It would be much better if a person asks this query what to take to strengthen bones in young age instead of at a mature age when already much damage has been done to bones. Including spinach, cheese, milk, curd, eggs, fish, citrus fruits and enough protein is necessary for every one. Remain active and reducing too much sitting can help, avoiding the craze of fast foods that one like eating but are dangerous for bones. One can do exercise, yoga, cycling, brisk walking, swimming etc., maintain a healthy lifestyle is crucial for optimum bone density.