“Dona”is the brand of crystalline glucosamine sulfate sold in the US. The crystalline form is actually patented and sold to Dona by a French pharma co. I scanned many studies that reported significant benefits of 1500mg daily. Reportedly, it’s the most effective form of glucosamine supplementation for osteoarthritis.
Update 10Mar2016: My MRI shows some lumbar arthritis. So started daily dose of 1500mg, powder form. Hoping for less lumbar pain in the future.
RESOURCES: Various papers on PubMed.