Mix foods and meds mindfully. Food, alcohol and dietary supplements can interact with prescription drugs, changing the effectiveness of the drug or the way your body absorbs nutrients. For example, vitamin K can make the blood clot faster, so if you're on a blood-thinning medication, your doctor may tell you to avoid large amounts of foods that are high in K. These include leafy greens, such as kale, spinach, broccoli and Brussels sprouts. Keep your doctor and pharmacist informed about any vitamin, mineral or herbal supplements you are using. And ask about interactions between whatever you are taking and food or alcohol.