Vitamins - 6% of your recommended daily intake of vitamin C doesn't really add much to your health in general let alone being enough to add anything to a joint health supplement. As for the 1mg of manganese could theoretically boost the effectiveness of Glucosamine slightly. The studies are pretty much 50/50 on this though and the reality is that the sample sizes are pretty small and we wouldn't say that it adds up to much meaning that Cosamin DS would've been better off including some known joint health related vitamins instead of these small amounts. For example vitamin D is essential for joint health and almost 60% of US adults over 40 are deficient in vitamin D which can cause joint pain all by itself.
Glucosamine HCL - Glucosamine HCL is a purer form of glucosamine sulphate, it is more likely to have mild side effects like nausea, but a dose of 1500mg is almost equivalent to 2500mg of it's counterpart. This means that Cosamin DS can get more into a smaller capsule. There are less studies directly demonstrating it's effectiveness so typically in countries where glucosamine is available on prescription for issues like knee or hip pain sulphate is used. There are enough studies to suggest that HCL is effective however, although whether or not some of the difference is lost due to it being less easily absorbed by the body is up for debate. It should be noted meta analysis of multiple trials shows that whilst Glucosamine reduces pain in joints, it doesn't do much to improve overall health. Some studies initially looked promising that it reduced joint space narrowing this doesn't seem to have been effectively replicated. Still a decent ingredient for Cosamin DS.
Chondroitin - Chondroitin is in a lot of joint health supplements and we think it is a fair inclusion in Cosamin DS, the problem is that there have been a few studies that have suggested it isn't as effective at improving the performance of Glucosamine as originally hoped. This doesn't mean it's a bad inclusion in Cosamin DS, in fact it's quite common for supplements of their type.
As you can see we're not really dealing with a lot here in the way of ingredients in Cosamin DS. The fact is it's pretty much just a glucosamine & chondroitin supplement. And there's nothing wrong with that, except for the fact you can pick that up for $20-30 for a month supply with a generic brand. And as US supplements have to be 3rd party lab tested, Cosamin DS won't be anything special when compared against those. The vitamin choice was disappointing.