Fish oil for normal joint health: fact or fiction?

Question

I've been living in Australia for a while and over there I bought supplements from Nature's Own. Their fish oil information reads:

Omega 3 is important for the maintenance of general health and wellbeing, as well as for heart, brain and joint health. For joint health: Take 5 capsules daily with food

Each capsule contains: 2000mg (2g) Equiv. Omega-3 Marine Triglycerides 600mg Equiv. Eicosapentaenoic acid (EPA) 360mg Equiv. Docosahexaenoic acid (DHA) 240mg

That makes 10 grams of fish oil daily, eq 1800 mg EPA, 1200 DHA.

Now, I'm back in Europe and I cannot find any brand claiming joint benefits, in the stores nor on the internet. What's more - the 10 g fish oil recommendations seems to be over the top that may lead to bleedings. For instance, the recommended dose EPA+DHA seems to be up to 2 g max.

In short: Does fish oil support normal joint health (not restricted to inflammatory diseases such as rheumatoid arthritis) and if yes, in what dose? *

_{* I am aware that fish oil may reduce the symptoms of arthritis and other inflammatory diseases. However, I'm relating to regular joint health, for example to support joints during periods (months) of intense physical exercise}

Answer 1

Intense athletic training could be the risk for physical damage ("wear and tear") of the joint cartilage. The closest condition to this I can think of is osteoarthritis.

Fish oil does not seem to prevent or treat osteoarthritis.

Marine Oil Supplements for Arthritis Pain: A Systematic Review and Meta-Analysis of Randomized Trials (PubMed Central, 2017):

A significant effect was found in patients with rheumatoid arthritis...but not in osteoarthritis patients.

Managing osteoarthritis (PubMed, 2015):

Fish oil has not been found to reduce the structural progression of knee arthritis.

About the fish oil dosage and safety: (Office of Dietary Supplements)

High doses of DHA and/or EPA (900 mg/day of EPA plus 600 mg/day DHA or more for several weeks) might reduce immune function due to suppression of inflammatory responses. Doses of 2–15 g/day EPA and/or DHA might also increase bleeding time by reducing platelet aggregation [5]. However, according to the European Food Safety Authority, long-term consumption of EPA and DHA supplements at combined doses of up to about 5 g/day appears to be safe [167]. It noted that these doses have not been shown to cause bleeding problems or affect immune function, glucose homeostasis, or lipid peroxidation. The FDA recommends not exceeding 3 g/day EPA and DHA combined, with up to 2 g/day from dietary supplements. Some doses used in clinical trials exceed these levels.

Answer 2

Most studies have mostly looked at fish or fish oil consumption and the incidence of rheumatoid arthritis whereas you appear to be asking about a chondroprotective effect of fish oil for the development of osteoarthritis.

This study What is the evidence for a role for diet and nutrition in osteoarthritis? published April 2018 has reviewed the literature as it is and has concluded

Since diet may potentially affect OA, we reviewed the literature on the relationship between nutrition and OA risk or progression, aiming to provide guidance for clinicians. For overweight/obese patients, weight reduction, ideally incorporating exercise, is paramount. The association between metabolic syndrome, type-2 diabetes and OA risk or progression may partly explain the apparent benefit of dietary-lipid modification resulting from increased consumption of long-chain omega-3 fatty-acids from oily fish/fish oil supplements. A strong association between OA and raised serum cholesterol together with clinical effects in statin users suggests a potential benefit of reduction of cholesterol by dietary means.

So, you might prevent osteoarthritis by keeping your cholesterol (and weight) low, and the pain might be less noticeable should you develop osteoarthritis if you have a diet high in long-chain n-3 fatty-acids.