The plasma proteome of plant-based diets: Analyses of 2920 proteins in 49,615 people

Circulating proteins are integral to many biological processes and could be influenced by diet. We aimed to assess differences in the plasma proteome between people of different dietary groups, defined by degree of animal food consumption.

The UK Biobank recruited middle-aged adults (mostly 40-69 years) throughout the UK between 2006 and 2010. Relative concentrations of 2920 plasma proteins were quantified using the Olink Proximity Extension Assay on blood samples from 49,615 participants, who were also asked to report their ethnicity and consumption of red and processed meat, poultry, fish, dairy and eggs. We defined six diet groups among the white British participants (23,243 regular meat eaters, 23,472 low meat eaters, 486 poultry eaters, 1081 fish eaters, 721 vegetarians, and 54 vegans), and two diet groups among the British Indians (391 meat eaters and 167 vegetarians). We used multivariable-adjusted linear regressions to assess the cross-sectional differences in protein concentrations between diet groups, with correction for multiple testing.

We observed significant differences in many plasma proteins by diet group (920 proteins in white British participants, 2 in British Indians). Of the biggest differences, compared with regular meat eaters, the non-meat eaters had significantly higher FGF21 (e.g. +0.40 SD in vegetarians), CKB (+0.34), GUCA2A (+0.33), FOLR1 (+0.32), IGFBP2 (+0.31) and DSG2 (+0.30); all groups except the vegans had lower HAVCR1 (-0.38 in vegetarians). Vegetarians also had significantly lower SELENOP (-0.46), while the vegans had lower FGFBP2 (-0.68). The observed differences were generally similar in direction in both ethnicities.

In this first comprehensive assessment of plasma proteins by diet group, we identified many differences in proteins between vegetarians, vegans and meat eaters; this variation in protein levels suggests differences in various biological activities, including gastrointestinal tract and kidney function, which may relate to differences in future disease risk.