Dear Science

Dear Science,

I’ve often heard that commercial cow’s milk has some percentage
of pus and blood allowed. Do you know if that’s true? I’m assuming
pasteurization removes any health risks from these contaminants. So
that leads me to wonder how safe raw (unpasteurized) milk is. Is a raw-milk mocha a health risk?

Raw Thirst

Science is perplexed by the raw-milk craze. Before pasteurization
became widespread, a good amount of human illness was caused by
contaminated milk. Why on earth would one subject him- or herself to
this danger? Answers are needed!

All milk contains pus and blood, but in a good way—pus
is mostly made up of white blood cells. Milk is filled with the
mother’s white blood cells and antibodies, providing a child with
protection from bacteria and viruses—one of the major reasons why
breastfeeding a child seems to be better than bottle-feeding. (Mammal
mothers lick or kiss their children to find out what bugs are infesting
the child, so the proper antibodies can be added to the milk. What, you
thought it was love?)

Milk typically comes out of the cow (or goat or human) without any
dangerous bacteria. But think of where most milking occurs—all
sorts of unsanitary things may be occurring. Milk is a particularly
dangerous food precisely because it is so nutritious; a miniscule
amount of contaminating bacteria can multiply in the welcoming
environment, greatly increasing the chance of someone becoming ill from
ingesting it. Pasteurization works by killing any of the bacteria that
find their way into the milk, before they can divide and make you sick
later. This little step of heating dairy before storage and transport
has been one of the most effective public-health inventions of all
time.

There are no health benefits in drinking raw milk—the
nutrients easily survive the heating. Only breast milk for a baby is
better raw, health-wise, so the white blood cells are allowed to live
and do their job. (In contrast, light is horrible for milk, rapidly
destroying whole classes of B vitamins.)

None of the milk-borne pathogens are fun. Salmonella causes a
pretty vicious fever, nasty cramps, and an
impressive amount of
diarrhea. Listeria infection is everything from flu-like
symptoms to meningitis. The nastiest E. coli infections result in the
destruction of the kidneys and liquefaction of the brain. Thanks to a
preformed toxin, powerful nausea and vomiting start within hours of
consuming milk contaminated with Staphylococcus aureus. Science
found himself violently ill from pasteurized milk, infested with
staph at a smoothie bar, purchased at the airport a few Thanksgivings
ago; it was a delightful way to greet the parents.

Despite a lesson previously learned, as your devoted empiricist,
Science purchased a pint of raw goat milk and poured himself a
glass. The milk was delicious—slightly salty and subtly flavorful
without being gamey or overpowering. The fever, headache, and nausea
came the next morning.

Sanitarily Yours, Science

Send your purulent science questions to

dearscience@thestranger.com.