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The Human Effect Matrix looks at human studies to tell you what supplements affect Length of Sickness.
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| Grade | Level of Evidence [show legend] |
|---|---|
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Robust research conducted with repeated double-blind clinical trials |
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Multiple studies where at least two are double-blind and placebo controlled |
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Single double-blind study or multiple cohort studies |
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Uncontrolled or observational studies only |
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Level of Evidence
?
The amount of high quality evidence. The more
evidence, the more we can trust the results.
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Supplement |
Magnitude of effect
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The direction and size of the supplement's impact on
each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
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Consistency of research results
?
Scientific research does not always agree. HIGH or
VERY HIGH means that most of the scientific research agrees.
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Notes |
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- | - See all 13 studies |
Although early studies and an early meta-analysis suggested a benefit in the common cold, a more recent meta-analysis that using a higher threshold for bias risk for study inclusion didn't find a meaningful effect for upper respiratory tract infection in general (the common cold being the most common infection observed). It's unclear when echinacea may be most potent, or if certain doses, forms, and populations modify its effects, and a lack of new, well-conducted studies limits further analysis.
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Minor
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Moderate See all 26 studies |
The evidence suggests that a small (roughly half a day) reduction is found when vitamin C is taken consistently, even when not sick, but not if it's only started once already sick. For other infectious diseases, it's unclear if vitamin C helps.
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Minor
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Very High See all 13 studies |
Zinc lozenges, particularly over 75 mg per day (taken in divided doses roughly every 2 hours while awake), and particularly from zinc acetate, have evidence for a small-moderate reduction in the duration of common colds. While evidence points to high dose zinc acetate as the most effective, this is from comparisons between different studies, and as such, isn't as strong as head-to-head comparisons. More research is needed to confirm the most effective method of zinc lozenge use.
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