Healthful, a.
1. Full of health; free from illness or disease; well; whole; sound; healthy; as, a healthful body or mind; a healthful plant.
2. Serving to promote health of body or mind; wholesome; salubrious; salutary; as, a healthful air, diet. The healthful Spirit of thy grace. Book of Common Prayer.
3. Indicating, characterized by, or resulting from, health or soundness; as, a healthful condition. A mind . . . healthful and so well-proportioned. Macaulay.
4. Well-disposed; favorable. [R.] Gave healthful welcome to their shipwrecked guests. Shak.
Shades of meaning
Fernald has no entry of its own for healthful; he lists it under healthy.
Where he writes about it:
Healthful signifies promotive of health, tending or adapted to confer, preserve, or promote health; as, a healthful climate. — from healthy
Wholesome food in a healthful climate makes a healthy man. — from healthy
With healthful are ranged the words hygienic, salubrious, salutary, sanitary, and wholesome, while the other words are associated with healthy. — from healthy