In your example both phrases are correct as the meaning of healthy and healthful are virtually the same, in this context. The 'Oxford English Dictonary' says:
• adjective (healthier, healthiest) 1 having or promoting good health. 2 normal, sensible, or desirable: a healthy balance. 3 of a very satisfactory size or amount: a healthy profit.
— DERIVATIVES healthily adverb healthiness noun.
healthful
• adjective having or conducive to good health.
— DERIVATIVES healthfully adverb healthfulness noun.
This extract is from 'The American Heritage - Book of English Usage".
Some people like to maintain a distinction between healthy and healthful. Healthy, they say, should be used to mean “possessing good health,” and only healthful should mean “conducive to good health.” People who hold this view are swimming against the tide of history, for healthy has been used to mean “healthful” since the 16th century. You can find the “healthful” use of healthy in the works of many distinguished writers, with this example from John Locke being typical: “Gardening … and working in wood, are fit and healthy recreations for a man of study or business.” Therefore, both healthy and healthful are correct in these contexts: a healthy climate, a healthful climate; a healthful diet, a healthy diet.
Healthful is a word I do not often hear, as a native speaker.
Hope you find this information useful.