Calcium and Vitamin D: Indications, Dosing & Side Effects

Calcium and vitamin D supplements are used to treat or help prevent osteoporosis. They may also help lower the risk of fractures, especially in people with low blood calcium levels.

Calcium is the primary mineral involved in bone strength, muscle contraction, nerve signaling, and blood clotting. Vitamin D is essential because it helps the body absorb calcium more effectively.

These supplements are sold in pharmacies, health food stores, and supermarkets, usually as tablets. They should only be used as recommended by a healthcare provider.

Indications for use

Calcium and vitamin D supplements are indicated to:

• Prevent or treat bone loss caused by osteoporosis.

• Prevent osteoporosis in women before and after menopause.

• Reduce the risk of fractures related to osteoporosis.

• Help meet daily calcium and vitamin D needs in people with nutritional deficiencies.

In populations with low dietary calcium intake, calcium supplements may be used during pregnancy to help reduce the risk of preeclampsia, according to the World Health Organization (WHO), but they should only be used under medical guidance.

In cases of osteoporosis, supplements are not the only option. Calcium‑rich foods like cheese, almonds, and flaxseed can also help increase blood calcium levels and support both the prevention and treatment of osteoporosis.

Dosing instructions

The recommended calcium intake for most adults is about 1,000 to 1,200 mg per day, and the recommended vitamin D intake is usually 600 to 800 IU per day.

According to the NIH Office of Dietary Supplements, recommended intakes for calcium and vitamin D vary by age and sex, and vitamin D helps the body absorb calcium and maintain bone health.

Because tablets provide different amounts of calcium and vitamin D, the correct way to take a supplement depends on the specific product, so it is important to read the label and follow your doctor’s instructions.

Below are some examples of calcium and vitamin D supplements and how they are typically taken:

• Caltrate 600+D3: take 1 tablet by mouth once or twice a day with food.

• Os-Cal +D: take 1 to 2 tablets by mouth per day with meals.

• Citracal + D Slow Release: take 1 tablet by mouth once or twice a day with food.

• Generic calcium carbonate with vitamin D3: follow the label, usually 1 to 2 tablets per day with meals.

These supplements should be taken with meals to help improve calcium absorption in the intestines. However, they should not be taken at the same time as certain foods.

High-oxalate foods, such as spinach or rhubarb, or high in phytic acid, such as wheat bran, rice bran, soy, lentils, or beans, can reduce how much calcium your body absorbs. In these cases, the calcium and vitamin D supplement should be taken 1 hour before or 2 hours after eating these foods.

The dose of these supplements may be adjusted based on your doctor’s or dietitian’s guidance, so regular medical or nutrition follow-up is important before and during calcium and vitamin D supplementation.

Possible side effects

Possible side effects of calcium and vitamin D supplements include irregular heartbeat, stomach pain, gas, constipation or diarrhea, nausea or vomiting, dry mouth, a metallic taste in the mouth, muscle or bone pain, weakness, drowsiness, headache, increased thirst, increased urination, confusion, or loss of appetite.

These supplements may also cause kidney problems, such as kidney stones or calcium buildup in the kidneys.

Calcium and vitamin D supplements can also cause an allergic reaction. In this case, stop using the supplement and seek immediate medical care or go to the nearest emergency room if symptoms such as trouble breathing, a feeling that the throat is closing, or swelling of the tongue or face develop.

Contraindications for use

Calcium and vitamin D supplements are contraindicated for people with an allergy or intolerance to any component of the formula. Other situations in which these supplements should not be used include:

• Kidney failure.

• Kidney stones.

• Heart disease, especially cardiac arrhythmia.

• Malabsorption syndrome or achlorhydria.

• Liver disease, such as liver failure or biliary obstruction.

• Excess calcium in the blood.

• Excessive calcium in the urine.

• Sarcoidosis, which is an inflammatory disease that can affect organs such as the lungs, liver, and lymph nodes.

• Parathyroid gland disorders, such as hyperparathyroidism.

In addition, people who regularly use aspirin, levothyroxine, rosuvastatin, or ferrous sulfate (iron pills) should talk to a healthcare provider before taking a calcium and vitamin D supplement, because it may affect how well these medicines work.

Calcium and vitamin D supplements should only be used under medical supervision during pregnancy, while breastfeeding, or in people with a history of kidney stones.