“I was working on understanding lipids, and I met a fellow working on the genes underlying lipid metabolism,” he said. “It was pure serendipity.” — José Ordovás, Tufts University.
It’s somewhat amazing to me how often chance events enter into our work. Almost any scientist you talk to will tell you that they have had similar experiences. The reason they lead to important, interesting, or even great discoveries is that the researcher was open and prepared for the opportunity. Dr. Ordovás had been thinking about diet and metabolism for a long time and found that the dietary interventions that reduced cholesterol or blood glucose levels worked in some people, but not in others. For example, one person could have blood sugar increase quickly after eating a piece of white bread, and another person sees no change at all. Further investigation would trace this back to small differences in their genomes. This piqued his curiosity. We are all the same, aren’t we? Why does altering diet help some people and not others?
Then one day, he ran into a colleague who worked on the genes underlying lipid metabolism. After discussions with them and probably many others, he hatched the concept of precision nutrition. (The name came decades after they started working on the idea.) In precision nutrition, dietary guidelines have to consider more than just what we eat. A person’s genetic background, amount of exercise, stress, sleep, age, and microbiome can influence how the diet impacts an individual’s health.
Many studies of the microbiome have shown that it influences the effectiveness of dietary interventions. Professor Frederico Rey in the Bacteriology Department of UW-Madison did studies looking at the ability of fiber to decrease the risk of cardiovascular disease. It had been known from cohort studies that eating more fiber worked for some humans but not for others. So, they did a very cool experiment. They took the microbiomes of various humans and placed them into mice that had no microbiome to begin with. These human microbiomes established themselves. Each group of mice was then split into two. One group was fed a normal diet, the other one a fermentable-fiber diet, to see if it could prevent cardiovascular disease. And, the microbiome made a difference. Only the mice with the DonA microbiome (from Donor A) saw a benefit as measured by looking at plaque buildup in the mice’s arteries. It turns out the DonA group was producing short-chain fatty acids, specifically butyrate. Potential producers were bacteria from the Clostridium, Oscillospira, Ruminococcus, Gemmiger, and Faecalibacterium genera. This butyrate fed their intestinal epithelial cells and had long-range impacts on the circulatory system. If you don’t have these bacteria in your microbiome, you don’t see a benefit.
Let’s circle back to precision nutrition. What this means is that to give people useful advice about what they can eat, you have to consider the whole person, their genetics, behavior, and their microbiome. If we ever have decent healthcare in this country, it could lead to a revolution in preventative care.