9 Vegetables That Get Healthier When Boiled Asparagus: Boiling breaks down cell walls, releasing vitamins A, B9, C, and E for better absorption. Mushrooms: Boiling releases the antioxidant ergothioneine, aiding in cell protection against damage. Spinach: Boiling and cooking breaks down oxalic acid, making iron and calcium more absorbable. Tomatoes: Boiling boosts lycopene, linked to lower risks of heart disease and cancer. Carrots: Boiling increases beta-carotene, vital for vision and immunity. Bell peppers: Heat enhances the absorption of immune-boosting antioxidants like beta-carotene. Brassica: Steaming preserves cancer-fighting compounds like myrosinase and glucosinolates. Green beans: Baking, microwaving, boiling, or griddling preserves antioxidants better than boiling. Kale: Light steaming deactivates enzymes hindering iodine absorption, which is crucial for metabolism.