Selecting strict vegetarians.

Vegetarians were filtered on four criteria: self-identifying as vegetarian on the first 24-hour recall survey (24HR) that they participated in, not eating meat or fish on the first 24HR, not eating meat or fish on the initial assessment (IA), and no major dietary changes over the past 5 years. Of 9,115 UK Biobank participants who self-identified as vegetarian at least once, 3,205 met these four criteria (top row, bold). The table shows counts from all UK Biobank participants who took the 24HR (N = 210,967); after filtering by ancestry, the total of 3,205 was reduced to 2,312 European vegetarians, the sample used in the analyses that follow.