Pasteurized: Pasteurization is the process of heating milk up and then quickly cooling it down to eliminate certain bacteria. It is common for milk to be heated up to at least 161.6 degrees Fahrenheit for 15 seconds, which is known as High-temperature Short-Time (HTST) pasteurization, or flash pasteurization. Pasteurization does not kill all micro-organisms in milk, but is intended to kill some bacteria and make some enzymes inactive. For me the key words here are “enzymes inactive.” This is where you run into issues, because enzymes are needed to digest the milk. Also, this process warps and distorts milk proteins, which further strains digestion.
Ultra-pasteurized: Same process as pasteurization, except the milk gets more heat; it’s heated to 280 degrees Fahrenheit for a minimum of two seconds. This processing results in a shelf life that can extend up to nine months (versus 2-3 weeks with regular pasteurization). You still encounter the same, and arguably greater, issues with regards to digestibility. Pasteurized or ultra-pasteurized, this form of milk is very hard for the body to digest.
Homogenization: Homogenization is a process whereby all the fat molecules are mechanically forced to be the same size. This “forcing” process means the original fat globule membrane is lost and a new one is formed that incorporates a much greater portion of casein (the protein found in milk) and whey proteins. I am not sure what the exact implications are, but the fact that this is an unnatural process, and we are getting more casein and more whey proteins tells me that, again, we are making it difficult for our bodies to digest.
Organic Milk: Like other organic products, this generally stipulates that livestock must be: allowed to graze, be fed an organically certified fodder or compound feed, not be treated with most drugs (including growth hormone), and in general must be treated humanely. Organic milk is typically higher in omega-3s compared to non-organic because it is primarily grass-fed versus grain- or corn-fed. Also, there are no GMOs or antibiotics. You can learn more about the omega 3 to 6 ratio in organic milk here. Organic milk farms produce significantly less milk per cow and cost more to operate, which is why the milk is more expensive, but it may be worth the extra cost.
Raw Milk: Raw milk is milk that has not been pasteurized or homogenized. So, this doesn’t mean the milk is organic per se, or that the animal is fed an optimal diet (i.e., primarily grass). In fact, diet is a major factor in the quality of raw milk. Studies have shown that over-feeding starchy grains can affect the acidity of the cow’s stomach environment and change fat and nutrient levels. This sort of reminds me of problems we see with the human diet, so it really isn’t quite that shocking or illogical.
GMO Milk: Milk that has been genetically modified. The common milk GMO is rBGH. BGH is the natural form of the hormone in cattle; the rBGH refers to the bovine growth hormone that is made in a lab using genetic technology. It promotes growth and cell replication, meaning you can get more milk, faster from the cow. Again, we’re messing with Mother Nature here, and from what I’ve seen, she doesn’t like it.