Lactose wani disaccharide ne da ake samu a cikin kayayyakin kiwo na dabbobi masu shayarwa, wanda ya kunshi kwayoyin glucose guda daya da kwayar galactose daya. Shi ne babban bangaren lactose, babban tushen abinci ga mutane da sauran dabbobi masu shayarwa a lokacin jariri. Lactose yana taka muhimmiyar rawa a jikin mutum. Tushen makamashi ne.