Short Wave (NPR)

Episode: "Drinking Turns Some Red With Asian Glow—And May Fight Tuberculosis"

Date: December 24, 2025
Hosts: Regina Barber, Emily Kwong
Guest: Katie Wu, staff writer at The Atlantic

Episode Overview

This episode explores the phenomenon known as "Asian flush" or "Asian glow"—a reaction where individuals (commonly of East Asian descent) turn red, get warm, and sometimes feel ill after drinking alcohol. Host Regina Barber and guest Katie Wu dive into the underlying science, discussing why this reaction happens, the genetic mutation behind it, and a surprising evolutionary theory that suggests this mutation may have protected ancestors from infectious diseases like tuberculosis. The episode balances personal anecdotes with clear scientific explanation and a dose of humor.

Key Discussion Points & Insights

1. Personal Stories: The First Drink and The Red Flush

• Hosts share their first experiences with alcohol:

  • Regina’s first taste was a sip of cognac during a snowstorm at age 8 or 9, offered by her mom to keep warm.
    • "Telling it now, it kind of feels like something out of a novel." (Regina Barber, 00:42)
  • Katie recalls a childhood taste of wine—"I'm spitting this out."—and watching her parents experience Asian flush.

• Onset of Symptoms:

  • Katie: "I would compare myself to a human stop sign, or if Rudolph's nose was the entirety of my face... the warmth blooms from my cheeks and then spreads all over and even starts to creep down my neck. You can see it from across the room." (Katie Wu, 01:51)
  • Regina: Gets splotchy patches, not just on the face.

2. What Is “Asian Glow” or “Asian Flush”?

• Prevalence: Affects roughly half a billion people worldwide, predominantly those of East Asian heritage.
• Symptoms: Redness (face, sometimes body), warmth, sweating, nausea, dizziness.
  • "For me, my top symptoms are definitely redness, warmth in the face, and tons of nausea and dizziness." (Katie Wu, 02:50)

3. The Biochemical Breakdown: Why Does It Happen?

• Aldehydes and the ALDH2 Gene Mutation:

  • Alcohol is broken down into toxic compounds called aldehydes.
  • "For people with Asian glow or alcohol flush, they lack the molecular machinery to break down those toxic aldehydes. And so they're kind of sitting there with poison stewing in their tissues for a lot longer." (Katie Wu, 03:19)
  • Both hosts possess a mutation in the ALDH2 gene. Most people with the condition are "heterozygous"—they have one normal and one mutated copy. The trait is dominant: one faulty gene means symptoms appear.

• Analogy: Katie uses the metaphor of a sink to explain:

  • Healthy individuals: the sink drains well.
  • Heterozygous (one faulty gene): the drain is partly blocked.
  • Homozygous (two faulty genes): the drain is plugged.
    • Drinking alcohol is like pouring a gallon jug into the sink—rapid toxic buildup. (07:42–08:53)

4. Toxicity and Health Risks

• Aldehydes as Carcinogens:

  • "Aldehydes, in short, are carcinogens. They are these pretty toxic compounds that can actually do direct damage to DNA and proteins. If they sit around too long in your cells, they will cause literal mutations in our genetic code. And that's really not great." (Katie Wu, 06:48)

• Health consequences: Higher risk for esophageal cancer and some cardiovascular diseases. Having lingering aldehydes is generally bad for health.

5. Evolutionary Puzzles: Why Does This Mutation Persist?

• If this mutation is so disadvantageous, "why are there so many flushers around today? Half a billion people. That is absolutely bonkers for a mutation that not only makes it difficult to drink, but raises your baseline risk of a bunch of health conditions that are not benign." (Katie Wu, 09:47)

6. The Evolutionary Theory: Infectious Disease Defense

• Research from NYU microbiologist Heron Darwin: Suggests this genetic quirk may have conferred a survival advantage against infectious diseases—possibly tuberculosis.

  • "Having this buildup of aldehydes in our body is bad for our tissues. But aldehydes are such a kind of all purpose toxin... they could be harming microorganisms that wanted to hurt us as well." (Katie Wu, 11:09)

• Aldehydes can kill TB bacteria in lab settings:

  • If carrying this mutation improved chances of surviving repeated outbreaks of TB or other infections, even slightly, it may have allowed the mutated gene to spread through the population.

• Cautions and Uncertainties:

  • Current research is still under peer review; the TB connection is a hypothesis, not proven.
    • "It is tricky to prove though. Right. And we know that, for instance, aldehydes can kill TB in the laboratory. That is super compelling. But it doesn't necessarily mean that TB is what drove this mutation to prominence thousands of years ago." (Katie Wu, 12:46)
  • The broader consensus is that infectious disease pressure—TB or others—likely contributed.

7. Pride in the Mutation: Turning a Flaw into a Badge

• "What I kind of love is that this story gives me a reason to be a little bit proud of this mutation, whereas I always had to be like, oh, yeah, I'm getting red again, I'm sorry... But you know what? I feel like it's something that you can wear proudly as a badge from now on if you choose to." (Katie Wu, 13:58)
• Regina agrees: "Oh, I'm going to." (Regina Barber, 14:18)

Notable Quotes & Memorable Moments

• Aldehyde sink analogy: "If you picture a sink that's draining... you want to get rid of all the poison. People who have two normal copies... the stopper is totally lifted. If you are heterozygous... it's lowered maybe halfway... If you have no functional copies, you've basically plugged that sink." (Katie Wu, 07:42–08:35)

• On future pride: "I feel like it's something that you can wear proudly as a badge from now on if you choose to." (Katie Wu, 13:58)

Important Timestamps

• 00:15–03:11 – Personal anecdotes about early experiences with alcohol and Asian flush
• 03:19–04:32 – Biochemistry: What causes Asian flush and the ALDH2 gene
• 05:35–07:05 – Genetics: Details of the ALDH2 mutation, how it works, dominant inheritance
• 07:42–08:53 – Aldehyde sink analogy: Explaining how aldehydes build up
• 09:34–10:24 – Evolutionary contradiction: Why does this mutation persist?
• 10:42–13:52 – New evolutionary theory: Possible protection against TB and infectious diseases; discussion of supporting and cautionary evidence
• 13:58–14:18 – Embracing the mutation; pride and a new perspective

Summary Takeaway

This episode of Short Wave unpacks the science and evolutionary history behind "Asian flush," explaining not just what causes it—but why it might have stuck around. Through engaging dialogue and vivid analogies, listeners learn that a genetic quirk that brings redness and discomfort may have helped ancestors survive deadly diseases. The overall message is one of scientific curiosity, cultural connection, and a shift from embarrassment to pride for a trait once seen solely as a nuisance.