What happens if you do not get enough calcium?

Over years, too little calcium weakens bones and can lead to osteoporosis. It can also cause rickets in children and osteomalacia (soft bones) in children and adults, although vitamin D deficiency is the more common cause of these two.^[1]

Women after menopause and people who avoid dairy, such as vegans and people with lactose intolerance or a milk allergy, are most likely to get too little.^[1] In the US, 39% of people aged 4 and older get less than the estimated average requirement.^[1]

A low level of calcium in the blood (hypocalcemia) usually has another cause. Examples are too little vitamin D or magnesium, a problem with parathyroid hormone, critical illness and some medicines.^[1] Its most common symptoms are numbness around the mouth, tingling in the hands and feet, and muscle spasms.^[1] A normal blood level does not prove a good intake, because the body keeps this level steady. A bone density scan shows calcium status over a lifetime.^[1]

One trial tested supplements for rickets where the diet is very low in calcium. In 123 Nigerian children whose diets gave about 200 mg a day, 1,000 mg a day gave better healing than vitamin D alone.^[2]