calcium

Calcium is an essential mineral and the most abundant mineral in the body; almost all of it is stored in the bones and teeth, where it provides structure and strength. The body also uses calcium to help muscles move, nerves carry messages between the brain and the rest of the body, blood vessels move blood, and certain hormones be released. Vitamin D helps the body absorb calcium. Because calcium is a mineral the body cannot manufacture, it must come from food or supplements. In supplements it most often appears as calcium carbonate (the form in this product) or calcium citrate.

Calcium is essential, and getting enough mainly benefits people who are not already meeting their needs from diet rather than adding benefit for those who are. According to the NIH Office of Dietary Supplements, the evidence that supplements improve bone outcomes is mixed: some studies have found that calcium supplements with or without vitamin D increase bone mineral density in older adults, but others have not, and ODS states it is not clear whether calcium supplements help prevent fractures. Evidence for other outcomes is also unsettled. Research on calcium and colorectal cancer is inconsistent, some studies link high calcium intake from dairy to a higher risk of prostate cancer in men, and findings on heart disease are mixed, with some research suggesting high intakes of supplemental calcium might even raise cardiovascular risk. Overall, ODS indicates more research is needed before firm conclusions can be drawn for most of these outcomes.

Recommended Dietary Allowances vary by age and sex: roughly 700 mg for ages 1-3, 1,000 mg for ages 4-8, and 1,300 mg for ages 9-18; 1,000 mg for most adults 19-50; 1,000 mg for men 51-70 but 1,200 mg for women 51-70; and 1,200 mg for everyone 71 and older. Pregnant and breastfeeding teens need about 1,300 mg and pregnant or breastfeeding adults about 1,000 mg. These targets include calcium from both food and supplements. ODS notes calcium is absorbed best in amounts of 500 mg or less at one time, so larger daily amounts are better split into smaller doses through the day. Talk to your doctor, pharmacist, or a registered dietitian before starting a calcium supplement to confirm you actually need one and to choose the right dose and form, especially if you have kidney disease, a history of kidney stones, or take other medications.

Calcium has Tolerable Upper Intake Levels, the maximum daily intake from all sources (food, beverages, and supplements) unlikely to cause harm: 2,500 mg for adults 19-50 and 2,000 mg for adults 51 and older, with different limits for children. Excessively high calcium in the blood and urine can cause problems such as poor kidney function, low phosphate levels, constipation, nausea, abnormal heart rhythms, and a higher risk of death from heart disease, though ODS notes that high blood and urine calcium are usually caused by an underlying health condition rather than by high calcium intake. Some research has linked higher supplemental calcium intake to a greater risk of kidney stones, although this association has not been consistently confirmed. People with kidney disease, a history of kidney stones, or high blood calcium should use calcium supplements only under medical supervision.

Calcium supplements can cause digestive side effects in some people, including gas, bloating, and constipation. Spreading the dose throughout the day, taking it with meals, or switching the form of calcium may help. Taking very high amounts over time may contribute to more serious problems such as elevated blood calcium. Staying within recommended amounts and not exceeding the upper limit reduces the likelihood of side effects.

Calcium can interfere with how the body absorbs certain medications, so timing matters. ODS notes that levothyroxine (thyroid hormone) is not absorbed well if taken within about 4 hours of a calcium carbonate supplement, and quinolone antibiotics such as ciprofloxacin, gemifloxacin, and moxifloxacin are poorly absorbed if taken within about 2 hours of calcium. Taking calcium at the same time as the HIV medicine dolutegravir can lower its blood levels, so dolutegravir should be taken 2 hours before or 6 hours after calcium. Long-term lithium use, or taking lithium with calcium supplements, can lead to abnormally high blood calcium. Tell your healthcare provider about all supplements and medicines you take so they can check for interactions.