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Calcium metabolism

Calcium is the 5th most abundant element on earth and sea, and the most abundant element in the human body. The body stores 99% of calcium in bones and teeth.  Calcium can also be found in blood, muscles and cells.  

Calcium serves as a structural element in bones.  It is essential for nerve conduction and muscle contraction.  In the heart, it is necessary for conduction of electrical impulses and hence, cardiac rhythm and rate.  Calcium is also necessary for the clotting of blood. 

The average human body contains about 1 kg of calcium.  Calcium levels are tightly controlled in various body compartments.  The major regulators of calcium are parathyroid hormone, vitamin D, and calcitonin.  

The parathyroid hormone which is released from the parathyroid glands, is responsible for increased absorption of calcium.  The parathyroid hormone responds to low levels of calcium in the blood.  It increases the gastrointestinal absorption of calcium.  It releases calcium from the bones.  And it decreases the excretion of calcium by the kidneys.  

Vitamin D is necessary for the absorption of calcium.  It is obtained from diet and can be produced by sunlight exposure. 

Calcium is deposited on bones and when needed, it is released from the bones.  Short term deficiency of calcium does not affect serum calcium levels.  Long term deficiency can cause bone demineralization.  


Normal daily requirement of calcium depends on age.            

            Infants 0-6 months- 400 mg/day

            6-12 months- 600mg/day

            1-10 yrs- 800 mg/day

            11-24- 1200 mg/day

            Adults and elderly- 1500 mg/day 

Sources of calcium

-         milk, milk products, cheese, and yogurt

-         sardines

-         salmon

-         tofu, turnip, kale, Chinese cabbage, spinach 


Calcium carbonate and calcium citrate are the two main forms of calcium supplementation.  Both forms are well absorbed.  Calcium carbonate is 40% elemental calcium, and calcium citrate is 21%.  

Amount of calcium absorbed from the stomach depends on the acidity of the stomach.  Calcium carbonate is absorbed more with food.  Calcium citrate is absorbed equally with or without food.  If the amount of calcium supplemented is increase, the percentage of absorption is decreased, so more than 500mg of calcium supplementation is not advised at one time, and therefore should be taken more than once a day. Vitamin D improves the absorption of calcium.  Caffeine and alcohol decrease the absorption. 

Posted By :Dr. Sunitha, NJ, USA   Contact Now

Questions of
 Questions & Answers
 1.  Posted on : 28.10.2015  By  :  vivek , Navi Mumbai View Answer (1) Post Answer

I m 21 years olg i m gymaholic my wet is 69 kg, per day how much protein i need for lean muscle gain?


Hi , Per day 8 grams of Protein you need to eat . Here we are offering some protein products for weight gain and muscle buildup . for more details Visit:www.lactonovasport.com

  Posted By :Lactonovasport , #81-3, IDA Mallapur,Hyderabad, Telangana-500076. | On 31.7.2020
 2.  Posted on : 3.2.2015  By  :  Ramji , Hyderabad View Answer (1) Post Answer

I am 77trs had cabag 15 years ago my blood sugar 90/118 take anti diabetics regularly do 2 km of cycling on cardi cycle my hbagvaries from 6.5to7 my wt is 67kgs please prescribe Diet sheet for me.


My weight is 70kg and my height is 5 ft so which food i will use to reduced weight,Kindly assist me I will very much appreciate. Thanks. Khyati

  Posted By :khyati dave , Nairobi | On 23.6.2017
 3.  Posted on : 6.5.2014  By  :  Shashi Borah , Assam View Answer (1) Post Answer

I am a 26 years old and 5'6" feet indian man my weight is 76 kg. I want to loss my weight. Please give me suggestions.


According to the weight chart, you are over weight by 10kg. In order to reduce weight you have to either increase your activity by excercise or decrease your food intake. please refer following links Calorie Needs https://www.webindia123.com/health/diet/calorie/calorie.htm , Weight Chart https://www.webindia123.com/health/diet/calorie/weight.htm , Calorie Calculation https://www.webindia123.com/health/diet/calorie/calculation.htm, Calore to gain/lose weight https://www.webindia123.com/health/diet/calorie/gain.htm

  Posted By :Admin , | On 26.5.2014
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