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Vegetarian, pescatarian and flexitarian diets: sociodemographic determinants
and association with cardiovascular risk factors in a Swiss urban population
Hannah Wozniak1†, Christophe Larpin1†, Carlos de Mestral2, Idris Guessous2, Jean-Luc Reny1and
Silvia Stringhini2
,
3*
1Department of General Internal Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland
2Unit of Population Epidemiology, Department of Primary Care Medicine, Geneva University Hospitals, 1205 Geneva,
Switzerland
3University Centre for General Medicine and Public Health, University of Lausanne, 1011 Lausanne, Switzerland
(Submitted 18 November 2019 –Final revision received 10 May 2020 –Accepted 12 May 2020)
Abstract
Prevalence and trends of different vegetarian diets remain unknown, with estimates varying depending on the source. Evidence suggests that
vegetarian diets are associated with a more favourable cardiovascular risk profile. The present study aimed to assess the prevalence and trends of
different types of vegetarian diets in a population-based representative sample, sociodemographic characteristics of participants following such
diets and the association of these diets with cardiovascular risk factors. Using repeated cross-sectional population-based surveys conducted in
Geneva, Switzerland, 10 797 individuals participated in the study between 2005 and 2017. Participants were classified as vegetarians,
pescatarians, flexitarians or omnivores using an FFQ. Sociodemographic and cardiovascular risk factors were evaluated through questionnaires,
anthropometric measurements and blood tests. Findings show prevalence of vegetarians increased from 0·5to1·2 %, pescatarians from
0·3to1·1 % and flexitarians remained stable at 15·6 % of the population over the study period. Compared with omnivores, vegetarians were
more likely to be young (OR 2·38; 95 % CI 1·01, 5·6), have higher education (OR 1·59; 95 % CI 1·01, 2·49) and lower income (OR 1·83; 95 % CI
1·04, 3·21); pescatarians and flexitarians were more likely to be women (pescatarian: OR 1·81; 95 % CI 1·10, 3·00; vegetarian: OR 1·57; 95 % CI
1·41, 1·75) and flexitarians were also more likely to have a lower income (OR 1·31; 95 % CI 1·13, 1·53). Participants who adhered to any diet
excluding/reducing meat intake had lower BMI, total cholesterol and hypertension compared with omnivores. The present study shows an
increase in the prevalence of vegetarians over a 13-year period and suggests that the different vegetarian diets assessed are associated with
a better cardiovascular risk profile.
Key words: Vegetarian diets: Pescatarian diet: Flexitarian diet: Vegetarian prevalence: Cardiovascular risk factors:
Sociodemographic factors: Diet trends
In Western countries, it is increasingly popular to consciously
reduce the consumption of meat, mainly due to environmental,
ethical and health concerns(1,2). However, the proportion of the
population following vegetarian or flexitarian diets remains
unknown as estimates vary widely depending on the source(2).
When estimates are driven by online or telephone surveys spon-
sored by vegetarian associations, the prevalence of self-reported
vegetarians can be up to 10–14 %(2–5). However, in population-
based studies, national surveys, or independent analysis, only
1–4 % of the population reports following a vegetarian diet(6–14).
An accurate estimation of the prevalence of individuals fol-
lowing a vegetarian diet is also complicated by the fact that a
large number of different types of dietary regimens fall under
the definition of ‘vegetarian’. Individuals may define themselves
as vegetarians depending on the questions that are being asked
or on the definition adopted in the specific survey. Indeed,
different types of vegetarian diets can be identified. The strictest
regimen is the vegan diet, where all animal products are avoided.
Lacto-ovo vegetarians, simplified as vegetarians, include in their
diet animal-derived products such as eggs and dairy products,
but exclude meat or fish. Pescatarians are defined as vegetarians
who also consume fish and seafood products(1,15). More recently,
the flexitarian diet (or semi-vegetarian) has been gaining popu-
larity and identifies individuals eating meat occasionally, with no
clear consensus on quantities of meat consumed per week or
month required for falling under this category(16). Omnivores
are defined as eating indifferently animal and plant products.
In the current literature, it is difficult to find reliable data on
the prevalence of vegetarians in the general population, and
there is even less data on trends in the prevalence of these diets.
*Corresponding author: Dr Silvia Stringhini, email silvia.stringhini@hcuge.ch
†These authors contributed equally to this work.
British Journal of Nutrition, page 1 of 9 doi:10.1017/S0007114520001762
© The Author(s) 2020. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://
creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original
work is properly cited.
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Furthermore, few studies have attempted to characterise individ-
uals following a vegetarian diet. Most of these reported that indi-
viduals following a vegetarian diet tend to be women, younger,
smoke less and have a higher education(9,17). Nonetheless, there
seems to be contradictory evidence about the link between
income and following a vegetarian diet(9,18).
The medical community is showing growing interest in the
potentially beneficial effects of a vegetarian diet, as shown by
the increasing number of studies on the subject(19–23).
Cardiovascular risk factors such as elevated BMI, hypertension,
hypercholesterolaemia and diabetes seem to be less prevalent in
the population following different vegetarian diets(22,24–26).
Furthermore, some meta-analyses have shown a link between
vegetarian diet and a protective effect on IHD and certain can-
cers(21). Finally, some but not all evidence suggests a link
between following a vegetarian diet and reduced all-cause
mortality(27,28).
The main purpose of the present study is to reliably assess the
prevalence and temporal trends of different types of vegetarian
diets in a yearly Swiss cross-sectional study. The secondary
objectives are to analyse the sociodemographic characteristics
of the cohort and to assess the possible correlation between
the different types of vegetarian diets and cardiovascular risk fac-
tors. With the presumed health benefits of different vegetarian
diets, it is essential to better identify and characterise who in
the general population is following such diets.
Materials and methods
Data were collected using the Bus Santé study, a cross-sectional
population-based study in the State of Geneva, Switzerland
conducted annually since 1993(29,30). The aim is to collect socio-
demographic data and information about cardiovascular risk fac-
tors from a representative sample of the Swiss adult
population. Each year, about 1000 participants aged from
18 to 74 years are selected to participate in the study and individ-
uals cannot be included more than once in the study. Eligible
participants are identified from an annual residential list made
by the Government of Geneva. Potential participants are con-
tacted first by mail. If no answer is given, eligible participants
can receive up to seven phone calls and up to two more mails.
People who do not answer are replaced by another eligible par-
ticipant. People who refuse to participate are not replaced.
Participants are met either at the Geneva University Hospital
or at a mobile medical unit (a bus), facilitating access to all
suburban areas. Participation rate varied between 45 and 55 %
with yearly variations.
First, participants receive a questionnaire at home about
lifestyle habits (smoking, physical activity and nutrition), socio-
demographic information and health, including questions
regarding cardiovascular risks factors. The dietary habits are
assessed using an FFQ with a recall period of 4 weeks.
Secondly, participants undergo a face-to-face interview with
trained nurses who verify the completeness of the question-
naires and take anthropometric measures including height
and weight, according to standard procedures. For weight
measurement, the participant is weighed on a medical scale
and has to take off his shoes and be lightly dressed. Height is
measured using a medical gauge. Blood pressure is measured
three times after 10 min of rest in a sitting position with a cuff size
adjusted to the arm circumference. The average of the three
blood pressure measures is used for the analyses. A blood
test is performed including the measurement of fasting plasma
glucose, total cholesterol and TAG.
The Bus Santé study complied with the declaration of
Helsinki and is approved by the institutional ethical committee
of the University of Geneva. Furthermore, patients gave their
written consent. No financial compensation was given to
participants.
Food frequency questionnaire
The FFQ used in the present study has been validated in the
Geneva population(31)and has been used in the previous
studies(32,33). It is based on ninety-seven different food items.
For each item, the participant must indicate the size of the
portion consumed (smaller, equal or larger than a reference size)
and the frequency at which it was consumed over the last
4 weeks (<1×over the last 4 weeks up to twice a day)(34).
Type of diet
Participants were classified according to the type of diet based on
the FFQ results. Participants were classified as omnivores when
they ate meat >1/week; as vegetarians when they excluded red
meat, poultry and fish from their diet but ate dairy products and
eggs; as pescatarians when they consumed fish, in addition to
dairy products and eggs but did not eat red meat or poultry(15)
and as flexitarians when they included eggs and dairy products
in their daily diet and red meat or poultry at a frequency
of ≥1/month but ≤1/week(19,28,35).
Cardiovascular risk factors
We chose to focus on five cardiovascular risk factors: overweight,
hypertension hypercholesterolaemia, diabetes and smoking.
BMI was calculated as weight/height2. Participants were
classified as having normal BMI (BMI <25 kg/m2), as being
overweight (BMI ≥25 and <30 kg/m2) or as being obese
(BMI ≥30 kg/m2). Hypertension was defined as either one
measurement of the systolic blood pressure ≥140 mmHg or
mean blood pressure ≥90 mmHg or if medications against high
blood pressure were taken or as having a previous diagnosis of
hypertension. Hypercholesterolaemia was defined as having
total blood cholesterol >6·5 mmol/l and HDL <1 mmol/l or if
medications against hypercholesterolaemia were taken or as
having a previous diagnosis. Diabetes was defined as a fasting
glucose >7 mmol/l or if medications against diabetes were taken
or as having a previous diagnosis. Smoking was defined as being
a current smoker.
Total cholesterol, systolic and diastolic blood pressure, fast-
ing plasma glucose and BMI were also assessed as continuous
biomarkers in relation to the different types of diet.
2 H. Wozniak et al.
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Statistical analysis
The analytical sample comprised all the participants included in
the Bus Santé study from 2005 to 2017. Although the Bus Santé
study started in 1993, biomarkers of interest for our study
became available from 2005 onwards, which is why earlier
data were not included in the analysis. We used χ2test for
differences in dietary pattern between men and women in
binary/categorical variables and student ttest in continuous
outcomes. All assumptions were met for normality and
homoscedasticity. Given the sex differences in diet patterns,
we conducted analyses separately for men and women, as well
as in the overall sample. To calculate the prevalence and 95 % CI,
we applied margins after logistic regression, adjusting for age in
sex-specific models and for age and sex in the overall model. To
assess the change in prevalence between the first (%
start
) and
last (%
last
) survey periods, we used the following formula:
((%
last
–%
start
)/(%
start
)) ×100. To test for linear trend in the preva-
lence of diet patterns, we included the survey period variable as
continuous predictor in the model. To assess for trends in food
groups (i.e. meat type consumption) and for the association
between diet patterns and biomarkers, we applied multivariable
linear regression. To investigate the association between diet
patterns and sociodemographic and cardiovascular risk factors,
we used multinomial logistic regression, adjusting the estimates
for age, sex and survey period. We further adjusted the estimates
for BMI in sensitivity analyses to assess its role in the link
between diet type and cardiovascular risk factors. All statistical
analyses were conducted using STATA version 15 (Stata
Corp.). The level of significance was set to P<0·05. Results
for daily dietary intake are expressed as β-coefficients and
95 % CI, for biomarkers as means and standard deviations and
for the association between diet patterns and sociodemographic
and cardiovascular risk factors as OR and 95 % CI.
Results
Baseline characteristics and prevalence
A total of 10 797 participants were included in the analyses,
which spanned over a period of 13 years, from 2005 until
2017 (Table 1). Of the total number of participants, 51 % were
women and the mean age was 48·9(
SD 13·4) years. The mean
BMI was 25·1(
SD 4·4) kg/m2, with 33·3 % of participants being
overweight and 13·3 % being obese. Current smokers were
Table 1. Description of sample, Bus Santé study 2005–2017 (n10 797)*
(Numbers and percentages; mean values and standard deviations)
n
Total Men Women
n%n%n%P
Sample size (n) 10 797 5246 5551
Age (years) 10 797 0·16
Mean 48·949·148·8
SD 13·413·413·3
Age categories 10 797 0·24
18–44 4450 41·2 2146 40·9 2304 41·5
45–64 4758 44·1 2297 43·8 2461 44·3
65þ1589 14·7 803 15·3 786 14·2
Living alone 10 290 3596 35·0 1555 31·1 2041 38·5<0·001
Swiss nationality 10 289 6827 66·4 3236 64·8 3591 67·80·001
University degree 10 148 4735 46·7 2408 49·2 2327 44·3<0·001
Manual occupation 9772 2652 27·1 1436 29·9 1216 24·5<0·001
Household income 9367
<5000 CHF/month 2078 22·2 892 19·3 1186 25·0<0·001
5000–9500 CHF/month 3668 39·2 1702 36·8 1966 41·5<0·001
>9500 CHF/month 3621 38·6 2033 43·9 1588 33·5<0·001
Dietary pattern 10 797
Omnivorous 8965 83·0 4526 86·3 4439 80·0<0·001
Flexitarian 1682 15·6 662 12·6 1020 18·4<0·001
Pescatarian 66 0·624 0·542 0·80·02
Vegetarian 84 0·834 0·750 0·90·07
Current smoker 10 281 2264 22·0 1161 23·3 1103 20·80·003
BMI (kg/m2)<0·001
Mean 25·126·024·3
SD 4·43·94·7
BMI categories 10 240
Normal 5466 53·4 2203 43·4 3263 63·2<0·001
Overweight 3414 33·3 2140 42·2 1274 24·7<0·001
Obese 1360 13·3 732 14·4 628 12·2<0·001
Hypercholesterolaemia 9438 3925 41·6 2093 47·1 1832 36·7<0·001
Hypertension 10 041 2981 29·7 1683 34·5 1298 25·1<0·001
Diabetes 9576 654 6·8 382 8·2 272 5·5<0·001
CHF, Swiss Francs (1 CHF =1·01 USD as of 14 November 2019).
*Pvalue for difference between men and women from ttest for continuous variables and from χ2test for binary/categorical variables. Hypertension was defined as having a previous
diagnosis or blood pressure ≥140/90 mmHg. Hypercholesterolaemia was defined as having a previous diagnosis or having total blood cholesterol >6·5mmol/l and HDL <1 mmol/l.
Diabetes was defined as self-reported diabetes or a fasting plasma glucose level of ≥7 mmol/l.
Vegetarian diets in a Swiss urban population 3
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22 % of the sample. In the sample, 46·7 % had been through
higher education or had a university degree.
Within the studied population, there were eighty-four vege-
tarians (0·8 %), sixty-six pescatarians (0·6 %) and 1682 flexitar-
ians (15·6 %). Due to the extremely low prevalence of vegans
(<10 people over the 13 years of data collection), no sub-group
analysis was conducted for this category.
Trends for diets and meat consumption
Over the 13 year study period, the prevalence of a vegetarian
diet increased from 0·5to1·2%(P=0·03; Table 2). In analysis
stratified by sex, an increase in the prevalence of vegetarians
was significant for women but not for men. The proportion of
participants following a pescatarian diet also increased signifi-
cantly from 0·3to1·1% (P<0·01) with a significant increase
for men but not for women. The prevalence of flexitarians
remained stable during the survey period (15·6 %). Over the
13 years, beef intake significantly decreased by 15 % for women
and by 9 % for men, which was barely non-significant (P=0·06),
while poultry intake significantly increased by 8 and 10 %,
respectively. Despite those variations, the overall total meat
intake remained stable (Table 3). When adjusted for education,
occupation and income, there was no longer a significant
decrease in poultry intake (online Supplementary Table S1).
Sociodemographic characteristics of different diet groups
Sociodemographic determinants of dietary choices are pre-
sented in Table 4. Compared with omnivores, vegetarians were
younger (OR 2·38; 95 % CI 1·01, 5·6) and more likely to be
women (OR 1·52; 95 % CI 0·98, 2·35), although this result was
non-significant. They were also more likely to have a university
degree than omnivores (OR 1·59; 95 % CI 1·01, 2·49). Compared
with omnivores, pescatarians were more likely to be women
(OR 1·81; 95 % CI 1·10, 3·00) and less likely to be Swiss
(OR 0·59; 95 % CI 0·36, 0·98). Flexitarians were more likely to
be female (OR 1·57; 95 % CI 1·41, 1·75), more likely to live alone
than omnivores (OR 1·49; 95 % CI 1·33, 1·66) and more likely to
be Swiss (OR 1·57; 95 % CI 1·38, 1·77). Conversely, individuals
with a low income were more likely to follow a vegetarian
(OR 1·83; 95 % CI 1·04, 3·21) or flexitarian (OR 1·31; 95 % CI
1·13, 1·53) diet. Smoking status was not associated with dietary
regimen.
Cardiovascular risk factors
The distribution of cardiovascular risk factor for each dietary
regimen is presented in Table 4. Vegetarians were less
likely to be overweight (OR 0·55; 95 % CI 0·31, 0·99), obese
(OR 0·27; 95 % CI 0·08, 0·89), hypercholesterolaemic (OR 0·25;
95 % CI 0·12, 0·49) and hypertensive (OR 0·45; 95 % CI 0·23,
0·89) when compared with omnivores. Pescatarians were less
likely to be obese (OR 0·18; 95 % CI 0·04, 0·75) and less hyper-
cholesterolaemic (OR 0·53; 95 % CI 0·29, 0·95) when compared
with omnivores. Finally, flexitarians were generally less likely
to be overweight (OR 0·72; 95 % CI 0·63, 0·82), obese
(OR 0·75; 95 % CI 0·63, 0·90) and hypertensive (OR 0·84; 95 %
CI 0·73, 0·96) than omnivores. Dietary regimen did not influence
Table 2. Trends in the prevalence of diet patterns by sex, Bus Santé study 2005–2017 (n10 797)
(Numbers; percentage values and 95 % confidence intervals)*
2005–2009 (n2340) 2010–2011 (n1959) 2012–2013 (n2061) 2014–2015 (n2182) 2016–2017 (n2256)
Δ%P
trend
n%95%CI n%95%CI n%95%CI n%95%CI n%95%CI
Total
Omnivorous 1947 83·281·7, 84·7 1650 84·282·6, 85·8 1737 84·382·7, 85·8 1808 82·981·3, 84·4 1824 80·979·2, 82·5−30·02
Flexitarian 376 16·114·6, 17·6 288 14·713·1, 16·3 290 14·112·6, 15·6 347 15·914·4, 17·4 381 16·915·4, 18·450·15
Pescatarian 6 0·30·1, 0·5110·60·2, 0·9140·70·3, 1·0100·50·2, 0·7251·10·7, 1·5 327 <0·01
Vegetarian 11 0·50·2, 0·8100·50·2, 0·8201·00·6, 1·4170·80·4, 1·2261·20·7, 1·6 145 0·03
Men
Omnivorous 991 86·784·7, 88·7 828 86·584·4, 88·7 866 86·183·9, 88·2 904 85·783·6, 87·8 937 86·484·3, 88·400·37
Flexitarian 149 13·011·1, 15·0 120 12·510·4, 14·6 125 12·410·4, 14·5 138 13·111
·1, 15·1 130 12·010·1, 13·9−80·89
Pescatarian 3 0·30·0, 0·630·30·0, 0·760·60·1, 1·150·50·1, 0·9100·90·4, 1·5 254 <0·01
Vegetarian 0 0·060·60·1, 1·190·90·3, 1·580·80·2, 1·380·70·2, 1·3170·32
Women
Omnivorous 956 79·977·6, 82·1 822 82·079·7, 84·4 870 82·580·3, 84·8 904 80·277·9, 82·5 887 75·873·3, 78·2−50·02
Flexitarian 227 19·016·7, 21·2 168 16·814·5, 19·1 165 15·713·5, 17·9 209 18·516·3, 20·8 251 21·419·1, 23·813 0·10
Pescatarian 6 0·50·1, 0·980·80·3, 1·480·80·2, 1·350·40·1, 0·8151·30·6, 1·9 156 0·06
Vegetarian 8 0·70·2, 1·140·40·0, 0·8111·00·4, 1·790·80·3, 1·3181·50·8, 2·2 130 0·04
* Prevalence in percentage and 95 % CI from margins after logistic regression, adjusted for age in sex-specific models and for sex in age-specific models. Pfor linear trend across survey years. Nrepresents the raw number of participants
reporting each dietary type. Δrepresents the percentage change in the prevalence of dietary pattern between 2005–2009 and 2016–2017, except for vegetarian diet pattern among men, for which the starting period is 2010–2011.
4 H. Wozniak et al.
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diabetes status. BMI explained part of the association between
flexitarians, vegetarians diets and hypertension as well as
between pescatarians and hypercholesterolaemia, so that
these associations were no longer significant after accounting
for BMI (online Supplementary Table S2). Adjustment for
education, occupation and income did not change the signifi-
cance or the magnitude of our results (online Supplementary
Table S3).
Association between cardiovascular risk factors on a continu-
ous scale and dietary choices is presented in Table 5. Vegetarians
had a lower BMI −2·22 (95 % CI −3·13, −1·31) kg/m2, total
cholesterol −0·44 (95 % CI −0·67, −0·21) mmol/l and
LDL −0·33 (95 % CI −0·52, −0·13) mmol/l. Pescatarians had a
lower BMI at −1·7 (95 % CI −2·72, −0·68) kg/m2, a lower total
cholesterol at −0·34 (95 % CI −0·60, −0·08) mmol/l and
LDL −0·36 (95 % CI −0·58, −0·14) mmol/l. They also had a lower
blood pressure with systolic at −4·90 (95 % CI −8·54, −1·27)
mmHg and diastolic at −3·31 (95 % CI −5·81, −0·81) mmHg.
Flexitarians also had a significant lower BMI at −0·66 (95 % CI
−0·88, −0·44) kg/m2and a lower blood pressure with systolic
at −0·97 (95 % CI −1·76, −0·17) mmHg and diastolic at −0·66
(95 % CI −1·21, −0·11) mmHg. Adjustment for education,
occupation and income did not change the significance or the
magnitude of our results (online Supplementary Table S4).
Table 3. Trends in the mean consumption of meat type by sex, Bus Santé study 2005–2017*
(Mean values and 95 % confidence intervals)
2005–2009 2010–2011 2012–2013 2014–2015 2016–2017
% Change P
trend
Mean 95 % CI Mean 95% CI Mean 95 % CI Mean 95% CI Mean 95 % CI
Men
All meat (g/d) 300 292, 308 305 297, 314 304 296, 312 299 291, 308 295 287, 303 −20·67
Beef (g/d) 133 129, 138 132 127, 137 131 127, 136 127 123, 132 122 117, 127 −90·06
Processed meat (g/d) 35 34, 37 34 32, 35 35 34, 37 35 33, 36 33 31, 34 −90·43
Poultry (g/d) 48 46, 51 52 50, 55 51 49, 54 53 51, 56 53 50, 55 8 0·04
Fish (g/d) 83 79, 87 87 83, 91 86 82, 90 84 81, 88 88 84, 91 5 0·44
Women
All meat (g/d) 228 220, 236 233 224, 241 232 223, 240 227 219, 235 223 215, 231 −20·17
Beef (g/d) 84 80, 89 83 78, 88 82 78, 87 78 74, 83 73 68, 78 −15 <0·001
Processed meat (g/d) 21 20, 23 19 18, 21 21 19, 23 20 19, 22 19 17, 20 −15 0·07
Poultry (g/d) 43 40, 45 47 44, 49 46 43, 48 48 45, 50 47 45, 50 10 0·05
Fish (g/d) 79 76, 83 83 80, 87 82 78, 86 81 77, 84 84 80, 88 6 0·31
* Mean and 95 % CI are from margins after linear regression with survey period as predictor, adjusted for age and sex. Pfor linear trend across survey years.
Table 4. Association of diet patterns with sociodemographic and cardiovascular risk factors, Bus Santé study 2005–2017* (n10 797)
(Numbers and percentages; odds ratios and 95 % confidence intervals)
Omnivorous Flexitarian Pescatarian Vegetarian
Flexitarian v.
omnivorous
Pescatarian v.
omnivorous
Vegetarian v.
omnivorous
n%n%n%n% OR 95 % CI OR 95 % CI OR 95 % CI
Women 4439 49·5 1020 60·642 63·65059·51·57 1·41, 1·75 1·81 1·10, 3·00 1·52 0·98, 2·35
Men 4526 50·5 662 39·424 36·43440·51·00 Ref. 1·00 Ref. 1·00 Ref.
Age categories
18–44 3708 41·4 670 39·827 40·94553·60·86 0·73, 1·01 0·60 0·31, 1·15 2·38 1·01, 5·61
45–64 3950 44·1 750 44·625 37·93339·30·92 0·78, 1·08 0·58 0·30, 1·12 1·79 0·75, 4·27
65þ1307 14·6 262 15·614 21·267·11·00 Ref. 1·00 Ref. 1·00 Ref.
Living alone 2852 33·4 680 42·326 40·03845·81·49 1·33, 1·66 1·35 0·82, 2·23 1·48 0·95, 2·29
Swiss nationality 5536 64·9 1203 74·935 53·85363·91·57 1·38, 1·77 0·59 0·36, 0·98 1·07 0·68, 1·70
University degree 3878 46·1 773 48·835 54·74960·51
·07 0·96, 1·20 1·34 0·82, 2·20 1·59 1·01, 2·49
Manual occupation 2263 27·9 362 23·710 16·11722·40·85 0·74, 0·97 0·55 0·28, 1·09 0·80 0·47, 1·38
Household income
<5000 CHF/month 1663 21·4 374 25·417 28·82432·01·31 1·13, 1·53 1·47 0·76, 2·83 1·83 1·04, 3·21
5000–9500 CHF/month 3039 39·2 582 39·522 37·32533·31·10 0·97, 1·26 1·05 0·57, 1·95 1·01 0·58, 1·76
>9500 CHF/month 3057 39·4 518 35·120 33·92634·71·00 Ref. 1·00 Ref. 1·00 Ref.
Current smoker 1879 22·0 365 22·7710·81315·71·06 0·93, 1·21 0·45 0·21, 1·00 0·59 0·33, 1·08
BMI categories
Normal 4408 51·7 966 61·142 65·65172·91·00 Ref. 1·00 Ref. 1·00 Ref.
Overweight 2945 34·5 433 27·420 31·31622·90·72 0·63, 0·82 0·75 0·43, 1·31 0·55 0·31, 0·99
Obese 1172 13·7 183 11·62 3·134·30·75 0·63, 0·90 0·18 0·04, 0·75 0·27 0·08, 0·89
Hypercholesterolaemia 3289 42·2 608 40·518 29·51013·30·95 0·84, 1·08 0·53 0·29, 0·95 0·25 0·12, 0·49
Hypertension 2531 30·4 423 26·816 25·01113·40·84 0·73, 0·96 0·70 0·38, 1·29 0·45 0·23, 0·89
Diabetes 547 6·9 102 6·72 3·333·81·04 0·83, 1·30 0·44 0·11, 1·86 0·75 0·23, 2·42
CHF, Swiss Francs (1 CHF =1·01 USD as of 14 November 2019).
* OR and 95 % CI from logistic or multinomial logistic regression models with the diet type as predictor, adjusted for age, sex and survey year. Hypertension was defined as having a
previous diagnosis or blood pressure ≥140/90 mmHg. Hypercholesterolaemia was defined as having a previous diagnosis or having total blood cholesterol >6·5 mmol/l and HDL
<1 mmol/l. Diabetes was defined as self-reported diabetes or a fasting plasma glucose level of ≥7 mmol/l.
Vegetarian diets in a Swiss urban population 5
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Discussion
In this 13 year cross-sectional population-based study, we
showed that the prevalence of vegetarians in the Geneva adult
population was low and slightly increased from 0·5to1·2 % from
2005–2009 to 2016–2017. An additional 1·1 % of the population
was pescatarian in 2016–2017, and flexitarians represented
15·6 % of the studied population and remained stable during
the study period. Vegans represented less than 0·1 % of the stud-
ied population. Compared with omnivores, vegetarians were
more likely to be young, have a higher education and a low
income; pescatarians were more likely to be women and flexi-
tarians were more likely to be women and had a lower income.
Total meat intake remained stable, but both sex reduced their red
meat consumption during the studied period with results
barely non-significant for men. All dietary regimens excluding/
reducing meat intake showed a more favourable cardiovascular
profile compared with omnivorous (i.e. lower BMI, lower total
cholesterol and hypertension).
The prevalence of vegetarians observed in previous studies
varies greatly. Our study found a mean prevalence in vegetarian
diet of 0·8 %, which is relatively similar to that reported in a
Finnish study(8). The present study was also a cross-sectional
examination and used an FFQ to determine the type of diet.
The prevalence was slightly lower than that in our study with
0·43 % vegetarians. Others studies have found higher prevalence
rates, ranging from 1·7to3·9 % in Europe(6,12,14)and in the
USA(13,36). Between-study differences in the prevalence of
vegetarians could be due to different methods used to identify
the type of diet. Indeed, evidence suggests that when people
self-report themselves as vegetarians, higher rates are found than
when the study design uses a specific questionnaire like the
FFQ(8). This could be due to a misunderstanding of the definition
of vegetarian, which can have a different meaning for each
participant and being influenced by cultural norms or health
literacy. In addition, it is likely that the population associates
vegetarianism with a positive behaviour and wishes to be
associated to it, thus producing an overestimation of its true
prevalence(8). For instance, the Swiss Vegetarian association
estimates the prevalence of vegetarianism in Switzerland in
2017 to be as high as 14 % (3 % vegans, 11 % vegetarians)(37),
but these latter estimates are based on a poll that included
self-defined vegetarians rather than on a report on actual food
intake as in our study. We also observed a positive trend with
the prevalence of the vegetarians having increased from 0·5%
at the beginning of the study to 1·2 % at the end. Several studies
mention an increase in vegetarianism, but they only cite surveys
conducted by vegetarian associations that may tend to overesti-
mate the prevalence of vegetarians(2,4,5). Two independent pop-
ulation-based studies have assessed trends on the prevalence of
vegetarian diets, but they presented limitations in their definition
of vegetarians(6,36). One of these focused on self-reported
vegetarians for health reasons and showed an increase from
1·6to1·9 % between 2002 and 2012 in the USA(36). Our study
provides new insight based on an independent data source.
In the present study, vegetarians were younger, had a higher
level of education and were more likely to be women compared
with omnivores, confirming the findings of previous studies(8,9).
Table 5. Association between dietary pattern and biomarkers, Bus Santé study 2005–2017 (n10 797)*
(Mean values and standard deviations; coefficients and 95 % confidence intervals)
n
Omnivorous Flexitarian Pescatarian Vegetarian Flexitarian v. omnivorous Pescatarian v. omnivorous Vegetarian v. omnivorous
Mean SD Mean SD Mean SD Mean SD Coefficient 95 % CI Coefficient 95% CI Coefficient 95 % CI
BMI (kg/m2) 10 527 25·34·324·44·323·53·222·53·8−0·66 −0·88, −0·44 −1·70 −2·72, −0·68 −2·22 −3·13, −1·31
Fasting plasma glucose (mmol/l) 10 394 5·21·05·21·15 0·55 0·90·01 −0·04, 0·07 −0·25 −0·49, −0·01 −0·02 −0·23, 0·19
TAG (mmol/l) 10 394 1·31·61
·20·80·90·51·10·6−0·01 −0·09, 0·07 −0·34 −0·71, 0·02 −0·03 −0·35, 0·29
Total cholesterol (mmol/l) 10 394 5·41·15·41·15 0·94·81·0−0·01 −0·06, 0·05 −0·34 −0·60, −0·08 −0·44 −0·67, −0·21
HDL (mmol/l) 10 394 1·50·41·60·51·70·51·50·30·03 0·00, 0·05 0·10 −0·01, 0·19 −0·08 −0·16, 0·01
LDL (mmol/l) 10 394 3·40·93·31·03 0·92·90·8−0·03 −0·07, 0·02 −0·36 −0·58, −0·14 −0·33 −0·52, −0·13
Systolic blood pressure (mmHg) 10 542 122 17·1 120 17·7 116·215·3 114·815·3−0·97 −1·76, −0·17 −4·90 −8·54, −1·27 −3·09 −6·32, 0·14
Diastolic blood pressure (mmHg) 10 548 73·510·972·311·069·49·969·59·8−0·66 −1·21, −0·11 −3·31 −5·81, −0·81 −1·90 −4·13, 0·32
* Means and standard deviations are adjusted for age, sex and survey year. Coefficients and 95 % CI are from linear regression and adjusted for age, sex, BMI and survey year.
6 H. Wozniak et al.
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The association between being vegetarian and higher level of
education could be explained by the fact that individuals having
a higher education level may be more health(38)and/or environ-
ment(39)conscious. Alternatively, this association may be due to
secular trends in education that imply that young individuals
have higher educational levels(17). The latter seems less likely
since the analyses were age adjusted. Income was inversely
associated with the following vegetarian diet, with participants
with a higher income being more likely to be omnivores in
our study. The link between income and meat consumption
seems to vary considerably depending on the country. For in-
stance, a German study found no association between following
a vegetarian diet and income(11), whereas a Canadian and French
study found an association between low income and the use of a
vegetarian diet(9,18). In Switzerland, the price of meat ranks
among the most expensive in the world(40). For low-income
individuals, meat prices could be a reason to reduce meat con-
sumption(9). Meat consumption is highly dependent on cultural
habits and social background, which may explain a variation
between countries(11).
Our study found that 15·6 % of the population could be
defined as flexitarians. To the best of our knowledge, this is
the first population-based study to precisely measure with an
FFQ the prevalence of this type of diet. Our prevalence of
flexitarians seems relatively similar to another study from the
Netherlands(12), which reported a prevalence rate of 11–15 %
flexitarians between 2009 and 2011, even though in the present
study being flexitarian was self-reported(12). Sociodemographic
data on flexitarians are lacking in the literature. Flexitarians were
more likely to be female and had a lower income than omni-
vores. However, unlike vegetarians, they did not have higher
education and were not younger than omnivores.
Interestingly, flexitarians seem to be a distinct population from
vegetarians.
Over the 13 years, the overall total meat intake and processed
meat remained stable. However, beef intake decreased by 15 %
for women and by 9 % for men, and an increase in poultry
consumption was observed. This result is interesting as it
suggests that the population may be receptive to public health
messages encouraging the reduction of red and processed meat
intake. Indeed, red and processed meat intake has been posi-
tively associated with higher incidence of CVD, type 2 diabetes,
certain cancers(3,41,42)and a higher mortality risk(41).
Compared with omnivores, individuals with reduced meat
intake generally showed a more favourable profile in terms of
cardiovascular risk factors. All dietary profiles had a lower
BMI compared with the omnivores (vegetarians of −2·2 kg/m2,
pescatarians of −1·7 kg/m2and flexitarian of −0·7 kg/m2). Both
vegetarians and pescatarians had lower rates of hypercholester-
olaemia, and flexitarians had lower values of total cholesterol
and LDL. Flexitarians and vegetarians had lower rates of hyper-
tension, and all three diets had lower values of blood pressure
compared with omnivores with results barely non-significant
for vegetarians, probably due to our small sample size.
Adjustment for education, occupation and income did not alter
the significance or magnitude of our results. However, as
expected, several of the observed associations between diet
and cardiovascular risk factors other than BMI seemed to be
mediated by BMI, supporting the hypothesis that vegetarian
diets may lead to a lower BMI, which could then result in a
decrease in cardiovascular risk factors. Overall, our findings
confirm the previous results from cross-sectional studies and
prospective cohorts(43–45)on the positive link between different
vegetarian diets and a positive cardiometabolic profile(17,20,46–50).
It has been proposed that the positive impact on health of
vegetarian diets is due to a lower energy density, a lower expo-
sure to harmful components contained in animal food (such as
saturated fats, cholesterol, haeme Fe and N-glycolylneuraminic
acid) and an increased consumption of protective elements such
as fibres and antioxidants(51), along with the positive impact on
weight discussed earlier. Although the cross-sectional nature of
our study does not allow us to conclude on the causal link
between vegetarian diets and cardiovascular risk factors, our
results are in line with those from important longitudinal
studies and several randomised controlled trials reporting the
beneficial effects of a vegetarian diet, with less evidence for
flexitarians(24,43,44,46,48,52,53). Finally, we cannot exclude that these
described positive effects may be due to unmeasured con-
founding factors. For example, these beneficial effects may be
related to the generally advantaged socio-behavioural profile
of vegetarians. In our study, this bias seems to be limited by
the fact that our population of vegetarians had a lower income
than omnivores, with low income generally being a cardio-
vascular risk factor(54).
Some limitations to our study need to be acknowledged. The
sample of vegetarians was low, which potentially leads to power
issues. Moreover, the study design did not allow to account for
how long participants had been following a specific diet. Since
an individual’s meat consumption can fluctuate from month to
month, it is possible that an FFQ conducted over a period of only
4 weeks could lead to a misclassification bias and thus mitigate
the overall results. In addition to this, although the Bus Santé
study aims to be representative of the Geneva population,
recruitment bias cannot be excluded. This could lead to an
over- or under-selection of participants with different profiles
from the population. However, the prevalence of cardiovascular
risk factors found in our study appears to be similar to that found
in the general population of Geneva(55).
Our study has several strengths. Unlike other studies
where the data came from self-reported online(9)or mailed(19)
questionnaires, in our study, the questionnaires, anthropometric
measurements and biological data came from standardised
measurements performed by trained personnel. Unlike many
previous studies(8,10,11), vegetarians were identified through an
FFQ rather than a subjective question on the type of diet that par-
ticipants were following. Evidence has shown that up to 80 % of
self-reported vegetarians were in fact omnivores(8). Finally, our
results are obtained from a cross-sectional study that was
government funded with a recruitment in the general popula-
tion, independent from parties with a potential conflict of
interests such as the industry or vegetarian associations. All these
strengths should result in more reliable and objective data.
Vegetarian diets in a Swiss urban population 7
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Conclusion
In our cross-sectional population study spanning over 13 years,
the proportion of vegetarians and pescatarians in the population
increased, whereas that of flexitarians remained stable at a
remarkably high rate. Vegetarians were younger, had a lower
income, higher education and were more likely to be women.
Like vegetarians, flexitarians were more prone to be female
and had a lower income but contrary to vegetarians they did
not have higher education and were not younger than
omnivores, suggesting that this population represents a distinct
pattern among the different vegetarians diet. Vegetarians, pesca-
tarians and flexitarians had a lower prevalence of cardiovascular
risks factors such as high BMI, hypertension or hypercholester-
olaemia. Our results confirm previous reports from longitudinal
and randomised controlled trials and reiterate that fact that pro-
moting a reduction of meat consumption would not only benefit
the planet but also population health.
Acknowledgements
This work was funded with grant from a donor of the Private
Foundation of the Geneva University Hospitals. The Private
Foundation of the Geneva University Hospitals had no role in
the design, analysis or writing of this article.
S. S., H. W. and C. L. designed research; S. S. and C. d. M. per-
formed statistical analysis; S. S., H. W., C. L., J.-L. R. and I. G.
wrote the paper; S. S. had primary responsibility for final content.
All authors read and approved the final manuscript.
The authors declare that they have no conflicts of interest.
Supplementary material
For supplementary material referred to in this article, please visit
https://doi.org/10.1017/S0007114520001762
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