It was headline news when The New England, I Journal of Medicine published a study that I cast doubt on the effectiveness of echinacea. The message to the countless consumers spending more than $300 million annually on the purported cold-fighting herb? Save your money.
Researchers at the University of Virginia School of Medicine had found echinacea to be no more effective than a placebo at combating cold and flu symptoms.
But don't clear out your herbal medicine chest just yet.
What went largely unreported was that study participants received only 900 milligrams (mg) of echinacea daily-less than one-third of the dose recommended by the' World Health Organization for combating upper-respiratory infections. That's akin to expecting one-third of a dose of aspirin to relieve a headache.
What's the other side of the story? Dozens of clinical studies point to echinacea's effectiveness, including a Canadian trial in which volunteers who took echinacea at the onset of colds experienced 23% milder and shorter symptoms, including sore throat, stuffy nose, chills and headache, than those who were taking a placebo-a benefit that researchers link to a marked increase in circulating white blood cells and other cells of the immune system.
More work is needed to identify the optimal echinacea species (supplements are commonly derived from E. purpurea, E. pallida or E. augustifolia) and the most potent plant parrs (roots, stems, leaves or flowers).
The best results have been achieved by taking 3,000 mg daily of an echinacea product that combines one of the above-mentioned species and parts at the first sign of a cold or flu and continuing this regimen until symptoms resolve.
Caution: If you're allergic to ragweed, avoid echinacea supplements that have been derived from stems, leaves or flowers-they may contain pollen and trigger a reaction. Use an echinacea root supplement.
Following are five other herbs that have scientific evidence on their side...
What it does: Helps prevent and possibly reverse arterial plaque buildup (atherosclerosis), a major cause of heart attack and stroke. . .reduces the risk of stomach and colorectal cancers...and acts as a blood thinner to reduce the risk of blood clots.
Scientific evidence: In a German study, 152 patients who had advanced atherosclerosis and took 900 mg of garlic powder daily for four years experienced a 3% decrease in existing arterial plaques in their carotid (neck) as well as their femoral (thigh) arteries.
Patients who took a placebo experienced more than a 75o/o increase in arterial plaques.
Potential side effects: Bad breath and indigestion. Because garlic has a blood-thinning effect, it should not be used if you take aspirin regularly or an anticoagulant drug, such as warfarin (Coumadin).
To minimize bleeding risk, ask your doctor about discontinuing garlic supplements at least one week before undergoing elective surgery.
Typical dose: One clove of fresh, minced garlic daily or 200 to 300 mg of standardized garlic powder, taken in pill or tablet form, three times daily.
What it does: Improves memory and concentration in people who have early-stage senile dementia or Alzheimer's disease, as well as in healthy adults, by increasing blood flow to the brain. May also relieve tinnitus (ringing in the ears), vertigo and altitude sickness, as well as vascular problems, such as intermittent claudication, a painful condition in the calf that is caused by decreased circulation to the legs.
Scientific evidence: An overwhelming majority of ginkgo trials have shown positive results. At least 33 randomized, controlled trials have shown that this herb enhances mental functioning or slows cognitive deterioration in older patients who have dementia. In addition, 13 other controlled studies have shown that ginkgo boosts memory and cognitive performance in healthy adults.
Potential side effects: Stomach upset, headache, rash and/or dizziness. Like garlic, ginkgo should not be taken with aspirin or a prescription blood thinner such as warfarin. The herb was previously believed to increase the effects of monoamine oxidase inhibitor (MAOI) antidepressants, such as phenelzine (Nardil), but this has been refuted.
Typical dose: 120 mg daily. Nearly all positive ginkgo trials have used one of three formulations that are produced in Germany and sold in health-food stores in the US under the brand names Ginkoba by Pharmaton Natural Health Products. . .Ginkgold by Nature's Way.. .and Ginkai by Abkit Inc.
What it does: Because of its strong antioxidant activity, milk thistle detoxifies the liver and may help regenerate liver cells. It may be appropriate for patients who have alcohol-related liver damage or infectious or drug-induced hepatitis, as well as anyone who is regularly exposed to industrial pollutants.
Scientific evidence: At least 19 out of 21 clinical studies (a total of 2,200 people out of 2,400) have shown that milk thistle protects the liver against invasive toxins and possibly even simulates the generation of new liver cells.
Potential side effect: Loose stools
Typical dose: Take 140 mg of milk thistle three times daily.
What it does: Relieves symptoms of benign prostatic hyperplasia (BPH), a noncancerous swelling of the prostate gland, which causes frequent and/or weak urination and is common in men older than age 50.
Scientific evidence: In nearly two dozen clinical trials, saw palmetto has proven almost equal to prescription drugs, such as Finasteride (Proscar) and terazosin (Hytrin), for relieving the symptoms of BPH. Unlike prescription prostate medications, which can cause side effects, including diminished libido, saw palmetto causes only minor adverse effects. Saw palmetto also does not inhibit the production of prostate specific antigen (PSA), a protein that, if elevated, may be an early warning for prostate cancer. Conventional BPH drugs suppress PSA, complicating prostate cancer screening.
Potential side effects: Stomach upset or nausea if taken on an empty stomach.
Typical dose: 320 mg daily. It requires four to six weeks to take effect.
What it does: The root combats insomnia and acts as a mild sedative to relieve anxiety or restlessness.
Scientific evidence: Al1 of the nearly 30 clinical studies to date have shown the herb to be effective against insomnia and anxiety. In a recent German trial, taking 6oo mg of valerian root extract daily proved as effective as the prescription tranquillizer oxazepam (Serax) for improving sleep quality, but with fewer side effects. Unlike prescription sleep aids, valerian is not habit-forming, won't leave you feeling groggy the next morning and doesn't diminish alertness, reaction time or concentration.
Potential side effects: None known. It is best to avoid combining valerian with conventional sedatives, such as diazepam (Valium), since the herb may increase the drug's sedating effects.
Typical dose: 2 to 3 grams (g) of the dried, crushed root, infused as a tea. . .or 400 to 800 mg in supplement form, one-half hour before bed.