Calcium

Dr. Parang Mehta, MD.

Calcium is the most abundant mineral in the human body.  It has many functions -- clotting of blood, transmission of messages in the nerves, working of the heart and other muscles, cellular functions, etc.  However, 99% of the body's calcium is in the bones, where it gives them strength.

Bone mineralisation by calcium is very important to avoid osteoporosis.  This is a condition in which bones have poor amounts of calcium, and are easily fractured.  People with osteoporosis have bent postures, and have frequent fractures.

Humans obtain calcium from their food.  The absorption of calcium, its use, transportation, and levels in the bloodstream are controlled by vitamin D and two hormones -- procalcitonin and parathormone.  Calcium deposition in bones (called bone mineralisation) is affected also by exercise in adolescents.

Sources of Calcium

On the whole, natural foods as calcium sources should be preferred, as they provide other nutrients also.  Besides, apart from providing enough calcium, it is good to encourage the right eating habits, that will provide adequate calcium at later ages also.

Most green vegetables have calcium, though large helpings are needed to get significant amounts.  Spinach is an exception - it has oxalates, which prevent the body from absorbing calcium.  

Natural calcium is better and safer than supplements.  Milk is a good source

However, for children who do not like dairy products, or are allergic, calcium tablets as supplements are an alternative.  Calcium tablets should have vitamin D also, which helps to absorb the calcium.  Calcium fortified juices are also available, which have about the same amounts as milk.  Fish where the bones are consumed are another good source.  Soya beans, nuts, and tofu also contain calcium.

The upper limit of calcium intake is 2500 mg a day.  Higher intakes than this can reduce the absorption of other minerals like magnesium, and iron from the intestines.  Too much calcium can also cause the formation of kidney stones.

Daily Calcium Requirements

0-6 months
7-12 months
1-3 years
4-8 years
9-18 years		   210 mg
270 mg
500 mg
800 mg
1200 mg

Calcium in the diet in childhood is very important.  It is essential to put away calcium in the bones in youth.  Poor calcium intake in childhood is related to fractures and osteoporosis in adolesents and old age.

Bone Health Issues

Childhood and adolescence are important periods in bone health.  It is at this time that the body is able to store calcium in the bones.  After the age of thirty, there is usually no storage of calcium, and after the age of fifty, there is a slow loss of calcium from the bones.  Putting away good stores of calcium in the bones will prevent the bent postures and frail bones caused by osteoporosis at late ages.

Most children and adolescents do not take adequate calcium.  Dieting is a major reason -- most diets cut out milk and milk products.  Teenaged girls, particularly, have been found to take only about half of the recommended intake.  This can have serious consequences in late age.

Exercise is an important part of bone health.  Regular weight bearing exercise promotes the storage of calcium in bones.

 

Last Revision: May 14, 2020