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When women think about what they can do to prevent osteoporosis, most immediately think of calcium. The abundant mineral improves bone health, increases bone mineral density, and improves the effectiveness of osteoporosis medications. And incidences of hip fractures in older women taking calcium and vitamin D supplements were significantly reduced, according to data from the Women’s Health Initiative (WHI) trial. Supplementing with calcium has also been shown to decrease bone loss in postmenopausal women. Other research shows that women who benefit the most from calcium supplements include those who are older, have osteoporosis, and/or have a low baseline intake of calcium.
Your Age Matters Most
As women age, especially after menopause, calcium requirements increase because of reduced intestinal calcium absorption and less efficient conservation of calcium by the kidneys. But the primary influence on effective calcium absorption is the actual amount of calcium ingested, either via diet or supplementation. Certain populations of women, including the elderly, the lactose intolerant, vegans, and those with poor diets, may not have adequate calcium intake. In fact, according to the Dietary Guidelines for Americans 2020–2025, some 60 percent of all adult women don’t get enough calcium from their diets.
The Dietary Reference Intakes for calcium, developed by the National Institutes of Medicine in 2011, advise that that girls aged 9–18 get 1,300 mg of calcium per day from food and supplements, while women up to age 50 should aim to get 1,000 mg per day, and women over age 50 need 1,200 mg per day.
To calculate the amount of calcium supplementation you need, you should first estimate your dietary intake. Start by assuming that you get 250 mg of dietary calcium per day—not counting dairy foods or calcium-fortified foods—if you eat two to three meals per day. Most women take in an additional 300 mg per day in the form of one serving of dairy. Add another 300 mg for each additional serving of dairy or calcium-fortified soy food. For example, if you drink one glass of milk per day, but eat no soy or other calcium-fortified foods, then your average daily intake is 550 mg per day. To up your intake of dietary calcium from there, consider focusing on a few of these calcium-rich foods.
Sesame seeds — 351 mg
Spinach, boiled — 245 mg
Blackstrap molasses — 118 mg
Tofu, raw — 100 mg
Kale, boiled — 94 mg
Broccoli, steamed — 75 mg
Oranges — 52 mg
How to Pick the Form
Once you’ve determined the baseline of calcium that you’re getting from your diet, you can calculate how much you need to get from supplements, keeping in mind that women under age 50 need about 1,000 mg of total calcium per day, while women over age 50 should try to get 1,200 mg total per day.
Did You Know?
Calcium citrate may be a better choice for older women whose lower stomach acid production and lower intake of vitamin D compromise optimal calcium absorption.
There is a great deal of confusion and controversy about which form of supplemental calcium is best. Some women suffer from constipation, nausea, and indigestion with calcium supplementation, especially from calcium carbonate. Calcium citrate is less likely to cause these problems. Calcium carbonate is absorbed well when taken with food. Calcium citrate can be taken with food, but when taken on an empty stomach, it is absorbed better than calcium carbonate. And calcium citrate may be a better choice for older women whose lower stomach acid production and lower intake of vitamin D—due to less exposure to sunshine and decreased fat absorption—compromise optimal calcium absorption.
A Word About Safety
Calcium supplementation is extremely safe. Even in amounts of up to 1,500 mg per day from both diet and supplements, there is no increase in the risk of kidney stones. However, calcium supplements are contraindicated without medical testing/assessment and supervision for women with a history of kidney stones. Total calcium intake greater than 2,500 mg per day—from diet and supplements combined—should be avoided.