This study aims to quantify the variation in postprandial AA profiles between (and within) individuals after consumption of a poorly digestible plant protein source (Lucerne) and to compare the variation in postprandial AA profiles between a poorly digestible plant protein source and an easy digestible protein source (whey).

The study has a randomised, cross-over, controlled design. Two different treatments, all representing a 20g protein load, will be evaluated on five occasions with a washout period of minimum one week between the test days. On test days, research subjects will receive two different protein sources, in the form of a protein drink, in randomised order; on three test days they will receive a poor-digestible protein source, on two test days an easily digestible protein source. Blood will be collected via a catheter before and up-to four hours after protein consumption. Wellbeing, health complaints or other adverse effects will be collected via short questionnaires during each test day. After each test day gastrointestinal complaints will be collected via an online questionnaire.

There is currently no information on personal protein digestion variability. We recently performed a human intervention study on protein digestibility and absorption and observed that postprandial plasma amino acid (AA) profiles from an easy digestible animal protein were highly comparable among individuals. However, the same profiles from a less digestible plant-protein source (e.g. water lentil) showed a large variability among individuals. But in order to really speak of personalized digestibility, we must be able to demonstrate that the absorption rate of an individual is reproducible. Demonstrating personal differences in AA uptake kinetics will affect the way we value (new) protein sources. Determining and quantifying individual differences in digestion and absorption will allow us to better predict nutritional value of products and diets.

The primary objective is to quantify the variation in postprandial AA profiles between (and within) individuals after consumption of a poorly digestible plant protein source (Lucerne). Secondary objective is to compare the variation in postprandial AA profiles between a poorly digestible plant protein source and an easy digestible protein source (whey).

The study has a randomised, cross-over, controlled design. Two different treatments, all representing a 20g protein load, will be evaluated on five occasions with a washout period of minimum one week between the test days. On test days, research subjects will receive two different protein sources, in the form of a protein drink, in randomised order; on three test days they will receive a poor-digestible protein source, on two test days an easily digestible protein source. Blood will be collected via a catheter before and up-to four hours after protein consumption. Wellbeing, health complaints or other adverse effects will be collected via short questionnaires during each test day. After each test day gastrointestinal complaints will be collected via an online questionnaire.

Inclusion Criteria:

• Apparently healthy men and women;
• Age between 18 and 40 years;
• Body mass index (BMI) between 18.5 and 30 kg/m2 ;
• Having veins suitable for blood sampling via a catheter (judged by study nurse/ medical doctor).

Exclusion Criteria:

• Any metabolic, gastrointestinal, inflammatory or chronic disease (such as diabetes, anaemia, hepatitis, cardiovascular disease),or having a condition or disease that may lead to an impaired immune system;
• History of gastrointestinal surgery or having (serious) gastrointestinal complaints;
• History of liver dysfunction (cirrhosis, hepatitis) or liver surgery;
• Kidney dysfunction (self-reported);
• Any use of medication that may suppress the immune system, this will be judged by the medical supervisor;
• Use of medication that may influence the study results, such as gastric acid inhibitors, laxatives, stomach protectors and drugs that can affect intestinal motility, this will be judged by the medical supervisor;
• Anaemia (Hb values <7.5 mmol/L for women and <8.5 mmol/L for men);
• Reported slimming, medically prescribed or other extreme diets;
• Use of protein supplements;
• Not willing to give up blood donation during the study;
• Current smokers;
• Alcohol intake ≥4 glasses of alcoholic beverages per day;
• Pregnant, lactating or wishing to become pregnant in the period of the study (self-reported);
• Abuse of hard drugs;
• Not having a general practitioner;
• Participation in another clinical trial at the same time;
• Being an employee of the department Food, Health & Consumer Research of Wageningen Food & Biobased Research or the department of Nutrition and Health of Wageningen University.