Red algae, particularly species such as Lithothamnion calcareum, are used in supplements for joint support primarily due to their high content of bioavailable minerals, especially calcium and magnesium. Scientific studies have investigated the mineralized remains of red algae as a source of plant-based calcium, which may play a supportive role in bone health and, indirectly, joint function. There is some evidence from animal models and small human studies suggesting that supplementation with red algae-derived minerals may reduce joint pain or contribute to the maintenance of cartilage and bone density, which are relevant for joint health. For example, a small randomized controlled trial found that supplementation with red algae minerals modestly improved pain and functional outcomes in individuals with osteoarthritis compared to placebo. The proposed mechanisms include anti-inflammatory effects and the provision of trace minerals important for cartilage integrity.

However, the quality and quantity of clinical evidence is limited; most studies are small, and results are not universally consistent. Red algae minerals are more commonly studied for bone health than for direct joint support, and while there is overlap in these systems, evidence specific to joint health is less robust. Overall, while there is some scientific validation for the use of red algae in joint health, it is not strong, and more rigorous, large-scale human trials are needed to establish efficacy.