Wednesday, August 9, 2017

What's to love about garlic?

So many things! But one in particular is fascinating: garlic's ability to block the aversiveness of high levels of salt.

In my mother's pre-culinary days, she used to make a salad dressing with vinegar, a generous dose of salt, and very little oil because she felt that oil was fattening (those were the days when good olive oil was hard to come by, and we couldn't have afforded it anyway). I used to hate salads—the sourness of the vinegar made me shudder, and the bitterness of the greens was intolerable. 

Then somewhere when I was around 11 or 12 she discovered the trick of rubbing the salad bowl with garlic (she still hesitated actually including the garlic in the dressing itself). Suddenly salads were much more palatable for me.

Cross-section of garlic bulb, from Darnok at

Garlic contains a compound, allyl isothiocyanate, that gives it the garlicky flavor, This compound (henceforth "AITC") also activates the cold/pain receptor, TRPA1, in the mouth, hence garlic's pungency. 

In experiments with mice, Oka and colleagues used AITC to dissect how high concentrations of salt (NaCl) become aversive.* 

It turns out that, while low concentrations of salt inhibit bitter-sensing taste bud cells, high concentrations of salt activate these cells and also activate sour-sensing cells. That's why high salt can bring out the bitterness of your salad greens and the sourness of the vinegar in your dressing. These activations can be inhibited by AITC!

High concentration salt also activates TRPV1, the hot/pain receptor.** When TRPA1 is activated, TRPV1 will usually be inhibited, and vice versa. 

So garlic in your salad dressing or sprinkled on a salty food will help hide the fact that you may have used too much salt...

* Oka, Y., Butnaru, M., von Buchholtz, L., Ryba, N. J. P., & Zuker, C. S. (2013). High salt recruits aversive taste pathways. Nature, 494(7438), 472+.

** Lyall V, Heck GL, Vinnikova AK, Ghosh S, Phan TH, Alam RI, Russell OF, Malik SA, Bigbee JW, & DeSimone JA. (2004). The mammalian amiloride-insensitive non-specific salt taste receptor is a vanilloid receptor-1 variant. J Physiol 558: 147+.

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