There have been numerous theories regarding the role diet plays in causing or worsening acne. It was once thought that chocolate and greasy foods were the main culprits behind break-outs but recent studies point toward foods high on the glycemic index, such as pasta, bread and potatoes and dairy as, if not causing acne, contributing or aggravating it.
High Glycemic Foods and Acne
The recent study, which is being published in the March 2013 issue of the Journal of the Academy of Nutrition and Dietetics, examined previous studies conducted between 1960 and 2012 on diet and acne. Researchers point out that previous studies have shown that diet does not cause acne but may aggravate the condition. The study showed that “a high glycemic index/glycemic load diet and high dairy intake are the primary factors in establishing the association between acne and diet.” 
According to an article, “The Relationship of Diet and Acne,” published in 2009 by Apostolos Pappas which discussed reviews of previous studies on diet and acne, certain non-Western populations have an absence of acne. One of these populations is in the Kitavan Islands (off the coast of New Guinea). Their diet consists of fresh fruits, vegetables and lean proteins – a low glycemic diet. Other studies have shown that diets rich in fish and seafood – high in Omega 3 fatty acids, have less inflammatory diseases which may lead to less acne.
Dairy and Acne
A study that pointed to a link between drinking milk and acne was completed in 2004. The study surveyed 47,355 women about what they ate during their high school years. Researchers in this study questioned the high level of milk consumption in the United States. They pointed out that most of the milk products in the U.S. come from pregnant cows and questioned whether hormones in the milk could contribute to acne. A second study with high school boys associated milk consumption with acne. However, these studies were based on self-assessment of the severity of acne and relied on the memory of the participants as to their diet – in the women’s study their diet from years before.
The Answer is There is No Answer
Pappas, in his article, determined that, unfortunately, there is no clear answer to the question, “does diet contribute to acne?” He states, “We emerged from our search disappointed and confess …this article will not settle this controversial issue and that the reader will not get a clear=cut message from us; such is the nature of the beast. We reviewed the updated arguments, facts and relevant data on this ancient debate, but we warn the truth-seekers that the jury is still out.” 
Despite the controversy, we do know that the food we eat impacts our overall health and that includes the health of our skin. For example, Vitamin A has been approved to topically treat skin conditions, such as photoaging, aging and acne. Vitamin D has been used to treat psoriasis, another skin condition and helps to protect against cancer and other diseases because of the positive effect on our immune system. The essential fatty acids, omega-6 and omega-3, are not manufactured by our bodies and we must obtained through our diets. These essential fatty acids help with inflammation and studies showing a deficiency in these can contribute to various skin problems.
Although what we eat could potentially worsen skin conditions, such as acne, scientists still aren’t ready to show a direct cause and effect. Because everyone who drinks high amounts of milk or eats a diet high on the glycemic index doesn’t develop acne it is impossible to state these are a “cause” rather than a contributing factor. Jennifer Burris, M.S., R.D. and lea author of the most recent review of literature believes that nutritional therapy could play a role in treating acne, “The medical community should not dismiss the possibility of diet therapy as an adjunct treatment for acne. At this time, the best approach is to address each acne patient individually, carefully considering the possibility of dietary counseling.” 
 “Acne: The Role of Medical Nutrition Therapy,” 2013, March, Jennifer Burris et al, Journal of the Academy of Nutrition and Dietetics, Volume 113, Issue 3
 “Hi GI-Diet and Dairy Intake Linked to Acne,” 2013, Feb. 20, Staff Writer, Medical News Today
 “The Relationship of Diet and Acne,” 2009, Sept-Oct, Pappas, Apostolos, Dermatoendrocinoloy