Calcium, the most abundant mineral in the body, is found in some foods, added to others, available as a dietary supplement, and present in some medicines (such as antacids).

Calcium is required for vascular contraction and vasodilation, muscle function, nerve transmission, intracellular signaling and hormonal secretion, though less than 1% of total body calcium is needed to support these critical metabolic functions.

Inadequate intakes of dietary calcium from food and supplements produce no obvious symptoms in the short term. Circulating blood levels of calcium are tightly regulated. Hypocalcemia results primarily from medical problems or treatments, including renal failure, surgical removal of the stomach, and use of certain medications (such as diuretics).

Symptoms of hypocalcemia include numbness and tingling in the fingers, muscle cramps, convulsions, lethargy, poor appetite, and abnormal heart rhythms. If left untreated, calcium deficiency leads to death. Over the long term, inadequate calcium intake causes osteopenia which if untreated can lead to osteoporosis. The risk of bone fractures also increases, especially in older individuals. Calcium deficiency can also cause rickets, though it is more commonly associated with vitamin D deficiency.

Now, according to a new study, it has been found that individuals with lower levels of calcium in the blood, are more likely to experience sudden cardiac arrest (SCA) than those with higher calcium levels.

Although frank calcium deficiency is uncommon, dietary intakes of the nutrient below recommended levels might have negative health consequences over the long term. The following groups are among those most likely to need extra calcium.

99% of the total calcium is in the bones and remaining 1% is in the extracellular space. Sudden cardiac arrest (SCA) is fatal for over 90% of patients, and more than half of men and close to 70% of women who die of SCA have no clinical history of heart disease prior to this cardiac event.

US is leading in the rate of sudden cardiac arrests and reported that it kills more than any single cancer. Scientists in the US compared blood calcium levels measured in 267 patients who experienced a cardiac arrest and an additional 445 others who did not.

Lead investigator Sumeet S. Chugh, MD, Pauline and Harold Price Chair in CardiacElectrophysiology, Cedars-Sinai Heart Institute, Los Angeles, CA, said, noted that serum calcium levels were lower in individuals who had a sudden cardiac arrest than in a control group.

Patients in the higher risk group had blood calcium levels of less than 8.95 milligrams per decilitre, which is just within the normal range of 8.5-10.2mg.

Data from 2002 until 2015 were gathered from the Oregon Sudden Unexpected Death Study (Oregon SUDS). The goal of the Oregon SUDS is to improve understanding of who is at risk for out-of-hospital sudden cardiac arrest.

“Patients with serum calcium in the lowest quartile (bottom 25 per cen) had twice the odds of sudden cardiac arrest compared to those in the highest quartile (top 25 per cent), even after controlling for multiple patient characteristics including demographics, cardiovascular risk factors and comorbidities, and medication use,” said Dr Sumeet Chugh, lead investigator from the Cedars-Sinai Heart Institute in Los Angeles.

In addition to cardiac arrests there are patients who were suffering from diabetes, chronic obstructive pulmonary disease and chronic kidney disease.

Further study and research are required to explain the adverse effects of associated with lower calcium levels. There is a scope to determine whether controlling calcium levels improves the effect in the general population or in high-risk patients. The researchers recommended that serum calcium levels should be examined and followed longitudinally more carefully.

Milk, yogurt, and cheese are rich natural sources of calcium and are the major food contributors of this nutrient to people in the United States [1]. Nondairy sources include vegetables, such as Chinese cabbage, kale, and broccoli. Spinach provides calcium, but its bioavailability is poor. Most grains do not have high amounts of calcium unless they are fortified; however, they contribute calcium to the diet because they contain small amounts of calcium and people consume them frequently. Foods fortified with calcium include many fruit juices and drinks, tofu, and cereals.