There is growing evidence that suggests that the consumption of cows milk can actually cause acne breakouts. There are many hormones, bioactive molecules, and other substances found in milk that have a direct relationship to the development of acne in humans.

One such substance is iodine. For people who have acne-prone skin, iodine can be a problem because it can stimulate pores into producing acne-causing oil. Dermatological studies have shown that 1,000 micrograms (or 1 milligram) of iodine a day can have acne-producing effects.

11% of milk samples gathered from over 150 dairy herds in the state of Wisconsin were found to contain over 1,000 micrograms of iodine per liter of milk. Iodine enters cows milk through milking equipment and through some medications given to milk-producing cows.

The hormone 5 alpha-dihydrotestosterone (DHT) is one hormone that is known to be a direct cause of acne flare-ups. DHT causes stimulation of the oil-making cells of human skin, which can cause acne.

While cows milk does not contain DHT, it contains many other hormones that are broken down into DHT. In fact, the volume of these hormones is particularly high in the milk of pregnant cows, which comprises 75% to 90% of the milk and dairy products found in supermarket coolers.

Many of the hormones found in the milk produced by pregnant cows also may break down to create androgen, a hormone that causes an increase in the production of sebum, the waxy material that is secreted by the sebaceous glands. Sebum is known to clog pores and to lead to acne breakouts.

In addition to the hormones found in cows milk, the fat, sugar, and animal proteins found in milk may also aggravate acne.

Research has shown that many of the foods commonly thought to be associated with acne, such as greasy french fries, oily pizza, or sugary chocolate, are not actually related to acne at all. Instead, it is milk and dairy products that are more likely to cause an increase in persistent acne breakouts.

Whole milk, reduced fat milk, and skim milk, are all equal in their potential to cause acne when consumed. Those who suffer from acne should also watch out for milk-based dairy products such as cottage cheese and cream cheese. Dairy products also often contain high levels of butterfat and milk sugars, both of which should be avoided by those who suffer from frequent acne breakouts.

Many dermatologists advise their patients to omit all milk and dairy products from their diets in an effort to minimize the appearance of acne. Patients who choose to adopt this method of acne-control, however, should be conscious that their milk and dairy-free diets have appropriate amounts of calcium. These people might consider taking a daily calcium supplement, and should talk with their doctors about how else they might compensate for the omission of milk and dairy products from their diets.

A clinical dermatological study conducted over 10 years concluded that milk contributed significantly to acne problems of a large percentage of the 1,088 teenagers who took part in the study. The study also showed marked improvements in the teens acne as they curbed their consumption of all milk and dairy products.