Neither Piascledine nor Glucosamine Should Be Used for Knee Osteoarthritis
Based on the strongest guideline evidence, glucosamine is strongly recommended against for knee osteoarthritis, and piascledine (avocado-soybean unsaponifiables/ASU) lacks sufficient evidence to recommend its use. The 2019 American College of Rheumatology/Arthritis Foundation guideline provides a strong recommendation against glucosamine for knee OA 1, representing an upgrade from previous conditional recommendations due to concerns about publication bias in industry-sponsored trials and lack of efficacy in publicly-funded studies with low risk of bias.
Glucosamine: Strong Evidence Against Use
The most recent and authoritative guidelines consistently recommend against glucosamine:
- AAOS 2014: Strong recommendation against glucosamine and chondroitin, stating "there is basically no evidence indicating that there are clinically important outcomes compared with placebo" 2
- ACR/AF 2019: Strong recommendation against glucosamine for knee, hip, and hand OA, citing discrepancies between industry-sponsored and publicly-funded trials, with the best evidence showing no important benefits over placebo 1
- NICE 2008: Does not recommend glucosamine and chondroitin products 3
The strength of recommendation is based on lack of effectiveness, not harm. While glucosamine has low toxicity, some patients may experience elevated serum glucose levels 1.
Piascledine: Insufficient Evidence
Piascledine (ASU) is not mentioned in any major North American or European osteoarthritis guidelines (AAOS, ACR, NICE, EULAR), which is telling—if it were effective, it would have been evaluated and included.
The single recent clinical trial comparing piascledine to glucosamine 4 showed:
- At 4 weeks: Glucosamine was superior to piascledine for pain (VAS) and function (WOMAC)
- At 8 weeks: No significant difference between groups
- Piascledine slightly increased triglyceride levels (2.3 to 2.7 mmol/L)
- 16% experienced side effects, primarily gastrointestinal (10% nausea)
This study actually demonstrates that piascledine performs worse than glucosamine initially, and only catches up at 8 weeks—yet glucosamine itself is strongly recommended against. This makes piascledine an even less attractive option.
What Should Be Used Instead
The evidence-based treatment algorithm for symptomatic knee OA should prioritize:
First-line (all patients):
- Exercise programs (strengthening, low-impact aerobic, neuromuscular education) - strong recommendation 2
- Weight loss if BMI ≥25 kg/m² - moderate to strong recommendation 2
- Self-management programs 2
Second-line pharmacologic:
- Topical NSAIDs (especially for patients ≥75 years) 3
- Oral NSAIDs at lowest effective dose for shortest duration, with PPI co-prescription 3
- Tramadol 2
Third-line:
- Intra-articular corticosteroid injections for moderate to severe pain (evidence is inconclusive but conditionally used in practice) 2
Critical Pitfalls to Avoid
Don't be swayed by patient perception: Glucosamine remains among the most commonly used dietary supplements in the US despite lack of efficacy 1. Patients often believe different formulations have different efficacy and seek brand recommendations—educate them about the evidence.
Industry-sponsored bias: The discrepancy between industry-sponsored and publicly-funded glucosamine trials is substantial 1. This same concern should apply to piascledine research.
Placebo effects are large: Both glucosamine and piascledine studies show significant placebo responses, which explains patient testimonials despite lack of true efficacy.
Don't delay effective treatment: Using ineffective supplements delays implementation of proven therapies like exercise and appropriate analgesics, potentially worsening long-term outcomes.
In summary: Neither agent should be recommended. Direct patients toward evidence-based core treatments (exercise, weight loss) and appropriate pharmacologic options (topical/oral NSAIDs, tramadol) that have demonstrated efficacy for pain relief and functional improvement.