A study has linked low calcium intake to hormone disorder known as primary hyperparathyroidism in women.
Primary hyperparathyroidism (PHPT) is caused by overactive glands secrete excessive parathyroid hormone, which results in weak bones, fractures and kidney stones, which may also lead to higher high blood pressure, heart attack and stroke risks.
The condition affects one in 800 people during their lifetime. It is most common in post-menopausal women aged between 50 and 60 years.
Calcium intake is known to influence parathyroid hormone production and may be important in the development of PHPT. So a team of Brigham and Women's Hospital researchers set out to examine the link between calcium intake and risk of developing PHPT in women.
They tracked 58,354 women participating in the Nurses' Health Study I aged between 39 and 66 years in 1986 with no history of PHPT.
Calcium intake (from both dietary sources and supplements) was assessed every four years using food frequency questionnaires over a 22-year period. During follow-up, 277 cases of PHPT were confirmed.
Women were divided into five equal groups, according to intake of dietary calcium. After adjusting for several factors including age, body mass index and ethnicity, women in the group with the highest intake of dietary calcium had a 44 percent reduced risk of developing PHPT compared with the group with the lowest intake, according to a Brigham statement.
Even for women taking a modest 500 mg of calcium supplements, daily the risk of developing PHPT was 59 percent lower than those taking no calcium supplements.
The study authors conclude: "Increased calcium intake, including both dietary and supplemental calcium, is independently associated with a reduced risk of developing primary hyperparathyroidism in women."
James Norman, chief of surgery at the Norman Parathyroid Center in Florida, argues that daily calcium supplements in modest doses "are likely to provide more benefits than risks and, over many years, even a moderate increase in calcium concentration probably helps reduce the incidence of parathyroid tumors."