Although cow's milk has a low glycaemic index, it contains androgens, oestrogen, progesterone and glucocorticoids, which also provoke keratinisation and sebum production. Milk also contains amino acids (eg arginine, leucine, and phenylalanine) that produce insulin when combined with carbohydrates. Other components of milk that might induce comedones include whey proteins and iodine.

Ans: When the follicle or pore becomes clogged due to excess oil, bacteria and dead skin cells then the pores swell by causing a break in the follicle wall. If the rupture occurs near the skin’s surface then lesion will be minor and gets healed quickly. Then this infected material extends into the dermis and destroys the healthy skin tissue then it forms scars on the skin.
Although acne remains largely a curse of adolescence, about 20% of all cases occur in adults. Acne commonly starts during puberty between the ages of 10 and 13 and tends to be worse in people with oily skin. Teenage acne usually lasts for five to 10 years, normally going away during the early 20s. It occurs in both sexes, although teenage boys tend to have the most severe cases. Women are more likely than men to have mild to moderate forms into their 30s and beyond.
Acne (acne vulgaris, common acne) is a disease of the hair follicles of the face, chest, and back that affects almost all teenagers during puberty -- the only exception being members of a few primitive Neolithic tribes living in isolation. It is not caused by bacteria, although bacteria play a role in its development. It is not unusual for some women to develop acne in their mid- to late-20s.