Quick answer
NIH gives 1,000 mg of calcium a day while breastfeeding for women 19 and older and 1,300 mg for teens, with upper limits of 2,500 mg and 3,000 mg. A 12-month randomized trial in 150 nursing women found no significant difference in bone changes between daily intakes of 300, 600 and 900 mg from milk powder.1,2
Key facts
- NIH gives 1,000 mg of calcium a day while breastfeeding for women 19 and older and 1,300 mg for teens.1,3
- The upper limit is 2,500 mg a day for nursing women 19 and older and 3,000 mg for teens, from food and supplements.1,3
- A 12-month randomized trial in 150 postpartum women gave milk powder with 300, 600 or 900 mg of calcium; bone mineral changes did not differ significantly.2
- Calcium carbonate causes gas, bloating and constipation more often than calcium citrate.1,3
- NIH says the body absorbs calcium best in amounts of 500 mg or less at a time.1,3
What NIH says about calcium while nursing
NIH gives the same calcium amounts and upper limits for breastfeeding as for pregnancy: 1,000 mg a day for women 19 and older and 1,300 mg for teens, with upper limits of 2,500 mg and 3,000 mg. It describes no breastfeeding-specific harm from calcium.1,3
Children aged 9 to 18 need 1,300 mg a day, as do pregnant and breastfeeding teens. Pregnant and breastfeeding women aged 19 and older need 1,000 mg.1,3
The upper limit for calcium from food and supplements combined is 2,500 mg a day for adults aged 19 to 50 and 2,000 mg from age 51. For children aged 9 to 18 it is 3,000 mg.1,3
The body absorbs calcium best in amounts of 500 mg or less at a time. Someone taking 1,000 mg a day from supplements does better with two smaller doses than one large one.1,3
What does a trial of calcium in nursing women show?
A randomized, double-blind trial in China enrolled 150 postpartum women. They took 40 g of milk powder with 300 mg of calcium and 5 mcg of vitamin D, or the same powder with an extra 300 mg or 600 mg of calcium, for 12 months. Of the 150, 102 finished, and they breastfed for an average of 7.9 months.2
The changes in bone density of the whole body, lumbar spine and hip did not differ significantly between the groups, with P values from 0.5 to 0.9. The researchers concluded that higher calcium intake did not significantly change bone mineral changes in these lactating women.2
The trial looked at bone measures. It did not report harms to the mothers or infants, and it used calcium in milk powder, not a tablet, so it does not answer a question about a supplement's safety.2
What cautions apply to calcium supplements while nursing?
The cautions are those for calcium in general. NIH says supplements can cause gas, bloating and constipation, and that calcium carbonate does so more often than citrate. It says higher intakes of supplemental calcium might increase the risk of kidney stones, and the sources describe that question as unsettled.1,3
Calcium supplements can cause gas, bloating, constipation or a mix of these. Carbonate causes them more often than citrate, especially in older adults with less stomach acid; smaller doses spread through the day, taking it with meals or switching forms can help.1,3
In the Women's Health Initiative, 36,282 women taking 1,000 mg of calcium and 400 IU of vitamin D a day had 17% more kidney stones than those on placebo over about 7 years. The upper limit was set on this evidence, although two later reviews of other trials found no such link.1,4
Who should ask a doctor about calcium while breastfeeding
- Nursing women who take calcium supplements together with antacids or a multivitamin, who should ask their doctor or pharmacist to add up the calcium.1
- Women who have had kidney stones or kidney disease, or high blood calcium.1
- Women who take levothyroxine, a quinolone or tetracycline antibiotic, a bisphosphonate, dolutegravir or lithium.1
- Women asking about a calcium and magnesium product, which the sources checked do not address in nursing.
Questions people ask
Is a calcium supplement safe while breastfeeding?
NIH gives 1,000 mg a day while breastfeeding and an upper limit of 2,500 mg, and describes no breastfeeding-specific harm. Ask your doctor whether a supplement fits you.1,3
Is calcium carbonate safe while breastfeeding?
NIH says carbonate causes gas, bloating and constipation more often than citrate, and the same upper limits apply while nursing. Ask your doctor or pharmacist.1,3
Is calcium magnesium safe while breastfeeding?
The sources checked do not report on calcium and magnesium products while nursing, which is not a finding either way. Ask your pharmacist to check each mineral against its upper limit.1
Is calcium citrate safe while breastfeeding?
NIH says calcium citrate can be taken without food and causes digestive effects less often than carbonate. The 2,500 mg upper limit applies. Ask your doctor.1
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Sources
- Office of Dietary Supplements, National Institutes of Health. Calcium: Fact Sheet for Health Professionals. Updated June 22, 2026. Opened 2026-10-07.
- Zhang ZQ, Chen YM, Wang RQ, Huang ZW, Yang XG, Su YX. The effects of different levels of calcium supplementation on the bone mineral status of postpartum lactating Chinese women: a 12-month randomised, double-blinded, controlled trial. Br J Nutr. 2016;115(1):24-31. A 12-month randomised, double-blinded, controlled trial in 150 lactating women. Opened 2026-10-11.
- Office of Dietary Supplements, National Institutes of Health. Calcium: Fact Sheet for Consumers. Updated September 14, 2023. Opened 2026-10-07.
- Jackson RD, LaCroix AZ, Gass M, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006;354(7):669-683. Opened 2026-10-07.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.