If you have researched enough, then, you must know that Vitamin D and Calcium are essential for bone density increase. Building strong bones requires you to have these two in sufficient amount. So, consuming foods that offer these can help you. However, there are also foods that would only increase your risks of reduced bone density which leads to Osteoporosis etc. These are:
These foods are usually harmful when they are consumed in large quantities every day. Besides that, non-vegan diet followers are having more risks with such foods which is why they should choose healthy foods for the bones if possible.