"The Sweet Wine Lovers' Manifesto"

Friend of Pairteas and wine genius Tim Hanni MW (= Master of Wine) is working on a new book, “The Sweet Wine Lovers' Manifesto,” and I’ve just read through a draft. It’s a bit embarrassing insofar as he mentions me a bit, but then I do prefer sweet wines, so the book does speak to my interests and preferences. 

What sweetness does, as I have mentioned before, is to cut the burn of alcohol to which I am genetically very sensitive. According to my 23andme results, I carry T at rs161364 in both of my copies of the TRPV1 gene, the hot receptor, on chromosome 17.  This means that I am exquisitely sensitive to the burn of alcohol.* This double T state is also relatively rare in people of European descent like me: while about 39% of people of European descent carry one T, only 10% carry two. The percentage of Asians and Native Americans with two T’s is even lower, between 4 and 5%, while the percentage of Sub-Saharan Africans is essentially zero.** In other words, the T is a gain-of-function genetic mutation that occurred after anatomically modern humans walked out of Africa to settle the rest of the world.

Interestingly, alcohol is also bitter. It activates at least two different bitter receptors: TAS2R13 and TAS2R38.* The latter receptor is also the one that responds to PROP (6-n-propylthiouracil) that researchers have used extensively to test for taste sensitivity. I happen to have the genetic markers that lead to high sensitivity to bitter for both of these receptors as well, but the burn I get from alcohol is so intense that bitterness takes a back seat.

Another genetic feature that I have: the most active version of a protein called gustin. This protein helps to govern the number and function of your taste papillae.*** A person can carry one or two copies of the most active (A) form of the gene for this protein, and I happen to carry two (I’m A/A at rs2274333), hence my tongue is a carpet of taste papillae and taste buds. Lest you think this is a great thing, you should know that being so sensitive means that I taste nasty stuff more strongly, too, and alcohol burns all the more.

This is my tongue, stained with blue food coloring. Taste papillae don't stain very much, which is why most of the tongue is pink, while the upper part, towards the back of the tongue, is blue. The fissures appear when there is a carpet of taste papillae, and you can also see some round papillae sticking up separately. Compare with the picture below, of a person with few papillae—most of the tongue is blue; the taste papillae are the pinkish dots that are scattered on the tongue surface.

Sweet activates TRPV5, which turns off TRPV1—that’s why I can tolerate Harvey’s Bristol Cream Sherry at 17.6% alcohol, while I cannot abide a Cabernet Sauvignon at 16% alcohol.

Though another confession is needed here, namely that I hate the taste of green peppers, which is characteristic of Cabs…but it’s the burn that gets to me first.

In any case, while genetics alters your degree of sweet wine liking (or to be more exact, your degree of high alcohol dry wine dislike), in fact more people enjoy sweet wines than really enjoy those high alcohol dry wines. According to Tim, if it weren’t for the snob appeal of the latter, people would be drinking sweet wines much more often, and not just with dessert. Keep an eye out for his book with more details!

* Alissa L. Allen, John E. McGeary, and John E. Hayes. Polymorphisms in TRPV1 and TAS2Rs associate with sensations from sampled ethanol. Alcohol Clin Exp Res. 2014 October ; 38(10): 2550–2560. doi:10.1111/acer.12527. 

** https://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs=rs161364. Note I used the HAPmap data for these percentages. While some people quarrel with HAPmap data, those percentages seem to correspond to my experience.

*** Melis M, Atzori E, Cabras S, Zonza A, Calò C, et al. (2013). The Gustin (CA6) Gene Polymorphism, rs2274333 (A/G), as a Mechanistic Link between PROP Tasting and Fungiform Taste Papilla Density and Maintenance. PLoS ONE 8(9): e74151. doi:10.1371/journal.pone.0074151.