Nutritional Evaluation - NuEva Study

The implementation of the vegetarian and vegan lifestyle is characterized by omitting defined food groups such as meat, sausage (vegetarians) or additionally dairy products and honey (vegans). This bears the risk of undersupply with valuable nutrients. Critical nutrients in the vegetarian-vegan lifestyle are low intakes of vitamin B12, vitamin D, n-3 LC-PUFA, calcium, iron, zinc as well as a high phytate intake.

The hype of the vegetarian and vegan lifestyle in combination with hints for critical nutrients following the adoption to these eating habits highlights the need of a comprehensive data collection that allows for making recommendations based on reliable scientific evidence.

To address this need, the proposed NuEva study will enroll 55 vegetarians (adherence of at least 1 year), 55 vegans (adherence of at least 1 year), as well as 55 flexitarians (characteristics: selected and rare meat/sausage consumption, once or twice per week, adherence of at least 1 year). Further, 55 participants who consume a Western diet (adherence of at least 1 year) will be recruited as control group).

Run-in/screening To record and document the varieties in dietary practices within and among each group, the 14 d run-in phase of the proposed study will include individual assessments of dietary habits using self-reports (FFPs, lifestyle questionnaires).

Screening (sampling): comprehensive nutrient analyses (vitamins, minerals, trace elements) in plasma/serum samples

Intervention Based on the screening data, critical nutrients will be identified for each participant and summarized for each group. Based on these data and published scientific data, defined nutrition plans and recommendations ensuring adequate nutrient intake will be developed for each group (according to the guidelines of the German Society of Nutrition (DGE)). The plans are adapted to individual energy requirements based on basal metabolic rate (BMR) and physical activity (PAL) of each study participant. The compliance with the menu plans and the physiological impact on health and disease status will be controlled by analyzing nutrient status in blood samples, which are complemented by metabolomic profiling every 6 months. In addition, a regularly health check and nutritional counselling in combination with the analysis of blood lipids and nutrition status are planned every 3 months. Optionally, we are interested to investigate the relationships between the different dietary habits and the participants' microbiomes. Therefore, collection of feces samples every 12 month is envisaged.

Inclusion criteria

• BMI < 30 kg/m2
• Participants must be subjectively healthy
• Adherence to one of the four groups (Western diet, flexitarians, vegetarians, vegans) confirmed by lifestyle and nutrition questionnaires, food frequency protocol (7 d)
• Precondition: stable eating habits for at least two years before enrollment

Exclusion criteria

• Subjects with any acute or chronic disease (tumor, infection, other), gastrointestinal diseases, diabetes mellitus (type I, II), chronic renal disease, diseases of the parathyroids, diseases necessitating regular phlebotomies
• Intake of additional dietary supplements (e.g. fish oil capsules, vitamins, minerals etc.)
• Weight loss or weight gain (> 3 kg) during the last three months before study begin
• Pregnancy or lactation
• Transfusion of blood in the last three months before blood sample taking