Cost with NK Coins: 15
Cost with Monkey Money: $4800
Healthy Bananas is a premium upgrade featured in Bloons Tower Defense 5 and Bloons Tower Defense 5 Deluxe. It makes Banana Farms generate +1 life per upgrade level per round (for example, a 3-0 Banana Republic generates 4 lives, 2 2-1 Banana Farms generates 8 lives, a 4-2 Banana Research Facility generates 7 lives).
This premium upgrade is the only way to let a M.O.A.B. Class Bloon escape and make the player have lives to spare. You need 617 lives to let a M.O.A.B. escape, 3165 for a B.F.B., and 16657 for a Z.O.M.G..