Aloe polysaccharides, primarily acemannan, are widely recognized as bioactive compounds in Aloe vera gel. Their use for sunburn is supported by a moderate body of scientific evidence, predominantly from in vitro, animal, and several human studies. Aloe vera gel, rich in these polysaccharides, has demonstrated anti-inflammatory, moisturizing, and wound-healing properties. Mechanistically, aloe polysaccharides are thought to promote skin healing by stimulating fibroblast activity, enhancing collagen synthesis, and modulating inflammatory cytokines. These effects can facilitate the repair of UV-damaged skin and alleviate sunburn symptoms such as redness and irritation.

Several clinical studies and reviews indicate that topical application of Aloe vera gel can reduce healing time in first and second-degree burns, including sunburn. However, results are not uniformly positive, and some systematic reviews highlight methodological limitations and variability in Aloe vera preparations. While Aloe's efficacy is not exclusive to its polysaccharide content, acemannan and related polymers are believed to be key active constituents.

In summary, the use of Aloe vera polysaccharides for sunburn is supported by moderate-quality scientific evidence, justifying its traditional and popular use, though more robust, standardized clinical trials are needed to establish definitive efficacy.