Thanks. I am 76 and had a by-pass heart surgery ( without heart attack) in 2004 . I am not diabetic. My lipid, and all other health parameters are normal. I have been taking shellcal HD 500 mg once a day for several years. Of late I developed stiffness in the neck apart from osteoarthritis. I am doing neck exercises as suggested by physiotherapist and leg exercises for arthritis. There is some improvement already after a week s exercise. My question: is long term use of Shellcal HD in some way responsible for stiffness in neck? If not, can I continue taking Shellcal HD for maintaining required calcium for the body?