Polysaccharides, particularly those derived from medicinal mushrooms (such as beta-glucans from Ganoderma lucidum and Lentinula edodes), algae (like fucoidan from brown seaweed), and some plants (like arabinogalactan), have been researched for their effects on immune modulation. The lymphatic system is closely linked to immune function, as it is responsible for transporting lymph, a fluid containing immune cells throughout the body. Some studies have shown that certain polysaccharides can stimulate the activity of lymphocytes, macrophages, and natural killer cells, and may enhance the production of cytokines. This immunomodulatory activity indirectly suggests support for the lymphatic system's function.

However, direct evidence of polysaccharides specifically enhancing or "supporting" the lymphatic system itself (such as improving lymph flow, lymphatic drainage, or treating lymphatic disorders) is limited. Most studies focus on immune endpoints rather than lymphatic system structure or function. Therefore, while there is some scientific rationale and preclinical evidence suggesting possible benefit, high-quality clinical trials directly measuring lymphatic health outcomes are lacking. Thus, scientific support exists but is limited in scope and strength, justifying a moderate evidence rating.