Yahoo news comes up on my screen when I sign out of an email account. Usually, I do a quick scan and then move on. Imagine my surprise when I read that Michelle Obama was quoted in Ladies’ Home Journal as saying, "Neither the president nor I have the beet gene". That inspired me to immediately look into what we know about the genomics of tasting.

I personally like beets: roasted, baked, pickled. I especially love pickled beets sliced up on my salad; but that is another topic. I must have the beet gene.

My memory is long enough that I remember when President George H.W. Bush made this statement about broccoli: “I do not like broccoli. And I haven't liked it since I was a little kid and my mother made me eat it. And I'm President of the United States and I'm not going to eat any more broccoli.” He got a lot of grief for that statement, but from my reading it is much more likely that he didn’t have the “broccoli gene”.

I reviewed a book last year called Survival of the Sickest. The author, Dr. Sharon Moalem, suggested that there are a lot of things that were adaptive to humans at an earlier time that have become detrimental to us in modern times. Although he did not say it, he implied that there are always trade-offs so that something which is good for us at one level can be harmful at others. According to a paper by Mari A. Sandell and Paul A.S. Breslin, our ability to detect bitterness is adaptive in detecting toxins in naturally occurring fruits and vegetables. And herein is the problem: glucosinolates found in the cruciferous vegetables (cabbage family, broccoli, cauliflower, curly kale, and Brussels sprouts) can be beneficial anticancer molecules yet have also been identified as anti-thyroid compounds since they inhibit iodine uptake by the thyroid, increasing risk for goiter and altering levels of thyroid hormones. There is a genetic reason that some children don’t like certain vegetables, and parents should be cautious in making children eat things they don’t wish to eat.

When I was a high school student, or perhaps in first year of university, I recall participating in a phenylthiocarbamide (PTC) tasting lab. At the time, PTC tasting was included as part of a demonstration of Mendelian traits. You can still find examples of this lab as an illustration of an autosomal dominant trait. By the time I was a teacher, PTC testing was not allowed in Alberta schools. The Material Safety Data Sheet (MSDS) indicates that PTC is extremely hazardous in case of ingestion*. I certainly caution teachers against doing this as a lab exercise for this very reason. I also question whether the gross simplification of the genetics of tasting is what leads some people to think that there is a specific gene for taste. A recent paper by Bernd Lindemann provides two possible pathways for bitter taste recognition. Each of these pathways involves receptor activation, coupled with proteins, activation of intracellular enzymes generating second messengers modulating membrane ion channels, depolarizing the cell membrane potential and causing an inflow of calcium ions from intracellular stores. I doubt this level of complexity is controlled by a single Mendelian gene.

* Youth Science Canada has banned all ingestion experimentation, unless carried out under professional supervision at a laboratory licensed to carry out such studies. This includes taste- testing, formerly a stalwart of elementary and junior high science experimentation. This complete ban has been instituted because there are rare cases of serious side effects from ingesting substances, including fatal interactions occurring between such items and other medications being taken by the participant.