What is calcium?

Calcium is one of 21 elements that are essential to humans. It is a mineral vital for healthy teeth and bones where most of it is stored in the body. It also plays a vital role in maintaining the health and functioning of nerves and muscle tissue.

Calcium alone may not be so useful to our health. For example, its utilization for strong bones depends on adequate availability of vitamin D. Dietary sodium greatly influences calcium reabsorption in the kidneys.

It is mainly stored in the bony skeleton, which serves to maintain its concentrations in the blood. About 99% of the body’s calcium is stored in bones and the balance 1% is found in blood, muscle, and other tissues.

Any reduction in its reserves of bone causes loss of bone mass, and similarly, an increase in the reserve causes an increase of bone mass.

Your body gets calcium mainly from the foods that you eat. Any deficiency can be corrected by taking its supplements.

Your body’s need depends on your age, gender, and the different stages in your life.

Role of calcium in the body

Calcium plays various roles in the body. These include the following:

  • Strengthens bones and teeth
  • Regulates the function of muscle
  • Controls the functioning of the heart
  • Plays an important role in clotting of blood
  • Plays a key role in the transmission of nervous system messages
  • It is required for the functioning of the enzyme
  • Lowers risk of developing high blood pressure during pregnancy
  • Lowers blood pressure in young people
  • Improves cholesterol levels
  • Lowers risk of colorectal adenomas (a type of benign tumor)

Calcium requirement

How much calcium you need every day depends on your age and gender.


  • 0 to 6 months — 210 mg
  • 7 to 12 months – 270 mg


  • 1 to 3 years – 500 mg
  • 4 to 8 years – 700 mg
  • 9  to 11 years – 1000 mg


  • 12 to 18 years – 1300 mg


  • 19 to 70 years – 1000 mg
  • 71 years and above – 1200 mg


  • 19 to 50 years – 1000 mg
  • 51 tears and older – 1200 mg

There is no need for women to take additional dietary calcium during pregnancy because they absorb it from food more efficiently. Breastfeeding women too do not need to increase their intake.

The recommended upper limit for calcium is 2,500 mg a day for adults aged 19 to 50 years. For those 51 and older, the limit is 2,000 mg a day.

Food sources

The following foods are natural sources of calcium

  • Milk and milk products such as yogurt, cheese, and buttermilk
  • Leafy green vegetables such as broccoli, collards (cabbage family), Chinese cabbage, and spinach
  • Soy and tofu
  • Fish like Sardines and canned salmon
  • Nuts and seeds such as Brazil nuts, almonds, and sesame seeds
  • Calcium-fortified foods such as breakfast cereals, fruit juices, and bread

For proper absorption of this mineral, your body also requires adequate levels of vitamin D. Some foods with naturally occurring vitamin D include canned salmon with bones and egg yolks. You can also get it from fortified foods though sunlight exposure is the best source of this vitamin D. Most adults require to take 600 or 15 micrograms of vitamin D every day.

Calcium deficiency and toxicity

Having adequate calcium levels in the blood is essential for vital daily functions. If the serum calcium levels drop too low, the parathyroid hormone (PTH) signals the bones to release it into the bloodstream and activates vitamin D to increase its absorption in the intestines. It also inhibits the kidneys to excrete less of it in the urine.

Similarly, when the serum calcium levels are enough, another hormone called calcitonin lowers its levels in the blood by stopping its release from bones and signaling the kidneys to rid more of it in the urine.


A more serious deficiency of calcium is called hypocalcemia. It is caused by kidney failure, surgeries of the digestive tract like gastric bypass, or medications like diuretics that interfere with absorption.

Symptoms of hypocalcemia include:

  • Muscle spasms or weakness
  • Paresthesia
  • Numbness or tingling in fingers
  • Abnormal heart rate
  • Loss of appetite
  • Seizures

A doctor may recommend calcium supplements for the following people:

  • Women have started menopause
  • Women who stop menstruating due to anorexia nervosa or excessive exercise
  • Those who have lactose intolerance and cannot have milk or milk products
  • Those who follow a vegan diet


Too much calcium in the blood is called hypercalcemia. It increases your risk of kidney stones, prostate cancer, and constipation. With too much calcium in the blood, it can accumulate in blood vessels with long-term high doses and cause heart problems.

Symptoms of hypercalcemia:

  • Stomach upset
  • Constipation
  • Bone pain
  • Weakness, fatigue
  • Nausea, vomiting
  • Shortness of breath
  • Chest pain
  • Heart palpitations, irregular heart rate

Factors that increase your risk of calcium deficiency

The following conditions or lifestyle habits may result in low calcium levels:

  • Eating disorders such as bulimia and anorexia
  • Long-term use of laxatives
  • Long-term use of some medicines, such as chemotherapy, or corticosteroids
  • Lack of the parathyroid hormone
  • High sodium diet
  • Very high protein diet
  • Some cancers
  • Too much consumption of caffeine, energy drinks, and soda
  • Very high fiber intake
  • Alcohol abuse
  • Smoking
  • Digestive diseases such as celiac disease, inflammatory bowel disease, and Crohn,s disease
  • Bariatric surgery
  • Kidney failure
  • Pancreatitis
  • Vitamin D deficiency
  • Phosphate deficiency
  • Sedentary lifestyle with little or no physical activity

What medications interact with calcium supplements?

If you are taking calcium supplements, discuss with your doctor about any other drugs you may be taking. The following medications will interfere with your supplements

  • Antacids that contain aluminum
  • Antibiotics
  • Anti-seizure medications
  • Beta-blockers
  • Calcium-channel blockers
  • Corticosteroids
  • Digoxin
  • Diuretics
  • Estrogen