The absorption and excretion of calcium in the body is controlled by hormones and Vitamin D. An inadequate supply of calcium in the body is closely related to an inadequate supply of Vitamin D. A deficiency of Vitamin D causes a weakening of bones, which can lead to a disease called rickets in children or osteomalacia in adults.
When the most recent National Nutrition Survey was completed in New Zealand, the average daily intake of calcium for men was 919mg and for women 745 mg.
RDI for Calcium (mg/day for NZ)
Men Up to 70yrs = 1000mg/day
Men Over 70yrs = 1300mg/day
Women Up to 50yrs = 1000mg/day
Women Over 50 years = 1300mg/day
Food Sources of Calcium
The amount of calcium present in foods varies greatly and people can find it hard to consume enough calcium to meet the Recommended Daily Intake (RDI) requirements. The best food sources of calcium are milk, cheese, yoghurt, dairy foods, nuts, fish with bones, broccoli and dried fruit. Although dairy foods are an excellent source of calcium, butter and cream are not good sources because of the high fat content of these foods.
Some foods contain components which bind to calcium making it unavailable for absorption in the body. People on high-fibre diets should include dairy sources in their eating plans, because fibre binds to calcium and decreases absorption. For people who are unable to consume dairy foods, owing to dietary restrictions, (e.g. lactose intolerance) calcium supplement tablets may be recommended by a medical professional.
Bread and Calcium
Bread contributes 10% of the calcium in our diet. All breads supply calcium, although white bread is a better source of calcium as it does not contain the phytates present in wholegrain breads which can bind to calcium and decrease its availability. However, mixed-grain breads are now available with added calcium, for example, Molenberg Vital (contains soy, linseed and calcium) and Tip Top UP HiFibre and calcium.