Srila Prabhupada: Children must get at least two cups of milk a day. If they drink plenty of milk, their body becomes stout and strong, and they develop a keen brain for understanding the distinction between their body and their soul.
From BTG. Original follows:
Children must get at least one pound milk. If they drink more milk they become stout and strong.
Then their life is built up strong, and nice brain to understand.
>>> Ref. VedaBase => Room Conversation — June 24, 1976, New Vrindavan