Image for milk and skin Findings from the Nurses Health Study II stirred the pot once again on an old topic: the impact of diet on your complexion. According to the study, women who said they consumed two or more daily servings of skim milk as a teen were also 44% more likely to say that a physician had diagnosed them with severe acne during their teen years than those who reported drinking one or fewer servings per week. We decided to see what else the literature had to say about the connection between diet and acne.

What is Acne?

Let’s start with the basics. Acne is a skin disease, in which the actions of hormones on the skin's oil glands (sebaceous glands) lead to plugged pores and outbreaks of lesions commonly called pimples or zits. Acne usually occurs on the face, neck, back, chest, and shoulders. In the US, nearly 17 million people have acne, making it the most common skin disease. Although acne is not a serious health threat, severe acne can lead to disfiguring, permanent scarring.

Acne develops when a sebaceous gland, which is connected to a follicle and contains a fine hair, becomes blocked with sebum, an oily substance made by the sebaceous glands that normally empties onto the skin surface through the opening of the follicle, or pore. If a follicle becomes plugged and prevents the sebum from reaching the surface of the skin, bacteria that normally live on the skin begin to grow in the plugged follicle. These bacteria produce chemicals and enzymes and attract white blood cells that cause inflammation. When the wall of the plugged follicle breaks down, it spills everything—sebum, shed skin cells, and bacteria—into the nearby skin, leading to pimples.

What Causes Acne?

The exact cause of acne is unknown, but doctors believe it results from several related factors:

  • An increase in hormones called androgens (These occurs in both boys and girls during puberty and in women who are pregnant or on oral contraceptives.)
  • Genetics (Researchers believe that the tendency to develop acne can be inherited from your parents.)

What Are Some Myths About Acne?

The Nurses Health Study II, mentioned earlier, found that women who consumed two or more daily servings of skim milk were 44% more likely to say that a physician had diagnosed them with severe acne during their teen years than those who drank one or fewer servings per week. The researchers conducting the study hypothesize that the association is caused by the hormones naturally present in milk. However, they also recommend that readers await the outcomes of further studies before dramatically changing their milk consumption habits.

Another literature review conducted in 2005 explored the popular perceptions that diet and hygiene are strongly associated with the causation and exacerbation of acne and that sunlight improves acne. At the end of the study, the researchers concluded that based on the present state of the medical evidence (or lack thereof), clinicians cannot assure patients that either diet or hygiene causes or exacerbates acne or that sunlight exposure improves acne.

Now, let's look at some popular myths about the causes of acne. Chocolate and greasy foods are often blamed, while there is little good evidence to suggest that they cause acne. Another common myth is that dirty skin causes acne; however, blackheads and other acne lesions are not actually caused by dirt. Finally, there is no good evidence that stress causes acne.

Factors that can cause an acne flare include:

  • Fluctuating hormone levels in adolescent girls and adult women two to seven days before their menstrual period starts
  • Friction caused by leaning on or rubbing the skin
  • Pressure from bike helmets, backpacks, or tight collars
  • Environmental irritants, such as pollution and high humidity
  • Squeezing or picking at blemishes
  • Hard scrubbing of the skin

So, What Does Work?

In the end, it seems that the answers to questions about the connection between complexion and various dietary measures remain elusive. However, this doesn't mean that skin care is unimportant.

Remember, acne is a skin disease. Therefore, doing those things that are known to promote general good health and well being, such as getting plenty of sleep, drinking lots of water, and eating a balanced, healthful diet (all those things your mother always told you to do, after all) are likely still your best defense against any disease, including acne.