Ecklonia cava is a type of brown algae (seaweed) native to the coasts of Japan and Korea. It has been studied for a variety of potential health benefits, including antioxidant, anti-inflammatory, and anti-arthritic effects. The main bioactive compounds in Ecklonia cava are phlorotannins, which have shown promise in laboratory and animal studies for reducing inflammation and oxidative stress—two factors involved in joint discomfort and degeneration (such as in osteoarthritis).

Some preclinical studies have demonstrated that extracts of Ecklonia cava can inhibit the production of inflammatory mediators (such as nitric oxide and prostaglandins) in cell cultures. Animal studies have also reported that supplementation with Ecklonia cava extracts may reduce symptoms of arthritis, including joint swelling and pain. However, there is a lack of high-quality, large-scale human clinical trials directly assessing its efficacy for joint health. Most available evidence comes from in vitro and animal models, which means that the strength of evidence for its use in supporting the joints body system is still preliminary.

Overall, while there is some scientific basis for the use of Ecklonia cava in supporting joint health, it is not yet strongly validated in humans. The evidence rating is therefore moderate to low.