"Could Lactose Explain the Milk - Parkinson’s Disease Link?"
Parkinson’s disease is the second most common
neurodegenerative disease after Alzheimer’s.
In the US, there are approximately 60,000
new cases diagnosed every year,
bringing the total number of current cases up to about a million,
with tens of thousands dying from it every year.
The dietary component most often implicated is milk,
for which contamination of milk by neurotoxins
has been considered the only possible explanation.
High levels of organochlorine pesticide residues
had been found in milk,
and in the most affected areas in the brains
of Parkinson’s victim’s on autopsy.
Since pesticides in milk have been found all over,
maybe the dairy industry should require toxin screenings of milk.
And there are indeed now inexpensive, sensitive, portable tests available.
No false positives; no false negatives,
providing rapid detection of highly toxic pesticides in milk.
Now we just have to convince the dairy industry
to actually do it.
Others though are not as convinced of the pesticide link.
Despite clear-cut associations
between milk intake and the incidence of Parkinson’s disease,
there is no rational explanation
for milk being a risk factor for PD.
If it were the pesticides present in milk
that could accumulate in the brain,
we would assume that the pesticides would build up in the fat,
and the link between skimmed milk and Parkinson’s
is just as strong.
So they suggest reverse causation—
the milk didn’t cause Parkinson’s,
the Parkinson’s caused the milk.
Parkinson’s makes some people depressed, they reasoned,
and depressed people may drink more milk.
So we shouldn’t limit dairy intake in Parkinson’s
especially since they are so susceptible to hip fractures,
but now we know that milk doesn’t appear
to protect against hip fractures afterall,
and may actually increase the risk
of both bone fractures and death—
but, ironically may offer a clue
as to what’s going on in Parkinson’s.
But first this reverse causation argument.
Did milk lead to Parkinson's or Parkinson's lead to milk?
What one needs are prospective cohort studies
where you measure milk consumption first
and then follow people forward over time,
and such studies still found a significant
increased risk associated with dairy intake.
The risk increased by 17%
for every small glass of milk a day
and 13% for every daily half slice of cheese.
Again, the standard explanation is that it’s from
the pesticides and other neurotoxins in dairy,
but that doesn’t explain why there’s more risk
attached to some dairy products than others.
Pesticide residues are found in all dairy products
so why should milk be associated with Parkinson’s
more than cheese?
Well, there are other neurotoxic contaminants
in milk besides the pesticides themselves,
like tetrahydroisoquinolines,
found in the brains of Parkinson’s disease victims,
but in higher levels in cheese than in milk,
though people may drink more milk than they eat cheese.
The relationship between dairy and Huntington’s appears similar
Huntington’s disease is a horrible degenerative
brain disease that runs in families,
whose early onset may be doubled by dairy consumption,
but again this may be more milk consumption
than cheese consumption,
which brings us back to the clue in the
more-milk-more-mortality study.
Anytime you hear disease risks associated with more milk than cheese—
more oxidative stress, inflammation—
we should think galactose, the milk sugar
rather than the milk fat, protein, or pesticides.
That's why we think milk drinkers specifically
appeared to have higher risk of bone fractures and death,
and may explain the neurodegeneration findings too,
as not only do rare individuals
with an inability to detoxify the galactose
found in milk suffer damage to their bones,
but also to their brains.