Does echinacea really work against the common cold?
Whether echinacea helps with the common cold depends strongly on which preparation you use. Standardised products made from Echinacea purpurea (herb and root) showed a modest reduction in symptoms in some studies, but root extracts and non-standardised products did not improve outcomes, and what you buy in a shop rarely corresponds to the products used in positive studies.
Whether echinacea helps with the common cold depends entirely on which product you buy. That is the honest summary of the available studies.
A large, well-designed study in the New England Journal of Medicine tested three chemically characterised extracts of Echinacea angustifolia root in nearly 400 volunteers, both for prevention and as treatment. None of the three extracts had any demonstrable effect on catching a cold, the severity of symptoms, or nasal secretion. Plain root powder that was not standardised did not improve outcomes either. A Cochrane review of 16 studies with a total of 3396 participants draws the same cautious conclusion: some preparations appear to work better than a placebo, but the evidence is too inconsistent to recommend any one specific product.
There are, however, studies with positive results. A study with 246 participants found that Echinaforce, a tablet made of 95% herb and 5% root of Echinacea purpurea, reduced symptoms significantly more than a placebo. A standardised liquid extract (Echinilin) showed a 23% lower symptom score than a placebo in 128 participants with a cold. The preparation therefore matters: herb and root of Echinacea purpurea, standardised for active compounds. A separate root extract from the same plant had no effect in the same study.
If you want to try it at the first signs of a cold, choose a standardised preparation of Echinacea purpurea containing both herb and root. On the label, look for 'Echinacea purpurea' and an indication that it is standardised. The form (tablet, capsule or liquid) and the time of intake during the day do not matter. In the studies, the dosage was 2 tablets of the product under investigation three times a day, or a liquid extract taken more frequently on the first day, until symptoms resolved, for a maximum of 7 to 10 days. For prevention, echinacea is not recommended: no prevention study demonstrated a significant effect, and no effective dose has been established. Echinacea appeared safe in the studies, but if symptoms persist or worsen, consult your doctor.
This answer is based on eight studies, including one large well-designed study (published in the New England Journal of Medicine, with nearly 400 participants) and a Cochrane review of 16 studies with 3396 participants. The large study showed no effect for root extract of Echinacea angustifolia. Smaller studies using other preparations did find positive effects. The evidence is therefore mixed and highly dependent on which preparation was tested: the researchers themselves emphasise that study shortcomings, non-standardised products and varying plant species make comparison difficult.
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Curcumin demonstrably lowers inflammation markers in the blood, with the strongest evidence for CRP. For joint complaints the results are positive but preliminary; doses of a few hundred milligrams per day appear to be safe.
Does quercetin work against ageing and inflammation?
In lab work and animal studies, quercetin shows measurable effects on inflammation and ageing processes. In people, the evidence so far is limited and mixed.
Does ashwagandha really work against stress?
Ashwagandha demonstrably lowers both cortisol levels and self-reported stress compared with a placebo. A dose of 300 to 600 mg per day of a standardised extract appears to be the most studied for this purpose.
Does Korean red ginseng help against fatigue?
For fatigue caused by illness or cancer therapy there are indications that ginseng makes a modest difference; for everyday fatigue the evidence is thinner. If you have an illness or are taking medication, it is wise to discuss this with your doctor.
Is curcumin well absorbed by your body?
Ordinary curcumin without any addition is barely absorbed by the body; choose a product with piperine (black pepper extract) or a specialised formulation to notice any effect.
Does taking vitamin E have any proven benefit?
For the most widely studied application, the heart, vitamin E demonstrably does not work; for skin and fertility the evidence is too thin to say it helps, so there is no clear reason to take it.