Westlake N-of-1 Trials for Macronutrient Intake (WE-MACNUTR)

This is a dietary intervention study in students and staff of Westlake University, which is designed to provide evidence in support of N-of-1 methods as an approach to advance personalized nutrition. The primary aim is using a series of N-of-1 trials to determine the impacts of a high fat, low carbohydrate diet (HF-LC) on glucose metabolism and gut microbiota in subjects versus a low fat, high carbohydrate diet (LF-HC) at both the individual and group level.

This study will employ a series of individual N-of-1 trials comparing a high fat, low carbohydrate diet (HF-LC) to a low fat, high carbohydrate diet (LF-HC). Participants will enter the study on a usual diet and will have a 6-day run in period for diet planning and baseline data collection before beginning their intervention. The HF-LC or the LF-HC will be randomized as the starting intervention followed by a wash-out period lasting for 6 days with normal diet between two interventions to eliminate previous intervention effects. Then the participants will be provided with the other diet. Both HF-LC and LF-HC last for 6 days in each set which consists of two wash-out periods and two intervention periods. There will be 3 sets in this study and investigators will aggregate the results of the completed N-of-1 trials across all participants to estimate the group level impacts of HF-LC compared to LF-HC.

Throughout the 6-day intervention, participants are provided with a high fat, low carbohydrate diet (HF-LCD), including a 3-day diet in which the percentage of fat, protein and carbohydrate is 60%, 15% and 25% respectively while the three macronutrients in the other 3-day diet account for 70%, 15% and 15% respectively. The sequencing of the two diets will be randomized.

Throughout the 6-day intervention, participants are provided with a low fat, high carbohydrate diet (LF-HCD), including a 3-day diet in which the percentage of fat, protein and carbohydrate is 20%, 15% and 65% respectively while the three macronutrients in the other 3-day diet account for 10%, 15% and 75% respectively. The sequencing of the two diets will be randomized.

Fecal metabolite extracts will be analysed by performing liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOF/MS).

Gut microbial communities and their abundant features will be analysed based on shotgun metagenomic sequencing.

Targeted metabonomics are analyzed based on urine and faeces at all visits (also based on serum in set 1).

insulin, leptin, adiponection, free fatty acid, Interleukin(IL)-6, IL-8, IL-10, IL-12, IL-17A, IL-1ra, tumour necrosis factor alpha (TNF-α), Lipopolysaccharide binding protein (LBP), cortisol, high-sensitivity C-reactive protein, serum amyloid A, soluble E-selectine, soluble intracellular adhesion molecule-1, plasminogen activator inhibitor-1, vascular cell adhesion molecule, monocyte chemoattractant protein (MCP)-1, adrenaline, noradrenaline, peptide YY, and neuropeptide Y are tested at all visits of set 1.

Triglyceride, cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoprotein A1 and apolipoprotein B are tested at all visits of set 1.

Inclusion Criteria: Willingness and capability to complete the study protocol Exclusion Criteria: Inability or unwillingness to approved to provide informed consent Neurological conditions that might affect the assessment of the study measurement Hospitalization or surgery planned within 3 months Gastrointestinal diseases Other serious medical conditions, such as liver, kidney, or systemic disease Women who are pregnant or lactating Tobacco, alcohol, or illicit drug abuse Had taken antibiotics in the past two weeks prior to the start of the trial Participants on a vegan diet Any food allergy Lack of smart phone and data plan for participating caregiver Non-Chinese speaking participants Participating in another concurrent intervention study

Tian Y, Ma Y, Fu Y, Zheng JS. Application of n-of-1 Clinical Trials in Personalized Nutrition Research: A Trial Protocol for Westlake N-of-1 Trials for Macronutrient Intake (WE-MACNUTR). Curr Dev Nutr. 2020 Aug 26;4(9):nzaa143. doi: 10.1093/cdn/nzaa143. eCollection 2020 Sep.