Did you know that a serving of Swiss chard has more than 600% the recommended daily allowance of vitamin K? It's also loaded with vitamin A and a variety of other vitamins, minerals and phytonutrients. Tip: this is one vegetable that may be healthier cooked. Boiling or steaming it will help reduce its concentration of oxalic acid, an organic compound that binds with other minerals like calcium, magnesium, iron, zinc, and copper in the intestines forming insoluble salts that interfere with absorption and are a primary component of kidney stones.