A major update this week: glucosamine; a supplement catered towards joint health.
The vast majority of research on glucosamine is not for general joint health, but specifically for osteoarthritis. When looking at this claim in particular, glucosamine appears to be quite reliable in regards to its statistical significance (the likelihood that the observed results are due to intervention rather than chance) and due to that it appears to be unanimous in our human trials tables, which are based on statistical significance. The clinical significance (magnitude of benefit over placebo in practical terms) appears to be present, but is not as remarkable; it is comparable to acetominophen which is the reference drug for osteoarthritis, but both options are nowhere near curative.
There appears to be concern over publication bias for glucosamine, but two separate meta-analyses have failed to find such evidence of publication bias; the concern still seems to linger though, and is really only a concern due to the social popularity of glucosamine and how that is somehow this bias was avoiding the analysis thereof (funnel plots) that it could dwindle the already small clinical significance.
For the purposes of osteoarthritis, glucosamine seems to be a safe and effective option assuming you are not looking for a cure; acetominophen (Tylenol) appears to be just as good an option if you don't mind taking a daily NSAID drug though.
For athletes, there is some evidence to support the idea that the slowing of collagen degradation applies to healthy athletes and that this may be of benefit to high impact sports involving running or jumping. The evidence is much less for this claim relative to the osteoarthritis claim, but appears to be suggesting a protective effect.
Overall, glucosamine is remarkably safe (aside from possible flatulence) and there does not appear to be a large concern in regards to the link between glucosamine and insulin resistance; not enough appears in the blood following oral ingestion to reliably induce insulin resistance, and it is likely a non-concern.
The other addition to our database this update is the entire topic of aromatherapy: bioactives that are lost to the air and find their way to the nose. Of these, Rose appears to be somewhat anxiety reducing when inhaled and Lemon Balm appears to be able to induce calmness and sedation (at the cost of alertness) when orally ingested. Patchouli is said to be calming but has no real evidence for this claim, although it may confer some anti-viral properties (that need to be investigated more) and clary sage also appears to have some possible uses but most studies using it are confounded with the inclusions of other herbs.
Aromatherapy is an interesting topic, but the body of evidence behind it is quite lackluster.
For more information, check out our bone health and joint pain category page.