Getting More Calcium
~ December 2009 No.230 ~
There is a great deal of interest especially for women in increasing calcium intake as a way of preventing osteoporosis. Genetics and lack of physical activity are risk factors, and dietary intake of calcium and vitamin D are also important factors in the prevalence of this chronic disease that thins and weakens the bones in the body. Broken bones, particularly the pelvis and the long bones in the legs, are common in older women with osteoporosis.
Many foods are rich in calcium including dairy products – milk (skim milk, 1%, 2%, or whole milk), cheese, yogurt, kefir etc. However, these foods are often avoided because of their fat content, and concerns about lactose digestion. Some calcium-fortified soy beverages and orange juices, lentils and beans are also good sources of calcium. Because in some cases doctors are recommending calcium intakes that many people cannot achieve through changes in their diet, consumers are turning to calcium supplements.
Pure calcium (elemental symbol Ca) is a metal. Pure calcium is not absorbed by the body. The calcium we consume is in the form of a calcium salt – a molecule that contains one or more calcium atoms together with a carbohydrate. The common forms of calcium supplements are calcium carbonate - CaCO3 ; calcium citrate - Ca3(C6H5O7)2 ; calcium lactate - C6H10CaO6 ; and calcium gluconate - C12H22CaO14. Remembering some basic chemistry, it is easy to see that not all these sources of calcium contain the same amount of calcium. One molecule of calcium citrate provides three molecules of calcium, while the other sources provide only one molecule. But the molecular weight of calcium carbonate is less than calcium citrate. So… it gets complicated.
The easiest way to tell which calcium supplement is providing the amount of calcium you want, is to compare the amount of “elemental calcium” each pill or capsule provides. Read the label carefully.
It is now recommended that adults get 1000-1500 mg of elemental calcium a day. That’s quite a bit, especially if you do not eat a lot of dairy products. Calcium supplements come in various doses, and because the calcium is often a very small part of the chemical form that is in the supplement, some of the pills can be quite large.
The absorption of calcium is influenced by conditions within the lumen of the small intestine. The acid secreted in the stomach aids in the digestion of calcium, but calcium is absorbed primarily in the duodenum part of the small intestine. Vitamin D is needed to help the absorption of calcium through the intestinal wall. Low vitamin D levels can lead to insufficient calcium being absorbed, even if there is enough calcium in the diet. Many supplements contain both vitamin D and calcium.
A varied diet provides most of us with the types and amounts of nutrients we need to grow and be healthy. However, in some cases, taking a supplement can ensure we are getting adequate levels of specific nutrients.
- University of Nebraska–Lincoln Extension Presentation
Suggested Link Osteoporosis Canada