Licorice Sucks

Why you shouldn't eat it

There are two kinds of licorice: red and black.

Red licorice

Ingredients: Corn Syrup, Wheat Flour, High Fructose Corn Syrup, Citric Acid, Artificial Flavor, Red 40.

Red licorice sucks because it’s basically just corn syrup and red food coloring, and what’s the point of eating that?¹

Black licorice

Black licorice, made from actual licorice root, provides the “authentic licorice experience”. But black licorice is still gross, and will also poison you.

The licorice plant produces a compound, glycyrrhizin, which inhibits² an enzyme (HSD11B2) that oxidizes cortisol to cortisone. Consuming glycyrrhizin results in increased levels of cortisol.

HSD11B2 oxidizes cortisol to cortisone, using NAD+ as a cofactor. The forward (oxidation) reaction is favored because NAD+ concentrations are typically higher than NADH concentrations.

You might have heard of cortisol as the “stress hormone”, and this is broadly correct, but there’s a bit more to the story. Cortisol has several biological effects, although for this post I will focus on the kidneys and placenta, which rely particularly strongly on HSD11B2 to locally decrease cortisol levels.

For the kidneys, this is important because cortisol activates the aldosterone receptor³, which results in a decrease in sodium excretion, increase in potassium secretion, and increase in blood pressure. Evolution, instead of making the aldosterone receptor selective for aldosterone over cortisol, created a kludge where HSD11B2 inactivates cortisol in the kidneys. Eating licorice breaks this system and causes high blood pressure and low blood potassium (which can cause heart problems).

Similarly, HSD11B2 in the placenta prevents maternal cortisol from affecting the fetus. As noted in the “Biodeterminist’s Guide to Parenting,” fetal exposure to cortisol can cause lots of developmental problems.⁴ So, eating black licorice during pregnancy is an especially bad idea.

But how bad is it anyway?

Bad enough for the FDA to issue this warning in October 2017:

https://www.fda.gov/consumers/consumer-updates/black-licorice-trick-or-treat

The best advice, of course, is to not have a fondness for black licorice in the first place.

Conclusions

• Red licorice is gross

• Black licorice is gross and will also poison you

• Why not eat some other candy instead?

But anyway, licorice is pretty gross and there are plenty of better sweets to eat instead.

Why not have these instead?

1. Your opinion may differ, but in the post-Halloween candy trading that I took part in growing up, Twizzlers were generally ranked as the second least-valuable candy. The least-ranked, of course, was Tootsie Rolls. These had just enough chocolate flavor to remind you that you could be eating chocolate, which made them even more disappointing.

2. Strictly speaking it’s the aglycone form (glycyrrhetinic acid) that has the effects. This is produced after hydrolysis of the glycoside in the intestines.

3. Also known as the mineralocorticoid receptor.

4. The linked study was performed in Finland; for some reason, Scandinavians really like licorice. They even eat licorice salted with ammonium chloride which is especially gross.