A U.S. health and wellness expert says an easy way to boost immunity is to eat more fruits and vegetables in different colors.

Amy Hendel says says a study published in the Phytonutrient Report found eight in 10 Americans are missing out on the health benefits of a diet rich in colorful fruits and veggies -- resulting in a phytonutrient gap.

The report looked at fruit and vegetable consumption in five color categories -- green, red, white, blue/purple and yellow/orange and the phytonutrients found in each color category.

Hendel recommends eating two foods from each of the five color categories. For optimal health, aim to eat two foods from each of the five color categories for a total of 10 servings each day.

Foods in the red category -- tomatoes, pomegranate, red cabbage, cranberries, even pink grapefruit -- boost immune systems and support heart health, Hendel says.

The health benefits of foods in the yellow/orange category -- carrots, squash, sweet potatoes and pineapple -- also boost immunity and help vision and heart health as well as maintain skin hydration.