There is increasing evidence of a cause-and-effect link between dairy consumption and acne in some individuals. Research is ongoing. Skim milk, whole milk and soft cheeses are more likely to trigger breakouts than other forms of dairy. A dairy-free diet may be beneficial for acne in those susceptible to milk products.

Cows produce milk to feed their baby calves and help them grow. Whey and casein, the proteins in milk, stimulate growth and hormones in calves — and in us when we drink their milk. When we digest these proteins, they release a hormone similar to insulin, called IGF-1. This hormone is known to trigger breakouts.

Most dairy products aren't particularly blemish-friendly, and cheese is believed to exacerbate skin damage even further—read: dairy face. "Dairy is a big one," notes Stanford Medicine-certified nutritionist Melissa Pfeister. "Dairy stimulates hormone production causing acne." What to eat instead: Probiotics.