People choose vegetarianism for a lot of reasons including religion, animal rights, environmental factors and health beliefs. Sometimes teens go through a vegetarian phase as they test their independence, and it becomes very important for them to choose a diet that meets their growth requirements. It is possible to eat a healthy vegetarian diet, but it takes planning and often some advice from a nutrition professional. Vegetarians who also forego milk products run the risk of calcium deficiency. While calcium is also found in broccoli and kale, it takes a large volume to meet current recommendations.
Protein can also be a cause for concern especially among vegetarians who avoid milk and eggs.
Plant proteins are considered incomplete. Rice, for example, lacks the protein building block lysine but is high in another protein building block, methionine, while legumes such as beans contain lysine but lack methionine. Combining the rice and beans at the same meal was believed to be essential, but recent research suggests that the different foods can be eaten over the course of the day. There are lots of good reasons to eat plenty of foods from the produce aisle.