Over the last few years, we have seen a steady increase in metabolic syndrome, a variety of conditions that happen together, that increase the risk of diabetes, stroke, and heart disease (high blood pressure, high blood sugar, excess body fat around the waist, high cholesterol/triglycerides). In the United States alone, one-third of the adult population has metabolic syndrome.
Researchers at the Weizmann Institute hypothesized that these problems might be rooted in each individual’s personal response to food. One such measure of response to food that easily allows us to keep track of blood glucose levels after a meal is known as the Postprandial Glycemic Response (PPGR). Postprandial glucose levels are important since sharp fluctuations in sugar levels are a risk factor for various metabolic diseases such as diabetes. If there are sugar spikes after a meal, the pancreas responds by releasing the hormone, insulin in large quantities, leading sugar to fall rapidly. Low sugar stimulates a feeling of hunger that leads us to eat again even if we’ve eaten recently.
Our goal is to ultimately maintain balanced sugar levels and avoid this vicious cycle.
Great... but How Do We Do That?
Eran Segal, PhD and Eran Eliav, MD, PhD, researchers from the Weizmann Institute, decided to examine the factors that influence PPGR levels and initiated the “Personalized Nutrition Project” study.
What Were the Findings of this Project?
The premise of this study is that the gut microbiome is a complex ecosystem responsible for many processes. For example, it breaks up various nutrients that we cannot digest and supplies energy to other bacteria through the byproducts as well as to the intestinal cells -- when this is absorbed back into the bloodstream we extract more nutrients from the food that we eat. This understanding leads to the conclusion that the microbiome can influence our blood glucose levels, and is worth understanding tits makeup each of us. By sequencing the DNA of stool samples, we can come to understand what’s hiding in our gut microbiome.
The study involved 1,000 healthy young men and women. These subjects shared data about their height, weight, lifestyle (exercise, sleep, stress levels, etc.) and comprehensive blood work. In addition to these biometrics, a stool sample was collected, sequenced, and examined.
Over the course of a week, the subjects were connected to continuous glucose monitoring, that measured the blood glucose levels every 5 minutes throughout the course of the day. Additionally, the subjects used a dedicated mobile app to log exactly what they ate, when they slept, what kind of physical activity they did, and what their level of vitality was. In this manner more than 50,000 meals, 2 million glucose tests, and tens of billions of DNA fragments from the microbiome were accumulated.
The data revealed fascinating findings:
- Every person responds differently. The same food, in the same amount, can cause a different blood sugar reaction in different people. Some people will have high sugar spikes, others might react moderately, and some will have a small spike. For example, the study found that 60% of the subjects had a sharp sugar spike as a response to eating rice, while 40% had a moderate sugar spike.
- Bacterial combinations are related to differential performance: the researchers found a link between certain bacterial populations in the gut and PPGR.
- The microbiome is directly related to PPGR glucose variance. Since each of us has a different microbiome, logic has it that by discovering more about the creatures that live in our gut, we can predict sugar response to different foods.