Nature Meets Nurture
So, yesterday I went to that talk by Dr. El-So-hottie1 that I mentioned the other day. His research in in the area of nutrigenomics – the field that applies genomics (i.e., studying the genome (i.e., all the genes in an individual)) to nutrients. What I really like about his lecture was that he talks about how neither genetics nor environment operate in isolation. We are past the time of talking about nature vs. nurture (although you will still often hear people debating this false dichotomy) and really need to think about how genes and the environment interact with one another.
In his talk, he discussed a few of his recent lines of research – specifically, research on sugar and research on coffee. Through a strange anomoly in one study (and then a systematic investigation to what the heck was going on2), he and one of his grad students discovered that a particular variation in one gene (called GLUT-2) resulted in people with that version of the gene eating more sugar. Not in the lab and not under some special diet – just in their every day lives. And it wasn’t that they taste the sugar less than people with the other version of the gene – but that their brains sensed the sugar less, leading them to eat more. Interestingly, people with this version of the GLUT-2 gene have a higher risk of diabetes. And so this research illustrates an interesting point: If you studied these people and just looked at their sugar intake (without looking at their genetic makeup), you would conclude that higher intake of sugar caused (or at least increased their risk of) diabetes. But if you looked at their genetic makeup (i.e., which version of the GLUT-2 gene they had) without looking at their food intake, you would conclude that the version of GLUT-2 they have causes (or at least increases the risk of) diabetes. But when you look at the whole picutre, you see that the relationship is more complex than that. So what increases the risk of diabetes in people with this version of GLUT-2? Maybe that version GLUT-2 has some action in the pancreas that leads to diabetes (as GLUT-2 is in the pancreas as well as the brain and, I believe, other places). Maybe it’s the sugar. That still remains to be determined, as this research is still quite young. But very cool, eh?
His research on caffeine was equally fascinating. There’s lots of conflicting research on whether regular caffeine intake increases risk of heart attacks. Some research says yes, other research says no3. And it appears that the reason behind these conflicting results may be – you guessed it – genetics. There’s a gene related to the body’s ability to break down caffeine – some people break caffeine down quickly (we call them “fast metabolizers”) while other people break down caffeine slowly (not surprisingly, we call them “slow metabolizers”). And if you look at caffeine intake and risk of heart attack while also looking at their genetic status (i.e., fast or slow metabolizers), you find something very interesting: people who are slow metabolizers have an increased risk of having heart attack if they regularly consume even 2 or 3 cups of coffee per day; meanwhile, fast metabolizers do not have an increased risk of heart attack even if they consume 4 cups of coffee per day – what’s more, fast metabolizers who drink 2 or 3 cups of coffee per day actually have a decreased risk of heart attack compared to those who don’t drink any coffee!
So, all this is pretty freaking cool, but I should point out (as did Dr. El-So-hottie), that this type of research is really in its infancy. Perhaps down the road we’ll be able to scan your genome and tell which diet (or other lifestyle factors) will work for you in particular, but we just aren’t there yet. And we won’t be for some time.
Not that this stops companies from trying to profit by selling you a DNA test, of course.
1Props to my friend Alicia for coming up with that name!
2This reminds me of the Issac Asimov quotation “The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ (I’ve found it!), but ‘That’s funny…’
3And yet other research says “wtf? I have no idea, yo.”