Accepted for/Published in: JMIR Research Protocols
Date Submitted: May 15, 2025
Date Accepted: Dec 29, 2025
Validating a multi biomarker panel for the assessment of quantity and quality of plant foods in the diet (PLAENTI): Study protocol of a parallel group designed randomized controlled trial
ABSTRACT
Background:
A high intake of plant foods is generally considered healthy, but there are also plant foods that are detrimental to health. To differentiate between healthful and unhealthful plant foods, plant-based diet indices have been developed. To examine the relationship between diet and disease precisely, reliable dietary assessment is crucial. Current methods for dietary assessment rely on self-reported intake data, which are subject to bias. Thus, objective measures of food intake are often sought for. For that, biomarkers of food intake could be used, but each biomarker has its own limitations. Combining several biomarkers of food intake into a multi-biomarker panel might be a strategy to mitigate these limitations, allowing for more accurate objective dietary assessment.
Objective:
The PLAENTI study aims to validate a multi-biomarker panel for the assessment of quantity and quality of plant foods in the diet.
Methods:
PLAENTI is a randomized controlled dietary intervention study with four groups in a parallel group design. Healthy females and males over the age of 18 were eligible to participate in the study. The study consisted of one week of run-in, with the same diet low in healthful plant foods for all participants, two weeks of intervention according to the assigned group, and one week of wash-out, during which participants returned to their habitual diet. The intervention consisted of either a low, medium, or high proportion of healthful plant foods or a high proportion of unhealthful plant foods in the diet. For the run-in and the intervention, daily menu plans were created and adjusted to the participants’ individual total energy expenditure. All food was provided on weekly visits to the Study Center and by home deliveries. At the visits, anthropometry as well as body composition were assessed and blood samples were collected. Throughout the study, multiple urine samples (24-hour urine, evening and morning spot urine) were collected by the participants. The blood and urine samples will be used for the analysis of biomarkers of food intake.
Results:
PLAENTI was conducted from January to August 2024. Of 66 enrolled participants, 59 completed the study successfully. The study population consists of 31 female and 28 male participants who were 45.5 (± 18.4) years old, had a body mass index of 24.8 (± 3.9) kg/m² and a calculated total energy expenditure of 2464 (± 440) kcal (data are mean values ± standard deviations).
Conclusions:
PLAENTI was performed in a highly controlled and standardized manner and yielded samples and data to examine if the quantity and quality of plant foods in the diet can be assessed using a multi-biomarker panel. A successful validation of the multi-biomarker panel would enable its application for objective dietary assessment. Clinical Trial: German Register of Clinical Studies DRKS00032738; https://drks.de/search/en/trial/DRKS00032738; Universal Trial Number (UTN): U1111 1298 1562
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