Milk is very unhealthy, in any quantity.
Meat is as well. Maybe organic in small quantities, not too often can help.
Fish is problematic as much is contaminated with mercury and other heavy metals (we poisoned the ocean).
What is your criteria for "very unhealthy" and do you have any evidence to back up that claim?
If milk if unhealthy in any quantity how did we all survive infancy?
So what then do you believe is a healthy diet? Surely eating animal protein on a regular basis is better than having to take a variety of unregulated supplements to stay within a healthy range of essential vitamins and minerals? Animal protein also has the upside of offering a tremendous amount of, well, protein, alongside the necessary vitamins.
Dairy (in certain forms) offers the same benefits.