Heart disease and cancer are leading killers in the US. Could it possibly mean that the average meat-eating American diet has something to do with this? Sure, one could say that refined sugars, packaged food and lack of exercise is also killing us, but cancer and diabetes hits even the skinny-fat runners on here.
We can go back and forth all day with studies that show associations (which may or may not be based on a plethora of strong evidence) arguing pretty much any point:
http://archinte.jamanetwork.com/article.aspx?articleid=1134845
Conclusions: "Red meat consumption is associated with an increased risk of total, CVD, and cancer mortality. Substitution of other healthy protein sources for red meat is associated with a lower mortality risk."
See, I can do that too.
Now with the logical argument against dairy: Why on Earth do we drink copious amounts of another mammal's (namely cow) milk? In evolutionary terms cow's milk is designed for one thing only: for baby cows! (and it makes them grow big really fast). So does it logically make sense that we could guzzle cups of this stuff daily? Full of puss and blood and hormones that need to be pasteurized because otherwise we'd get food poisoning from it. I mean, why not just drink dog's milk or some other mammal's milk? Finally it's likely casein protein (in all dairy) leads to cancer as well. Countries that consume a lot of dairy tend to have higher cancer rates than those that do not.
Fruits and veggies have a more cancer reversing role...
And protein concerns? In the US we are obsessed with protein much like the characters in the movie Idiocracy are obsessed with "electrolytes." Have you honestly EVER met anyone (who didn't have an eating disorder) who was low on protein? Being low in iron or B12 is one thing, but honestly low in Protein? Virtually non-existent unless you live in poverty and are extremely malnourished (eating disorder etc). Of course we always hear subjective stories of people "feeling weak" because they think they missed their "essential" protein shake or got less than 100g in during a day, but science tells us otherwise. Protein is totally overrated.
What made our brains grow and develop back in the day? It was likely fruit and tubers (early potatoes/starches) . Your brain needs carbs the most. It only needs a little protein and it can pool amino acids over time very well. As much as the Paleo crowd (which follows absolutely no solid archeology evidence whatsoever) likes to believe, our ancestors were pretty crappy at hunting. We forged, we scavenged, and we ate whatever we could to survive (including eachother sometimes). Does that make it a health diet nowadays? Absolutely not. Cavemen barely lived to be in their 30s and many remains had signs of developing coronary heart disease (unfortunately they usually died of some other causes before getting a heart attack though). Nowadays is when we die of heart attacks from our crappy meat and dairy diets.