Leafy greens can contribute calcium, but absorption varies by plant. Some greens contain calcium yet also high oxalates that reduce bioavailability—so “high content” doesn’t always mean “high absorption.” The practical principle is to use lower-oxalate greens regularly and keep higher-oxalate options as part of variety. Many people use cabbage-family greens, arugula, certain lettuces, and broccoli as supportive choices; spinach contains calcium but has lower absorbability. Treat greens as part of a bone-supportive plate rather than the sole calcium source—pair with dairy/fortified foods and adequate protein. Cooking method and portion size matter: very large raw portions may increase gas; steaming or soups can be better tolerated. If you have kidney stones or oxalate restrictions, personalize choices.