Carnívoros más saludables que vegetarianos: estudio
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Nutrition and Health – The Association between Eating Behavior and Various Health Parameters: A Matched Sample Study
Population-based studies have
consistently shown that our diet has an influence on health. Therefore,
the aim of our study was to analyze differences between different
dietary habit groups in terms of health-related variables. The sample
used for this cross-sectional study was taken from the Austrian Health
Interview Survey AT-HIS 2006/07. In a first step, subjects were matched
according to their age, sex, and socioeconomic status (SES). After
matching, the total number of subjects included in the analysis was 1320
(N = 330 for each form of diet – vegetarian, carnivorous diet rich in
fruits and vegetables, carnivorous diet less rich in meat, and
carnivorous diet rich in meat). Analyses of variance were conducted
controlling for lifestyle factors in the following domains: health
(self-assessed health, impairment, number of chronic conditions,
vascular risk), health care (medical treatment, vaccinations, preventive
check-ups), and quality of life. In addition, differences concerning
the presence of 18 chronic conditions were analyzed by means of
Chi-square tests. Overall, 76.4% of all subjects were female. 40.0% of
the individuals were younger than 30 years, 35.4% between 30 and 49
years, and 24.0% older than 50 years. 30.3% of the subjects had a low
SES, 48.8% a middle one, and 20.9% had a high SES. Our results revealed
that a vegetarian diet is related to a lower BMI and less frequent
alcohol consumption. Moreover, our results showed that a vegetarian diet
is associated with poorer health (higher incidences of cancer,
allergies, and mental health disorders), a higher need for health care,
and poorer quality of life. Therefore, public health programs are needed
in order to reduce the health risk due to nutritional factors.
Citation: Burkert NT,
Muckenhuber J, Großschädl F, Rásky É, Freidl W (2014) Nutrition and
Health – The Association between Eating Behavior and Various Health
Parameters: A Matched Sample Study. PLoS ONE 9(2):
e88278.
https://doi.org/10.1371/journal.pone.0088278
Editor: Olga Y. Gorlova, Geisel School of Medicine at Dartmouth College, United States of America
Received: May 17, 2013;
Accepted: January 9, 2014;
Published: February 7, 2014
Copyright: © 2014 Burkert et al. This is an open-access article distributed under the terms of the
Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are credited.
Funding: The authors have no support or funding to report.
Competing interests: The authors have declared that no competing interests exist.
Introduction
Our
diet has an impact on our well-being and on our health. Studies have
shown a vegetarian diet to be associated with a lower incidence of
hypertension, cholesterol problems, some chronic degenerative diseases,
coronary artery disease, type II diabetes, gallstones, stroke, and
certain cancers
[1]–
[7].
A vegetarian diet is characterized by a low consumption of saturated
fat and cholesterol, due to a higher intake of fruits, vegetables and
whole-grain products
[3],
[4],
[8]. Overall, vegetarians have a lower body mass index
[1],
[4],
[5],
[7],
[9]–
[12], a higher socioeconomic status
[13], and better health behavior, i.e. they are more physically active, drink less alcohol, and smoke less
[9],
[13],
[14].
On the other hand, the mental health effects of a vegetarian diet or a
Mediterranean diet rich in fruits, vegetables, whole-grain products and
fish are divergent
[9],
[15]. For example, Michalak et al.
[16]
report that a vegetarian diet is associated with an elevated prevalence
of mental disorders. A poor meat intake has been shown to be associated
with lower mortality rates and higher life expectancy
[17],
and a diet which allows small amounts of red meat, fish and dairy
products seems to be associated with a reduced risk of coronary heart
disease as well as type 2 diabetes
[18].
Additionally, evidence concerning lower rates of cancer, colon diseases
including colon cancer, abdominal complaints, and all-cause mortality
is, however, inconsistent
[5]–
[7],
[19]–
[22].
Not only is the intake of certain nutrients, like red meat, associated with an increased health risk
[18],
[23]–
[26], high-caloric intake also plays a crucial role
[23],
[27].
Moreover, there seems to be proof that lifestyle factors like physical
activity may be more crucial in lowering disease rates than individual
dietary habits
[20],
[28]–
[29].
While, generally speaking, diets based on plants, like vegetarian
diets, seem to be associated with a certain health benefit, a lower risk
to contract certain chronic diseases
[30], and the ability to improve health
[31]–
[32], restrictive and monotonous vegetarian diets include the risk of nutritional deficits
[2],
[18],
[19],
[30],
[33]. Baines et al.
[9] report that vegetarians take more medication than non-vegetarians.
To
summarize, a number of studies have shown vegetarian diets and diets
with poor meat intake to be associated with lower mortality rates for
certain diseases. Research about the dietary habits in Austria is,
however, rather sparse and mainly focused on genetic factors
[33]–
[36].
Therefore, the aim of this study was to investigate health differences
between different dietary habit groups among Austrian adults.
Methods
Study Design and Study Population
The
sample for this cross-sectional study was taken from the Austrian
Health Interview Survey (AT-HIS) which ran from March 2006 to February
2007
[37].
The AT-HIS is a standardized survey which is conducted at regular
intervals in Austria (currently every eight years). The subjects
included in the survey form a representative sample of the Austrian
population. They were chosen from the central population register and
are distributed across the different geographic regions of Austria. The
AT-HIS is part of the European Health Interview Survey (E-HIS;
http://www.euhsid.org),
an important high-quality survey. The interviews were conducted by
free-lancers engaged by the Austrian Statistic Agency. To ensure that
all interviews were conducted in the same way, interviewers had to
participate in a training day where they were instructed on how to
conduct the survey. Time measurement, non-response analyses, and
analyses of error dialogs were performed in order to ensure consistency
between interviewers. Additionally, all interviewers were supervised by
field supervisors. Overall, 15474 individuals, aged 15 years and older,
were questioned in computer-assisted personal interviews (CAPI; 54.7%
female; response rate: 63.1%).
While
0.2% of the interviewees were pure vegetarians (57.7% female), 0.8%
reported to be vegetarians consuming milk and eggs (77.3% female), and
1.2% to be vegetarians consuming fish and/or eggs and milk (76.7%
female). 23.6% reported to combine a carnivorous diet with lots of
fruits and vegetables (67.2% female), 48.5% to eat a carnivorous diet
less rich in meat (60.8% female), and 25.7% a carnivorous diet rich in
meat (30.1% female). Since the three vegetarian diet groups included a
rather small number of persons (N = 343), they were analyzed as one
dietary habit group. Moreover, since the vegetarian group was the
smallest, we decided to match each of the vegetarians (1) with an
individual of each other dietary habit group (carnivorous diet rich in
fruits and vegetables (2), carnivorous diet less rich in meat (3) and a
carnivorous rich in meat (4)).
Matching Process
In
a first step, subjects consuming a vegetarian diet were identified
(N = 343). All vegetarians were categorized according to their sex, age
(in age-groups spanning 5 years, e.g. 20- to 24-year-olds), and
socioeconomic status (SES). Each such vegetarian was then matched with
one subject consuming a carnivorous diet rich in fruits and vegetables,
one individual eating a carnivorous diet less rich in meat, and one
subject consuming a carnivorous diet rich in meat. Only 96.2% of the
vegetarians were included in the analyses, since not all of them
corresponded to a subject of the same sex, age, and SES from a different
dietary habit group. Therefore, the total number of analyzed subjects
was 1320 (comprising 330 vegetarians, 330 subjects consuming a
carnivorous diet rich in fruits and vegetables, 330 individuals eating a
carnivorous diet less rich in meat, and 330 subjects consuming a
carnivorous diet rich in meat). Each dietary habit group was set-up
according to the demographic characteristics shown in
Table 1.
Ethical Approval
The
study was carried out in compliance with the principles laid down in
the Helsinki Declaration. No minors or children were included in the
study. Verbal informed consent was obtained from all subjects,
witnessed, and formally recorded. The Ethics Committee of the Medical
University of Graz approved the consent procedure as well as the
conductance of this study (EK-number: 24–288 ex11/12).
Variables and Measurements
Face-to-face
interviews were conducted by questioning the subjects about their
socio-demographic characteristics, health-related behavior, diseases,
medical treatments, and also psychological aspects.
The
independent variable in this study was the dietary habit of
individuals. Concerning eating behavior, the respondents were given a
list of six different dietary habits and asked which one describes their
eating behavior best (1 = vegan, 2 = vegetarian eating milk/eggs,
3 = vegetarian eating fish and/or milk/eggs, 4 = carnivorous diet rich
in fruits and vegetables, 5 = carnivorous diet less rich in meat,
6 = carnivorous diet rich in meat). Participants described their dietary
habit, without interviewers giving a clear definition of the various
eating categories. Since, overall, only 2.2% of all participants
consumed a vegetarian diet, these individuals were analyzed as one
dietary habit group. We created a scale that would reflect the animal
fat intake for each dietary habit (1 = vegetarian diet, 2 = carnivorous
diet rich in fruits and vegetables, 3 = carnivorous diet less rich in
meat, 4 = carnivorous diet rich in meat).
Since age, sex, and the socioeconomic background of subjects all have an influence on health
[38]–
[41],
we matched the subjects according to these variables in order to
control for their influence. The SES of the subjects (ranging between 3
and 15) was calculated using the following variables: net equivalent
income, level of education, and occupation. Net equivalent income was
calculated based on an equivalence scale provided by the OECD
[42],
and divided by quintiles. Level of education was measured by an ordinal
variable, distinguishing between (1) basic education (up to 15 years of
age), (2) apprenticeship/vocational school, (3) secondary education
without diploma, (4) secondary education with diploma, and (5)
university education. The occupation of the subjects was differentiated
into the following five levels: (1) unskilled worker, (2)
apprentice/skilled worker, (3) self-employed/middle job, (4) qualified
job/academic, (5) executive position. To verify the combination of
variables that served to calculate the SES, correlations with the
different variables were calculated. They ranged between r = .70 and
r = .80.
The
body mass index (BMI) and lifestyle factors (physical activity,
smoking, and alcohol consumption) were included as covariates in all
analyses. The BMI was calculated by dividing the weight of a person in
kilograms by the square of their height in meters (kg/m
2)
[43].
Physical exercise was measured using the short version of the
International Physical Activity Questionnaire (IPAQ), a self-reported
instrument, which asks for an estimate of the total weekly physical
activity (walking, moderate- and vigorous-intensity activity) performed
during the last week. The short version of the IPAQ does not
discriminate between leisure-time and non-leisure time physical
activity. The total MET score was calculated by weighting the reported
minutes per week within each activity by a MET energy expenditure
estimate that was assigned to each category
[44].
Smoking behavior was measured as the number of cigarettes smoked per
day. Alcohol consumption was surveyed as the number of days on which
alcohol was consumed during the last 28 days.
The
dependent variables focusing on ill-health included self-perceived
health, ranging from 1 (very good) to 5 (very bad), and impairment to
health, ranging from 1 (very impaired) to 3 (not impaired). We further
assessed the presence of 18 specific chronic conditions (asthma,
allergies, diabetes, cataract, tinnitus, hypertension, cardiac
infarction, apoplectic stroke, bronchitis, arthritis, sacrospinal
complaints, osteoporosis, urinary incontinence, gastric or intestinal
ulcer, cancer, migraine, mental illness (anxiety disorder or
depression), and any other chronic condition). Each condition was coded
as present (1) or absent (0). We calculated a total frequency score by
summing up the chronic conditions present (0–18, sum index).
Additionally, a vascular risk score was calculated by summing up the
variables “hypertension”, “enhanced blood cholesterol level”,
“diabetes”, and “smoking” (0–4, sum index). Each variable was coded as
present (1) or absent (0).
A
dependent variable concerning health care was created as the sum index
of the number of doctors consulted in the last 12 months (0–8, sum
index). Each of the 8 medical treatments (general practitioner,
gynecologist, urologist, dermatologist, ophthalmologist, internist,
orthopedist, and ENT physician) was coded as “consulted” (1) or “not
consulted” (0). The number of vaccinations was analyzed by calculating a
sum index combining 8 different vaccinations (influenza, tetanus,
diphtheria, polio, FSME, pneumococci, hepatitis A and B; 0–8, sum
index). Each vaccination was coded as present (1) or absent (0). In
addition, preventive health care was analyzed by calculating a sum index
of the variables “preventive check-ups”, “mammography”, “prostate gland
check-up”, and “Papanicolaou test” (0–4, sum index). Each variable was
coded as present (1) or absent (0).
The dependent variable concerning quality of life was measured using the short version of the WHOQOL (WHOQOL-BREF)
[45].
Four domain scores (physical health, psychological health, social
relationships, and environment) were calculated. These domain scores
ranged between 4 and 20.
Statistical Analysis
In
a first step subjects with different dietary habits (vegetarian,
carnivorous diet rich in fruits and vegetables, carnivorous diet less
rich in meat, carnivorous diet rich in meat) were matched according to
their sex, age, and SES. Differences in lifestyle factors (BMI, total
MET score, number of cigarettes smoked per day, and alcohol consumption
in the last four weeks) between the different dietary habit groups were
calculated by multivariate analysis of variance.
In
order to analyze the differences between the dietary habit groups,
multivariate analyses of variance were calculated for the three domains:
(1) health (self-reported health, impairment due to health problems,
number of chronic conditions, vascular risk), (2) health care (number of
visits to the doctor, number of vaccinations, number of used preventive
care offers), and (3) quality of life (physical and psychological
health, social relationships, and environment). To address the bias of
lifestyle factors impacting health, analyses of variance were
calculated, controlling for the aforementioned lifestyle variables (BMI,
physical activity, smoking behavior, and alcohol consumption).
In
the domain of “health”, the two variables “self-reported health” and
“impairment due to health problems” were originally assessed using an
ordinal scale. Therefore, we controlled the results using non-parametric
tests (Kruskal Wallis Test). Since the results were the same, only
results of the analyses of variance are reported.
In
addition, Chi-square tests were calculated for the aforementioned 18
chronic conditions in order to establish which one occurs significantly
more often, depending on the form of nutrition.
p-values <.
050 were considered as statistically significant. All analyses were calculated using IBM SPSS software (version 20.0) for Windows.
Results
Participant Characteristics and Lifestyle Differences between the Dietary Habit Groups
In
total, we analyzed the data of 1320 individuals (330 in each dietary
habit group). Each dietary habit group was set-up according to the
demographic characteristics shown in
Table 1.
Overall, 23.6% of all subjects were male and 76.4% female. 40.0% of the
individuals were younger than 30 years, 17.8% between 30 and 39 years,
17.6% between 40 and 49 years, 9.4% between 50 and 59 years, 8.4%
between 60 and 69 years, 4.4% between 70 and 79 years, and 2.4% than 80
years or older. 30.3% of the subjects had a low SES (they had an SES
score of ≤6), 48.8% a middle one (SES between >6 and ≤10), and 20.9%
had a high SES (SES>10).
Our
multivariate analysis regarding lifestyle showed a significant main
effect for the dietary habit of individuals (p = .000), showing that the
different dietary habit groups differ in their overall health behavior.
However, results of the univariate analyses showed that the dietary
habit groups only differ concerning their BMI and their alcohol
consumption.
Concerning
BMI: vegetarians have the lowest mean BMI (M = 22.9), followed by
subjects eating a carnivorous diet less rich in meat (M = 23.4), rich in
fruits and vegetables (M = 23.5), and rich in meat (M = 24.9). Heavy
meat eaters differ significantly from all other groups in terms of their
BMI (p = .000).
Concerning
physical exercise: no significant difference was found in the total MET
score between the various dietary habit groups (p = .631).
Concerning
smoking behavior: the number of cigarettes smoked per day did not
differ between the various dietary habit groups (p = .302).
Concerning
alcohol consumption: Subjects following a vegetarian diet (M = 2.6 days
in the last 28 days) or a carnivorous diet rich in fruits and
vegetables (M = 3.0 days) consume alcohol significantly less frequently
than those eating a carnivorous diet less rich in meat (M = 4.4 days) or
rich in meat (M = 4.8 days; p = .000).
Health Differences between the Dietary Habit Groups
In
the domain of health, the multivariate analysis of variance showed a
significant main effect for the dietary habit of individuals (p = .000).
Overall, vegetarians are in a poorer state of health compared to the
other dietary habit groups. Concerning self-reported health, vegetarians
differ significantly from each of the other groups, toward poorer
health (p = 000). Moreover, these subjects report higher levels of
impairment from disorders (p = .002). Vegetarians additionally report
more chronic diseases than those eating a carnivorous diet less rich in
meat (p = .000;
Table 2).
Significantly more vegetarians suffer from allergies, cancer, and
mental health ailments (anxiety, or depression) than the other dietary
habit groups (
Table 3).
Subjects who eat a carnivorous diet rich in meat more often report
urinary incontinence (p = .023). No differences between individuals
consuming different forms of diet were found regarding their vascular
risk (p = .150;
Table 2).
Differences in Health Care between the Dietary Habit Groups
Our
multivariate analysis regarding health care has shown a significant
main effect for dietary habits (p = .000) and confirmed that, overall,
subjects with a lower animal fat intake demonstrate worse health care
practices. Vegetarians and subjects eating a carnivorous diet rich in
fruits and vegetables consult doctors more often than those eating a
carnivorous diet less rich in meat (p = .003). Moreover, vegetarians are
vaccinated less often than all other dietary habit groups (p = .005)
and make use of preventive check-ups less frequently than subjects
eating a carnivorous diet rich in fruits and vegetables (p = .033;
Table 2).
Differences in Quality of Life between the Dietary Habit Groups
Regarding
quality of life, the main effect of the multivariate analysis of
variance showed no significant difference between the dietary habit
groups (p = .291). The results obtained in the univariate analyses of
variance, however, revealed that vegetarians have a lower quality of
life in the domains of “physical health” (p = .026) and “environment”
(p = .037) than subjects consuming a carnivorous diet less rich in meat.
Moreover, vegetarians have a lower quality of life regarding “social
relationships” than individuals eating a carnivorous diet rich in fruits
and vegetables, or those with a carnivorous diet less rich in meat
(p = .043). All results are shown in
Table 4.
Discussion
Overall,
our findings reveal that vegetarians report poorer health, follow
medical treatment more frequently, have worse preventive health care
practices, and have a lower quality of life. Concerning the variable
“eating behavior”, we tried to generate a variable that would reflect
the animal fat intake (1 = vegetarian, 2 = carnivorous diet rich in
fruits and vegetables, 3 = carnivorous diet less rich in meat,
4 = carnivorous diet rich in meat). The mean BMI of subjects is coupled
in nearly linear progression with the amount of animal fat intake. This
is in line with previous studies showing vegetarians to have a lower
body mass index
[1],
[4],
[5],
[7],
[9]–
[12].
Our
results have shown that vegetarians report chronic conditions and
poorer subjective health more frequently. This might indicate that the
vegetarians in our study consume this form of diet as a consequence of
their disorders, since a vegetarian diet is often recommended as a
method to manage weight
[10] and health
[46].
Unfortunately, food intake was not measured in more detail, e.g.
caloric intake was not covered. Hence, further studies will be necessary
to analyze health and its relationship with different forms of dietary
habits in more detail.
When
analyzing the frequency of chronic diseases, we found significantly
higher cancer incidence rates in vegetarians than in subjects with other
dietary habits. This is in line with previous findings, reporting that
evidence about cancer rates, abdominal complaints, and all-cause
mortality in vegetarians is rather inconsistent
[5]–
[7],
[19]–
[22].
The higher cancer incidence in vegetarians in our study might be a
coincidence, and is possibly related to factors other than the general
amount of animal fat intake, such as health-conscious behavior, since no
differences were found regarding smoking behavior and physical activity
in Austrian adults as reported in other studies for other countries
[9],
[13],
[14].
Therefore, further studies will be required in Austria in order to
analyze the incidence of different types of cancer and their association
with nutritional factors in more depth.
Several studies have shown the mental health effects of a vegetarian diet to be divergent
[9],
[15],
[16].
Vegetarians in our study suffer significantly more often from anxiety
disorder and/or depression. Additionally, they have a poorer quality of
life in terms of physical health, social relationships, and
environmental factors.
Moreover,
the use of health care differs significantly between the dietary habit
groups in our study. Vegetarians need more medical treatment than
subjects following another form of diet. However, this might be due to
the number of chronic conditions, which is higher in subjects with a
vegetarian diet.
Among the
strengths
of our study are: the large sample size, the matching according to age,
sex, and socioeconomic background, and the standardized measurement of
all variables. Other strengths of our study include considering the
influence of weight and lifestyle factors on health, e.g. physical
exercise and smoking behavior.
Potential
limitations
of our results are due to the fact that the survey was based on
cross-sectional data. Therefore, no statements can be made whether the
poorer health in vegetarians in our study is caused by their dietary
habit or if they consume this form of diet due to their poorer health
status. We cannot state whether a causal relationship exists, but
describe ascertained associations. Moreover, we cannot give any
information regarding the long-term consequences of consuming a special
diet nor concerning mortality rates. Thus, further longitudinal studies
will be required to substantiate our results. Further limitations
include the measurement of dietary habits as a self-reported variable
and the fact that subjects were asked how they would describe their
eating behavior, without giving them a clear definition of the various
dietary habit groups. However, a significant association between the
dietary habit of individuals and their weight and drinking behavior is
indicative for the validity of the variable. Another limitation concerns
the lack of detailed information regarding nutritional components (e.g.
the amount of carbohydrates, cholesterol, or fatty acids consumed).
Therefore, more in-depth studies about nutritional habits and their
effects on health are required among Austrian adults. Further studies
should e.g. investigate the influence of the various dietary habits on
the incidence of different cancer types. To our knowledge this is the
first study ever in Austria to analyze differences in terms of dietary
habits and their impact on health. We admit that the large number of
participants made it necessary to keep the questions simple, in order to
cover the large sample. Overall, we feel that our results are of
specific interest and contribute to extant scientific knowledge,
notwithstanding some limitations regarding causes and effects.
Conclusions
Our
study has shown that Austrian adults who consume a vegetarian diet are
less healthy (in terms of cancer, allergies, and mental health
disorders), have a lower quality of life, and also require more medical
treatment. Therefore, a continued strong public health program for
Austria is required in order to reduce the health risk due to
nutritional factors. Moreover, our results emphasize the necessity of
further studies in Austria, for a more in-depth analysis of the health
effects of different dietary habits.
Author Contributions
Conceived
and designed the experiments: NTB WF. Performed the experiments: NTB.
Analyzed the data: NTB JM FG ER WF. Contributed
reagents/materials/analysis tools: NTB JM FG WF. Wrote the paper: NTB ER
WF.
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https://www.gob.mx/salud/articulos/alimentacion-sana-y-balanceada-para-una-buena-salud
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