Sister Sutton, you made a very basic and obvious fact that we need to really take into account: “About calcium: Let's just think about it--where does the cow, elephant, hippo, rhino, etc. get their calcium that helps make strong bones and teeth? Do we see any lack here? They get it from plant sources: green plants, etc.”
It is true that the cow, elephant, etc. obtain their calcium only from plant sources. However, in order for calcium to be well absorbed we need a good source of vitamin D and a significant portion of our vitamin D comes from exposure to sunlight. Vitamin D plays a major role in calcium absorption and bone health. The relationship between calcium absorption and vitamin D is similar to that of a locked door and a key. Vitamin D is the key that unlocks the door and allows calcium to leave the intestine and enter the bloodstream. Vitamin D also works in the kidneys to help reabsorb calcium that otherwise would be excreted.
Vitamin D is manufactured in the skin following direct exposure to sunlight. The amount of vitamin D produced in the skin varies depending on time of day, latitude, season, and skin pigmentation. Many individuals are afraid of prolonged sun exposure due to the potential damage that overexposure to ultraviolet light can do like premature skin aging or melanoma.
Another reason the cow, elephant, etc. are able to keep strong bones only through plant sources is because besides having more prolonged sun exposure than humans living in well developed countries, they are more dependent on physical activities for their daily survival. In a similar way, in under-developed countries, the incidence of osteoporosis is less than in other parts of the civilized world because people are forced to have more prolonged exposure to sunlight and because they have a less mechanized way for performing their daily activities.
I do believe that we should avoid dairy products as much as possible because of the potential allergies they may provoke, the high cholesterol and the challenge they represent to our immune system. However, we need to be aware of the limitations imposed to us through our modern way of living. I believe that if we are going to avoid dairy products, we should also make an effort to do more physical exercise, have some healthy exposure to sunlight and use vitamin supplements wisely.
FF