New paper on postprandial (after a meal) tissue optical property changes in SPIE Biophotonics Discovery
Very happy to announce that today my lab published our first paper in hashtag#SPIE hashtag#BiophotonicsDiscovery. Manuscript here: link
My talented student Anahita Pilvar, along with our collaborator Jorge Plutzky at Harvard Med/Brigham and Women’s Hospital, went on a several year journey to try to understand how a specific meal could affect your skin and tissue optical properties in the few hours after the meal was consumed. The results were quite surprising, and I’ll provide a brief summary here:
First, we used a custom technique called Spatial Frequency Domain Imaging (SFDI) to image the back of the hand of subjects every hour for 5 hours after they had either a very low or very high fat meal. 15 subjects were measured, each had a low fat and high fat meal, but on different days. SFDI can quantify tissue optical properties, as well as tissue hemoglobin, water, and lipid concentrations dependent on the wavelengths used. Here we quantified properties at 3 wavelengths, 730, 880, and 1100 nm.
We also took blood pressure, heart rate, and serial blood draws to measure the amount of triglycerides, cholesterol, and glucose in the blood.
What we found is that the high fat and low fat meals caused dramatically different changes in the optical properties and oxygen saturation of the peripheral tissue we measured (back of the hand). A very high fat meal caused an increase in tissue oxygen saturation, and a very low fat meal caused a decrease. The peak of the changes occurred at 3 hours after the meal, the same time triglycerides spikes (see figure below). We also saw changes in optical absorption at 880 nm, oxyhemoglobin concentration, and a few other parameters.
We then trained a machine learning model to predict triglyceride levels using SFDI measurements, and achieved a pretty good accuracy, with errors around 40 mg/dL.
The several hour period after a meal (called the postprandial window) is well known to provide important information about cardiovascular disease risk. For example, if your triglyceride levels spike too high, or stay elevated for too long, you are at higher risk for future cardiovascular events, like heart attack and stroke. Serial blood draws are impractical except for research. Optical techniques like SFDI might be a better non-invasive way to track the postprandial state and assess cardiovascular disease risk.
Main methods and results shown here below, adapted from the manuscript figures with annotation added.
