Which combination best increases net calcium absorption from a meal that contains high-oxalate greens?

Consume the greens with a vitamin D–rich food (e.g., fortified milk or sunlight-exposed vitamin D status) and include a low-oxalate calcium source like canned sardines with bones

Add a high-phytate whole grain to the same meal to bind more oxalates so calcium becomes more bioavailable

Consume the high-oxalate greens alone on an empty stomach to maximize gastric emptying and therefore calcium uptake

Avoid vitamin D and instead rely solely on supplemental calcium carbonate taken with the greens for maximal absorption