Calcium is important for bone health, but it’s also essential for the heart, nerves, hormones, arteries, and muscles to work properly. Yet it’s estimated that only 3 in 10 Americans consume the recommended 1,000–1,300 mg of calcium daily, and myths and confusion persist.
Myth #1: Taking extra calcium will ensure strong bones
Calcium is certainly essential for bone health, but by itself, it doesn’t guarantee that bones will stay strong throughout life. A British Medical Journal analysis of 59 studies that followed more than 13,000 people over age 50 found that adequate calcium, from either food or supplements, increased bone mineral density by up to 1.8 percent in a year; however, that wasn’t enough to prevent fractures. Strong bones also require a whole-foods diet, regular exercise, and supporting nutrients.
When elderly people are deficient in calcium and vitamin D, taking both supplements can significantly improve the condition of their bones. A study of 3,800 women with an average age of 84 found that daily supplements providing 1,200 mg of calcium and 800 IU of vitamin D reduced risk of hip fractures by 23 percent.
These are key nutrients that enable calcium to fully do its job:
- Vitamin D is required to enable proper calcium absorption.
- Magnesium helps prevent bones from becoming brittle and fragile.
- Vitamin K2 helps ensure that calcium is utilized in bones rather than deposited in arteries or kidneys.
- Potassium from fruits and vegetables—at least as much as the daily sodium intake—prevents excess sodium buildup, which leads to calcium excretion.
Myth #2: All adults should take 1,000–1,200 mg of daily calcium supplements
These amounts are recommended daily calcium totals from both food and supplements: 1,000 up to age 50 and 1,200 mg after that. Supplements should be used to make up any shortfall from your diet. To get a sense of how much calcium is in your food, see “Food Sources of Calcium,” right, and check labels. Calcium is usually listed as a percent of daily value (%DV), meaning a percent of 1,000 mg. For example, 10% is 100 mg, 15% is 150 mg, 20% is 200 mg, and so on. Add up the calcium content of your staples and, depending on your age, subtract from 1,000 or 1,200 to determine an appropriate supplement dose.
Some studies have found that excess calcium from supplements may be bad for the heart or contribute to kidney stones, so more isn’t always better.
Myth #3: Calcium must be taken at the same time as vitamin D
Although vitamin D is essential for calcium to be used effectively, it doesn’t matter whether it’s taken at the same or another time of day. Your body will release an active form of vitamin D when needed, as long as you have adequate stores of the vitamin.
Answers to Common Calcium Questions
Is calcium best absorbed when taken with other minerals?
The answer isn’t clear. Although one study of postmenopausal women found that trace minerals (5 mg copper, 2.5 mg manganese, and 15 mg zinc) with calcium citrate malate improved bone density more than the calcium alone, it’s also known that large amounts of calcium or magnesium compete for absorption with each other and with other minerals. Smaller amounts of minerals, such as those found in multivitamins, aren’t problematic.
How should calcium be taken?
For best absorption, and to prevent calcification of your arteries, take no more than 500 mg at one time from food and supplements combined. Calcium citrate can be taken with or without food, but other forms should be taken with a meal, as they need stomach acid to be broken down.
Which form of calcium is best?
Calcium citrate and calcium citrate malate are regarded as the most absorbable. Calcium carbonate, the least expensive form, is also the least absorbable and most likely to cause gas, bloating, and constipation in high doses. Other forms vary in absorption, and may be bulkier, requiring more pills for a higher dose.
Food Sources of Calcium
|Serving size||Calcium content in milligrams (mg)|
Collard greens, frozen
Sardines, canned with bones
Yogurt, plain, low-fat
Milk or almond milk
Tofu, made with calcium
Salmon, canned with bones
Bok choy, cooked
Source: National Osteoporosis Foundation