The Prevalence of British Veganism

In an article for the BBC, Dr Michael Mosley wrote:

There are now four times as many vegans in the UK as there were four years ago.

This article looks at the survey data behind this claim, and compares different survey questions for estimating how many people are vegan.

How many vegans are there?

The Food Standard Agency’s Food and You survey seeks to estimate the public’s reported behaviour, attitudes and knowledge on food and food safety.

The first three waves (2010, 2012, 2014) were conducted by TNS BMRB, which are now part of Kantar Public. NatCen and the Northern Ireland Statistics and Research Agency (NISRA) have been contracted to run the next three waves (2016, 2018, 2020).

The FSA is responsible for food safety in England, Wales and Northern Ireland. From the fourth wave, these random probability samples of adults aged 16 or over do not include Scotland. For comparability, analyses of prior waves have been conducted to exclude Scotland.

So far, five waves of the Food and You survey have been published. Differences between the third, fourth and fifth waves need to be treated with caution, due to changes in the relevant survey question.

Food and You Wave 5 Question

The relevant question and responses for Wave 5 of the Food and You survey is:

Which, if any, of the following applies to you? Please state all that apply

Completely vegetarian; Partly vegetarian; Vegan; Avoid certain food for other reasons, excluding allergies; None

The fourth wave’s response options gave a similar list, but specified that: ‘Avoid certain food for religious or cultural reasons’. Prior to that, the third wave’s question contained many more response options, including dieting to achieve weight loss.

Given the central estimates, self-reported veganism rose from about 0.2% in 2014 to an estimated 0.9% in 2018. Estimated self-reported veganism in England, Wales and Northern Ireland has roughly quadrupled between 2014 and 2018. These are the central estimates, where the research company and other responses options have changed.

The Vegan Society

The Vegan Society makes the same claim that veganism has quadrupled, but compares two different surveys. The comparison is between the NatCen and NISRA estimate in 2014 (of adults aged 16 or over in England, Wales and Northern Ireland) with an Ipsos MORI survey in 2018 (of adults aged 15 or over in England, Wales and Scotland). These are different populations.

Vegan Society survey questions

Funded by the Vegan Society, the Ipsos MORI surveys use a different pair of questions to identify ‘dietary vegans’: people who have no meat, fish or other animal products in their diets.

How often, if at all, do you personally eat any form of meat, fish or shellfish?

How often, if at all, do you personally consume any animal products other than meat, fish or shellfish?

Every day; Every 2–3 days; Every 4–5 days; About once a week; Every 2–3 weeks; About once a week; Less than once a month; Never

People who respond ‘never’ to both questions are classed as dietary vegans. There is also a self-identification question for veganism, though its wording is unclear from the Ipsos MORI data tables. The Vegan Society implies the Food and You survey question is used.

Questioning Quality

In February — April 2016, the Ipsos MORI estimate for dietary vegans (about 1%) is somewhat higher than for self-identified vegans (about 0.7%).

The question is: why?

The answer is the accuracy in which people answer questions. This is based on self-reported behaviour, and people may be unable to precisely recall if they have or have not eaten a described product. Also, people may wish to give desirable answers.

Answering ‘never’ may not mean never ever. According to The Vegan Society, mismatches between the two questions in 2018 were principally due to people responding ‘never’ but actually not following a vegan diet.

‘It’s eggs and milk!’ (GIF: Scott Pilgrim vs The World/Giphy)

Veganism is a restrictive dietary practice. Given the prevalence of meat and other animal products, ‘accidental’ veganism is plausibly uncommon. Since it requires an conscious and sustained choice, self-identification may provide the most accurate question type.

Despite differences in the target population, fieldwork dates and weighting procedures, central estimates for self-identified veganism in 2018 were similar for NatCen & NISRA (0.9%) and Ipsos MORI (1.2%).

When making claims about the rising prevalence of veganism, we should consistently look at the same population.

An edited Google Sheet of the FSA Food and You Wave 5 Excel file contains the graph data. An R Pubs article showing how to make the graph is available.

This blog looks at the use of statistics in Britain and beyond. It is written by RSS Statistical Ambassador and Chartered Statistician @anthonybmasters.

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