The primary objective of this study is to assess the construct validity and criterion validity for associations of the VEGANScreener with nutrient intakes from reference methods and associations with biomarkers of dietary intake. The investigators hypothesize that the screener is a valid tool to assess diet quality in the vegan population. The study will assess construct validity by testing whether the measure relates as it should to other measures (e.g., age, gender, education, socioeconomic status differences).

The investigators will assess concurrent and predictive validity (types of criterion validity) by evaluating associations and agreement between 'gold standards', such as diet records, biomarkers, and multi-metabolite signatures of intake. The investigators will examine associations of vegan diet quality with biomarkers of nutritional status, biomarkers of disease, and anthropometric measures and hypothesize that a higher diet quality in vegans is associated with a more favourable profile among vegans, for example, a lower blood pressure. This study is part of the European VEGANScreener Consortium.

Inclusion Criteria:

1. Self-reported vegans (≥2 years on a vegan diet; vegan diet defined as not consuming any dietary animal products more often than once/month, honey excluded)
2. Self-reported omnivores. Consuming on average daily (at least 5 times/week) meat/meat products.
3. Age 18 to 65 years (1:1 ratio 18-35,99 and 36-65)
4. Males and females (1:1 ratio)

Exclusion Criteria:

1. Self-identified pescatarians (excluding all meat, except for fish/seafood) and reductarians/flexitarians (intentionally reducing intake of animal-based products)
2. History of a disease known to affect intermediary metabolism (e.g., any diabetes on treatment, i.e. medication or lifestyle recommendations, thyreopathies, cancer etc.)
3. BMI>30 kg/m2
4. History of disease of intestinal integrity (i.e., inflammatory bowel disease, chronic pancreatitis, other malabsorption, etc.).
5. Pregnant or breastfeeding females.

An equal number of male and female participants will be included. Inclusion is based on self-representation of gender identity.

Healthy participants following a vegan or omnivours diet (ratio 1:1).

Data transfer agreements are made with all parties within the VEGANScreener consortium