Promephy - Metabolic Fate of Plant-based Proteins

Few human intervention studies have examined the short term (<4 weeks) effects of high(plant and animal) protein diets (25‐30 percent of total energy intake) on intestinalmicrobiota composition [Beaumont et al., 2017; David et al., 2014]. One study suggeststhat long‐term dietary patterns which involve increased consumption of protein (meat anddairy) can shift the composition of the gut microbiota towards an ecosystem in which taxapossessing proteolytic fermentation pathways are most abundant [Blachier et al., 2019].Increased proteolytic activity is associated with increased gene expression of negativebacteria and increased uremic toxins and microbial metabolites which can potentiallyresult in damage to the gut microstructure, activation of immune/ inflammatory responseswhich over a prolonged period of time may have negative health outcomes [Windey et al,2012]. These system‐level shifts in composition and metabolism hint at the complexity ofmetabolic interactions occurring in the host‐microbiome symbiosis, but more informationis needed on the processes underlying these changes.There is current interest in the functional benefits of plant‐based proteins, but with alower bioavailability it is unclear as yet what the metabolic fate of these proteins is.Furthermore, relative to dairy proteins, plant‐based sources of protein have differentcompounds within the structure, such as micronutrients and fibre and it is unclear ifthese compounds can modulate the potential negative impact of high diary protein diets onthe microbiome.The PROMEPHY study will focus on better understanding the metabolic and physiologicalimpact of high protein diets from different (alternative) protein sources in humans. Theresults will provide novel insights into plant‐based protein sources and may enablefuture application in products available to the consumer.The primary objective of this study is to compare the changes in serum essential aminoacid bioavailability after two weeks of daily consumption of a plant based protein mixwith the changes in serum essential amino acid bioavailability after two weeks of dailyconsumption of a milk protein isolate.Secondary objectives of this study are: ‐ To compare the changes in serum essential and total amino acid bioavailability aftertwo weeks of daily consumption of a milk protein isolate, a milk and plant basedprotein mix, a plant based protein mix and finally a plant based protein mix withfibre. ‐ To compare the changes in taxonomic microbiota and proteome composition after oneweek and after two weeks of daily consumption of a milk protein isolate, a milk andplant based protein mix, a plant based protein mix and finally a plant based proteinmix with fibre.This is a randomised, double‐blind, crossover, single centre study. It is anticipatedthat 15‐20 healthy participants will be recruited (men and women, aged 18‐50 years) forthis cross‐over design study (see eligibility).Proposed methodsThis study will involve participants attending an initial screening session, followed by3 laboratory visits to the Human Physiology Laboratory at Anglia Ruskin University,Cambridge, UK, for each of 4 trials (total of 13 visits). A brief overview of the keyvisits are provided here:Screening session Volunteers will initially be required to attend a study briefingsession and screening assessment to confirm eligibility. This will take place at AngliaRuskin University, Cambridge, UK. Participants will be required to provide written,informed consent and will receive information on study arrangements.Volunteers eligiblefor participation will be provided with stool collection material and will receiveinstructions on collection and storage of the stool sample. Subjects eligible forparticipation will then visit the Human Physiology Laboratory, Anglia Ruskin University,Cambridge, UK a further 12 times over 4 trials.This is a longitudinal, cross‐over designstudy, with at least 6 weeks between each trial (hence the study period will last atleast 32 weeks). The outline of each trial is provided below. For each trial there willbe 3 visits i.e. trial 1a, 1b, 1c.Visits 1a, 2a, 3a and 4a (same general protocol for visits 1c,2c,3c,4c) Following anovernight fast (10 hours), subjects will come to the Human Physiology Laboratory, AngliaRuskin University, UK for a bioavailability assessment. The research team will receive astool sample that subjects collected at home maximally three days prior to the studyvisit and the Bristol Stool Chart that subjects completed on the same day of the stoolsample collection. Habitual dietary intake will be assessed via a mobile application(MyFitnessPal). Body weight will be measured. Subjects will consume one serving of one ofthe four study products (randomization at Visit 1a, one portion contains 20 grams ofprotein) dissolved in water 200 ml water, and consumed within 10 minutes. Blood sampleswill be drawn at T= ‐20 and ‐5 min (baseline) and at t= 15, 30, 45, 60, 75, 90, 105, 120,150, 180, 210, and 240 min after study product intake by a qualified phlebotomist.Samples will be assessed for uremic markers (baseline only) and amino acid profiles. Agastrointestinal tolerance questionnaire will be completed at several time points (beforestudy product intake and at 90 and 240 min). Throughout the study visits subjects are notallowed to eat, but will drink 200 ml water at T=95 and T=185 min. In addition,participants will be asked to abstain from any physical exercise other than incidentalwalking during the study visits. After this study visit a 2‐week (± 2 days) dietaryintervention will start, with the first serving at home taken in the evening.Participants will receive 50 g of protein to consume daily at home (1 x 25 g in morningand 1 x 25 g in evening), not combined with a meal. Participants will undertake afollow‐up assessment 2 weeks later using the same protocol outlined above.Visits 1b, 2b, 3b and 4b One week after visit a, participants will visit the HumanPhysiology Laboratory, Anglia Ruskin University, Cambridge, UK again for visit b after anovernight fast (at least 10 hours). The research team will receive a stool sample thatparticipants collected within 3 days prior to the study visit and the Bristol Stool Chartthat participants completed on the same day of the stool sample collection. Body weightwill be measured. A fasting blood sample will be taken only for assessment of uremicmarkers.Each trial will be separated by at least a 6 weeks washout period.In this study four study products will be investigated: ‐ Product A: Milk protein isolate ‐ Product B: Milk and plant based Protein mix ‐ Product C: Plant based protein mix ‐ Product D: Plant based protein mix with fiber