lactose vs sugar of milk

lactose

noun
  • The disaccharide sugar of milk and dairy products, C₁₂H₂₂O₁₁, a product of glucose and galactose used as a food and in medicinal compounds. 

sugar of milk

noun
  • Lactose, a disaccharide found in milk. 

How often have the words lactose and sugar of milk occurred in a corpus of books? (source: Google Ngram Viewer )