Milk production is a demand driven process. I was thinking at the biological level, rather than at the economy level.
When a newborn baby drops water weight, which he does as he uses up his glycogen before starting to feed properly, there comes a "tick box" percentage drop in weight at which your UK midwife will start asking if you'd like to give a formula feed, "just while his mother's milk comes in". But it's a demand and supply system. How can demand possibly work to increase supply if the baby is full of denatured cow casein and fast asleep?
The shut down of milk production at the end (or start!) of lactation is not something that just happens. On the biological basis, any mammary gland which is not being asked to produce milk will "assume" there is no infant to feed. Continued lactation then needs to be stopped. Casein, the primary protein in milk, is the signal to cease lactation!
If the casein is not removed from the mammary gland it starts sending signals that nothing is feeding. Milk is actively secreted in to the mammary gland. It's kept sealed in to to ductal system by the "tight junctions" between the cells lining the secretory system. It's worth noting that the first sentence of this abstract is generic, ie tight junctions are probably the same throughout the body, they're not limited to mammary glands.
Tight junctions become leaky when there is milk stasis.
It's important that casein per se does not do this as there is always some in the milk glands, it's hydrolysed casein that does it. This is logical as fresh casein should leave lactation in tact, provided it's removed promptly. If it hangs around for any period of time it gets broken down by plasmin, a proteolytic enzyme also present in milk.
So it's quite convincing that casein hydrosylates open up tight junctions. Then the leakage of milk in to the tissue spaces of the mammary gland produce an inflammatory reaction which shuts down milk production.
There is quite good evidence that it is amino acids 1-28 of beta casein that do the tight junction opening, maybe 2-28.
That's the basics of mammary gland involution at the end of lactation.
Fascinating, but so what?
There are tight junctions in the gut too, the ones that gluten opens up to cause auto immune diseases. Does casein open those junctions up as well as gluten does? There is no hard science here, so I'll speculate.
Why not? Because a cow does not intend to maim the digestive system of her calf, any more than a mother does that of her baby.
The tight junction opening peptide from casein needs to be 27 or 28 amino acids long to work. This is what is produced by the action of plasmin in the udder/breast. Milk is normally delivered directly from mother to offspring, being deposited immediately in to the stomach. The enzyme here is pepsin. There is nothing gentle about pepsin. It's an industrial grade hydrolysing agent working best in a strong hydrochloric acid solution, pH around 2. If it just manages to cleave that initial amino acid sequence in even one place it will deactivate the tight junction opening ability. Ditto if the sequence is repeated elsewhere in the protein. How much in the way of active peptides are left after churning beta casein with acid pepsin for two hours at pH 2? Not a lot if you believe this report. No biological activity is left. Not much anyway.
So does that mean that casein is problem free? Of course not. How many people maintain that ideal pH of 2 for their pepsin to work in? Just take a swig of Gaviscon and your pepsin is not going to do its job. A pH of 7 is not the one at which it was designed to work. Even worse, take a ranitidine (H2 antagonist) tablet and the gastric pH is raised for 12 hours. Yet even worse (worser?) pop an omeprazole tablet, a proton pump inhibitor, and you simply are not going to pump any protons for 24 hours. Take one a day and forget your pepsin is ever going to do much protein digestion.
Once you've eliminated a functional stomach all bulk protein digestion is down to pancreatic trypsin. This is one of the better enzymes for making the casein hydrosylates used to open up the tight junctions in the mammary glands of experimental cows and goats. It's acting in your small intestine to manufacture a tight junction disruptor from milk.
That doesn't sound good to me.
Omeprazole is a market leader. Gaviscon and ranitidne are available OTC. I know at least one baby which has acid reflux so badly that she has spent (and still spends) most of her life on the latter two drugs. What's happening to her gut?
I think there is a case to be made for both the pasteurisation of liquid milk and the drying of powdered milk altering the shape of the protein structure of casein to render the 1-28 amino acid sequence protected from digestion in the stomach. This is absolute speculation, there's no data to support this. Except the world is full of anecdotes about people tolerating raw milk but not pasteurised milk. I'm also willing to speculate that bacteria used to ferment milk to yogurt or kefir may cleave this amino acid sequence, making fermented dairy products far less problematical, even if they are derived from pateurised milk. More speculation.
Bear in mind that once tight junctions in your gut are open, it does not have to be the casein which triggers the allergy, exactly as in the case of wheat gluten. Any intestinal protein can freeload through the opened epithelium.
BTW: Why on earth should a baby have acid reflux so badly she needs to live on ranitidine? It can all start from that suggestion, made with the best intentions by the midwife (ignoring box ticking), to give "just one" formula feed as baby is being slow to regain birth weight..... Considering formula milk appears to be made of sucrose and dried casein, with loads of omega 6 fatty acids (partly oxidised?), I think there are a host of suspects as to why it happens. But an unlucky baby can end up needing antacids as a lifesaver if she regurgitates repeatedly and projectilely on formula milk. I don't much like formula milk.
I also really don't like the idea of removing the functional ability of anyone's stomach either, at any age.
It's just asking for trouble.