There are many dairy trends out there right now. People are obsessed with everything from Greek yogurt to reportedly diet-friendly full-fat milk. And though most dairy products are packed with calcium, it turns out the specific source it comes from is important. New studies are showing that milk helps fight arthritis in women's knees, but other products, like yogurt and cheese, don't. In fact, while women who drank more low-fat milk in the study saw a slower progression of knee arthritis, those who ate more cheese saw it speed up. (Neither trial had a large effect on men.)
It's an important idea to keep in mind, since the average American woman may see signs of knee arthritis as early as age 25. And considering ballet dancers put a lot of stress on their knees, I wouldn't exactly call them "average."