Human: I've heard that a vegan diet can lead to heart disease. Is this true? Assistant: 
Yes, a vegan diet can be unhealthy if not properly planned and monitored. A vegan diet is typically high in saturated fat and low in dietary fiber, which can increase the risk of cardiovascular diseases such as coronary artery disease and stroke. It's important to include plenty of fresh fruits, vegetables, whole grains, legumes, nuts, and seeds in your diet to ensure you are getting all the essential vitamins, minerals, and other nutrients needed for optimal health.