"Does A2 Milk Carry Less Autism Risk?"
One of the main sources of protein fragments with opiate-like activity
in the diets of autism patients are dairy products.
The main dairy protein, casein, breaks down into casomorphins,
which have been considered to be factors involved
in the cause and exacerbation of symptoms
in food allergy and eczema, diabetes, schizophrenia,
postpartum psychosis, crib death, and autism.
According to this "opioid-excess" idea,
the development of autism includes a genetic predisposition,
early exposure to some kind of environmental stressors
that affect the gut, which may cause more of these casomorphins
to leak into the blood, and then the brain,
where they may play a role in the development of autism.
But you don't know until you put it to the test.
First of all, do these bovine casomorphins
form in the human digestive tract when we drink milk?
Researchers decided to stick tubes down into people's intestines
to find out, and indeed, considerable amounts
of casomorphin were found.
OK, but do they get absorbed into the bloodstream?
Yes, apparently so,
but this study was on infants who naturally have leakier guts.
Do fully intact casein protein fragments
make it into the bloodstream after infancy?
Yes, even into adulthood,
elevating levels in the blood for at least 8 hours after consumption.
And those with autism may have an especially leaky gut, at significantly
higher risk for abnormally high intestinal permeability,
which may explain why the vast majority of autistic children
may have antibodies in their blood to wheat and dairy proteins,
compared to a small minority of normal children.
And based on allergy studies, even if an infant is strictly breastfed,
they may still be exposed to bits of bovine milk proteins
if the mother drinks milk, as the bovine protein fragments
can get into her blood, then her breast, then into her baby's body.
But does it get into the baby's brain?
Yeah, those with autism are more likely to suffer from leaky gut,
but the so-called "opioid excess" theory depends
on casomorphins not only getting into the bloodstream
but up into the central nervous system, the brain.
And there's something called a blood-brain barrier
that helps cordon off the brain, but when you examine the brain tissues
of those with autism, their blood brain barrier seems leakier, too.
And indeed, evidence for the presence of casomorphins
within the brains of infants has since been confirmed,
which again just makes sense.
That's the whole presumed point of casomorphin opioids,
to affect the brains of babies so they crave the milk, cry out for the milk,
strengthening the mother-infant bond, the cow-calf bond.
That's what's supposed to happen; it's normal, natural.
OK. Then why are casomorphins associated with disease?
Well, this is normal and natural.
This? Not so much.
Human infants with evidence of higher baseline levels
of bovine casomorphins in their blood seem more likely
to be suffering from psychomotor delay, which is a measure
of muscle, language, and mental function development,
but the reverse was found for human infant exposure
to human casomorphins, meaning human casomorphins
appeared to be beneficial in humans.
See, just like bovine casomorphin levels in the babies' blood
appear to rise after feeding cows' milk formula,
human casomorphin levels rise in the baby after breastfeeding,
and that's what's supposed to happen.
The greatest baseline human casomorphins was revealed
in breastfed infants with normal psychomotor
development and muscle tone.
In contrast, elevated baseline bovine casomorphins,
found in cows' milk formula-fed infants, were associated with
delayed psychomotor development and stiffened, more rigid muscle tone.
The explanation of the opposite effects of human versus
bovine casomorphins on infant development
probably has to do with species-specificity.
Cows' milk is good for calves; breast milk is good for babies.
Indeed, the structure of bovine and human casein
is dramatically different, and the bovine and human
casomorphins themselves are different molecules, differing
by 2 amino acids, which results in greatly different potencies.
Compared to human casomorphin, bovine casomorphin
"is highly potent and more similar to morphine in its effects."
A 2 amino acid difference doesn't seem like a lot,
but casomorphins are only 7 amino acids long!
This 30% or so difference likely
defines the difference in their biological properties.
Both human and bovine casomorphins interact
with opioid and serotonin receptors, which are known
to be of great importance for brain maturation, but cow casomorphin
binds tighter to these receptors, and so has more of an effect.
This can, therefore, help explain not only why breast is best, but
the psychomotor delay linked with higher bovine casomorphin levels
in the blood supports this concept that cow casomorphins
may play a role in a disease such as autism.
This is why bovine casomorphins have been called
"the devil in the milk."
But are they formed from all cows' milk?
What about so-called "A2" milk?
The A2 milk corporation points out there are different variants of casein.
Some cows produce milk with a kind of casein dubbed A1,
and other cows produce milk with A2 casein,
which differs from A1 casein by a single amino acid,
but strategically located such that A1 casein breaks down
into casomorphin, which acts like morphine, "and is implicated
in digestive, immune, and brain development changes,"
but supposedly A2 milk does not.
Put A1 milk in a test tube with some digestive enzymes
and the A1 casein breaks down into casomorphin.
But because of that amino acid difference, the A2 casein
breaks down at a different spot, and so no casomorphin is formed.
But this was using digestive enzymes from pigs or cows,
which are just cheaper and easier to buy for laboratory experiments,
but human digestive juices are different.
And so what happens in a pig's stomach or cow stomachs
may not necessarily be what happens in the human digestive tract.
But the A1 versus A2 breakdown experiment had never been performed
with human enzymes before until now.
Human stomach and intestinal juices were collected, and the devil was in both.
The opioid casomorphin was produced from both A1 and A2 milk.
So A2 milk may be better for this Babe, but not necessarily for this one.