Calcium and oxalate: eat them together
By Oliver Silen · Updated November 2, 2026 · Not medical advice
Eat calcium with your meals, and don't cut it. Calcium and oxalate eaten together bind in the gut and leave in stool, so less oxalate reaches your urine. Cutting calcium does the opposite.
What the trials found
- Normal calcium beat low calcium. In a 5-year trial of 120 men with recurrent calcium oxalate stones, 12 of 60 on a normal-calcium diet (about 1,200 mg a day, with less salt and animal protein) had another stone, against 23 of 60 on a low-calcium diet [1].
- More dietary calcium, fewer stones. Among 45,619 men followed for 4 years, those eating the most calcium had about half the stone risk of those eating the least [2]. In 91,731 women followed for 12 years, the top fifth for dietary calcium had 35% lower risk [3].
- Less calcium, more urine oxalate. When a 250 mg oxalate diet dropped from 1,002 mg to 391 mg of calcium, urine oxalate rose 28% [4].
How much
The American Urological Association advises 1,000 to 1,200 mg of calcium a day for stone formers [5]. Spread it across meals, and put the biggest share with the meal that carries the most oxalate. One cup of milk has about 300 mg of calcium, and 6 oz of yogurt about the same.
Food or supplement
Food is better. In the women's cohort, calcium supplements carried 20% higher stone risk, while dietary calcium lowered it, and 67% of the women taking supplements took them away from meals or with low-oxalate meals [3], where there's no oxalate to bind. If you take a supplement, take it with food, and ask your doctor which kind.
Without dairy
Dairy is near zero in oxalate: milk (grade A, <1 mg per 1 cup), yogurt (grade A, <1 mg per 6 oz), cheese (grade A, <1 mg per 1 oz cheddar). Without it, the options are:
- Calcium-fortified plant milk. Pick a low-oxalate one: oat milk (grade A, 3.6 mg per 1 cup) or rice milk (grade A, <1 mg per 1 cup). almond milk (grade D, 27 mg per 1 cup) is high, and soy milk is moderate. Several plant milks measured in one 2022 lab study ran from below detection to 27 mg a cup [6].
- Calcium-set tofu. tofu (grade B, 9.1 mg per 3 oz) carries some oxalate, so count it.
- Low-oxalate greens. kale (grade A, <1 mg per 1 cup raw) has calcium and very little oxalate. Spinach has calcium too, but its own oxalate ties up most of it.
Lactose-free milk and yogurt have the same calcium and oxalate as the regular kind.