Dear Science,
Why are oranges orange?
Dear Navel Gazer,
Oranges are orange because of anthocyanins. These compounds serve an
analogous role to melanin in human skin—protecting plant tissues
from UV damage. The blue of blueberries, the black of blackberries, and
the grape of grapes is caused by anthocyanins stuffed into the tissues.
Anthocyanins are part of a broader family of plant molecules, including
flavonoids and carotenoids—all powerful antioxidants grabbing up
DNA-damaging free radicals created by sunlight and metabolism. Eating
these compounds helps protect against cancer, heart disease, and
stroke.
How much of these compounds do we eat? Grab some packaged food and
run down the label. The macronutients, the carbohydrates, the fats, and
the proteins are right there in fat black type. When scientists first
started ripping apart food to figure out what chemically makes it work,
the macronutrients were the first discoveries. Make a slurry with the
right amount of sugar, fat, and protein, and everyone would be dandy,
right? Viva Fritos. But keep reading the label and you’ll see the
micronutrient content, often with a sad note that begins “not a
significant source of….” Processing foods strips them of their
micronutrients, even when preserving macronutrients. Once the
micronutrients were discovered, cataloged, and isolated, they could be
stuffed back into processed foods or compressed into pill form. Hence,
Hi-C (with lots of vitamin C) and various foul-tasting breakfast
cereals. Where are the anthocyanins? Replaced with various dyes.
Anthocyanins are only now being discovered and cataloged. This is
why you can’t survive on Twinkies, Total, and Tang alone.
Multivitamins, regardless of how “complete” they are, still cannot
replace eating five or six servings of fruits and vegetables per
day.
Dear Science,
Why is poop brown?
Dear Shit Talker,
Rusting, worn-out bits of red blood cells make poop brown. Red blood
cells have a tough life, continuously crushed through tiny vessels and
subjected to blasts of damaging oxygen. As the cells wear out, the
hemoglobin—oxygen carrying, iron containing, and highly
toxic—has to be disposed somewhere. Ever resourceful, the liver
grabs up the decaying bits of hemoglobin and converts them into bile
salts. With every meal, particularly a greasy extravaganza, the liver
drops the bile salts into the intestines, where they bind up fats and
allow them to enter the body. The extra bile continues down to the
large intestines, where a multitude of bacteria devours what
remains—rusting the iron originally in the hemoglobin. Hence,
brown.
Send your crappy questions to dearscience@thestranger.com.
