Green Lipped Mussel has become increasingly popular as a natural support for managing osteoarthritis (OA) in dogs in the United States and around the world. But what it is, how it works, its clinical studies and more are somewhat still relatively unknown in the veterinarian community.
Known as the New Zealand mussel, Green Lipped Mussel (GLM), Perna canaliculus, is endemic to the coastal waters of New Zealand, and for hundreds of years has been a source of food to the indigenous Polynesian people of New Zealand known as the Maori.
Interest in the health benefits of GLM actually started when researchers saw a much lower incident rate of joint and mobility issues in the Maori, who lived in the coastal regions, compared to their neighbors living inland.
So, what was the main difference between these two groups? Their diet. Once understood, researchers focused their attention on understanding the benefits of GLM as it related to joint health.
Green Lipped Mussel contains a unique combination of omega-3 fatty acids and other bioactive lipids, vitamins, minerals, anti-oxidants and glycosaminoglycans, which includes Chondroitin sulphate1. With dogs with OA, double-blind, placebo-controlled studies saw that this combination of nutrients demonstrated:
Reduced joint pain2
Reduced joint swelling2
Reduced total arthritis score (combined assessment of mobility, degree of joint pain, swelling, crepitus, and reduction in range of movement)3
Increased activity (as measured by accelerometers)4
The health benefits of GLM continue to be reported as more than 150 publications over the last 40 years have reported on GLM. During this time, a number of well-designed, double-blind, placebo-controlled studies have been conducted in dogs and cats (Bierer & Bui 2002; Bui & Bierer 2003; Hielm-Bjorkman et al, 2009). In 2018, a broader review of the literature relating to GLM research was published (Eason et al, 2018).
Omega-3 fatty acids continue to be highlighted as a natural anti-inflammatory action through extensive research. In fact, in vitro studies propose fatty acids from GLM affect the metabolism of Arachidonic Acid by both cyclo-oxygenase and lipoxygenase pathways5, while other lipids, such as pro-resolving lipid mediators, bioactive peptides and F-acids, may also play a role in the beneficial effects that have been demonstrated and may act via different pathways.
Current research is exploring additional modes of action for the omega-3 fatty acids and the role of non-lipid bioactive compounds from GLM.
For Dogs with OA, veterinarians should recommend supplements containing GLM. In the UK, the number one veterinarian recommended joint supplement is a clinically-proven GLM containing product which has now passed the traditional glucosamine and chondroitin supplements that are widely given to dogs. While historically GLM products have had limited U.S. appeal, these types of products now entering the U.S with higher levels of clinical proof are showing greater adoption in the U.S. veterinary market.
For dogs using clinically-proven GLM supplements, both veterinarians and pet owners are seeing general improvement in mobility—range of motion, ability to rise from rest and possible increases in the distance that dogs can walk. The timeframe for improvement is approximately 4-6 weeks, which is crucial as it allows for incorporation of the GLM omega-3 fatty acids into joint tissues, with associated reductions in discomfort and increased mobility. During this time, pet owners may observe their dogs are now more easily able to jump on the couch, chase a ball, interact with other dogs and climb stairs again.
It’s important to note the difference between GLM products and those only made with glucosamine and chondroitin, which are the most common supplements used. For several decades, the use of glucosamine and chondroitin in isolation has been the subject of controversy. The evidence base is equivocal, and many of the studies used to justify products using principally glucosamine and chondroitin are bench-top studies—with little or no evidence for effect in real life situations. That is compared with the growing body of evidence supporting and understanding the role of omega-3 fatty acids in joint health, and specifically GLM, in both in vitro and in vivo studies. There is now a strong body of evidence for both GLM in isolation1,2,3, and also in combination with glucosamine and chondroitin, demonstrating an effect in dogs with OA, including an objective improvement in mobility in dogs in placebo-controlled studies4.
But not all GLM extracts are created equal, and extract quality can vary significantly. This is why it’s imperative for manufacturers of GLM products to follow principals to create the highest efficacy of GLM products.
GLM is only grown in the coastal waters of New Zealand. The location of the bays and position of the lines within the bays can significantly impact the quality of the mussels by effecting the levels of omega-3 fatty acids. GLM manufacturers need to select reputable farmers, working in specific bays, and the best-performing areas within these bays, to ensure they source the highest-quality mussels.
The actual time when mussels are harvested significantly affects their quality. Manufacturers need to research and understand the best time to harvest in each individual bay. The local environment, including tidal nutrient flow, geographic location, the genus of spat (juvenile mussel) used and the time of year influences the optimal time of harvesting for maximum quality.
GLM is usually freeze dried for extraction over a 24-48-hour process involving high heat, which can actually damage GLM’s quality. This form of processing with poor quality mussels results in a less effective product. Smart manufacturers are now using a very rapid vacuum-drying process, reducing the mussels to powder in mere seconds, and importantly, protecting the essential omega-3 fatty acids and other important properties. The result is high-quality powder with significantly higher levels of omega-3s compared to most GLM powders.
Today, the best manufacturers test literally every single batch of GLM powder, checking the levels of more than 40 different fatty acids in order to measure bioactivity and to look at oxidative stability. This constant monitoring ensures high-quality GLM powder consistently.
In summary, GLM supplements are effective for supporting dogs with OA and joint issues. Veterinarians, who currently aren’t using GLM products, should explore using clinically-proven GLM products as part of a multi-modal strategy. Our canine patients will benefit as the science continues to advance and new treatment options and choices continue to be developed. +
1. Hielm-Björkman A, Tulamo RM, Salonen H, Raekallio M. Evaluating Complementary Therapies for Canine Osteoarthritis Part I: Green-lipped Mussel (Perna canaliculus). Evid Based Complement Alternat Med. 2009;6(3):365–373. doi:10.1093/ecam/nem136
2. Bierer TL, Bui LM. Improvement of Arthritic Signs in Dogs Fed Green-Lipped Mussel (Perna canaliculus). The Journal of Nutrition. 2002;132(6):1634S–1636S. doi.org/10.1093/jn/132.6.1634S
3. Bui LM, Bierer TL. Influence of green lipped mussels (Perna canaliculus) in alleviating signs of arthritis in dogs. Vet.Ther. 2003;4(4):397-407
4. Pead MJ, et al. A novel nutraceutical versus placebo in dogs with degenerative joint disease: a randomised double blind placebo controlled clinical trial. Data on file, Royal Veterinary College, London. 2018;1-19.
5. Eason CT, Adam SL, Puddick J, et al. Greenshell™ Mussels: A Review of Veterinary Trials and Future Research Directions. Vet Sci. 27 Mar 2018;5(2). doi:10.3390/vetsci5020036