Aloe polysaccharides, particularly acemannan, are among the active constituents in Aloe vera gel that have been investigated for their therapeutic effects, including in dermatological conditions like psoriasis. Scientific studies have suggested that Aloe vera gel, which contains a significant amount of polysaccharides, may help alleviate symptoms of psoriasis due to its anti-inflammatory, immunomodulatory, and wound-healing properties.

Several randomized controlled trials have examined the topical use of Aloe vera gel in psoriasis patients. For instance, a double-blind, placebo-controlled study published in 1996 found that a cream containing Aloe vera extract improved psoriatic plaques compared to placebo. These effects are thought to be due, in part, to the modulation of inflammatory cytokines by Aloe polysaccharides. However, these studies have often used whole gel or crude extracts, making it difficult to attribute effects solely to the polysaccharide fraction.

Overall, while there is some scientific evidence supporting the topical use of Aloe vera gel (and thus its polysaccharide content) for mild to moderate psoriasis, the evidence base remains limited and of variable quality. More rigorous studies isolating Aloe polysaccharides are needed. Therefore, the evidence is rated as 2 out of 5, reflecting preliminary scientific support, but not strong or conclusive validation.