Health of vegetarians
Lead Research Organisation:
University of Oxford
Department Name: Cancer Epidemiology Unit
Abstract
Health of vegetarians: lay summary
EPIC-Oxford is a large study following the health of vegetarians and similar non-vegetarians. The aim of the proposed research is to examine the long-term health of vegetarians in the UK. This will help understanding of the impact of several related dietary factors on long-term health, and will provide important information for the 1.2 million vegetarians living in the UK.
The participants in EPIC-Oxford comprise 65,500 men and women who volunteered to join the study in the 1990s. Recruitment was targeted at vegetarians and other people with an interest in diet, and 34,000 meat-eaters, 10,000 people who eat fish but not meat, 19,000 lacto-vegetarians and 2,500 vegans joined the study. All the participants completed a questionnaire about their diet and other aspects of lifestyle, and 20,000 of them also provided a blood sample to be stored frozen for future analysis. The diet and lifestyle of the participants has been followed by questionnaires completed 5, 10 and 15 years after recruitment, and their health has been followed by linkage to National Health Service data on hospital diagnoses, cancers and death.
Previous analyses in EPIC-Oxford have shown several large differences in dietary intake, nutritional status or other markers of health between vegetarians and non-vegetarians. Some of these differences might be expected to lead to better health in the vegetarians, whereas others might lead to worse health. For example, we have shown that the vegetarians have relatively low levels of overweight and obesity, low blood cholesterol, high fruit and vegetable intake and high fibre intake, all of which may reduce the risk for some types of heart disease and perhaps other diseases. In contrast, we have also shown that the vegetarians have low dietary intakes and blood levels of potentially beneficial types of fat (especially n-3 fatty acids from fish), vitamin B12 and vitamin D; these low levels might contribute to an increased risk in vegetarians for some diseases, such as stroke.
The proposed research will utilize the information we have already collected over the last 20 years on the diet and lifestyle of the participants in EPIC-Oxford, together with extended follow-up by continued linkage to data from the National Health Service, to examine the risk for a range of diseases in vegetarians compared to non-vegetarians.
The main dietary factors examined will be vegetarian and vegan diets. We will also examine the impact on health of meat, fish, dairy products, animal protein, dairy protein, saturated fats, fats from vegetable oils and fish, dietary fibre, vitamin B12, and calcium. We will then examine the health records of the participants to answer several questions:
Whether the already reported low risk of ischaemic heart disease in vegetarians is largely due to the low intake of saturated fatty acids, and whether it may also be affected by other dietary factors such as particular compounds in meat.
Whether the risk of stroke may be high in vegetarians, and this may be related to the low intake of proteins from animal foods and of vitamin B12.
Fracture risk may be high in vegans and other individuals with low intakes of calcium due to low or zero intakes of dairy products. The risk for joint replacement for osteoarthritis may be low in vegetarians, due to low intakes of animal protein.
The risk of several disorders of the digestive system may be low in vegetarians, primarily due to high intakes of dietary fibre and absence of meat.
EPIC-Oxford is a large study following the health of vegetarians and similar non-vegetarians. The aim of the proposed research is to examine the long-term health of vegetarians in the UK. This will help understanding of the impact of several related dietary factors on long-term health, and will provide important information for the 1.2 million vegetarians living in the UK.
The participants in EPIC-Oxford comprise 65,500 men and women who volunteered to join the study in the 1990s. Recruitment was targeted at vegetarians and other people with an interest in diet, and 34,000 meat-eaters, 10,000 people who eat fish but not meat, 19,000 lacto-vegetarians and 2,500 vegans joined the study. All the participants completed a questionnaire about their diet and other aspects of lifestyle, and 20,000 of them also provided a blood sample to be stored frozen for future analysis. The diet and lifestyle of the participants has been followed by questionnaires completed 5, 10 and 15 years after recruitment, and their health has been followed by linkage to National Health Service data on hospital diagnoses, cancers and death.
Previous analyses in EPIC-Oxford have shown several large differences in dietary intake, nutritional status or other markers of health between vegetarians and non-vegetarians. Some of these differences might be expected to lead to better health in the vegetarians, whereas others might lead to worse health. For example, we have shown that the vegetarians have relatively low levels of overweight and obesity, low blood cholesterol, high fruit and vegetable intake and high fibre intake, all of which may reduce the risk for some types of heart disease and perhaps other diseases. In contrast, we have also shown that the vegetarians have low dietary intakes and blood levels of potentially beneficial types of fat (especially n-3 fatty acids from fish), vitamin B12 and vitamin D; these low levels might contribute to an increased risk in vegetarians for some diseases, such as stroke.
The proposed research will utilize the information we have already collected over the last 20 years on the diet and lifestyle of the participants in EPIC-Oxford, together with extended follow-up by continued linkage to data from the National Health Service, to examine the risk for a range of diseases in vegetarians compared to non-vegetarians.
The main dietary factors examined will be vegetarian and vegan diets. We will also examine the impact on health of meat, fish, dairy products, animal protein, dairy protein, saturated fats, fats from vegetable oils and fish, dietary fibre, vitamin B12, and calcium. We will then examine the health records of the participants to answer several questions:
Whether the already reported low risk of ischaemic heart disease in vegetarians is largely due to the low intake of saturated fatty acids, and whether it may also be affected by other dietary factors such as particular compounds in meat.
Whether the risk of stroke may be high in vegetarians, and this may be related to the low intake of proteins from animal foods and of vitamin B12.
Fracture risk may be high in vegans and other individuals with low intakes of calcium due to low or zero intakes of dairy products. The risk for joint replacement for osteoarthritis may be low in vegetarians, due to low intakes of animal protein.
The risk of several disorders of the digestive system may be low in vegetarians, primarily due to high intakes of dietary fibre and absence of meat.
Technical Summary
Health of vegetarians: technical summary
EPIC-Oxford is a population cohort of 65,500 men and women recruited throughout the UK in 1993-2000. The cohort comprises 34,000 meat-eaters, 10,000 people who eat fish but not meat, 19,000 lacto-vegetarians and 2,500 vegans. Participants completed a questionnaire on diet and lifestyle and gave written consent for follow-up through medical records. 20,000 participants gave a blood sample at recruitment, and 1,000 gave a second blood sample 5 years later. Follow-up questionnaires were completed 5, 10 and 15 years after recruitment. Participants are followed through record linkage to NHS data for all hospital episodes, cancers and deaths. The main dietary exposures examined will be vegetarian and vegan diets, and consumption of meat, fish, dairy products, animal protein, dairy protein, saturated fat, n-6 polyunsaturated fatty acids, n-3 fatty acids, fibre, vitamin B12 and calcium.
The main disease endpoints will be: cardiovascular disease including ischaemic heart disease and stroke, skeletal health including fractures and joint replacement for osteoarthritis, and gastrointestinal disorders. The data will be analysed by standard methods for cohort studies. Repeat measures of diet and other factors will be included, and adjustments made for smoking and other relevant confounding factors.
In addition to these specific research objectives, a further important part of the work proposed is to make the data from EPIC-Oxford accessible to other medical researchers, thus maximising the scientific output from the study. This will include the incorporation of the EPIC-Oxford databases into the Richard Doll Centenary Data Archive, as well as linkage to the MRC Gateway and other communications with external medical researchers.
EPIC-Oxford is a population cohort of 65,500 men and women recruited throughout the UK in 1993-2000. The cohort comprises 34,000 meat-eaters, 10,000 people who eat fish but not meat, 19,000 lacto-vegetarians and 2,500 vegans. Participants completed a questionnaire on diet and lifestyle and gave written consent for follow-up through medical records. 20,000 participants gave a blood sample at recruitment, and 1,000 gave a second blood sample 5 years later. Follow-up questionnaires were completed 5, 10 and 15 years after recruitment. Participants are followed through record linkage to NHS data for all hospital episodes, cancers and deaths. The main dietary exposures examined will be vegetarian and vegan diets, and consumption of meat, fish, dairy products, animal protein, dairy protein, saturated fat, n-6 polyunsaturated fatty acids, n-3 fatty acids, fibre, vitamin B12 and calcium.
The main disease endpoints will be: cardiovascular disease including ischaemic heart disease and stroke, skeletal health including fractures and joint replacement for osteoarthritis, and gastrointestinal disorders. The data will be analysed by standard methods for cohort studies. Repeat measures of diet and other factors will be included, and adjustments made for smoking and other relevant confounding factors.
In addition to these specific research objectives, a further important part of the work proposed is to make the data from EPIC-Oxford accessible to other medical researchers, thus maximising the scientific output from the study. This will include the incorporation of the EPIC-Oxford databases into the Richard Doll Centenary Data Archive, as well as linkage to the MRC Gateway and other communications with external medical researchers.
Planned Impact
Health of vegetarians: impact summary
The research will benefit vegetarians and the general public in the UK and elsewhere. Individuals will gain information on both potential benefits and risks of following a vegetarian diet. This type of information could not only lead to long-term health improvements for many people, but also more directly help to avoid deficiencies, such as vitamin B12 deficiency.
For scientists, the research will provide direct information on the health of vegetarians, and also help give insight into the health effects of related factors such as intake of animal protein and saturated fat.
For the private sector, food companies and caterers will gain information on dietary patterns which can be followed by ordinary people and on their associations with health.
For the NHS, the research will provide information to inform their advice, e.g. as on their website: http://www.nhs.uk/Livewell/Vegetarianhealth/Pages/Goingvegetarian.aspx
For Defra, the research will inform evaluation of the likely impacts on health of any moves towards lower meat consumption to reduce greenhouse gas emissions, which would be expected to increase the number of vegetarians (for example http://sd.defra.gov.uk/2011/01/food-climate-change-and-land-use/)
For other policy makers, the research will provide essential information on the long-term health of vegetarians and related dietary patters. This may contribute, for example, to the evaluation of guidelines for food providers in schools, hospitals and prisons.
In the third sector, charities such as the Vegetarian Society, the Vegan Society, Viva and the Jewish Vegetarian Society will gain information to communicate to their members.
The research will benefit vegetarians and the general public in the UK and elsewhere. Individuals will gain information on both potential benefits and risks of following a vegetarian diet. This type of information could not only lead to long-term health improvements for many people, but also more directly help to avoid deficiencies, such as vitamin B12 deficiency.
For scientists, the research will provide direct information on the health of vegetarians, and also help give insight into the health effects of related factors such as intake of animal protein and saturated fat.
For the private sector, food companies and caterers will gain information on dietary patterns which can be followed by ordinary people and on their associations with health.
For the NHS, the research will provide information to inform their advice, e.g. as on their website: http://www.nhs.uk/Livewell/Vegetarianhealth/Pages/Goingvegetarian.aspx
For Defra, the research will inform evaluation of the likely impacts on health of any moves towards lower meat consumption to reduce greenhouse gas emissions, which would be expected to increase the number of vegetarians (for example http://sd.defra.gov.uk/2011/01/food-climate-change-and-land-use/)
For other policy makers, the research will provide essential information on the long-term health of vegetarians and related dietary patters. This may contribute, for example, to the evaluation of guidelines for food providers in schools, hospitals and prisons.
In the third sector, charities such as the Vegetarian Society, the Vegan Society, Viva and the Jewish Vegetarian Society will gain information to communicate to their members.
Organisations
People |
ORCID iD |
Tim Key (Principal Investigator) | http://orcid.org/0000-0003-2294-307X |
Publications
Appleby P
(2015)
The long-term health of vegetarians and vegans
in Proceedings of the Nutrition Society
Appleby P
(2019)
Letter: Veganism, vegetarianism, bone mineral density, and fracture risk: a systematic review and meta-analysis
in Nutrition Reviews
Appleby PN
(2016)
Mortality in vegetarians and comparable nonvegetarians in the United Kingdom.
in The American journal of clinical nutrition
Bradbury KE
(2015)
Serum concentrations of cholesterol, apolipoprotein A-I and apolipoprotein B in a total of 1694 meat-eaters, fish-eaters, vegetarians and vegans.
in European journal of clinical nutrition
Bradbury KE
(2017)
Human Nutrition
Bradbury KE
(2020)
Diet and colorectal cancer in UK Biobank: a prospective study.
in International journal of epidemiology
Bradbury KE
(2017)
Essentials of Human Nutrition
Fensom G
(2020)
Genome-wide association study of vegetarianism in UK Biobank identifies association with VRK2
in Wellcome Open Research
Godfray HCJ
(2018)
Meat consumption, health, and the environment.
in Science (New York, N.Y.)
Description | Plant-based diets and their impact on health, sustainability and the environment: a review of the evidence: WHO European Office for the Prevention and Control of Noncommunicable Diseases (2021) |
Geographic Reach | Multiple continents/international |
Policy Influence Type | Contribution to a national consultation/review |
URL | https://www.euro.who.int/en/health-topics/disease-prevention/nutrition/publications/2021/plant-based... |
Description | Article about vegan diets in The Conversation |
Form Of Engagement Activity | Engagement focused website, blog or social media channel |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Article for The Conversation titled "Five reasons why it's difficult to find conclusive answers on whether or not vegan diets are healthy", to address common issues surrounding epidemiological research on the topic. |
Year(s) Of Engagement Activity | 2021 |
URL | https://theconversation.com/is-a-vegan-diet-healthier-five-reasons-why-we-cant-tell-for-sure-152131 |
Description | Cooking class at Oxford Science Festival |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | A cooking class where participants were invited to cook various vegetarian meals. |
Year(s) Of Engagement Activity | 2017,2018 |
Description | Created a game on nutrition and cancer that was trialed at a departmental organised science fair for local secondary school aged children |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | Created a game on nutrition and cancer that was trialed at a departmental organised science fair for local secondary school aged children |
Year(s) Of Engagement Activity | 2017 |
Description | Good food Oxford cooking class |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Cooking plant-based meals with members of the public |
Year(s) Of Engagement Activity | 2019 |
Description | ITV Tonight interview 'Meat: is it still safe?' |
Form Of Engagement Activity | A broadcast e.g. TV/radio/film/podcast (other than news/press) |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Interviewed on the health effects of consuming red and processed meat |
Year(s) Of Engagement Activity | 2019 |
Description | Invited plenary lecture on "Health of vegetarians" VegMed Conference, King's College London 12th October 2019 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Professional Practitioners |
Results and Impact | Invited plenary lecture on "Health of vegetarians" VegMed Conference, King's College London 12th October 2019 |
Year(s) Of Engagement Activity | 2019 |
Description | Invited plenary presentation (Berlin) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Presentation "Health of vegetarians - findings from the EPIC-Oxford study" at VegMed conference April 22-24, 2016, Berlin, a scientific congress on vegetarian nutrition and medicine for medical doctors, medical students and health care professionals |
Year(s) Of Engagement Activity | 2016 |
URL | http://www.vegmed.de/program |
Description | Invited presentation of evidence on "Food, Poverty, Health and the Environment" House of Lords Select Committee on Food, Poverty, Health and the Environment - Evidence session 2 3rd September 2019 |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Policymakers/politicians |
Results and Impact | Invited presentation of evidence on "Food, Poverty, Health and the Environment" House of Lords Select Committee on Food, Poverty, Health and the Environment - Evidence session 2 3rd September 2019 |
Year(s) Of Engagement Activity | 2019 |
Description | Invited presentation on "Plant-based diets and health" All Party Parliamentary Food and Health Forum, Westminster 4th February 2020 |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Policymakers/politicians |
Results and Impact | Invited presentation on "Plant-based diets and health" All Party Parliamentary Food and Health Forum, Westminster 4th February 2020 |
Year(s) Of Engagement Activity | 2019 |
Description | Lunchtime talk to students and researchers at Oxford University |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Postgraduate students |
Results and Impact | Gave a talk on our research to postgraduate students and researchers from across different departments within Oxford university, which sparked questions and discussion afterwards on the research topic and related areas. |
Year(s) Of Engagement Activity | 2017 |
Description | Meat the Future: Food For Thought |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Prof. Tim Key discussed the health impacts of reducing meat consumption with Prof. Susan Jebb, Dr Pete Scarborough, Dr Rachel Pechey. The event was organised as part of a series by the Oxford University Museum of Natural History. |
Year(s) Of Engagement Activity | 2021 |
URL | https://www.youtube.com/watch?v=rKIPtEPhzas&t=1253s |
Description | Meat the future schools day |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Schools |
Results and Impact | This was a full day event organised for sixth form students at the Oxford University Museum of Natural History. Dr Tammy Tong gave a talk about the health impacts of reducing meat consumption, other Oxford University researchers talked about public perception of the healthiness of meat and food choices, lab grown meat, and environmental impact of meat consumption. |
Year(s) Of Engagement Activity | 2021 |
Description | Meat your persona public engagement activity |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Discussion about meat consumption with general public in local shopping mall |
Year(s) Of Engagement Activity | 2019 |
Description | Media interviews about veganism/veganuary |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Various members gave interviews about evidence on veganism. |
Year(s) Of Engagement Activity | 2019,2020 |
Description | OxWest event: The Science of Veganism |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Dr Keren Papier joined a panel of speakers to discuss issues relating to nutrition, food systems and societal behaviour as they relate to veganism with the aim of cutting through the plethora of misinformation about this topic online. The event was organised by OxWEST (Oxford Women in Engineering, Science, and Technology) |
Year(s) Of Engagement Activity | 2022 |
URL | https://www.youtube.com/watch?v=9M22XfOQH-k |
Description | Presented results of vegetarian diets and fracture risk at a Plant-based Health Professionals UK meeting |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Professor Timothy Key gave a webminar on the findings from recent paper on vegetarian diets and fracture risk to over 200 audience members, which included a mix of health professionals and general public. |
Year(s) Of Engagement Activity | 2021 |
Description | Press briefing on veganism |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Prof Tim Key attended a press briefing on veganism in London on the 18th December, organised by the Science Media Centre |
Year(s) Of Engagement Activity | 2019 |
Description | Press release and media interviews for publication on diet and stroke |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | A press release was issued with publication of the paper on diet and stroke, which were covered in multiple national newspapers and featured in radio shows. |
Year(s) Of Engagement Activity | 2018,2020 |
URL | https://oxfordjournals.altmetric.com/details/76573209 |
Description | Press release and media interviews for publication on vegetarian diets and CVD |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | The publication was reported in many national and international newspapers and radio channels, which generated much interest on the topic. |
Year(s) Of Engagement Activity | 2019 |
URL | https://bmj.altmetric.com/details/65924701 |
Description | Press release for paper on vegetarian diets and fracture risk |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | The research was covered widely in national and international news, and had 903 media hits as of 8th December, including in New Scientist, The Telegraph, The Independent and The Times. |
Year(s) Of Engagement Activity | 2020 |
URL | https://www.biomedcentral.com/about/press-centre/science-press-releases/23-11-20 |
Description | Primary school science day |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | Discussion what data are with children in year 1-6 |
Year(s) Of Engagement Activity | 2019 |
Description | Public engagement event at local gym |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Participated and helped at an event where a researcher met with a personal trainer and a vegan athlete at BUZZ gym to discuss the relationship between protein and sporting performance. 25 adult attendees came along to listen and ask questions. Attendees asked many questions about meat-free protein alternatives and were keen to help guide the discussion. This was a successful event that raised awareness about protein consumption and meat-free diets, |
Year(s) Of Engagement Activity | 2018 |
Description | Radio interview for BBC Health Check |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Interview for radio show BBC Health Check to further comment on our invited commentary titled "Meat, vegetables and health - interpreting the evidence" and to discuss new related research on the topic. |
Year(s) Of Engagement Activity | 2022 |
Description | School Visit (Oxford) |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | School Careers Evening, Prof Tim Key |
Year(s) Of Engagement Activity | 2016 |
Description | Vegetarian lecture Nutrition Society |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited plenary lecture on Vegetarian diets and health; at the Nutrition Society Symposium "The future of animal products in the human diet" July 2015, Prof Tim Key |
Year(s) Of Engagement Activity | 2015 |