The reason that milk products cause acne is because milk contains hormones that "turn on" oil glands.  The cows that give the milk are pregnant and milking most of their lives.  These hormones are not injected into the cows - they are natural hormones that cows make during every "menstrual" cycle, but during pregnancy these hormones are produced continuously at high levels and so are found in all cows' milk.

Some doctors suspect that the fat, animal protein, sugar, and hormones in milk irritate the skin, causing break-outs. 

Dr. Jerome K. Fisher conducted a clinical study of 1,088 teen-age patients over 10 years and reported to the American Dermatological Association that milk was a principal contributor to some patients' acne. Dr. Fisher found that their acne tapered off as their milk consumption did.   If you would like to read the entire orginal paper that Dr. Fisher wrote just click here (it's a large document):  Fisher Scientific paper

Dr. Fisher noted that dairy products often contain large amounts of butterfat and milk sugar, both of which, he believed, aggravate acne. He also suspected that the high volume of hormones produced naturally in the milk of pregnant cows may break down into androgen when consumed, which in turn stimulates the production of sebum, the waxy substance secreted by the sebaceous glands that clogs pores and creates acne when the pores become infected.

Milk may also contain excessive amounts of iodine, which can irritate pores, bringing on acne flare-ups. According to James E. Fulton Jr., M.D., head of the Acne Research Institute in Newport Beach, Calif., "In some who are acne-prone, I'd say 1,000 micrograms or one milligram of iodine a day could be a problem." A recent analysis of milk samples collected from 175 dairy herds throughout Wisconsin averaged 466 micrograms of iodine per liter; 11 percent of the samples contained more than 1,000 micrograms of iodine per liter. (The iodine gets into the milk through the use of contaminated milking equipment and medication given to the cows.) 

Other health-care providers agree that clearing refrigerators of dairy products can help clear up skin:

According to Dr. Laura E. Skellchock, Clinical Associate Professor of Dermatology at the University of California, San Francisco, and dermatologist at Kaiser Permanente, "Some people find that consuming large quantities of dairy products may worsen their acne."

Gynecologist Christiane Northrup, M.D., author of Women's Bodies, Women's Wisdom, believes that acne is associated with the consumption of dairy foods.

Australian naturopath Dr. Russell Setright advises: "It is important to stay away from…dairy products" in order to prevent acne.

Columbia University's Health Education Program offers these dietary tips to avoid acne:

Eat a diet high in fiber–salads, bran, complex carbohydrates and drink lots of water. Fiber helps the digestive tract eliminate wastes, so the skin doesn't have to.

Keep your diet low in fat and sugar. Eating healthier foods ensures that your skin gets all the nutrients it needs.

Food allergies may also aggravate acne. Common allergenic food substances include dairy products, wheat, and preservatives. 

What is most important to be learned from the study is that the reason that milk products cause acne is because milk contains hormones that "turn on" oil glands.  Over active oil glands then act as a repository for toxins and bacterial agents which cause the inflamation.  You need a way to selectively remove unwanted acne causing agents from the skin.

The SkinClean system has been shown to be beneficial and a remarkable solution for thousands of people who have suffered from problem skin for many years.  It is certainly worth reading about how SkinClean works in a very unique way using a remarkable colloidal complex to remove the unwanted oils,  toxins and bacterial agents, which accompany any root cause of acne, whether from dairy products or other reasons.  How SkinClean works.