Acute Meat and Alternative Intake (PRotEin DIet SatisfacTION Trial 3)

Introduction: Protein rich foods that are alternatives to farm-grown meat have received considerable consumer attention. Whilst meat alternatives were once niche food products aimed at vegetarians, they are increasingly marketed to omnivores and "flexitarians", thus contributing to a trend for reductions in red meat intakes \[1\]. Studies to date have addressed the environmental benefit, plus consumer perceptions and acceptability of meat alternatives \[2, 3, 4\], yet there is surprisingly a paucity of data compared the nutritional and digestive differences to meat. The aim of this trial is to compare the digestive consequences of pasture-fed and grain-finished, beef versus a plant-based meat analogue blinded meal.

Methods and analyses: Healthy, young (20-34 y) participants will be asked to consume three separate meals in a crossover, blinded investigation followed by five hours of blood testing and questionnaires to assess the digestive consequences of meat and a plant-based meat analogue. The three meals will include either pasture-fed, or grain-finished, or laboratory based protein alternative as a mixed meal, in random order, separated by one week minimum. Plasma samples will be assessed amino acid content, neurotransmitter proteins, chylomicron fatty acid distribution and general health indices.

Ethics and dissemination: The trial has been granted ethical approval by the Ministry of Health, Health and Disability Ethics Committee (Ref: 19/STH/226). All results originating from this study will be submitted for publication in scientific journals and presented at meetings.

Introduction: Red meat consumption contributes important nutrients to the diet, including essential amino acids, long chain and complex lipids, vitamins (including B12) and minerals (including iron and zinc) \[5\]. While supplying these important nutrients, red meat may contain components which may negate optimal health such as the saturated fat content and nitrates, that are added during processing \[5\]. The degree to which red meat affects health is likely related to its inherent nutritional profile, the quantity consumed and any processing (e.g. nitrates or cooking techniques). Regardless, the simple notion of a complex whole-food containing single nutrients which are 'good' or 'bad' for health is now considered overly simplistic \[6\]. For example, to reduce heart disease, nutritional guidelines now suggest an increase in polyunsaturated fats at the expense of saturated fat, rather than a complete reduction of all fats \[6\].

Alongside the controversy over the health consequences of red meat, recent attention has focused on the possibility of using "plant-based" proteins as an alternative to red meat consumption. The search for meat alternatives has resulted in a sharp increase in the production of novel "plant-based" meat analogues that have been designed to replicate the taste and eating experience of red-meat. To date there are very few studies addressing the nutritional differences between traditional red meat and plant-based meat analogues, and the nutritional differences that arise due to different production systems. Given the nutritional composition of red meat is likely to be influenced by the farming and feeding practices of the animals, production procedures and end-user cooking techniques \[7\], these differences need to be accounted for in the research design and application.

Aims: To investigate the digestive responses to an acute intake of pasture-fed beef, grain-finished beef, lamb and a plant based meat-analogue consumed as a component of a mixed meal. This study is part of a larger programme to understand the nutritional implications of consuming New Zealand, pasture-fed red meat as part of a balanced diet.

Study Design and Setting: The study is designed as randomised cross-over trial to capture biological difference in postprandial nutrient dynamics. Research subjects will act as their own controls and will consume each meal (pasture raised, grain-fed beef, lamb and a meat alternative meal) on a separate occasion in random order. The study compares exemplars of pasture-fed New Zealand beef, grain-finished New Zealand beef, lamb and a meat analogue. The plant-based meat analogue has been selected on the basis of its macronutrient profile (protein and fat) and appearance in order to that best matches that of meat.

The digestion and metabolism of key nutrients in beef will be measured immediately after the ingestion of a single meal. This experimental setting will also be used to examine some subjective qualities of the meal experience, such as satisfaction score (i.e., liking, satisfaction, enjoyment, satiety, appetite) and gastrointestinal score (i.e., comfort, fullness, bloating, rumbling, flatulence, faecal urgency, diarrhoea).

Eligibility Criteria:
Inclusion Criteria:

* All participants will be required to be omnivores willing to consume both red meat and plant-base alternatives for the purposes of the trial.

Exclusion Criteria:

* Those with chronic health conditions, hyperlipidaemia, obesity (BMI ≥ 30), use of medications (except occasional use of NSAIDs and antihistamines), history of anosmia and ageusia (issues with taste and smell), current dieting or disordered eating pattern and smoking tobacco or recreational drugs will be excluded from participating.
* Participants will be asked to complete an on-line screening which will include the Three-factor Eating Questionnaire-R18 (TFEQ) and a health survey. Participants with a TFEQ score greater than 75% will be excluded from participating on the basis their perception of food is potentially influenced by underlying psychological issues