How much calcium adults need
The NIH Office of Dietary Supplements sets the adult RDA at 1,000 mg/day, rising to 1,200 mg for women 51+ and everyone 71+ [1]. Most experts favor meeting this through food first.
Best food sources
- Dairy: milk, yogurt, and cheese are the richest and best-absorbed sources.
- Fortified foods: many plant milks, orange juice, and cereals are calcium-fortified.
- Plant and other sources: tofu set with calcium, canned salmon and sardines (with bones), kale, bok choy, broccoli, and almonds.
Note that some greens (like spinach) are high in calcium but also in oxalate, which limits how much you absorb — kale and broccoli are better-absorbed greens.
Absorption tips
Calcium is absorbed best in amounts of about 500 mg or less at a time, so spreading it across meals beats one big dose [1]. Adequate vitamin D helps the body use calcium (see getting vitamin D).
Why food calcium may be preferable
Very high-dose calcium supplements have been debated for possible cardiovascular and kidney-stone concerns, whereas calcium from food has not raised the same questions. Food also delivers calcium alongside protein and other nutrients. For many people, improving dietary calcium is a better first step than a high-dose pill — see calcium intake and safety.
Who may need more attention
People who avoid dairy, postmenopausal women, and older adults are more likely to fall short. If diet can't close the gap, a modest supplement (often paired with vitamin D) can help — but more isn't better, and timing matters around medications.
Practical guidance
- Build calcium from a mix of dairy and/or fortified and plant sources.
- Spread it across the day rather than one large dose.
- Use supplements to fill a gap, not to megadose, and keep totals under the [upper limit](/learn/upper-intake-levels-explained).