If you're like most British citizens, you spend about 20 days each year blowing inflammatory fluids out of your respiratory system through irritated, reddened nostrils. Such upper-respiratory-system malaises can do more than make you miserable; they can also - perish the thought! - greatly curtail your training.

So, what can you do to cut your 'common-cold down time' to just a few - or even zero - days per year? In order to stay healthy, many athletes take Echinacea supplements, in the belief that it can reduce the misery associated with viral illness or even prevent respiratory infections entirely.

Why is Echinacea viewed as an immune-system booster? The story begins hundreds of years ago with the medical practices of Native-American Indians, who were often skilled herbalists. The Plains Indians used plants such as golden seal to treat wounds and palliate infections, sassafras to enhance energy, and slippery elm to help slip phlegm out of their respiratory systems. But Echinacea was revered above all other herbal remedies: the Cheyenne used the herb to soothe sore gums; the Comanches used it for sore throats; the Crows for colic; the Delaware for its anti-gonorrhea properties; the Kiowa for coughs; the Fox for fits; the Winnebago for anaesthesia; and the Sioux to cure maladies originating in the bowels or blood. Almost all of the tribes believed there was no better medicine for infections, and a common practice for a Native American feeling out of sorts was to walk around all day sucking on a piece of Echinacea root!

The Indians' rather heavy reliance on Echinacea was noticed by European settlers travelling through North America in the 1800s, and Echinacea therapy ultimately became a standard treatment in orthodox medical practice in the United States. In fact, by 1910 it had become the most popular herb used by US physicians, prescribed both as a digestive stimulant and 'blood purifier'. About 200,000 pounds of Echinacea were marketed each year in the USA in the early 1900s, and the herb became known popularly as the 'prairie doctor.' Prestigious companies such as Merck, Wyeth, and Parke-Davis marketed their own Echinacea products.

In about 1930, Echinacea crossed the Atlantic and became extremely popular in Germany, where it has been a highly-prized herbal preparation ever since: in 1990, an Echinacea product ranked 131st on the list of the 2,000 most-prescribed drugs in Germany. Today, there are about 250 medicinal products sold in Germany which contain Echinacea as an important ingredient, and each year the United States ships about 25 tons of the stuff to European markets. Echinacea is native to the United States, and it grows naturally nowhere else in the world, except for the southernmost parts of Canada. Surprisingly, however, American interest in Echinacea began to wane in the 1930s, and the pretty little plant was left to gather dust until very recently, when it was suddenly 'rediscovered.'

Proof that Echinacea fights infection
This rediscovery seemed to be spurred in part by new high-quality German research, which suggested that Echinacea really could help fight infections. In a double-blind, placebo-controlled study of 180 people, researchers determined that four 'droppersful' (from a standard medicine dropper) of Echinacea extract per day were better than a placebo preparation at relieving the symptoms and duration of influenza (1), although two droppersful were not enough to do the trick.

In another human study, 108 people who suffered from fairly frequent upper-respiratory tract infections (including ear infections, sinusitis, bronchitis, tonsillitis and laryngitis) were given either Echinacea or a placebo over an eight-week period. The Echinacea was administered in a fairly widely-used liquid preparation called Echinacin¨, and the dosage was 4ml twice-daily for eight weeks.

In comparison with the control group, the Echinacea guzzlers suffered significantly fewer infections. In addition, the time between infections was lengthened, the duration of illness was shortened and the severity of symptoms reduced (2). The Echinacea formulation seemed to be most helpful to individuals with lowered T4/T8 immune cell ratios (T4 cells spur the immune system to activity, while T8 cells tell it to chill out).

A good deal of research carried out with lab animals and cell cultures suggests that Echinacea works as an immune-system booster. However, before you invest in a bottle of prairie doctor, it's important to remember that not all Echinacea products are the same. In fact, as the esteemed Dr Rudolph Bauer, professor of pharmaceutical biology at the University of Dusseldorf in Germany, points out, the Echinacea you end up buying to lessen the effects of your common cold or infection may not be the same as the form of Echinacea which has actually been found to be effective for those purposes in carefully controlled scientific research (3).

How can that be true?
Well, bear in mind that there are actually three different species of Echinacea, each with its own unique pharmacological properties. The three species are known as Echinacea purpurea, Echinacea augustifolia, and Echinacea pallida. Echinacea purpurea, also known as the 'purple coneflower' because of its bright purple flowers and a big, cone-shaped projection in the midst of its petals, is the most widely studied of the three species. Incidentally, the word Echinacea comes from the Greek word 'echinos', which means sea urchin; thus, Echinacea refers to the plant's sea-urchin-shaped flowering head.

As a consumer, your first step is to decide which of the three species you'd like to introduce into your body, but your troubles don't end there! An additional complication is that various parts of the plants may be used to make the herbal preparations. Sometimes entire plants are used, but other Echinacea products are formulated only from roots, and in some cases only the leaves and stems end up in the supplement bottle. This is a matter for concern because the compounds in the leaves may have quite different pharmacological activities from those in the roots. Ready for a third complication? Well, a variety of different techniques are used to create and preserve the supplements you buy. Your product may, for example, contain 'dried-pressed' juice from the whole Echinacea plant or 'cold-pressed' juice obtained from the leaves. Alternatively, you might end up with dry pieces of whole root, powdered roots, powdered leaves, or capsules containing bits and pieces from the whole plant or just part of it! An important decision you have to make is whether to go for the dry or liquid form of Echinacea. Most scientific research has been carried out with liquid, alcohol-based extracts of the prairie doctor rather than the dry stuff, and many devotees believe that Echinacea's constituents are best protected from spoilage in liquid-extract form. There is little evidence to support this contention, however, and some experts contend that the alcohol in extracts might actually break down Echinacea's potentially beneficial polysaccharides. A glycerol-based Echinacea extract is now available to get around this potential problem.

The point is, as Dr Bauer warns, that favourable results from the study of one type of Echinacea product cannot be generalised to other Echinacea products. So when you visit your supermarket, pharmacy or health food store to purchase Echinacea, you need to make sure that you don't buy a leaf formulation when it is the roots that have been linked to the specific health benefits you are interested in. If you are sufficiently on the ball to select both the right plant and the correct plant part, you might suddenly become unstuck when it comes to picking out the formulation (dry vs liquid, for example).

Take action at the first sign of a cold
Bauer points out that there have been 28 good clinical studies carried out with Echinacea. Those that support the herb's therapeutic effectiveness have used one of four preparations:

1. A 'pressed-juice' preparation from the aerial parts of E purpurea;
2. A '95:5' mixture of hydro-alcoholic extracts of E purpurea aerial parts and roots;
3. The hydro-alcoholic extracts of E pallida roots;
4. The hydro-alcoholic extracts of E purpurea roots.

In Germany the pressed juice of E purpurea aerial parts has been accepted as a drug for adjuvant therapy of recurring infections of the respiratory and urinary tract. In addition, E pallida roots have been approved for the adjuvant therapy of the common cold, and there is widespread use of approved forms of Echinacea for children with colds.

However, says Bauer, 'Echinacea preparations have to be taken at the first signs of a cold'. Don't wait a few days - or even 24 hours - if you expect to get any benefits. And be wary of ingesting Echinacea if you are allergic to plants of the Compositae family, including ragweed, dandelion, feverfew, sneezeweed and tansy as well as cultivated varieties like asters, cornflowers, dahlias, daisies and sunflowers. Echinacea preparations should be avoided by patients with tuberculosis, leukocyte disorders, collagen problems, multiple sclerosis, HIV infections, and autoimmune diseases, because of lack of clinical experience and research. And, according to Dr Bauer, Echinacea has been associated with worsening of metabolic status in people with diabetes.

So what's the bottom line? 'Only those products that have been tested can be recommended,' says Dr Bauer. We concur: if you decide to take Echinacea in an effort to ward off illness or limit the severity of a respiratory infection, use one of the four preparations mentioned above, manufactured by a reputable supplier.

Owen Anderson