Take a look at the following sentence:
Eating healthy foods that are low in fat reduces the risk of some cancers.
It sounds correct, right? Well, yes and no. It depends on whom you ask.
There is an ongoing debate over the usage of healthy versus healthful. Some say healthy should be used to refer only to the wellness of living things (for example, a healthy body), while healthful is the word of choice to refer to anything that promotes good health (like food, exercise, etc.). Others believe that both words are acceptable to use in reference to health-promoting substances or practices (for example, healthy or healthful food). Healthy is used more often than healthful, by far, and it is stated as correct usage by reputable sources. So take your pick.