As technology and science continue to advance, so too does our understanding of what truly personalized nutrition can look like. And, based on the first results from PREDICT (Personalized Responses to Dietary Composition Trial), the largest ongoing nutritional study of its kind, that personalization may be deeper than previously realized.

Inflammation

Results from the study published in Nature Medicine and abstracts shared at the American Society of Nutrition show a wide range of inflammation responses after eating, even among apparently healthy people. Food-induced inflammation is linked with increased risk for conditions such as heart disease, type 2 diabetes and obesity. The findings suggest improved weight management and health could be achieved by eating foods that are personalized to reduce inflammation after meals.

The studies are led by ZOE Global in collaboration with researchers and scientists at Massachusetts General Hospital, Harvard T.H. Chan School of Public Health, Stanford Medicine, Tufts University and King’s College London. ZOE is a health science company using data-driven research to tackle the world’s health issues. By using artificial intelligence (AI) combined with digital technologies like mobile phones, ZOE enables large-scale scientific studies to tackle issues like COVID-19, inflammation and the impact of nutrition on health.

COVID Symptom Tracker

The COVID Symptom Study smartphone-based app (previously known as COVID Symptom Tracker) was developed by ZOE Global, in collaboration with King’s College London and Massachusetts General Hospital and was launched in the United Kingdom on March 24, 2020 and in the United States on March 29, 2020. After three weeks, it had reached more than 2.6 million users. It enables the capture of self-reported information related to COVID-19. On first use, the app records self-reported location, age and core health risk factors. With continued use and notifications, participants provide daily updates on symptoms, health care visits, COVID-19 testing results and whether they are self-quarantining or seeking health care, including the level of intervention and related outcomes. Individuals without apparent symptoms are also encouraged to use the app.

Blood sugar levels

The Nature Medicine study, conducted with 1,103 subjects including 660 identical and fraternal twins, examined a wide range of health markers, including blood glucose, fat and insulin levels and gut bacteria as well as the effect of sleep, exercise and other activities. Participants wore a continuous glucose monitor and activity tracker throughout the duration of the study, took finger prick blood samples to monitor blood fat levels and collected stool samples for microbiome analysis.

Results showed that, despite eating identical meals at identical times, individual responses to those meals were widely varied; this variation was seen even amongst identical twins, highlighting that genetics may play a lesser role than previously believed.

“When we looked at blood sugar and fat levels across participants who ate the same meal, we could see up to ten times difference in their bodies’ response,” said Andrew T. Chan, MD, MPH, lead researcher, Professor of Medicine, Harvard Medical School, Professor of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Chief of the Clinical and Translational Epidemiology Unit, CTEU Massachusetts General Hospital.

The initial stage of the study, PREDICT 1, sought to examine the impact of postprandial glycemia (PPG) and lipemia (PPL) on inflammatory responses within the body following specific, controlled meals. The impact of PPG and PPL were determined by concentrations of traditional inflammation biomarker interleukin 6 (IL-6) and emerging biomarker glycoprotein acetyls (GlycA). Additionally, glucose, triacylglycerol (TG), microbial diversity (via 16S Shannon diversity) and visceral fat mass (VFM) were measured.

The study’s results showed GlycA and IL-6 concentrations increased significantly after meals (by 4.5% and 169%, respectively). Additionally, peak postprandial TG and glucose concentrations were strongly associated with GlycA, but not IL-6. The study’s results also showed individuals with higher microbial diversity and lower VFM had an attenuated inflammatory response.

The study authors concluded, based on the observation that PPL was a stronger determinant of systemic inflammation than PPG, “The clinically significant and variable postprandial inflammatory response, and its association with lipemia and glycemia, highlights the potential for personalized dietary strategies to lower postprandial metabolic responses to reduce low grade inflammatory related diseases.”

Major takeaways

The major takeaway from the study is clear: Responses to various foods and when they are consumed are highly individualized; thus, so too must personalized nutrition. Everything from type of food consumed to its composition of fats, carbohydrates, protein, etc., to the best time to consume it is unique to each individual. As a result, any health and wellness plan centering on diet must be even more personalized than previously thought.