses of E. purpurea on 180 men and women who had developed a "flu-like or feverish infection."3 People taking 450 mg a day had no more relief than those taking the placebo. But people given 900 mg a day did better than the placebo group. They reported modest improvement after three to four days.

For example, "moderately inflamed" noses improved slightly in the echinacea group, but were unchanged in the placebo group. Headache symptoms also improved more in those taking echinacea. But coughs, coated tongues, and swollen lymph glands didn't. After eight to ten days, the difference between the echinacea-takers and the placebo-takers was even greater.

In a similar study by the same researchers, 900 mg a day of E. pallida root extract relieved cold symptoms better than the placebo, but only after eight to ten days.[4]

On the other hand, Swedish factory workers taking EchinaGuard reported no difference in cold symptoms than workers taking a placebo.[2] Ditto for Canadian university students taking E. angustifolia.

What's Going on?

Why the see-saw evidence? Some experts blame it on flawed studies.

"Maybe echinacea works, maybe it doesn't, but these studies haven't been designed well enough to find out," says Jack Gwaltney, chief of virology at the University of Virginia Medical School in Charlottesville and one of the country's leading cold experts. Among the problems:

* Were the volunteers chosen carefully? "Did the participants really have colds or the flu?" asks Gwaltney. If some had allergies or other illnesses that echinacea can't fight, he says, that might explain why it didn't work in some studies.

* Could people distinguish the placebos from the echinacea? Echinacea has a distinctive taste. If the placebos didn't taste exactly the same, people's reports of symptoms might have been influenced by what they thought they were getting.

* Did the studies really use echinacea? "How do we know if some of these studies were using real echinacea unless they had their preparations analyzed?" asks immunologist Tim Lee.

That's not an idle concern. Commercial echinacea preparations have a long history of being diluted with inactive ingredients.

"I've documented five different species mixed into what is supposed to be E. angustifolia in the U.S.," reports botanical expert Steven Foster.

Says Lee: "Only two of the ten commercial echinacea products I've tested passed a standard laboratory assay for immune system stimulation."

* Was the echinacea absorbed? "Both our lab and a German group believe that the active ingredients in echinacea are large carbohydrates called polysaccharides," says Lee. "But we don't know whether they are destroyed by enzymes in our intestines before they can be absorbed intact."

The Downside

Echinacea may or may not help ward off colds or lessen their symptoms. But what's the harm in taking it for insurance'?

Some researchers worry that it may depress a key part of the immune system.

"At least two studies have found that echinacea lowers T4 cell levels," says Jack Gwaltney. "That's worrisome, because T4 cells form a vital part of our immune defense against viral infections."

One thing to keep in mind: The two studies Gwaltney cites used injected echinacea, which may or may not act in the same way as swallowed echinacea.

Even so, other researchers agree that taking echinacea--in any form--could be a dicey proposition for some.

"People suffering from autoimmune diseases like lupus, multiple sclerosis, and scleroderma should play it safe and avoid echinacea until we know more about its effects," cautions physician Donald Brown.

Eeny Meeny Miney Moe

If you decide to try echinacea, what should you buy?

"It's tough for consumers to figure out the labels, since there are more variables involved in echinacea products than for probably any other supplement," says Foster.

Take Celestial Seasonings Herbal Comfort echinacea lozenges. The label says that six lozenges contain 300 milligrams of "echinacea root extract." But how would you know that 300 mg of concentrated root extract is the same as 900 mg of regular echinacea? There's nothing on the label to clue you in.

What's Ahead

The first--and only well-controlled--trial of echinacea in the U.S. is currently under way at Bastyr University in Seattle.

Researchers are testing whether EchinaGuard can prevent--or relieve the symptoms of-respiratory tract infections in people who seem to be susceptible to them.

Results are expected later this year.

[1] Forum Immunologie 8: 2, 1992.

[2] Eur. J. Clin. Res. 9: 261, 1997.

[3] Zeitschrift fur Phytotherapie 13: 7, 1992.

[4] Naturheilpraxis 1: 72, 1993.

RELATED ARTICLE: ZINC OR SWIM

For more than a decade, researchers have been trying to figure out whether zinc lozenges help relieve cold symptoms. Marketers, of course, took far less time to decide. Why else the explosion of zinc products on health food store, drug store, and even supermarket shelves?

A new study may help resolve the question.

"We compared the effect of Cold-Free zinc acetate lozenges to a placebo in 101 people with colds," says Luke Bucci of Weider Nutrition International, which makes Cold-Free. The men and women in the Weider-sponsored study sucked on lozenges with nine milligrams of zinc acetate or a placebo every 11/2 waking hours until their colds ended. Neither the researchers nor the volunteers knew which they were getting.

"And we made certain that the placebo tasted as bad as the zinc, so that the participants wouldn't be influenced by the taste," says Bucci.

While details aren't available (the results are being reviewed for publication in a scientific journal), Bucci did say that "the study confirmed what the Cleveland Clinic found with zinc gluconate."

In that 1996 study, Cold-Eeze (zinc gluconate) lozenges cut the length of colds in half.[1]

So the next time you're shopping for a cold remedy, keep in mind that only Cold-Eeze is backed by at least one good published study. Cold-Free may work, too, but we can't tell how well until the results are published.

As for the dozens of other zinc cold remedies: Who knows?

One to watch out for is Warner Lambert's new "Halls Zinc Defense," which is billed as a "cold season dietary supplement" that "defends against dietary zinc deficiency."

Whether these zinc acetate lozenges work as well as Cold-Eeze or Cold-Free no one knows (there are no studies).

One thing's clear, though. If you take them not just when you have a cold, but three times a day "during the cold season or throughout the year," as the package suggests, they're a ripoff.

All you're doing is paying 60 cents a day for 15 mg of zinc. Buy Centrum or another multivitamin and you get that much zinc--plus a few dozen other vitamins and minerals--for about ten cents a day.

One caveat on taking any zinc: While loading up on the mineral for a week or two may help whip a cold, large doses over long periods of time can weaken your immune system and lower your HDL ("good") cholesterol (see "That Zincing Feeling," April 1996).

The recommended levels for zinc are only 15 mg a day for men and 12 mg a day for women. Zinc experts caution against taking more than 30 mg a day from supplements--and that includes lozenges--on a regular basis.

[1] Annals of Internal Medicine 125: 81, 1996.

RELATED ARTICLE: THE BOTTOM LINE

* The evidence on echinacea is inconclusive. In some studies, it shortened colds and lessened cold and flu symptoms. In others, it didn't. There's no good evidence that echinacea prevents colds.

* Avoid echinacea if you are HIV-positive or have autoimmune diseases like lupus, multiple sclerosis, or scleroderma