Calcium is the most abundant mineral in the human body. About 99% of it sits in your bones and teeth, while the remaining 1% circulates in blood, muscles, and other tissues. That 1% might sound insignificant, but it handles cell metabolism, muscle contraction, blood clotting, nerve transmission, and hormone secretion. When blood calcium levels drop too low, the consequences can be life-threatening.

Research has linked dietary calcium deficiency to obesity, high blood pressure, and metabolic syndrome. Calcium markers in the body also appear connected to blood sugar regulation, insulin balance, and lipid profiles.

Why consider calcium supplementation?

Survey data from multiple countries shows that Western dietary patterns have shifted calcium intake downward. In many populations, average daily calcium consumption hovers around 400-500 mg, well below the 1,000 mg recommended by the World Health Organisation. Add in high processed food intake and sedentary lifestyles, and calcium deficiency becomes increasingly common.

The NHS recommends that adults need 700 mg of calcium daily, though requirements increase during pregnancy, breastfeeding, and after menopause. Getting enough from diet alone can be difficult for people who avoid dairy or have limited food variety.

What are the potential benefits of calcium tablets?

1. Slowing bone loss and reducing fracture risk

After middle age, hormonal changes and other factors cause bone breakdown to outpace bone formation. The skeleton becomes porous, losing strength and flexibility. This affects women disproportionately, with osteoporosis occurring in roughly 50% of women after menopause.

Since bone loss produces no symptoms, doctors often call it a “silent disease”. As the skeleton weakens, fracture risk climbs.

In the United States alone, osteoporosis causes over 2 million fractures annually. Hip fractures are the most serious, carrying mortality rates up to 24% in elderly patients, with healthcare costs reaching tens of billions of dollars yearly.

A meta-analysis reviewing 29 studies with 63,897 participants found that calcium supplements combined with vitamin D slowed bone loss in the hip and spine while reducing overall fracture incidence by 12%. Source

The researchers noted that for best results, people should aim for at least 1,200 mg of calcium and 800 IU of vitamin D daily.

Another meta-analysis of 8 studies with 30,970 participants reported that calcium plus vitamin D reduced total fracture risk by 15% and hip fracture risk by 30% in middle-aged and older adults. Source

Summary: Taking calcium with vitamin D appears to slow bone loss and reduce fracture incidence.

2. Possible reduction in oesophageal cancer risk

Oesophageal cancer receives less attention than other cancers despite ranking about sixth among common malignancies. It tends to be aggressive with low survival rates, divided mainly into squamous cell carcinomas (37%) and adenocarcinomas (57%).

Known risk factors include obesity, gastro-oesophageal reflux, smoking, drinking very hot beverages, high red meat consumption, poor oral hygiene, low fruit and vegetable intake, and Barrett’s oesophagus.

A meta-analysis examining 17 studies (3,396 gastro-oesophageal cancer cases and 346,815 controls) found that people with the highest dietary calcium intake had 20% lower oesophageal cancer rates compared to those with the lowest intake. Source

Subgroup analysis showed the protective effect was strongest for squamous cell cancers and more pronounced in Asian populations than European or American ones.

Summary: Calcium-rich diets may offer some protection against oesophageal cancer, though more research is needed.

3. Lower ovarian cancer incidence

Ovarian cancer accounts for only about 4% of cancers (roughly 200,000 cases diagnosed worldwide each year), but it remains one of the more lethal cancers affecting women. Survival rates have barely improved over 30 years, partly because no reliable early screening method exists. Only 30% of patients receive diagnosis at an early stage.

A meta-analysis of 15 epidemiological studies (7,453 ovarian cancer cases among 493,415 participants) found an inverse relationship between dietary calcium and ovarian cancer. Those with the highest calcium intake had lower incidence rates. Source

The mechanism may involve calcium’s effects on parathyroid hormone and insulin-like growth factor (IGF-1), which influences cell division and apoptosis.

Summary: Higher dietary calcium intake correlates with lower ovarian cancer risk, though causation isn’t established.

4. Reduced breast cancer risk

Breast cancer tops the list of female cancers. It develops when cells in milk ducts or mammary lobules divide abnormally and expand.

Breast tissue contains abundant blood vessels, lymphatic vessels, and lymph nodes. If cancer cells escape local control, metastasis to surrounding organs becomes likely. Early detection dramatically improves outcomes.

A meta-analysis of 11 cohort studies involving 872,895 participants found that those consuming the most calcium reduced breast cancer risk by 8% compared to those consuming the least. For every 300 mg increase in daily dietary calcium, cancer risk dropped by 2% to 8%. Source

The exact mechanism remains unclear but may relate to calcium’s role in regulating cell proliferation, differentiation, and programmed cell death.

5. Improved blood lipid profiles

Hyperlipidaemia (abnormally high cholesterol or triglycerides) is a primary risk factor for cardiovascular disease. About 90% of coronary heart disease patients have elevated blood lipids.

US statistics indicate that 48% of adults have dyslipidaemia, with elevated LDL cholesterol being the most common abnormality.

Research suggests that reducing LDL cholesterol by 40% while increasing HDL cholesterol by 30% could cut cardiovascular disease risk by 70%.

A meta-analysis of 22 randomised controlled trials found that calcium supplementation improved blood lipid profiles, lowering LDL (“bad”) cholesterol by an average of 4.64 mg/dL and raising HDL (“good”) cholesterol by 1.93 mg/dL. However, most included studies ran for less than 6 months, so longer-term research is needed. Source

Researchers believe calcium may regulate calcitrophic hormones, promoting fat breakdown and reducing lipid storage.

6. Colorectal cancer risk reduction

Colorectal cancer ranks third among common cancers (about 10% of all cases), trailing lung and prostate cancer in men, and breast and lung cancer in women.

Survival depends heavily on stage at diagnosis. When detected while still localised, the 5-year survival rate reaches 90%. If the cancer has metastasised, survival drops to around 10%. Early detection matters enormously.

A large observational study following 88,509 women and 47,740 men over 33 years found that participants with total daily calcium intake above 1,400 mg (from food or supplements) had 22% lower colorectal cancer risk compared to those consuming less than 600 mg. Source

The protective effect appeared stronger for proximal colon cancer (the portion connected to the small intestine, including the caecum, ascending colon, and transverse colon), which tends to be more aggressive than distal colon cancer.

7. Cardiovascular disease considerations

Heart disease remains one of the leading causes of death globally. The Framingham Heart Study found that heart disease often presents suddenly. Among men, 62% experience sudden death or heart attack as their first cardiac event. For women, the figure is 46%. Heart disease frequently kills without warning.

Some studies have linked calcium intake to reduced cardiovascular mortality. In one large study of over 3,000 postmenopausal women, calcium supplementation (from food or supplements) reduced deaths from ischaemic heart disease. Source

The protective mechanism may involve calcium’s ability to regulate blood lipids, blood sugar metabolism, and blood pressure.

However, other studies raised concerns that calcium supplements might increase cardiovascular risk, generating considerable alarm. So far, this concern hasn’t been confirmed by subsequent research. Source

More recent large database analyses (following participants for 3 to 7 years) found no increased cardiovascular disease risk from calcium or vitamin D supplementation, including no increased incidence of heart attacks, angina, or acute arterial events. Source

8. Relief from premenstrual symptoms

About 75% of women of childbearing age experience some physical or emotional discomfort before menstruation. Symptoms range from mild (20-50% of cases) to severe premenstrual dysphoric disorder (about 5%). Common complaints include irritability, anxiety, depression, breast tenderness, and abdominal pain, often interfering significantly with daily life.

The menstrual cycle produces two oestrogen peaks, with calcium concentrations dropping to their lowest point during the luteal phase.

Clinicians have noted substantial overlap between premenstrual symptoms and hypocalcaemia symptoms, suggesting calcium supplementation might help.

A double-blind controlled study published in the American Journal of Obstetrics and Gynecology found that calcium tablets improved premenstrual symptoms by 48% (measured by standardised scales), compared to 30% improvement in the placebo group. Core symptoms including negative mood, water retention, food cravings, and pain all showed significant reduction. Source

9. Diabetes risk reduction

Diabetes rates continue climbing worldwide. In the United States alone, 41 million people are at risk, though only 1 million receive diagnosis each year. Rising obesity rates compound the problem; the World Health Organisation estimates that 300 million people will have diabetes by 2025.

Beyond elevated blood sugar, diabetes disrupts lipid metabolism. Combined with hypertension, it multiplies cardiovascular disease risk several times over, accelerating complications affecting nerves, kidneys, and eyes.

Research published in the Journal of Clinical Endocrinology found that calcium or vitamin D deficiency directly affects insulin secretion. Large observational studies showed that daily intake of more than 1,200 mg calcium and 800 IU vitamin D reduced type 2 diabetes risk by 33%. Source

10. Weight management support

Excess weight affects health far beyond appearance. Estimates suggest 2.3 billion people are overweight (BMI 25.0-29.9) and 700 million are obese (BMI over 30).

Enlarged fat cells function like inflammation factories, secreting inflammatory hormones (particularly interleukin-6) that trigger systemic inflammation and increase risk of cardiovascular disease, hypertension, cancer, and diabetes.

Epidemiological research has consistently found that higher dietary calcium intake, especially from dairy products, correlates with lower obesity rates.

A double-blind controlled study of 32 obese people on calorie-restricted diets found that diets high in calcium (whether from milk or supplements) produced greater decreases in weight and body fat. Dairy sources outperformed calcium tablets, possibly due to other bioactive compounds in milk. Source

A meta-analysis of 33 studies with 4,733 participants found that overall, calcium intake didn’t significantly change body weight compared to controls. However, when researchers accounted for age, sex, BMI, and supplementation duration, moderate calcium intake did help reduce weight in specific groups: those with normal BMI, children, adolescents, adult men, and premenopausal women. Source

The mechanism may involve calcium binding to fatty acids in the gut, promoting fat excretion in faeces, altering gut bacteria, reducing fat accumulation, and increasing resting energy expenditure.

What are the side effects of calcium tablets?

Calcium supplements can cause constipation, stomach pain, bloating, and diarrhoea. Excessive doses may lead to nausea, vomiting, appetite loss, kidney damage, irregular heartbeat, and frequent urination (signs of hypercalcaemia).

For most adults, the upper daily limit of calcium intake is 2,500 mg (including food and supplements). Exceeding this may cause adverse reactions and interfere with absorption of other minerals including zinc, magnesium, and phosphorus.

People with a history of kidney stones should discuss calcium supplementation with their doctor. While kidney stones aren’t directly caused by calcium supplements, the relationship is more nuanced than commonly assumed. According to Mayo Clinic, calcium from food may actually reduce kidney stone risk by binding to oxalate in the digestive tract, but calcium supplements taken apart from meals could increase stone risk.

Safety precautions

Do not combine with these medications:

Antibiotics ceftriaxone and gentamicin (may cause dangerous interactions)
Osteoporosis drugs (bisphosphonates)
Blood pressure medications (beta-blockers, calcium-channel blockers)
Cholesterol-lowering drugs (bile acid sequestrants)
Thyroid hormones
Quinolone and tetracycline antibiotics (calcium may reduce their effectiveness)
Psoriasis drug calcipotriol (may cause hypercalcaemia)
Cardiac drug digoxin (may produce cardiotoxicity)

Medical conditions requiring caution:

Williams-Beuren syndrome (avoid calcium tablets with vitamin D; hypercalcaemia may occur)
Hyperparathyroidism
Sarcoidosis
Kidney failure
Cancer (may increase hypercalcaemia risk)

Other considerations:

Excessive calcium tablets during pregnancy may affect foetal development
Certain antiepileptic drugs (carbamazepine, phenytoin) lower calcium levels; take calcium supplements at least 2 hours apart from these medications
For conditions involving frequent urination or bladder issues, discuss any new supplements with your healthcare provider

References

Tang BM, et al. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: a meta-analysis. Lancet. 2007. PubMed
Weaver CM, et al. Calcium plus vitamin D supplementation and risk of fractures: an updated meta-analysis. Osteoporos Int. 2016. PubMed
NHS. Calcium - Vitamins and minerals. NHS Website
Mayo Clinic. Kidney stones - Symptoms and causes. Mayo Clinic