Isn't it just the craziest ideas ever that we aren't made to drink COW milk? That a substance produced by another species, for their young isn't an essential part of our diet? Preposterous. Insanity I say!
I am going to go beyond the easiest arguments against it, like the fact that no other species drinks another's milk passed toddler-hood.
Did you know a calf that feeds on its mother milk will double in size in 47 days. A human baby on breast milk does this in 180 days. No wonder we are getting fatter and less and less healthy! The ratio of carb/fat/protein is also totally different, 30/49/21 for cow and 40/53/7 for human mothers, on average. The massive difference in protein content is the first to acknowledge. We as human beings have become so obsessed with getting enough of the wrong macro-nutrient. Babies, who go through massive growth spurts, only need 7% of their calories to come from protein. I think that speaks for itself. The higher carbohydrate content is explained by our needs for glucose to fuel our bodies and brains. The fat content is higher than what an adult needs simply because it is a more concentrated form of calories and children only develop the stomach size for carbohydrates as their main source of calories once they are weaned (which is supposed to be when they decide to, on average around 4 years old)
Let's add to this, shall we? Commercial milk contain high levels of pus, antibiotics, growth hormones, pesticides and other bacteria. Basically it's the perfect food with which to feed disease, including cancer and diabetes. Even if you are buying organic, there are still high levels of natural growth hormones that are supposed to help a calf grow,would you like to be size of a full grown cow?
Now let's also put the calcium "issue" to rest! Cow's milk does contain calcium. But the problem is that the milk digests acid, and since our bodies want to remain in an alkaline state, our body does it's best to re-balance our pH levels by pulling more calcium from our bones and thus, rending the calcium it contained completely useless since our bodies pull more calcium that it provides. Green leafy veggies and citrus contain tons of calcium that our bodies can use, as do almonds.
Next! There's is a reason why so many people on this planet are lactose intolerant. So many actually don't even know they are and the uncomfort they live with everyday goes unexplained, I should know I was one of them. We lose the ability to digest lactose after we are weaned as babies/toddlers.
One more point as to why milk isn't made for human consumption, cow milk contains opiates called casomorphin. The purpose of this drug is to get the calf "hooked" on it's mother's milk so that it will feed frequently and survive/thrive. It has the same effect on humans as any other opiate would. An addiction is created and this explains clearly why many people say: "I couldn't live without cheese/milk/sour cream". It isn't because you need it, it's because you are addicted.
And to be honest with all the alternatives available now, there is absolutely no excuse to keep supporting an industry that takes away calves from their mothers as soon as they are born which has them crying for weeks, that keeps cows pregnant their whole lives and just dumps them(aka slaughter) when they stop producing enough for the standards put in place, that can only be achieved with drugs and genetic modification. There is no excuse to keep these animal in restrained spaces and have them suffer their whole lives for something that we never needed.
Do the right thing, for you, for the animals, for the planet.