Calcium: comparing dairy, plant drinks and vegetables

Comparing calcium sources is not about picking the highest number. Consider the portion actually eaten, possible fortification and, for some vegetables, compounds that limit absorption.

NIH lists dairy foods, vegetables such as kale, broccoli and bok choy, and plant drinks or tofu when fortified. Fortification depends on the product, not the whole category.

The nutrition table shows the amount present in food, not the amount absorbed. Oxalates and phytates can form compounds that are less absorbable. Spinach illustrates this limit; some cabbages and broccoli may have relatively better availability, but this does not rank every vegetable.

Start with calcium in mg per 100 ml, then relate it to the volume actually consumed. Check whether calcium is added and read the ingredients, which may mention calcium carbonate or phosphate. The form alone cannot predict absorption in every situation.

Also compare sugars, protein, salt, fat and processing. Vitamin D, when present, promotes intestinal calcium absorption, but it does not replace checking the calcium line.

Milk and yoghurt provide naturally occurring calcium. Cheese can contribute too, but portions are often smaller and salt varies. Compare per 100 g or 100 ml, then check the portion, sugars, salt and any vitamin-D fortification. The exact composition is the one on the label.

Leafy vegetables are not one homogeneous group. Spinach and rhubarb contain oxalates; broccoli, kale and some cabbages are often more interesting for calcium availability. Contribution also depends on serving size and the vegetable’s place in the meal.

For another food comparison, see our chia or flax comparison.

Vitamin D helps maintain calcium balance and promotes intestinal calcium absorption. On a label, check calcium, vitamin D, serving size and ingredients separately. Anses lists oily fish, cod-liver oil and egg yolk among dietary vitamin-D sources; common plant foods generally provide little unless specifically fortified.

1. 01Start with calcium in mg per 100 ml or 100 g.
2. 02Relate it to the portion actually consumed.
3. 03Check whether calcium is naturally present or added.
4. 04Read the vitamin-D line separately.
5. 05Compare sugars, protein, salt and ingredients.
6. 06For vegetables, add variety, possible oxalates or phytates and portion.