Osteoporosis is a very serious issue and women need to have a good intake of calcium from young ages to prevent osteoporosis later. Although milk and dairy products are good sources of calcium, but some reasons such as being vegan, animal rights and lactose intolerance may prevent us from having milk and dairy products.
Lactose intolerance is the inability to digest lactose, a type of sugar found in milk and other dairy products. Lactose intolerance causes abdominal pain, abdominal bloating, gas, diarrhea and nausea 30 minutes to 2 hours after consumption of milk or dairy products.
The prevalence of lactose intolerance is high: 90 percent of Asians, 70 percent of blacks and Native Americans, 50 percent of Hispanics, 15 percent of people of Northern European descent are lactose intolerant. Therefore, these people need to substitute milk and dairy products with non-dairy veggie options.
For a more complete list take a look at this pdf file.