Potential Health Impacts on Modern Humans
The duplications in the AMY1 gene could have allowed humans to better digest starches. And it’s conceivable that having more copies of the gene means being able to break down starches even more efficiently, and those with more copies “may be more prone to having high blood sugar, prediabetes, that sort of thing,” Jorgensen said.
Whether those with more AMY1 genes have more health risks is an active area of research. “Researchers tested whether there’s a correlation between AMY1 gene copies and diabetes or BMI [body mass index]. And so far, some studies show that there is indeed correlation, but other studies show that there is no correlation at all,” said Yilmaz.
Yilmaz pointed out that only 5 or 10% of carb digestion happens in our mouths, the rest occurs in our small intestine, plus there are many other factors involved in eating and metabolism.
“I am really looking forward to seeing studies which truly figure out the connection between AMY1 copy number and metabolic health and also what type of factors play a role in metabolic health,” said Yilmaz.
It’s also possible that having more AMY1 copies could lead to more carb cravings as the enzyme creates a type of sugar in our mouths. “Previous studies show that there’s a correlation between AMY1 copy number and also the amylase enzyme levels, so the faster we process the starch, the taste [of starches] will be sweeter,” said Yilmaz.
However, the link between cravings and copy numbers isn’t clear. And we don’t exactly know what came first — did the starch in humans’ diet lead to more copies of amylase genes, or did the copies of the amylase genes drive cravings that lead us to cultivate more carbs? We’ll need more research to find out.
How Will Today’s Processed Carbs Affect Our Genes Tomorrow?
As our diet changes to increasingly include processed carbs, what will happen to our AMY1 genes is fuzzy. “I don’t know what this could do to our genomes in the next 1000 years or more than 1000 years,” Yilmaz noted, but she said from the evidence it seems as though we may have peaked in AMY1 copies.
Jorgensen noted that this research is focused on a European population. She wonders whether the pattern of AMY1 duplication will be repeated in other populations “because the rise of starch happened first in the Middle East and then Europe and then later in the Americas,” she said.
“There’s individual variation and then there’s population-wide variation,” Jorgensen pointed out. She speculates that the historical diet of different cultures could explain population-based variations in AMY1 genes — it’s something future research could investigate. Other populations may also experience genetic changes as much of the world shifts to a more carb-heavy Western diet.
Overall, this research adds to the growing evidence that humans have a long history of loving carbs — for better and, at least over our most recent history and immediate future, for worse.
A version of this article appeared on Medscape.com.