Why Does Drinking Milk Ease the Pain of Eating Spicy Food?

I'm pretty wimpy when it comes to eating spicy foods — but if I must indulge in some peppery Chinese food or a plate of hot wings, you'll surely see a glass of milk close to my reach.

You can find me with a plate of hot wings, and a glass of milk.
Source: falovelykids (Pixabay)

Chili peppers contain an active component called capsaicin, which is part of the vanillioid family (the same family that includes the vanilla bean). Capsaicin binds to a receptor called the vanilloid receptor subtype 1 (TRPV1).

While TRPV1 receptors are found in several different organs throughout the body, activation of the TRPV1 receptor on the tongue produces the sensation of heat or abrasion, causing that characteristic burning sensation. Eating a chili pepper does not actually cause a chemical burn — but it certainly feels like it.

So why does milk soothe the savage serrano?

The chemical structure of capsaicin (below) reveals a long hydrocarbon tail, shown in black (carbon) and white (hydrogen):

Chemical structure of capsaicin. (Source: Jacopo Werther/Favourites/Chemistry, Wikimedia Commons)

That hydrocarbon tail means that oily or soapy compounds can act as a detergent to dissolve capsaicin, but water cannot. It's similar to how you can't clean grease off of a cooking pan simply with water, but dish soap will get the job done.

Source: Unsplash (Pixabay)

Milk from mammals contains a protein called casein (the same protein which creates curds in sour milk). Casein is a lipophilic (literally, "fat-loving") protein, which means that it acts as a detergent on capsaicin, thanks to that fatty hydrocarbon tail.

Alcohol also dissolves capsaicin well (wings and beer, anyone?), although its concentration in most alcoholic beverages is often too low to have much of an effect. (On the other hand, casein represents roughly 80% of the protein in cow's milk.)

But remember: it must be mammal's milk! Plant-based milks — such as soy, rice, coconut, or almond — do not contain casein.

Fun fact: Interestingly, in birds, the TRPV1 receptor does not respond to capsaicin, which means that the seeds of chili pepper plants can be dispersed widely. Biologists believe that some species of peppers, such as ghost peppers, have evolved to contain such high levels of capsaicin in order to deter animals from eating them — unless they are also able to help disperse the seeds!

Learn more about the Scoville Scale and how spiciness is quantified here.

Do you have a favorite home remedy for combating the pain of spicy foods? Let me know in the comments!

What are Migraines, and What Do They Feel Like?

I am lucky to have never experienced a migraine before. *knocks on wood*

Sasha Wolff (Wikimedia Commons)

But 15% of the world's population suffers from migraines, and those folks will easily rattle off all of the painful symptoms: pulsating pain — sometimes localized to one side of the head — often accompanied by sensitivity to light, sound, or smell. Some also experience nausea. About 1/3 of migraine sufferers perceive auras before the onset of pain, or brief periods of strange visuals, scents, or confusing thoughts.

In more lay terms, Huffington Post columnist Lisa Belkin once described a migraine as feeling "like you are trying to give birth through your forehead."

But what exactly causes migraines, and how are they different from headaches?

It's important to know that although the brain perceives pain from all parts of the body, the brain itself does not feel pain. The brain lacks nociceptors, or specialized sensory nerve fibers that transmit pain signals, which are present in our skin, muscles, and joints.

Headaches, then, are not pain in the brain, but rather activation of nociceptors located in the layers between the brain and the skull: the pia mater and dura mater (collectively, the meninges):

The pia mater (yellow) and dura mater (gray), collectively called the meninges, cushion and 

protect the brain from the skull. OpenStax (Wikimedia Commons)

As you can see from the image above, these layers are highly vascularized, or contain many blood vessels. Common headaches are triggered by fatigue, stress, head injury, or medications which, one way or another, lead to dilation of blood vessels, blood vessel spasms, or inflammation of the meninges.

While the source of pain in migraines is similar to that of headaches, migraines are actually thought to originate in the brain. Many specialists believe auras are caused by sudden increased, then decreased, neural activity in the cortex (outer layer) of the brain.

The activation of these nerves releases a number of proteins, such as serotonin, which can cause inflammation to the meninges as well as dilate blood vessels. A family of migraine medications called triptans work by constricting blood vessels and blocking serotonin. Many people report that "triggers," such as certain foods or changes in the weather, will reliably cause the onset of their migraines, though it is not entirely clear why this happens.

Do you suffer from migraines? Are there specific things that "trigger"  your migraines? What treatments work for you (or don't work)? Let me know in the comments.

Why Do We Feel 'Pins and Needles' When our Appendages Fall Asleep?

Medical Treasure

We've all experienced the strange sensation. Maybe it's when your alarm goes off in the morning and you realize you can't feel your arm to shut it off. Or when your legs are folded into a pretzel on the floor while playing Barbie with your kid and you can't stand back up. You give your dead appendages a shake, and suddenly you feel a surge of pins and needles. What causes that feeling?

There's actually a medical term for it  – paresthesia – defined as the tingling sensation caused by pressure or damage to peripheral nerves.

Don't pinch these! Gray's Anatomy
(Wikimedia Commons)

It occurs when there's prolonged pressure on a limb, like your arm positioned awkwardly under your head while sleeping or sitting cross-legged on the floor. The limb "falls asleep," either due to (1) arteries being compressed, thus blocking blood flow of oxygen and glucose to feed the nerves, or (2) directly pinching nerve pathways, causing normal neurotransmission to slow or cease.

Although your limbs may feel lifeless, your brain is receiving a signal of pain, saying "change your position already, idiot!" When you finally free your limb, the sensation of pain intensifies as blood returns to the area and nerves begin firing regularly. The "pins and needles" sensation occurs as certain areas nerve fibers receive blood nutrients and begin re-firing before others. Eventually, after a few seconds, equilibrium is established again.

A common misconception is that blood flow is blocked entirely to the affected limb when it "falls asleep." If that were true, we'd be experiencing a much more serious medical problem. Luckily, the 50,000-60,000 miles-worth of capillaries in our bodies ensure that our other tissues stay satiated and healthy. It would be as though a tourniquet were applied to a limb, and that's simply not what's happening.

Prolonged, regular compression to nerves can result in a more long-term sensation of "pins and needles," such as carpal tunnel syndrome. Consult a doctor if pain, tingling, and numbness is not relieved when you change body position.

Now, I'm going to undo my leg from under me (as I always do when I write) and go for a short walk to wake it back up. OUCH. Sometimes I never learn.

Mirror mirror on the wall, relieve me of pain once and for all

A very exciting event is happening as I type this: Neuroscience 2011, the annual meeting of the Society for Neuroscience.

This nerd-tastic event attracts a bevy (over 30,000, to be more precise) of the best and brightest in brain research under one roof once a year. This year's meeting is in Washington, D.C. Unfortunately for me, I am not in attendance; but fortunately for myself and, hopefully, my readers, new research radiating from this meeting gives me some great material to share.

On Saturday, the first day of the meeting, a new study was described that involves tricking arthritis sufferers with mirrors to alleviate their pain. Wait—what? Mirrors?