Eating nutritious food is only half the equation; how you prepare it determines how much your body actually absorbs. Fat-soluble nutrients, including vitamins A, D, E, and K, along with carotenoids like lutein, beta-carotene, and lycopene, require dietary fat to be absorbed, and without it, a meaningful portion of these compounds passes through the digestive system largely unused. A 2025 study from the University of Missouri, published in Food Nutrition, found that raw kale alone produced very low carotenoid absorption, and cooking it slightly further reduced bioavailability. The significant increase came when researchers added an oil-based sauce, and crucially, it didn't matter whether the oil was present before or after cooking. The presence of fat was the critical variable, not the timing. Supporting research from Iowa State, published in the American Journal of Clinical Nutrition, found a roughly dose-dependent relationship, with two tablespoons of oil producing meaningfully greater absorption than smaller amounts. In my kitchen, I cook vegetables on medium or low heat with extra-virgin olive oil and use avocado oil, ghee, or tallow for higher-heat applications. All of these fats appear to support the absorption of fat-soluble nutrients. Sautéing greens, roasting vegetables with a drizzle of oil, or using an olive oil-based salad dressing are all effective approaches. The principle is simple, and it's one of the easiest ways to get more nutritional value out of the meals you're already making.