Or do they?
Well, if you've read the 70+ news articles covering this story, you would think vegans were going to fall apart at the seams, their bones snapping like twigs.
The articles are reporting about this study in the American Journal of Nutrition called "Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis". I am always fond of Bayesian meta-analysis because it sounds fun and scientificky.
Anyway, the news agencies love to report scientificky stuff in the most unscientific ways, like by saying "vegans have lower bone densities" when, in fact, the actual study showed there wasn't a clinically significant difference and that vegans were not treated more frequently for bone fractures. This means being a vegan does not mean being brittle-boned any more than being omnivorous means being able to leap tall buildings in a single bound.
Contrast that with the findings on bone fractures in the elderly, where 70% of fractures occurred in elderly female. That merited like a line. There are a lot more elderly females who could benefit from further research on this matter than there are vegans who would benefit (because we are not brittle-boned, darnit!)
In any event, my favorite quote is from Nutritionist Dr. Rosemary Stanton:
The push to have everyone eat massive amounts of dairy products is invalidInvalid! Take that, eat massive amounts of dairy products promoters!
My conclusion is that you should eat well and healthy. In fact, take the advice of the American Dietetic Association (which is not a Vegan Group by any means) and what they say in their most recent issue of Journal of the American Dietetic Association
It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life-cycle including pregnancy, lactation, infancy, childhood and adolescence and for athletes.
Healthful. Nutritionally adequate. Yummy (well, they don't mention this but they should).