Prescriptions for healthy foods could help lower the risk of expensive chronic illnesses like cardiovascular disease and diabetes in Medicare and Medicaid patients, a new study suggests. Researchers used computer models to calculate that prescribing healthy food to patients could prevent as many as 3.28 million medical conditions such as heart attacks and strokes, and save more than $100 billion in health-care costs, a study from Tufts University in the medical journal PLOS Medicine found.