IPA: /ˈhɛlθfəl/
KK: /ˈhɛlθfəl/
Something that helps to improve or maintain good health.
Eating fruits and vegetables is a healthful choice for your diet.
Healthful is formed from "health" (from Old English "hælu", meaning wholeness or well-being) and "-ful" (meaning full of). The word "healthful" means full of health or promoting good health.
Think of 'health' as wholeness and remember that 'healthful' means full of health or promoting well-being.