Thinking of supplementing with calcium and scared of cardiovascular disease? by Humaira Rehan
Osteoporosis is a skeletal disorder in which bones become thinner, brittle, and more susceptible to fractures. Although Osteoporosis affects both men and women, post-menopausal women account for 80% of all cases for osteoporosis. Oestrogen in the body plays an important role in preventing bone loss, and this protection declines sharply after menopause.
Bone tissue is not inert but dynamic in nature. It serves as a repository for vital minerals including calcium phosphate. Resorption of calcium from bones and its deposition back to the bones (bone remodelling) plays an important role in calcium homeostasis within the body.
Here comes the important bit: calcium cannot be made by the body. We need to get calcium from our diet. Not having enough calcium can adversely affect bones. Usually calcium supplements are given to people over 65 as a standard to prevent or treat Osteoporosis. It’s recommended to take 1200mg of calcium every day.
Recently there has been controversy surrounding the calcium supplements and its association with cardiovascular disease (BMJ. 2010 Jul 29; 341:c3691. doi: 10.1136/bmj.c3691). This created an intense interest because of the widespread use of calcium supplements. Other studies raised similar concerns (BMJ. 2010 Jul 29; 341:c3691. doi: 10.1136/bmj.c3691).
However, a number of studies – including RCTs (randomised clinical trial), show no significant increases in cardiovascular effects connected to calcium supplements (Journal of Bone and Mineral Research, Vol. 26, No. 1, January 2011, pp 35–41). Meta-analysis of data from other studies also showed intake of calcium to reduce the risk of clinical fractures without raising any concerns of high cardiovascular risks.
In the absence of any conclusive evidence it would not be wise to stop prescribing calcium supplements until independent confirmation from other RCTs is observed. But in all of the studies it was seen that elderly and institutionalised population with low intake of calcium, patients on glucocorticoid, and patients with osteoporosis, benefited from high doses of calcium (1200mg-1500mg per day).
Calcium is not only important for bone health, it is very important for a myriad of functions in the body. It’s essential in cell signalling, blood clotting, muscle contraction and nerve functions. It’s essential for a number of vital processes in the body. New research has linked calcium to being a factor in reducing obesity, colorectal cancer and hypertension. But a lot more research is needed in these areas.
Its best to get calcium from diet and most of the people eating a varied diet will have enough calcium intakes. Dairy is a very good source of absorbable calcium. Calcium is also present in green leafy vegetables, tofu, okra, almonds and fish like sardines and pilchards. However, if you feel that your dietary intake is not sufficient and you take a calcium supplement, just be wary of the fact that very high doses of calcium from supplements (> 2500mg/day) can cause calcification in soft tissues, disturbances of GI tract, and kidney stones.
Role of Calcium in the Body’s Nutrition by Arielle Kamps, Demand Media at SFGate.com
High Calcium Intake Linked to Heart Disease, Death by M. Bridget and M. S. J. Kuehn
Role of oestrogen in the development of osteoporosis by T. C. Hillard and J. C. Stevenson
Humaira Rehan is a year 2 BSc Nutrition and Dietetics student at King’s College London.