Galactose is a monosaccharide produced from animal (lactose) or herbal (galactoarabinan) sources. It is a building block for glycolipids and glycoproteins. In addition, it stimulates calcium absorption and the immune system and improves cell communication.
Galactose is used in cosmetics for tissue repair, as an anti-inflammatory ingredient, and moisturizer that increases water retainment of the skin.
Is galactose a polyhydroxy acid (PHA)?
If you look at the structure of the galactose, there is no acidic group, so it isn't acid at all. But, it has multiple hydroxide groups; thus, many authors frequently confuse it with PHA.