Being an analytical chemist and nutritional scientist, I truly believe that we need more objective ways of assessing diet and, with the increased uptake of plant-based diets for health and sustainability, we need a way to assess plant-based diets accurately. Here, we’ve identified biomarkers of healthy, plant-rich dietary patterns that, in the future, we think will help to assess relationships between diet quality and health.
Dr Ana Rodriguez-Mateos, Reader in Nutritional Sciences at King’s and senior author of the paper
28 November 2024
New way to measure diet quality using plant metabolites
Researchers have developed a new way to measure diet quality by looking at metabolites in the body specific to healthy, plant-based foods. The researchers hope their method can be used as a more objective way to measure diet quality and the impact of plant-based diets on health.
A healthy diet is important for maintaining good health, but accurately measuring the quality of someone’s diet can be difficult. Many diet quality evaluations are based on observational studies that collect information on dietary patterns using food frequency questionnaires. These questionnaires rely on people to self-report how often they consumed a particular food item or drink over a specified time period, which can be inaccurate and subject to bias.
In a study, published today in the European Journal of Nutrition, researchers at King’s College London propose a new way of measuring diet quality using a set of chemical markers (known as a metabolic signature) found in blood and urine that are associated with the consumption of healthy, plant-based foods.
The study looked at over 200 healthy adults who had completed a food frequency questionnaire, and scored their answers against five plant-rich diets commonly used in nutritional studies - Dietary Approaches to Stop Hypertension (DASH), healthy and unhealthy Plant-based Diet Index (hPDI and u-PDI), Original Mediterranean Score (O-MED), Amended Mediterranean Score (A-MED), and the Mediterranean-DASH Diet Intervention for Neurodegenerative Delay (MIND).
The team then measured the levels of over 100 plant food metabolites in participants’ urine samples (collected over 24 hours) and fasting blood samples. In those who scored highly in their questionnaire for adherence to each plant-rich diet, there was a particular pattern of metabolites present.
Using these patterns, the team developed a metabolic signature for each diet, made up of between 15-42 plant metabolites, that reflected how well the individual followed each diet. In those who adhered strongly to the diet, the metabolic signature was high, and in those who did not follow the diet, the metabolic signature was low. The team also saw the same effects in a second, smaller group of participants from the TwinsUK cohort.
The metabolites that make up the signatures are phytochemicals, specifically (poly)phenols and methylxanthines, which naturally occur in plants and have been associated with a variety of health benefits, including supporting brain and heart health.
“Previous studies have proposed metabolic signatures that reflect adherence to certain diets, but these have looked at all the metabolites in blood or urine, such as fatty acids and proteins, which we get from different kinds of foods and are not very specific. What’s unique about our approach is we’ve developed a panel of biomarkers using metabolites that come only from healthy, plant-based foods.
Dr Rodriguez-Mateos
As next steps for this research, the metabolic signatures developed in this work will be used to investigate associations between adherence to plant-rich diets, cardiometabolic and cognitive health in different observational studies.
The research was funded by a Chronic Disease Research Foundation grant and King’s-China Scholarship Council (K-CSC) joint scholarship.
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Reader in Nutritional Sciences