That's an interesting question, and one that should concern all women, so I did some research.

Here's one explanation of how acidity might make one vulnerable to osteoporosis. When we eat animal meat, we take in sulfur-rich proteins. (These proteins differ from the proteins in plant foods.) When we digest the animal proteins, the sulfur they contain forms acid. Depending on other dietary and health factors, this can result in acidosis, or high acidity.

Our bodies are always working towards balance -- in this case, to counteract the acidity. One way to do this is by borrowing calcium phosphate from our bones, That increases our risk of osteoporosis.

Here's an interesting study that looked at the role animal proteins might play in osteoporosis:
http://www.ars.usda.gov/is/AR/archive/mar03/osteo0303.htm

Another study looked at supplementing with potassium citrate to buffer a high-acid diet:
http://www.medicalnewstoday.com/articles/54202.php

Your physician can order a lab test to determine your ph levels. More about that here:
http://www.labtestsonline.org/understanding/conditions/acidosis.html

Those whose diets are too heavily weighted in the direction of animal meats, starches, and sugars would do well to balance with more vegetables (especially leafy greens) and fruits.

Here is a page that lists alkaline and acid foods:
http://www.ctds.info/acidic-foods.html

I hope you find this answer helpful.