Rheumatism: do green shells help?

The green-mouthed mussel owes its name to the beautiful color.

Ingredients from the green mussel are said to help fight inflammation. However, this effect has not been demonstrated in rheumatoid arthritis.

Stiff, painful joints – people with rheumatoid arthritis, or “rheumatism”, have to deal with this. In Germany and Austria, the disease affects about one percent of the population [6].

The number of dietary supplements that are advertised as a cure for joint problems is correspondingly large. These include the three-winged fruit, cat’s claw, rosehip powder, brown millet or turmeric.

The alleged drugs also include dietary supplements containing green mussels. The reader asked us what these products can do for rheumatoid arthritis.

Help with rheumatism from the sea?

Theory behind the propagated anti-rheumatic effect: The shell species originating in New Zealand contains a number of substances that are said to have beneficial effects on the joints. These include omega-3 fatty acids, antioxidants and chondroitin. Mussel is available in the form of lyophilized meat, in capsules, tablets or as a powder [10].

Of course, theory is not proof. That’s why we went looking for studies [1-5]who studied the benefits of the green mussel in rheumatism.


Insufficient studies do not allow any conclusions

We found five. However, the result is disappointing: in most studies, the funds did not benefit more than the placebo. Only in the investigation [2] The study team reports a positive effect of the green mussel. How the team came to this conclusion cannot be understood from the confused analysis of their data. So this statement is not very plausible for us. However, four studies that found no effect of mussels also have major shortcomings. Whether or not the green mussel is helping rheumatism cannot be said for sure at this time.

Ads for “healthy joints” are not permitted

By the way: There is also no evidence that green mussels have a protective effect on healthy joints. The European Food Safety Authority (EFSA) came to this conclusion in 2009. Claims such as “for healthy joints” or “helps to keep joints healthy” on food supplements are therefore not allowed. [7]. However, it does not seem to have reached everyone on the Internet.


Rheumatism: Inflammation out of control

When people talk colloquially about “rheumatism,” they usually mean rheumatoid arthritis. In this joint disease, inflammatory processes gradually destroy the affected joints. Inflammation is triggered by the body’s own immune system when immune cells attack the cartilage tissue in the joints. For the affected, this usually means pain and, depending on the extent of the disease, limited mobility [8].

There are currently a number of drugs available to stop the immune response and inflammation. However, how well they work can vary greatly from person to person [9].

Detailed and scientifically based information on rheumatoid arthritis and how it can be treated is available at www.gesundheitsinformation.de.

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Study in detail

Which studies did we consider?

Randomized controlled trials are the most meaningful to examine the therapeutic benefit of the drug. To find them, we searched three research databases. We found five such studies [1-5]who studied the benefits of green mussel supplements in people with rheumatoid arthritis.

Most of the participants were women, in whom this joint disease is much more common than in men. They were randomly assigned to receive either a green mussel supplement or a placebo. In two studies [1,3] participants were first given one remedy, then another. Each study lasted 2 to 6 months.

The same New Zealand product was used in all studies, but sometimes in different doses. It is not clear whether the results can be transferred to other products or batches.

How meaningful are the studies?

No reliable conclusions can be drawn from the studies found. There are several reasons for this:

  • The studies were relatively small, each with 6 to 47 participants.
  • All studies are poorly performed according to today’s standards: it is not clear how reliable the measurements of treatment success are. Data from some participants are missing in all studies in the analysis. In publications, research teams often do not provide all the details of the study, which would be important for our assessment.
  • The studies also date back to a time when rheumatoid arthritis was treated very differently. Today, people with disabilities are slowed down relatively soon after diagnosis to slow the progression of the disease [9]. It remains unclear whether patients with rheumatism would still benefit from green mussel products.

Scientific resources

[1] Hightton (1975)
Highton TC ua Pilot study of the effect of New Zealand green mussels on rheumatoid arthritis. NZ Med J 1975; 81: 261–262 (Summary of studies)

[2] Gibson (1980)
Gibson RG et al., Perna canaliculus in the treatment of arthritis. practitioners 1980; 224: 955-60 (study summary)

[3] Huskisson (1981)
Huskisson E et al., Seatone is ineffective in rheumatoid arthritis. BMJ 1981; 283: 1358-9. (study summary)

[4] Caughey (1983)
Caughey DE et al. Perna canaliculus in the treatment of rheumatoid arthritis. Eur J Rheumatol Inflamm 1983; 6: 197-200 (study summary)

[5] Larkin (1985)
Larkin JG and Seatone in rheumatoid arthritis: a six-month placebo-controlled study. Ann Rheum Dis 1985; 44: 199-201 (Leisure time studies)

[6] IQWiG (2020)
Rheumatoid arthritis. Retrieved May 31, 2022 from www.gesundheitsinformation.de

[7] EFSA (2009)
Scientific opinion on substantiation of health claims concerning mussel extract and joint, bone and muscle maintenance (ID 1571, 1813) pursuant to Article 13 (1) of Regulation (EC) No 1924/2006. EFSA Journal 2009; 7 (9): 1265

Downloaded 31.05.2022 from www.efsa.onlinelibrary.wiley.com

[8] Updated (2022)
Pathogenesis of rheumatoid arthritis. Retrieved 31.05.2022 from www.uptodate.com (paid)

[9] Updated (2022)
General principles and overview of rheumatoid arthritis treatment in adults. Retrieved 31.05.2022 from www.uptodate.com (paid)

[10] Consumer Center North Rhine-Westphalia (2021)

Downloaded 6. 8. 2022 from www. Verbraucherzentrale.de

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