( ( Osteoporosis ( -LRB- ( ( loss ( of ( ( ( bone density ) , ) ( brittle bones ) ) ) ) -RRB- ) ) ) ( ( has ( been ( taught ( to ( be ( caused ( by ( ( too ( little calcium ) ) ( in ( the diet ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Osteoporosis)) (PRN (-LRB- -LRB-) (NP (NP (NN loss)) (PP (IN of) (NP (NP (NN bone) (NN density)) (, ,) (NP (JJ brittle) (NNS bones))))) (-RRB- -RRB-))) (VP (VBZ has) (VP (VBN been) (VP (VBN taught) (S (VP (TO to) (VP (VB be) (VP (VBN caused) (PP (IN by) (NP (NP (RB too) (JJ little) (NN calcium)) (PP (IN in) (NP (DT the) (NN diet)))))))))))) (. .)))
Osteoporosis (loss of bone density, brittle bones) has been taught to be caused by too little calcium in the diet.
(ROOT (S (NP (RB Too) (JJ little) (NN calcium)) (VP (MD can) (VP (VB cause) (NP (DT the) (NN disease) (NN osteoporosis)))) (. .)))