Some science behind the scenes
A naturally occurring opioid peptide from cow's milk, beta-casomorphine-7, is a direct histamine releaser in man - Kurek M, Przybilla B, Hermann K, Ring J; Department of Dermatology, Ludwig-Maximilian-University, Munich.
beta-Casomorphine-7, a naturally occurring product of cow's milk with opiate-like activity, was studied for possible direct histamine liberation activities in humans.
It was found to cause concentration-dependent in vitro histamine release from peripheral leukocytes of healthy adult volunteers.
Intradermal injection of beta-casomorphine-7 induced a wheal and flare reaction in the skin similar to histamine or codeine.
Oral pretreatment with the H1 antagonist terfenadine significantly inhibited the skin responses to beta-casomorphine-7. The intradermal injection of an opiate receptor antagonist, naloxone, inhibited in vitro histamine release and skin reactions only in a 100-fold excess over beta-casomorphine-7.
These findings suggest that beta-casomorphine-7 can be regarded as a noncytotoxic, direct histamine releaser in humans. The clinical relevance of these findings deserves further studies.
The most important casomorphins from bovine milk are those released from the digestion of β-casein into β-casomorphins, sometimes denoted as BCM followed by a numeral indicating the number of amino acids in the sequence. In cattle, the amount of β-casein - and, hence, the potential release of β-casomorphins - varies between species and breeds. Typically, β-casein comprises about one-third of the casein in milk, or about 12 grams per litre of milk. The potential release of BCM7 [beta-casomorphine-7 ] is about 0.4 grams per litre of milk (assuming as above that there are 12g of β-casein per litre). Not much.
As we have seen above Casein has been documented to break down in the stomach to produce the peptide casomorphin, an opioid that acts as a histamine releaser.