I don't actually think dairy should be ingested by humans, at all, ever. Don't get me wrong, cheese is my favorite. But if you think about it, humans are the only crazy animals on the planet that a) drink milk past infancy and b) drink another animals milk. For the most part I don't consider all things that exist in nature to be natural, and/or healthy. It's more important to consider what you SEE in nature as opposed to what exists in nature. Another example can be seen in animals when they drink or eat. They do just that. They do one or the other, not both at the same time. It's not the wisest choice to drink while you eat, as the fluid dilutes ones digestive enzymes, which can make your body pretty cranky about the food you just inhaled. But I digress.
The other reason is dairy is an inflammatory food. It's not just about lactose intolerance (lacking the enzyme lactase to break down the lactose into galactose and glucose which your body can then use for fuel, or store as glycogen or fat), which we hear so much about. It's actually about dairy irritating the gastrointestinal lining, such that little pores are created in the matrix that glues enterocytes (gut cells) together. This causes something called "leaky gut syndrome" in which big, not-fully digested protein molecules, can enter the blood stream. The body does not recognize these proteins and starts creating antibodies against them as if they were a virus! This sets up a whole cascade of inflammation and deposition of immune complexes which can cause a myriad of symptoms including headaches, sinusitis, seasonal allergies, eczema, acne, menstrual cramps, gas, bloating, abdominal pain, brain fog, ADD, ADHD, depression, and asthma.
Also, the protein casein in dairy has been found on the opiate receptors in the brain!!! This means that this protein is triggering the same neurochemical response in the brain that say, morphine, heroine, or codeine do!!! Talk about a dairy addiction!!! When we don't supply dairy to the body, we go into a state of withdrawal, and to feel "normal" we need to consume it. It's amazing though when you eliminate certain problem foods including dairy how "normal"/better you actually feel. The neuroendocrine system in the body adapts so that it does not constantly send the same incoming signal to the brain. So only by removing a stimulus is the body able to acknowledge how it feels with or with out that stimulus (in this case the dairy). We are often addicted to foods we are allergic to.
... and lastly, because it's time for my cardio, if you're worried about getting your 1000-1200 mg of calcium in a day eat almonds, spinach or other green leafy veggies. I track my daily intake at fitday.com, and never come up short in Ca, and don't eat dairy. A great nutrition website I recommend is whfoods.com. Besides the best thing one can do for their bone health is weight bearing exercise.
Ok, I'm done! I'm curious to know other's thoughts...