Calcium 101: Daily Targets, High‑Absorption Foods & Common Myths

**One cup of cooked kale provides 180 mg calcium—absorbed up to 50 % better than the same dose from milk.**

- Adults 19‑50 y need 1 000 mg Ca/day (UL = 2 500 mg) - Oxalate‑rich greens (spinach) ≠ good Ca source - Vitamin D + K2 + weight‑bearing exercise maximize absorption

It’s the most abundant mineral in the body—99 % in bones & teeth; remaining 1 % regulates muscle contraction, nerve signalling and blood clotting.

| Age | RDA | UL | |-----|-----|----| | 19‑50 y | 1 000 mg | 2 500 mg | | 51‑70 y (♂) | 1 000 mg | 2 000 mg | | 51‑70 y (♀) & ≥ 71 y | 1 200 mg | 2 000 mg |

| Food | Ca (mg) | Absorption | |------|---------|------------| | Dairy milk 250 ml | 300 | ~30 % | | Yogurt 170 g | 250 | ~30 % | | Canned sardines 90 g (with bones) | 325 | ~35 % | | Fortified tofu 100 g | 350 | ~30 % | | Cooked kale 1 cup | 180 | **~50 %** | | Almonds 30 g | 75 | ~20 % |

- **Boosters**: vitamin D, K2, lactose, prebiotics (inulin) - **Blockers**: high oxalate (spinach, beet greens), phytate (raw bran), excess sodium (> 2 g/day)

- Low intake → osteopenia, stress fractures, hypertension risk - Chronic > 2 500 mg + high supplements → kidney stones, calcification

| Myth | Fact | |------|------| | “Only dairy counts.” | Many greens, fish with bones & fortified plant milks rival dairy. | “Supplements are always better absorbed.” | Citrate > carbonate on empty stomach; whole‑food Ca often better tolerated. | “More calcium = stronger bones.” | Needs vit D, K2, protein & load‑bearing exercise too.

Aim for 3‑4 servings of calcium‑rich foods daily, pair with vitamin D and resistance training—supplements only to fill gaps.

1. Institute of Medicine DRI Tables, 2024. 2. Weaver CM. *Nutr Rev* 2022. 3. NIH Office of Dietary Supplements—Calcium Fact Sheet, 2024.