What contains Casein protein?

T writes:
Casein is only an issue if someone is *sensitive* to it. I use the word sensitive, because very few people are truly allergic to it (If you've been properly allergy tested and have tested positive for casein allergy,
then you should not use milk and should carry an Epipen with you as well as wearing a Medicalert bracelet.) If someone has leaky gut, and improperly digested casein is getting into their system, then they are
going to react because inappropriate proteins are what the immune system is designed to attack. The other problem is that the peptides that result from incompletely broken down casein behave like opioids and they will have a similar CNS effects.. hence, brain fog, lethargy, etc.

BUT... there are lots of different kinds of casein, and the casein that's found in cow milk is the one that people generally react to. This is REALLY IMPORTANT to remember, since dairy can be in important
source of calories and there's no point removing something from your diet that you don't have to... so, I'm going to say it again. there are lots of different kinds of casein, and the casein that's found in cow milk is the one that people generally react to. So... I did a very simple Google search using the words, "casein cow vs. goat milk" and here's what I got.

From:
"There is only an 85% overlap in milk protein makeup across different species so people who have an unusual milk allergy, or who are merely lactose intolerant, may find that a milk other than cow's milk is
digestable. Also, remember that since each mammal has protein and sugar variants in their milk, it's possible to be allergic to the milk of only one, or one set of, mammals."

From:
"Apha-s1 is the major casein protein present in cow milk and has been identified as one of the major cow milk allergens. By contrast the major casein in goat milk is ß-casein, and alpha-s2 casein is the main alpha