First of all, don't give up! "Don't let anyone tell you that it's all over by 20. That's just silly," Dr. Northrup says. "We know that women build bone mass throughout their entire lives."
Every woman needs 1,000 milligrams of calcium a day, but the real reason osteoporosis is so prevalent is an "epidemic" of vitamin D deficiency. "It's because we have vilified the sun because of fear of skin cancer," she says.
Dr. Northrup says every woman's vitamin D level should be at least 30, but 50 is better. "Those with the highest vitamin D levels have the lowest risk not only of osteoporosis but also of breast cancer, colon cancer and multiple sclerosis," she says.
An easy way to get vitamin D is to spend time in the sun. Dr. Northrup says that people with lighter skin need 10–15 minutes of sun, and people with darker skin need much longer. "Don't ever burn," she says. "That's what's associated with skin cancer. And if you have enough antioxidants in your system from eating lots of fruits and vegetables, there is much less risk of skin cancer."
Exercise also helps prevent osteoporosis. "Vertical vectors of force on your bone from exercising, that builds bone," Dr. Northrup says. "So you need vitamin D. You need magnesium. You need trace elements. You need exercise."