Increased consumption of nutritious food (fruits, vegetables, nuts, legumes) and a minimal intake of junk food (food that is excessively oily or high in sugars) can increase longevity. In fact, when more nutritious food is consumed, a person is less likely to eat unhealthy food, as they are already full.
When a study analysed the eating habits of people between the ages of 30 and 75 across 20 years, they were encouraged to have a healthier lifestyle by eating larger amounts of nutritional food. It was found that those who improved their diets by 20% had an 8% reduction in their mortality likelihood, and 7-15% reduction in likeliness to develop cardiovascular diseases. As cardiovascular diseases are the leading causes of death, an improvement of diet can definitely support a person's longevity in the long run.