Cross-sectional analysis of BMI and some lifestyle variables in Flemish vegetarians compared with non-vegetarians.

Abstract

Epidemiological studies on vegetarians indicate that appropriately planned vegetarian diets are associated with certain health benefits, which may lower mortality and morbidity. A healthy lifestyle, such as regular physical activity and avoidance of harmful practices, such as smoking and heavy drinking, could also influence these positive health-related outcomes in vegetarians. This study reports BMI, smoking and drinking habits, engagement in physical activity, medication use and subjective health perception in a vegetarian population (women: n = 206, mean age 37.0 +/- 12.3 years; men: n = 120, mean age 42.3 +/- 15.9 years) as compared with a reference Belgian population (women: n = 4993, mean age 49.8 +/- 18.0 years; men: n = 4666, mean age 48.0 +/- 17.1 years). When considering the vegetarian group as a whole, the vegetarians had a lower mean BMI compared with the reference population (respectively 22.1 +/- 3.1 kg/m2 compared with 24.6 +/- 4.8 kg/m2 for women (p < 0.001) and respectively 22.6 +/- 3.6 kg/m2 compared with 25.7 +/- 4.0 kg/m2 for men (p < 0.001)). Vegetarians smoked less than subjects of the reference group (13.5% compared with 28.5% respectively; p < 0.001). During weekdays the percentage of subjects consuming alcoholic drinks in the two populations was comparable (32.8 in the vegetarian and 35.8 in the reference population; p = 0.159). During the weekend, more subjects of the reference population drank alcohol compared with the vegetarian subjects (70.2% vs. 58.6% respectively; p = 0.026). More vegetarians were involved in intensive physical activity (over 4 h per week) compared with the reference population (36.8% vs. 17.3% respectively; p < 0.001), while fewer vegetarians were involved in moderate physical activity (up to 4 h per week) compared with subjects of the reference group (28.2% and 51.0% respectively; p < 0.001). Percentages of subjects involved in no physical activity were comparable in both groups (vegetarians 34.9 vs. reference subjects 31.8; p = 0.625). Use of prescribed medication was lower among the vegetarians (25.5% compared with 47.3% in the reference population; p < 0.001), while use of non-prescribed drugs was comparable between both groups (34.1% in the vegetarian group and 28.2% in the reference group; p = 0.580). More vegetarian subjects perceived their health to be good to very good compared with the subjects of the reference population (90.4% vs. 77.2% respectively; p < 0.001). The significant difference for the BMI values when comparing the vegetarian males and females with the reference population cannot be completely explained by the evaluated lifestyle characteristics. However, the lower BMI values in vegetarians are in agreement with the literature.

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Cross-sectional analysis of BMI and some lifestyle variables in FlemishCross-sectional analysis of BMI and some lifestyle variables in Flemish
vegetarians compared with non-vegetariansvegetarians compared with non-vegetarians
K. Alewaetersa; P. Clarysb; M. Hebbelinckb; P. Deriemaekerb; J. P. Clarysa
a Department of Experimental Anatomy, Faculty of Physical Education and Physiotherapy, Vrije
Universiteit Brussel, Brussels, Belgium b Laboratory of Human Biometry, Faculty of Physical Education
and Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium
To cite this ArticleTo cite this Article Alewaeters, K. , Clarys, P. , Hebbelinck, M. , Deriemaeker, P. and Clarys, J. P.(2005) 'Cross-sectional
analysis of BMI and some lifestyle variables in Flemish vegetarians compared with non-vegetarians', Ergonomics, 48: 11,
1433 — 1444
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Cross-sectional analysis of BMI and some
lifestyle variables in Flemish vegetarians
compared with non-vegetarians
K. ALEWAETERSy*, P. CLARYSz, M. HEBBELINCKz,
P. DERIEMAEKERz and J.P. CLARYSy
yDepartment of Experimental Anatomy, Faculty of Physical Education and
Physiotherapy, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium
zLaboratory of Human Biometry, Faculty of Physical Education and Physiotherapy,
Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
Epidemiological studies on vegetarians indicate that appropriately planned
vegetarian diets are associated with certain health benefits, which may lower
mortality and morbidity. A healthy lifestyle, such as regular physical activity and
avoidance of harmful practices, such as smoking and heavy drinking, could also
influencethesepositivehealth-relatedoutcomesinvegetarians.Thisstudyreports
BMI, smoking and drinking habits, engagement in physical activity, medication
use and subjective health perception in a vegetarian population (women:
n=206, mean age 37.0+12.3 years; men: n=120, mean age 42.3+15.9 years)
as compared with a reference Belgian population (women: n=4993, mean age
49.8+18.0 years; men: n=4666, mean age 48.0+17.1 years).
When considering the vegetarian group as a whole, the vegetarians had a
lower mean BMI compared with the reference population (respectively
22.1+3.1 kg/m2compared with 24.6+4.8 kg/m2for women (p50.001)
and respectively 22.6+3.6 kg/m2compared with 25.7+4.0 kg/m2for men
(p50.001)). Vegetarians smoked less than subjects of the reference group
(13.5% compared with 28.5% respectively; p50.001). During weekdays the
percentage of subjects consuming alcoholic drinks in the two populations was
comparable (32.8 in the vegetarian and 35.8 in the reference population;
p=0.159). During the weekend, more subjects of the reference population
drank alcohol compared with the vegetarian subjects (70.2% vs. 58.6%
respectively; p=0.026). More vegetarians were involved in intensive physical
activity (over 4 h per week) compared with the reference population (36.8%
vs. 17.3% respectively; p50.001), while fewer vegetarians were involved in
moderate physical activity (up to 4 h per week) compared with subjects of the
reference group (28.2% and 51.0% respectively; p50.001). Percentages of
subjects involved in no physical activity were comparable in both groups
(vegetarians 34.9 vs. reference subjects 31.8; p=0.625). Use of prescribed
medication was lower among the vegetarians (25.5% compared with 47.3%
*Corresponding author. Email: Katrien.Alewaeters@vub.ac.be
Ergonomics,
Vol. 48, Nos. 11–14, 15 September–15 November 2005, 1433–1444
Ergonomics
ISSN 0014-0139 print/ISSN 1366-5847 online ª 2005 Taylor & Francis
http://www.tandf.co.uk/journals
DOI: 10.1080/00140130500101031
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in the reference population; p50.001), while use of non-prescribed drugs
was comparable between both groups (34.1% in the vegetarian group and
28.2% in the reference group; p=0.580). More vegetarian subjects perceived
their health to be good to very good compared with the subjects of the
reference population (90.4% vs. 77.2% respectively; p50.001).
The significant difference for the BMI values when comparing the
vegetarian males and females with the reference population cannot be com-
pletely explained by the evaluated lifestyle characteristics. However, the lower
BMI values in vegetarians are in agreement with the literature.
Keywords: Vegetarianism; Healthy lifestyle; Smoking; Alcohol consumption;
Physical activity
1. Introduction
Vegetarians do not eat meat, fish or fowland basetheir diet mainly on vegetables andfruit,
cereals, pulses, nuts and seeds. A classification is made based on whether dairy products
andeggs are included or excluded from the diet. Lacto-ovo-vegetarians include both, while
lacto-vegetarians exclude eggs and ovo-vegetarians exclude dairy products. Vegans
excludeall animal products from theirdiet, so in addition tothe exclusion ofmeat, fish and
fowl, they exclude both dairy products and eggs (Sabate ´ et al. 2001). Epidemiological
studies on vegetarians indicate that appropriately planned vegetarian diets are healthful,
nutritionally adequate and can provide certain health benefits in the prevention and
treatment of certain diseases and, hence, could lower morbidity and mortality (Key et al.
1999, American Dietetic Association 2003). Nevertheless, several authors have pointed to
vitamin B12deficiencies for strict vegetarians (vegans) (American Dietetic Association
2003). Vegetarians are shown to have lower BMI and a lower risk of death from ischaemic
heart disease when compared with non-vegetarians (Key et al. 1998). Other reported
advantages of vegetarianism are lower blood pressure, lower blood cholesterol levels and a
reduced risk of hypertension, type 2 diabetes, obesity, prostate and colon cancer (Fraser
1999, 2003, Rajaram and Sabate ´ 2000). These positive health-related outcomes in
vegetarians could be influenced by factors other than dietary practices. A healthy lifestyle,
including regular physical activity and the avoidance of harmful practices such as smoking
and drinking, may also play a role (Whitten 2001). It is also possible that certain health
benefits associated with a vegetarian diet only become apparent after a certain (perhaps
long) period of adherence. A longer duration of vegetarianism (at least 20 years) has been
shown to lead to a lower risk of early death (Chang-Claude and Frentzel-Beyme 1993).
The aim of this study on vegetarians is to report BMI, smoking and drinking habits,
engagement in physical activity, medication use and subjective health perception in a
vegetarian population as compared with a reference Belgian population (Demarest
et al. 2002).
2. Participants and methods
2.1. Subjects
Subjects were recruited in the Flemish region of Belgium through advertising in health
food shops, in publications and on the web site of vegetarian and animal rights
1434K. Alewaeters et al.
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associations, and through word of mouth. Criteria for inclusion were being a
vegetarian (for at least 1 year) and being at least 20 years of age. A total of 650
people responded, of whom 405 actually completed a health and fitness-related
questionnaire. Of these 405 volunteers, 375 met the inclusion criteria, corresponding to
a completion rate of 58%. This rather low completion rate could have been due to
subjects being discouraged when seeing the length of the questionnaire, to not having
sent a reminder to the non-responding subjects, or to the fact that no deadline for
returning the questionnaires was specified. Volunteers were able to choose between
completing an online questionnaire or a regular questionnaire, which was then sent to
them by post.
The self-administered questionnaire consisted of general questions on socio-economic
characteristics, medical history, current smoking and drinking habits, physical activity
and nutrition. Most of the items were taken from the National Health Survey (Demarest
et al. 2002), which is a validated instrument used to estimate health-related issues in the
Belgian population every 5 years. Information on physical activity was collected using
the questionnaire of Baecke et al. (1982) since questions related to physical activity were
sparse in the National Health Survey. A test–retest reliability study of the used
questionnaire was conducted over a 1-month interval (n=13). Test–retest reliability
results indicated that 57% of the questions correlated perfectly (r=1.000), 22% of the
questions had a correlation coefficient between 0.800 and 0.999 and the remaining 21% of
the questions had a correlation coefficient between 0.799 and 0.598. Of these correlations,
81% were significant on a 0.01 level, while the remaining 19% was significant on a 0.05
level. Only two questions on time dependent items did not correlate significantly
(p=0.388 and p=0.059).
The 133 responding men and 242 responding women all considered themselves
‘vegetarians’, but after closer analysis of their nutritional habits, 9.8% of the men
(n=13) and 14.9% of the women (n=36) were excluded from the test group for being
fish-eaters (i.e. people who do not eat meat but do include fish in their diet). The
majority of the remaining 120 male and 206 female subjects were lacto-ovo-vegetarians
(79.8%). Because of the small number of ovo-vegetarians (1.8%), lacto-vegetarians
(2.1%) and vegans (15.0%), all the subjects were handled as one group, referred to as
‘vegetarians’ in the rest of the article. The male subjects ranged between 23 and 98 years
old with a mean (+SD) age of 42.3+15.9 years and a median age of 38, while the
female subjects ranged between 20 and 78 years old with a mean (+SD) age of
37.0+12.3 years and a median age of 34. More women participated than men,
respectively 63.2% and 36.8%.
2.2. Data analysis
All calculations were performed using Microsoft Excel. All values were calculated
separately for men and women. Since most of the parameters were age related,
comparisons between vegetarians and non-vegetarians were made by age group (Malina
1996). The results of the vegetarians were compared with the results of a recent health
survey of a representative sample of the Belgian population (n=9000), held by the
Belgian government (Demarest et al. 2002). Statistical comparisons were performed using
SPSS (version 11.0). BMI were compared using an independent samples t-test, and a
nonparametric two-independent samples test was used to compare tobacco and alcohol
consumption, perception of health status, physical activity level and medication use.
Significance level was set at 0.05.
Analysis of BMI and lifestyle variables in Flemish vegetarians 1435
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3. Results
3.1. BMI
BMI was calculated from the body mass and the body height data given by the vegetarian
subjects. When compared with the mean BMI of the female Belgian population
(24.6+4.8 kg/m2), the BMI of the female vegetarian subjects was significantly lower with
a mean value of 22.1+3.1 kg/m2(p50.001). The same observation was made for the
men; vegetarian subjects had a mean BMI of 22.6+3.6 kg/m2compared with a BMI of
25.7+4.0 kg/m2(p50.001) for the subjects of the reference population (table 1). Only
11.9% of the men and 7.3% of the women had a BMI over the reference value of 27.
Although a BMI cut-off of 25 is more usual to indicate overweight, a cut-off of 27 was
used in order to compare these data with the results of the reference group, where a cut-
off of 27 was used. For both the vegetarian group and the reference population, mean
Table 1. Lifestyle characteristics by gender and by group.
MenWomen
Vegetarian group
(n=120)
Reference group
(n=4666)
Vegetarian group
(n=206)
Reference group
(n=4993)
Age at recruitment (years)
20–24
25–34
35–44
45–54
55–64
65–74
75+
Mean+SD (median)
4.2%
39.2%
21.7%
11.7%
12.5%
6.7%
4.2%
7.4%
18.6%
21.2%
17.8%
14.6%
12.1%
8.2%
11.7%
41.3%
21.8%
15.0%
7.3%
1.9%
1.0%
6.9%
18.0%
19.3%
17.6%
13.9%
13.5%
10.7%
42.3+15.9 (38)48.0+17.1 (46)37.0+12.3 (34)49.8+18.0 (47)
BMI+SD (kg/m2) 22.6+3.625.7+4.022.1+3.124.6+4.8
Alcohol consumers
Week
Weekend
33.3%
58.3%
41.9%
75.4%
32.5%
58.7%
28.9%
64.1%
Tobacco use
Current smokers15.8% 33.7%12.1%23.6%
Physical activity
44h/week
54h/week
Sedentary
42.5%
24.2%
33.3%
18.6%
42.8%
29.0%
33.5%
30.6%
35.9%
9.0%
45.9%
38.3%
Drug use (last 2 weeks)
Prescribed
Non-prescribed
20.8%
26.7%
39.4%
23.7%
28.2%
38.3%
54.9%
32.5%
Subjective perception of
health
Good–very good
Fair–very bad
94.8%
5.2%
79.6%
20.4%
87.9%
12.1%
74.9%
25.1%
Evolution of health
Better–a lot better
About the same
Worse–a lot worse
27.7%
57.1%
12.6%
11.7%
67.3%
11.0%
29.8%
65.4%
4.8%
14.2%
70.5%
14.6%
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BMI values increased with age, except for the upper age group (75 years and above)
where BMI values decreased. This was true for both men and women. Some age groups
were excluded from statistical analysis because of the small number of vegetarian
subjects. The excluded groups were for the men: 20–24 years (n=5), 65–74 years
(n=8), 75 years and above (n=5); and for the women: 65–74 years (n=4), 75 years
and above (n=1). For the remaining groups, the BMI value of the male vegetarian
subjects aged between 55–64 years was significantly lower than the BMI value of the
reference subjects of the same age (p=0.038) (figure 1a). The BMI values of the
Figure 1. Mean BMI (kg/m2) by gender for the vegetarian group and the reference
population. Values were significantly different: *p50.05.
Analysis of BMI and lifestyle variables in Flemish vegetarians1437
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vegetarian women aged between 25–34 years and 35–44 years were significantly lower
compared with the BMI values of the women of the same age groups from the reference
group (p=0.001 and p=0.003 respectively) (figure 1b).
3.2. Smoking
Results showed that fewer vegetarians smoked compared with the subjects of the
reference population (13.5% compared with 28.5%; p50.001) (table 1). Among the
vegetarians, the number of male smokers was comparable to the number of female
smokers (15.8% compared with 12.1% respectively; p=0.332), whilst in the reference
group more men smoked compared with women (33.7% compared with 23.6%;
p50.001). In some age groups, the number of vegetarian subjects was very small;
hence, it was decided not to subject these age groups to statistical comparison with the
matching age groups of the reference population. Because of the small number of
subjects, percentages of smokers could be somewhat misleading. For the sake of
completeness, the results of these age groups are mentioned (men: 20–34 years: n=5,
one smoker: 20.0%; 65–74 years: n=8, one smoker: 12.5%; 75 years and above:
n=5, one smoker: 20.0%; women: 65–74 years: n=4, one smoker: 25.0%; 75 years
and above: n=2, no smokers, 0.0%). In the remaining age groups, for both men
(figure 2a) and women (figure 2b), fewer vegetarian subjects smoked compared with
the reference group, reaching significance for the following age groups: men: 25–34
years (p=0.002), 35–44 years (p=0.008), 45–54 years (p=0.015); women: 20–24
years (p=0.010), 25–34 years (p=0.012), 35–44 years (p50.001), 45–54 years
(p=0.044).
3.3. Alcohol consumption
In Belgium, 35.8% of the subjects of the reference group reported consuming alcohol
during the week (Monday–Thursday) (table 1). The percentage of vegetarians drinking
alcohol during the week was comparable (32.8; p=0.159). During the weekend
(Friday–Sunday) more of the Belgian population seemed to consume alcohol than the
vegetarian population (70.2% compared with 58.6% respectively; p=0.026). No
differences were found when comparing male and female vegetarians concerning
alcohol consumption during the week (33.3% and 32.5% respectively; p=0.864). This
was not the case for the reference group, where more male subjects drank during the
week than female subjects (41.9% and 28.9% respectively; p50.001). During the
weekend, fewer Belgian women consumed alcohol than the men (64.1% and 75.4%
respectively; p50.001), whereas no difference between the vegetarian men and women
was noticed (58.3% men vs. 58.7% women; p=0.967). No difference was found
between the alcohol consumption throughout the entire week (Monday–Sunday) of
the Belgian population and the vegetarian subjects when compared by age group,
except for the female age group 25–34 years, where significantly more vegetarian
women consumed alcoholic beverages (28.2% vegetarian subjects compared with
14.4% reference subjects; p=0.028). Among the men, in the upper age group (75 years
and above), significantly fewer vegetarian subjects drank compared with the Belgian
men in the same age group (20.0% and 39.1% respectively; p=0.018). Once again, in
this latter case results must be interpreted with care because of the small number of
vegetarian subjects (n=5), and the lack of information about the amount of alcoholic
beverages consumed.
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3.4. Physical activity
The number of subjects not involved in any physical activity as leisure was comparable
between the reference group and the vegetarian group (34.9% vegetarians compared with
31.8% of the reference group; p=0.625) (table 1). The percentage of vegetarians
participating in physical activities up to 4 h a week was smaller compared with the
Belgian population (28.2 and 51.0 respectively; p50.001). In contrast, the involvement
Figure 2. Number of current smokers among vegetarian group and reference population
by gender. Values were significantly different: *p50.05.
Analysis of BMI and lifestyle variables in Flemish vegetarians 1439
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in physical activity for more than 4 h per week was remarkably higher among vegetarians
than among the subjects of the reference group (36.8% compared with 17.3%
respectively; p50.001). Both for men and women, when comparing vegetarian with
reference subjects within age groups, differences were not significant, except for the
women between the ages of 35 and 44 years (p=0.023). Within this age group, there were
a lot more vegetarian women involved in sporting activities over 4 h per week compared
with the Belgian women of this age (35.6% compared with 9.9% respectively). Of the
vegetarian females aged 35–44 years, 37.8% were involved in physical activities less than
4 h per week, whilst 26.7% did no physical activity, compared with 50.4% and 34.0% for
the reference female subjects in this age group respectively.
3.5. Medication use
3.5.1. Prescribed drugs.
declared using a prescribed drug in the last 2 weeks, whilst this was the case for only a
quarter (25.5%; p50.001) of the vegetarian subjects (table 1). For both men and women,
in most age groups, significantly fewer vegetarian subjects took prescribed drugs
compared with the Belgian subjects of the same age group (men: 25–34 years (p=0.032),
45–54 years (p=0.002), 55–64 years (p=0.005), 75 years and above (p=0.001);
women: 20–24 years (p=0.040), 25–34 years (p=0.005), 35–44 years (p=0.002),
45–54 years (p=0.002), 55–64 years (p50.001)). Once again, because of the low
number of male subjects in the upper age group (n=5), interpretation should be done
cautiously. More female subjects in the reference group used drugs than the male subjects
(54.9% and 39.4% respectively; p50.001). This was not the case in the vegetarian group
(28.2% and 20.8% of the women and men respectively; p=0.183). Whilst drug use
increased with age in the reference population, this was not noticeable among the
vegetarian subjects.
In the reference group, almost half of the subjects (47.3%)
3.5.2. Non-prescribed drugs.
vitamin and mineral supplements, non-steroidal anti-inflammatants) was comparable
between the vegetarian group and the reference population (34.1% compared with 28.2%
respectively; p=0.580) (table 1). Among the vegetarians, female subjects took more non-
prescribed drugs compared with the male subjects (38.3% vs. 26.7% respectively;
p=0.044). This was also the case among the reference subjects (32.5% women compared
with 23.7% men; p50.001). After statistical analysis none of the differences between the
age groups of the vegetarian group and the matching age groups of the reference
population was significant. Comparison of percentages of men and women indicated that
the women used more non-prescribed drugs than the men, both in the vegetarian as in the
reference group.
The use of non-prescribed drugs (homeopathic medication,
3.6. Subjective health perception
Approximately four times more people of Belgium described their health to be ‘good’ to
‘very good’ (77.2%), while the rest (22.8%) did not find their health very satisfying
(‘reasonable’, ‘bad’, ‘very bad’) (table 1). Significantly more vegetarians (90.4%;
p50.001) described their health ‘good’ to ‘very good’, whilst only 9.6% found it
‘reasonable’, ‘bad’ or ‘very bad’. In both the vegetarian group and the reference
population, more men seemed satisfied about their health compared with the women. Of
the vegetarian men 94.8% compared with 87.9% of the vegetarian women (p=0.018)
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answered ‘good’ or ‘very good’, while 79.6% of the male compared with 74.9% of the
female reference subjects (p50.001) found their health to be ‘good’ to ‘very good’. When
comparing age groups, a significantly higher number of vegetarian men in the age group
55–64 years (n=15; p=0.010) answered ‘good’ or ‘very good’. The difference was also
significant in the two following age groups (65–74 years and 75 years and above), but
because of the low number of subjects in those groups (n=8 and n=4 respectively), no
definite pronouncement about those findings can be made. Among the vegetarian women,
a significantly higher number found their health to be ‘good’ or ‘very good’ in the age
groups 20–24 years (n=22; p50.001), 25–34 years (n=83; p50.001), 35–44 years
(n=45; p50.001) and 45–54 years (n=30; p=0.001).
When asked about how their health evolved over the last 12 months, 13.0% of the
reference population answered their health to be ‘somewhat to a lot better’ compared
with 1 year ago, whereas more than double the percentage of vegetarian subjects (29.3;
p50.001) did so. Of the reference group, 74.3% of the subjects found their health to be
‘about the same’ compared with 62.8% (p=0.004) of the vegetarian subjects.
Respectively 12.8% and 7.9% (p=0.008) found their health to be ‘somewhat to a lot
worse’ when compared with 1 year ago. When comparing matching age groups,
differences between the vegetarian group and the reference population were significant for
the men in age group 45–54 years (p=0.011) and for the women in age groups 20–24
years (p=0.002), 35–44 years (p=0.000) 45–54 years (p=0.004) and 55–64 years
(p=0.010).
4. Discussion
As in most studies on vegetarians, it was not possible to work with subjects from a
random sample, since no register of vegetarians exists. Recruited vegetarian volunteers
were used in this study. Hence, conclusions about health practices of vegetarians should
be handled cautiously, due to a possible ‘healthy volunteer effect’. Vegetarians are often
also more health conscious compared with the general population and hence motivated to
participate in health-related research projects concerning their chosen diet.
Although the term vegetarianism is well defined in literature (American Dietetic
Association 2003), society is not fully familiarized with these definitions. Among the
volunteers of this study 13.1% called themselves vegetarians, while in fact they ate fish.
Values of the mean BMI in this analysis were lower than the mean of 25.7+4.8 kg/m2
for men and 24.6+4.8 kg/m2for women in a representative sample of the Belgian
population. Although underestimation of the BMI is possible, because of the tendency to
overestimate body height and underestimate body weight when self-administered
(Appleby et al. 1998), it is not likely that this can account for a large difference in
BMI values. Furthermore, since height and weight data from the reference population
were also self-reported, a possible error may have occurred in both groups. The low BMI
value found in the vegetarian group was not surprising as this is in full agreement with the
literature (Appleby et al. 1998, Sabate ´ and Blix 2001, Fraser 2003). A high BMI is
considered a risk factor for mortality and numerous conditions including diabetes and
heart disease (Spencer et al. 2003), whilst values at the lower side of the BMI scale are
generally related with a good health status (Troiano et al. 1996).
The prevalence of smoking was less than half among the vegetarian subjects compared
with the reference population. Furthermore, this difference was significant for the men
between the ages of 20–24, 25–34 and 35–44 years, whilst a significant lower amount of
female smokers occurred in the age groups 20–24, 25–34, 35–44 and 45–54 years.
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Other studies on vegetarians have also found lower smoking rates among vegetarians
compared with the general population as well as to comparable non-vegetarians (Key
et al. 1998, Davey et al. 2002). Smoking is considered one of the major causes of coronary
heart diseases (Key and Appleby 2001).
Alcohol consumption was comparable for the vegetarian subjects and the reference
group, with only less vegetarians consuming alcohol during the weekend. Yet, other
studies reported a relatively low alcohol use among Western vegetarians (Appleby et al.
1998, Clarys et al. 2004). Recently, some analyses suggest that moderate intake of alcohol
has a protective effect against coronary heart disease, yet there is no evidence that alcohol
intake actually decreases the risk of coronary heart disease among vegetarians (Key and
Appleby 2001). Willett (2002) also suggested that a daily moderate intake of alcohol
could have a positive effect on coronary heart disease.
No more vegetarians in this analysis were involved in moderate physical activity (less
than 4 h per week) compared with the reference population and about one-third of
both groups was not involved in any sports whatsoever. In contrast, a higher
percentage of vegetarian subjects were involved in physical activity for over 4 h per
week compared with the reference group. Other authors also found a higher per-
centage of high exercisers among the vegetarian subjects compared with the general
population (Key et al. 1998). Low physical activity in vegetarians was associated with
an increase in the risk of dying from cardiovascular diseases (Chang-Claude and
Frentzel-Beyme 1993).
Both the fact that the vegetarian group consumed significantly less alcohol (during the
weekend) and was significantly more involved in (intensive) physical activity could be
attributed to the fact that the reasons for following a vegetarian diet among the
volunteers in this study were health-oriented. A vegetarian diet is not per se a healthy diet.
This may be more the case in people choosing a vegetarian diet for ethical reasons (Clarys
et al. 2004).
In most age groups, significantly fewer male and female vegetarians took prescribed
medication compared with the reference subjects. The number of vegetarian and reference
subjects taking non-prescribed drugs was comparable. This may be attributed to the fact
that vegetarians are more likely to choose alternative medicine such as homeopathy,
although no literature on this subject was found. Further research will also evaluate
morbidity and co-morbidity in the vegetarian group, because a possible lower occurrence
of illness may also be the basis of a reduced intake of prescribed medication.
Most of the vegetarian subjects in the current study were satisfied with their health and
one-third of the group claimed their health to have improved over the last year. The latter
was not the case in the reference group, where only 13% reported an improvement over
the same time period.
Vegetarians generally enjoy better health, exemplified by low rates of obesity (Key and
Davey 1996, Appleby et al. 1998, Singh and Lindsted 1998), coronary heart disease
(Snowdon et al. 1984, Thorogood et al. 1994, Fraser et al. 1995), diabetes (Snowdon and
Phillips 1985) and some cancers (Thorogood et al. 1994). This may be due to the absence
of meat and a greater amount and variety of plant foods in the vegetarian diet (Willett
1999). Beneficial non-dietary lifestyle factors, such as absence of smoking, of heavy
drinking and participation in physical activities, generally more prevalent among
vegetarians, explain only part of the health benefits of vegetarians (Phillips et al. 1980,
Mills et al. 1994, Key et al. 1996). However, in the present study, significantly more
female vegetarians aged between 25–34 years consumed alcoholic beverages compared
with the reference subjects of the same age group.
1442 K. Alewaeters et al.
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The lower BMI values in the vegetarian population studied may be a result of a
healthier diet. Vegetarian diets are known to be high in fibre content and low in animal
fat (Messina and Messina 1996). Appleby et al. (1998) found a significantly inverse
association between dietary fibre and BMI, and a significant positive association
between animal fat intake and BMI. Further research on the test group in the present
study, including food questionnaire analysis, is required in order to corroborate these
findings.
Acknowledgements
The authors wish to thank all the volunteers for their willingness to complete the
questionnaire. They also wish to acknowledge the organizations EVA, GAIA & NVB for
their support, and the Unit of Epidemiology of the Scientific Institute of Public Health,
Brussels, Belgium, for providing the data of the reference population.
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