Both supplements are marketed for joint comfort, but they work differently and have quite different evidence behind them.

Glucosamine is a compound naturally found in cartilage. Trials in knee osteoarthritis have given mixed results: some show modest pain relief, particularly with prescription-grade glucosamine sulfate, while others show no better than placebo. Several clinical guidelines don’t recommend it, though some people report benefit and it’s generally well tolerated.

Collagen supplements, usually hydrolysed collagen peptides, have a smaller and newer body of research. Some small trials suggest reduced joint pain in people with osteoarthritis or active people, but many studies are short, small or industry-funded. Your body breaks collagen down into amino acids and peptides during digestion, so how it would end up in your joints specifically is still being worked out.

Neither supplement is a clear winner. If you try one, give it around 8 to 12 weeks and stop if you notice nothing.

Take care: most glucosamine comes from shellfish, so check the label if you have an allergy. It may also interact with warfarin.

Bottom line: The most reliable strategies for joint health are regular exercise (especially strength training), maintaining a healthy weight and physiotherapy. Supplements are a possible extra, not a replacement.