Quick answer

Women need 1,000 mg of calcium a day until 50 and 1,200 mg from 51, counting food and supplements. US women average 842 mg a day from food, so many fall short. In trials in adults over 50, supplements raised bone density by 0.7% to 1.8%, a small gain that did not grow over time.^1,2,3

Key facts

Counting supplements, US women average 1,009 mg of calcium a day.²
Pregnant and breastfeeding women aged 19 and older need 1,000 mg a day, the same as other women their age.²
Women with low stomach acid, which is most common later in life, absorb calcium citrate more easily than carbonate.¹
The upper limit drops from 2,500 mg to 2,000 mg a day at age 51.¹

How much women need at each age

Calcium for girls and women per day, from food and supplements²
Age or stage	Recommended	Upper limit
9 to 18 years	1,300 mg	3,000 mg
19 to 50 years	1,000 mg	2,500 mg
51 to 70 years	1,200 mg	2,000 mg
71 years and older	1,200 mg	2,000 mg
Pregnant or breastfeeding, 14 to 18	1,300 mg	3,000 mg
Pregnant or breastfeeding, 19 and older	1,000 mg	2,500 mg

The step up at 51 is meant to lessen the bone loss that follows menopause. A woman in her 40s needs 1,000 mg; in her 60s and 70s, 1,200 mg.²

What changes at menopause

After menopause, lower estrogen reduces calcium absorption and increases the calcium lost in urine and drawn from bone. On average, women lose about 1% of their bone density a year after menopause.²

Adult women carry about 1,200 g of calcium and men about 1,400 g. The amount stays steady in men but starts to fall in women at menopause.²

The loss is fastest during menopause and for about 5 years afterward, when falling estrogen means bone is broken down faster than it is rebuilt. Men lose bone with age too, though bone loss is more common in women.^1,2

What supplements do for bone density

Trials in women after menopause have measured bone density with a scan that reflects the calcium stored in bone over a lifetime. The gains from calcium, with or without vitamin D, have been real but small.^2,3

Produces small gains in bone mineral density in adults over 50*^2,3,4

Moderate evidence

A meta-analysis of 51 randomized trials of calcium supplements in 12,257 people over 50 found bone density 0.7% to 1.8% higher at five skeletal sites, with similar gains from extra dietary calcium. The gain appeared within a year and did not grow after that; it was similar with or without vitamin D and at higher or lower doses, and the authors judged it too small to be likely to matter clinically. In the Women's Health Initiative, 1,000 mg of calcium with vitamin D a day left hip bone density 1.06% higher after about 7 years.

Amount studied: Calcium supplements from under 500 mg to over 1,000 mg a day, with or without vitamin D, for one to several years

Helps you reach the recommended daily calcium intake when food falls short*²

Moderate evidence

National survey data from 2007 to 2010 show that 39% of people aged 4 and older get less calcium than the estimated average requirement from food and supplements, including 49% of children aged 4 to 18. Women average 842 mg a day from food alone; counting supplements, their average rises to 1,009 mg, close to the 1,000 to 1,200 mg they need.

Amount studied: Recommended intake: 1,000 to 1,200 mg a day for adults, from food and supplements combined

A pooled analysis of 15 trials in 78,206 postmenopausal women found that calcium with vitamin D, or dairy foods fortified with both, raised bone density at the spine, arms and hip. Whether gains of this size matter clinically is not clear.²

How much women get now

Men in the US average 1,083 mg of calcium a day from food and women 842 mg. About 22% of men and 32% of women take a supplement that contains calcium.²

People who eat no dairy, including vegans, are more likely to fall short of calcium and usually need fortified foods or a supplement to reach the recommended amount.^1,2

Lactose-free and reduced-lactose dairy products contain the same amount of calcium as regular dairy.²

The gap between an average 842 mg from food and the 1,000 to 1,200 mg women need is about 160 to 360 mg. That is roughly one cup of milk or calcium-fortified soy drink, at about 299 mg, so food can often close it before a supplement is needed.²

Pregnancy and breastfeeding

Pregnancy and breastfeeding do not raise the calcium recommendation: women 19 and older need 1,000 mg a day, and teens 1,300 mg. Multivitamins commonly contain 200 to 300 mg of calcium, so check a prenatal vitamin's label before adding a separate calcium product.²

Cautions for women

In the Women's Health Initiative, women taking 1,000 mg of calcium and 400 IU of vitamin D a day had more kidney stones, and the supplements did not significantly reduce hip fractures overall. The US Preventive Services Task Force concluded that less than 1,000 mg of calcium with less than 400 IU of vitamin D does not prevent fractures in postmenopausal women.^2,4

For pregnant women whose diets are low in calcium, supplements may lower the risk of preeclampsia, and the World Health Organization recommends 1,500 to 2,000 mg a day for them. That amount should be set by a prenatal care provider, not chosen alone.²

Bisphosphonates such as alendronate, which are used for bone loss, are absorbed poorly when taken near calcium, and so is levothyroxine. A pharmacist can plan the timing.^5,6

Ask first if you have had kidney stones
Ask first if you take a bisphosphonate, levothyroxine, or a quinolone or tetracycline antibiotic
Ask first if you are pregnant and your diet is low in calcium

Questions people ask

Should women over 50 take calcium?

Only if food leaves them short of 1,200 mg a day. Supplements raise bone density slightly in women over 50, but they also bring stomach side effects and, in one large trial, more kidney stones.^1,3,4

Is calcium citrate better for older women?

It can be. Citrate depends less on stomach acid, which is more often low in older people, and it causes gas and bloating less often than carbonate. Carbonate works well too when it is taken with meals.^1,2

What about women in their 30s and 40s?

They need 1,000 mg a day. NIH notes that bones slowly start losing calcium from about age 30, so intake matters well before menopause.¹

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*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.