Nature has provided a wealth of natural remedies that can both alleviate symptoms of a cold and strengthen your immunity.

One that has perhaps received more than its fair share of exposure is Echinacea - purple coneflower - used for centuries to treat the common cold, coughs, bronchitis, upper respiratory tract infections (URTIs) and some inflammatory conditions.

Different parts of the plant are thought to work in a number of ways to prevent the spread of viruses and enhance the immune system (see Viewpoint, p 4). But herbs contain dozens of (often unidentified) constituents with beneficial properties that behave synergistically, so we still don’t fully know which of Echinacea’s many chemical components are responsible for its effects, despite over 350 studies so far (Biochem Pharmacol, 2000; 60: 155-8).

In mice, root extracts from Echinacea purpurea, E. pallida and E. angustifolia enhanced phagocytosis - where an immune cell consumes and destroys a ‘foreign invader’ such as a virus or bacteria (Arzneim Forsch, 1988; 38: 276-81). Phagocytosis activation has also been found in humans (Int J Immunopharmacol, 1991; 13: 931-41). Thus, Echinacea may also guard against the development of arthritis, allergies and other immune-related disorders.

Studies of the effectiveness of Echinacea against colds have produced mixed results (Antimicrob Agents Chemother, 2000; 44: 1708-9; Am J Med, 1999; 106: 138-43; Arzneim Forsch, 2001; 51: 563-8; Phytomedicine, 1999; 6: 1-6).

But overall, the results suggest that some Echinacea preparations may be better than placebo for URTIs and may be particularly beneficial in their early treatment, reducing the number of symptomatic days (Cochrane Database Syst Rev, 2000; 2: CD000530; Arzneim Forsch, 2001; 51: 563-8). There is only a small body of evidence supporting its prolonged use for URTIs.

Echinacea root and leaf extracts have also demonstrated antioxidant properties (J Agric Food Chem, 2000; 48: 1466-72; J Pharm Pharmacol, 2001; 53: 849-57).

Several compounds in Echinacea may be relevant to the herb’s actions. Caffeic acid, found in both E. purpurea and E. angustifolia, is the backbone of a number of medicinal compounds from other plants as well.

Echinacoside, the first compound believed to be unique to Echinacea, was eventually found to be composed of caffeic acid. This substance accumulates in the roots and, in smaller concentrations, in the flowers as well (Helv Chim Acta, 1950; 33: 1877-93).

Other important caffeic-acid derivatives include cichoric and chlorogenic acids. Cichoric acid is found in much higher concentrations in E. purpurea than in E. pallida and E. angustifolia, both of which, however, contain greater amounts of other caffeic-acid derivatives.

Various varieties of Echinacea, especially the above-ground (aerial) parts of E. purpurea, also contain high concentrations of polysaccharides - large sugar molecules essential for the plant’s primary life structures - plus lipophilic (fat-attracting) components.

But no type of Echinacea is necessarily better than another and many combinations are available. Supplements are made from the aerial and root portions of the plant, depending on species. By using the leaf and root of two varieties of Echinacea, manufacturers are trying to ensure that all of the important compounds are included in their product.

But which is the most important active ingredient? No one really knows. Clinical studies are thin on the ground and many laboratory studies have been misinterpreted or overblown. Nevertheless, in-vitro evidence provides some important clues. It is commonly believed that echinacoside is the most important ingredient, prompting manufacturers to extract high levels of this. Yet, no test has shown it to have any specific immunological activity, and the literature suggests that it may be an inactive compound (Altern Med Rev, 1997; 2: 87-93).

In the lab, cichoric acid has been shown to stimulate phagocytosis, and other studies have shown that lipophilic alkylamides aid Echinacea activity on the immune system (Arzneim Forsch, 1988; 38: 276- 81).

And what is better: dried preparations or those preserved in alcohol (tinctures)? Again, no one knows for sure. Some suggest that you might be better off with a tincture, although these usually use far less herbs. The lipophilic components are prone to oxidation, so any powdered preparation from the plant’s roots shouldn’t be stored for a lengthy time as it will lose its potency (Altern Med Rev, 1997; 2: 87-93).

However, there is also evidence that the all-important cichoric acid, which breaks down easily due to enzymes, is most stable in preparations made from dried E. purpurea, as these enzymes have usually been inactivated (Altern Med Rev, 1997; 2: 87-93).

The logical conclusion is that dried products may be superior, provided you purchase them well before the sell-by date.

Another myth is that tinctures containing ethanol don’t work, but the evidence for this is based on tainted studies of tainted samples. In one study, products containing high concentrations of ethanol (alcohol) in root extracts markedly enhanced immune system function compared with water-soluble tinctures (Z Phytother, 1989; 10: 43-8).

What this means is that both types of Echinacea work, and you should choose the product that most suits your requirements.

Three of the products in our test use standardised extracts of the active ingredients - what we think makes the herb effective - extracted from the whole plant, measured and sometimes concentrated, then packaged. This guarantees that the product contains what it should in amounts sufficient to produce the desired effect. There isn’t a yes-or-no answer as to whether standardised herbs are better than whole (non-standardised) herbs. Even herbalists are split on the subject (see box below).

As vitamins A, D and E are measured in terms of potency (effect produced by their actives) as international units (IU), so are standardised herbal extracts measured in actives delivered rather than weight.

Although we can’t say what an Echinacea product ought to contain, we can use the various actives as markers to evaluate the quality of the product, as was done by the lab in our latest test.

OUR TEST

Our six products (three liquid, three dry) were tested by high-performance liquid chromatography (HPLC) assay by a private laboratory (which wishes to remain anonymous as it tests for industry). But unlike vitamins, it’s difficult to know which active ingredients are present in each preparation. Analyses can only be based on markers - the caffeic-acid derivatives found in the raw material and finished product, if we’re lucky. Specifically, the lab tested for caftaric acid, echinacoside and cichoric acid.

To determine value for money, we considered all the markers identified by the lab and divided by the price. Given the generally lower levels of markers in the liquid products (except for Nature’s Answer), we evaluated the products as two groups. We also awarded extra points for high levels of cichoric acid, the one marker with scientific evidence of activity.

Echinacea Herb Extract
Manufacturer: Solgar Vitamin and Herb
Price: £13.05 for 60 vegicaps
Rating: *****
This product has the most Echinacea per capsule. With 2185 mg of cichoric acid per 512-mg capsule, Solgar also offers more than twice as much of this marker as Viridian and more than three times Kudos’ product. For efficacy alone, we give Solgar top marks.

Despite the high price tag of £13.05, the high levels of markers place it first for value for money of our dry products, with 17,710 mcg of marker ingredients for your £.

Extracts of both the leaf and root of E. purpurea and E. angustifolia have been used to ensure that all the important compounds are present in the product (echinacosides and polysaccharides are standardised to 4 per cent and 15 per cent).

Suitable for vegans, this also contains the whole root/leaf as a powder to compensate for standardisation - which may cause loss or distortion of the herb’s natural properties - ensuring synergy as Nature intended.

The company claims that each one-a-day capsule has the equivalent of 425 mg of Echinacea. It also has a PHYTO2X base, a mix of antioxidants (tocopherols, carotenoids, rosemary and vitamin C) to maintain the freshness of the herb in the capsule, rather like vitamin E does in oil-based products.

If you’re looking for a high-potency capsule, Solgar’s product takes some beating.

Echinacea Root and Leaf
Manufacturer: Viridian Nutrition
Price: £5.90 for 30 capsules
Rating: ****
Although this product has only the second highest amount of markers of our dry products, a low price tag means that it offers a close runner-up for best value for money, offering 9895 mcg of our test ingredients per £. It also has the second highest level of cichoric acid per capsule.

Daventry-based Viridian Nutrition uses raw Echinacea leaf powder as well as root and leaf extract (standardised to 4 per cent echinacosides and 15 per cent polysaccharides) in this preparation. Each 468-mg one-a-day vegetarian capsule claims to provide the equivalent of 257 mg of Echinacea, and uses a naturally beneficial blend of bilberry, alfalfa and spirulina as its base.

This young company operates a ‘green’ recycling programme (you get 25 p back on the empty bottle), and gives 50 per cent of its available profit each year to charity - which was £15,000 last year. Viridian is also vehemently opposed to animal testing, and will not use suppliers who do so.

Echinacea 900 mg High Potency
Manufacturer: Kudos Vitamins
Price: £19.53 for 60 capsules
Rating: **
Despite its claim of high potency, Kudos’ offering came last among the dry products tested, although it does contain a respectable collection of the test markers.

This four-year-old company has its own manufacturing facility in north London.

Like Solgar and Viridian, Kudos uses both raw herb and standardised extract of
E. purpurea (4 per cent echinacosides and 15 per cent polysaccharides), which again may not be the most important ingredients.

Kudos calls this a 900-mg product - from the amount of powdered raw herb or its equivalent in extract that it contains - but each one-a-day 445-mg capsule contains only 1573 mcg of our test markers.

At 4833 mcg of active markers per £, this high-potency product is the most expensive of the dry herbs tested, but is of reasonable value if you plan to take only one capsule a day, as this will at least stretch the purchase out over two months.

Fresh Echinacea
Manufacturer: Nature’s Answer
Price: £6.45 for 30 mL
Rating: *****
Nature’s Answer says its Fresh Echinacea is a 'holistically balanced product, suitable for vegans, and which contains all of the active constituents of the fresh plant as found in Nature'. The company also sells Echinacea capsules standardised to 4 per cent echinacosides and 2 per cent cichoric acid.

Of the three liquid products, this offers a very high concentration of markers right across the board - more than four times the second-place preparation. It is also spectacular value for money - 15,521 mL of test markers for your £. A single dose provides 1846 mcg of cichoric acid, not far from Solgar’s daily dosage, making this product our runner-up for overall favourite.

This fluid herbal-extract formula claims a 1-mL dose equivalent to 1000 mg of Echinacea, and contains the root of E. angustifolia and the whole of E. purpurea. Extracting the plant constituents requires the use of alcohol, but this is a low (organic) alcohol preparation (15-20 per cent), which the evidence shows doesn’t matter. Coconut glycerin is used to bind the plant constituents.

Echinaforce Drops
Manufacturer: Bioforce
Price: £6.99 for 50 mL
Rating: ***
Bioforce’s Echinaforce Drops and Tablets both contain the root and aerial parts of organic E. purpurea, and are made from the fresh herb extract. The growing and extraction procedures are carried out at Bioforce AG in Switzerland.

Echinaforce Drops contains relatively low marker values - only 297 mcg of cichoric acid per dose three times a day (half the amount of Nature’s Answer product). The company maintains that the 15-drop (0.6 mL) dose is equivalent to 285 mg of the whole fresh plant or 64.5 mg of dried plant.

Despite the low price tag, Bioforce also offers poor value for money compared with Nature’s Answer - 6234 mcg of marker ingredients for every £ you spend.

Bioforce claims to operate a system of holistic, rather than chemical, standardisation that considers a whole spectrum of active constituents. Its herbs are tested by various assays to ensure that the products contain the range of constituents found in the whole plant. The company says that the E. purpurea in Echinaforce is as close to the original plant as can be.

Bioforce also uses ethanol as an excipient, which they say is no more harmful than taking 100 mg of grated apple.

Bioforce is clearly a quality product produced with great care, but it may be more suitable for children or if you only wish to give your immune system a gentle lift rather than a jolt into hyperdrive.

Organic Echinacea
Manufacturer: Ortis
Price: £7.95 for 100 mL
Rating: *
Ortis’ Organic Echinacea is made up of a tincture of E. purpurea, and each 20-drop
(1-mL) dose is claimed to be the equivalent of 100 mg of the whole dried plant.

This preparation trailed a long way behind the others in third-best place in terms of value for money, with a series of low marker values, including only 166 mcg of cichoric acid in a 1-mL dose. Overall, the product only gives you 3384 mcg of test markers per £.

Ortis is based in the Hautes-Fagnes - an environmentally protected region of Belgium - and proud of its ‘green’ credentials as well as its humble beginnings.

Ortis’ founder Adolphe Horn (who died in 1982) began as a baker but, after World War II, became a timber merchant. In 1958, he was forced to leave the wood business, but this allowed him to pursue his lifelong interest in natural health foods.

With his wife Irene’s help, it took him only a few months to perfect his first product, based on royal jelly - Api Regis. They used the family farm’s dairy as a workshop and their first deliveries to customers were made by public transport. Initially, their clientele was limited to some 15 chemists and healthfood shops scattered the length and breadth of Belgium. Nevertheless, by 1964, Ortis had expanded to supply markets in France and the UK.

Irene died in 1999, and the company is now run by Adolphe and Irene’s two sons, Michel and Philippe Horn, and Michel’s wife Solange. They say that they can successfully combine intimacy and family feeling with the managerial efficiency needed to run a modern enterprise.

Despite the folksy mom-and-pop image of the company, the bottom line is that, compared with our other test products, you don’t get much from Ortis for your money.

Herbs don’t have to be standardised to be effective, and manufacturers like Solgar and Bioforce produce a range of non-standardised herbs as well. However, in non-standardised products, it is difficult to be certain of the amount of active ingredients they contain.

All you can really say is that the extract is of a certain strength. Thus, a 5:1 extract means there are five units of starting herb to one unit of extract, but this doesn’t tell you the amount of active ingredients in the extract. In fact, batches of raw herb vary, resulting in a variably active extract. Standardised herbs are blended to contain uniform levels of compounds (echinacosides and polysaccharides in the case of Echinacea) that research shows to be the main actives for a herb’s particular function (for example, immune stimulation or sleep induction). Scientists use standardised extracts to ensure a repeatable experiment.

Says Paul Chamberlain, Solgar’s technical services manager, 'Standardised extracts may be stronger than their non-standardised equivalent, but it is impossible to say by how much. All we can say with certainty is that every single batch of a standardised extract will be the same, and therefore give the same results - something that is harder to achieve with the natural variability of non-standardised herbal products.

• Clinical studies show that Echinacea is safe in the short or longer term (Phytomedicine, 1999; 6: 1-6; Arzneim Forsch, 1991; 41: 1076-81; Arzneim Forsch, 2001; 51: 563-8). An eight-week study showed no significant differences in side-effects with Echinacea versus placebo (Am J Med, 1999; 106: 138-43). Another found that '. . . adverse events on oral administration [of Echinacea] for up to 12 weeks are infrequent and consist mainly of unpleasant taste.' (Phytomedicine, 1996; 3: 95-102). Echinacea safety for longer than 12 weeks has not been evaluated, although one review says that, traditionally, it was used for chronic conditions such as psoriasis, diabetes, cancer and even syphilis. Indeed, Echinacea was used in a study for up to nine months with a positive outcome and no untoward effects (Altern Med Rev, 1997; 2: 451-8).
  
• To obtain maximum benefit, take Echinacea as early as possible (Curr Med Res Opin, 1999; 15: 214-27; J Altern Complement Med, 2000; 6: 327-34). Although not much in the way of therapeutic dosages has yet been established, according to Melvyn Werbach (Botanical Influences on Health, Third Line Press, 1994), the following dosages are recommended three times daily:
  
  • Dried root (or as tea) 0.5-1 g
  • Freeze-dried plant 325-650 mg
  • Juice of aerial portion of Echinacea purpurea in 22 per cent ethanol 1-2 mL
  • Tincture (1:4) 2-4 mL (1-2 tsp)
  • Fluid extract (1:1) 1-2 mL (0.5-1 tsp)
  • Solid (dry powder) extract (6.5:1 or 3.5 per cent echinacoside) 100-250 mg