original article Wien Klin Wochenschr (2014) 126:113–118 DOI 10.1007/s00508-013-0483-3
Nutrition and health: different forms of diet and their relationship with various health parameters among Austrian adults Nathalie Tatjana Burkert · Wolfgang Freidl · Franziska Großschädel · Johanna Muckenhuber · Willibald J. Stronegger · Éva Rásky
Received: 26 July 2013 / Accepted: 1 December 2013 / Published online: 17 December 2013 © Springer-Verlag Wien 2013
Summary Population-based studies report a beneficial health effect and a lower mortality rate for diets rich in fruits and vegetables. Therefore, the aim of our study was to analyze differences between various forms of diet and health-related variables. The sample for this study was taken from the Austrian Health Interview Survey 2006/07 (N = 15,474). Multivariate analyses of variance adjusted by sex, age, and socioeconomic status (SES) were conducted to examine health-related behavior, health, and quality of life depending on different forms of diet. Additionally, differences in the SES and body mass index (BMI) were analyzed. Our results show that a vegetarian diet is associated with a better health-related behavior, a lower BMI, and a higher SES. Subjects eating a carnivorous diet less rich in meat self-report poorer health, a higher number of chronic conditions, an enhanced vascular risk, as well as lower quality of life. In conclusion, our results have shown that consuming a diet rich in fruits and vegetables is associated with better health and health-related behavior. Therefore, public health programs are needed for reducing the health risks associated with a carnivorous diet. Keywords Eating behavior · Nutrition · Diet · Healthrelated behavior · Health · Quality of life
Univ.-Ass. Mag. N. T. Burkert, MA () · Prof. Dr. W. Freidl · Dr. F. Großschädel · Dr. J. Muckenhuber · Prof. Dr. W. J. Stronegger · Prof. Dr. É. Rásky Institute of Social Medicine and Epidemiology, Medical University Graz, Universitaetsplatz 6/I, 8010 Graz, Austria e-mail: [email protected]
13
Ernährung und Gesundheit – Unterschiedliche Ernährungsweisen und Zusammenhänge mit verschiedenen Gesundheitsparametern bei ÖsterreicherInnen Zusammenfassung An Populationen durchgeführte Studien zeigen, dass sich eine Ernährung, die viel Obst und Gemüse beinhaltet, vorteilhaft auf die Gesundheit und die Mortalität auswirkt. Daher war das Ziel unserer Untersuchung, Unterschiede zwischen verschiedenen Ernährungsweisen in gesundheitsrelevanten Variablen zu analysieren. Dazu wurden die Daten der österreichischen Gesundheitsbefragung (AT-HIS 2006/07; N = 15.474) analysiert. Mittels multivariater Varianzanalysen wurden Unterschiede zwischen verschiedenen Ernährungsgewohnheiten im Gesundheitsverhalten, der Gesundheit und Lebensqualität kontrolliert nach dem Geschlecht, Alter und sozioökonomischen Status (SES) berechnet. Zusätzlich wurden Unterschiede im sozioökonomischen Status (SES) und dem Body Mass Index (BMI) analysiert. Unsere Ergebnisse zeigen, dass eine vegetarische Ernährung mit einem besseren Gesundheitsverhalten, einem niedrigeren BMI und höherem SES einhergeht. Personen, die moderat Fleisch essen, haben eine schlechtere subjektive Gesundheit, leiden an mehr chronischen Krankheiten, haben ein höheres vaskuläres Risiko und eine niedrigere Lebensqualität. Zusammenfassend zeigen unsere Ergebnisse, dass der Konsum einer Ernährung mit viel Obst und Gemüse mit einer verbesserten Gesundheit und einem besseren Gesundheitsverhalten einhergeht. Daher sind Gesundheitsförderungsprogramme, die das Gesundheitsrisiko, das mit Fleischkonsum einhergeht, nötig. Schlüsselwörter Essverhalten · Ernährung · Diät · Gesundheitsverhalten · Gesundheit · Lebensqualität
Nutrition and health: different forms of diet and their relationship with various health parameters
113
original article Introduction The effect of different forms of diet on health outcome has been under research for the past decades. Studies have shown that vegetarians consume little saturated fat and cholesterol due to a higher intake of fruits, vegetables, and whole-grain products [1–3]. Overall, vegetarians have a lower body mass index (BMI) [2, 4–10], a higher socioeconomic status (SES) [11], and better health behavior, e.g., they are more physically active, drink less alcohol, and smoke less [5, 11, 12]. However, the mental health effects of a vegetarian diet or a Mediterranean diet rich in fruits, vegetables, whole-grain products, and fish are divergent [5, 13]. Moreover, these diets are associated with lower rates of hypertension, cholesterol, some chronic degenerative diseases, coronary artery disease, type 2 diabetes, gallstones, stroke, and certain cancers [1, 2, 4, 6, 8, 14–16]. Therefore, a vegetarian diet is often recommended as a method to manage weight [7] and health [17]. Even after adjustment for lifestyle factors (e.g., smoking, BMI, social class), mortality rates were lower for all causes of death, ischemic heart disease, and malignant neoplasms at a 12-year follow-up for non-meat eaters in the Oxford Vegetarian study [14]. However, other studies could show that the effect of lifestyle factors, such as physical activity, accounts for the lower disease rates, stronger than the nutritional status of the subjects [18, 19]. Moreover, convincing evidence exists that a non-meat diet is associated with lower rates of coronary heart disease, which can, at least partly, be explained by lower cholesterol levels [20]. Singh et al. [21] could show that also a diet with low meat intake is associated with lower mortality rates and increased life expectancy. Evidence concerning lower rates of cancer, colon diseases, including colon cancer, and abdominal complaints is, however, inconsistent [6, 8, 22]. Austin et al. [23] have shown that the risk to have a colorectal adenoma is significantly higher for subjects consuming a carnivorous diet, whether rich or less rich in meat. Many
studies report that consumption of red meat is associated with certain health risks, such as diabetes, colon adenomas, and colon cancer [24–28]. However, a diet that 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 [26]. Other studies report that the increased health risk is not due to consuming specific nutrients, but rather that caloric intake plays the crucial role [25, 29]. Although diets based on plant foods, such as a vegetarian diet, seem to be associated with a health benefit and a lower risk of several chronic diseases [20], and lastly, to be able to improve health [30, 31], restrictive and monotonous vegetarian diets like veganism include the risk of nutritional deficits [14, 15, 20, 26, 31]. To summarize, most studies showed a vegetarian diet to be associated with better health and lower mortality rates for specific diseases. Despite the possible overall health effects of a vegetarian diet, research about the nutritional characteristics of Austrian vegetarians is scarce and mainly focused on genetic factors [32–35]. Therefore, the aim of this study was to analyze differences in health, health-related behavior, and quality of life for various forms of diet.
Methods Study population The sample for this study was taken from the Austrian Health Interview Survey 2006/07 [36]. The analyzed data were obtained from adults aged 15 years and older (15,474 participants; 54.7 % female). The study was conducted through home-based personal interviews, with interviewees representative of the Austrian population. They were chosen from the central population register and stratified by geographic region. The age and sex distribution according to the form of nutrition for all subjects is shown in Table 1.
Table 1 Data definition and structure: number (n) and valid percentage (%) per category. (Austrian Health Interview Survey 2006/07) Sociodemographics
Vegetarian
Carnivorous diet rich in fruits and vegetables
Carnivorous diet less rich in meat
Carnivorous diet rich in meat
n
Valid %
n
Valid %
n
Valid %
n
Valid %
Men (n = 7,005)
84
24.5
1,197
32.8
2,941
39.2
2,783
69.9
Women (n = 8,469)
259
75.5
2,451
67.2
4,562
60.8
1,197
30.1
15–29 (n = 3,111)
132
38.5
682
18.7
1,191
15.9
1,106
27.8
30–44 (n = 3,979)
89
25.9
966
26.5
1,771
23.6
1,153
29.0
45–59 (n = 3,759)
66
19.2
914
25.1
1,810
24.1
969
24.3
60 or older (n = 4,625)
56
16.3
1,086
29.8
2,731
36.4
752
18.9
Total
343
2.2
3,648
23.6
7,503
48.5
3,980
25.7
Sex
Age
N = 15,474
114 Nutrition and health: different forms of diet and their relationship with various health parameters
13
original article
Overall, only 0.2 % of the interviewees were pure vegetarians (57.7 % female), 0.8 % were vegetarians consuming milk and eggs (77.3 % female), and 1.2 % were vegetarians consuming milk and fish and/or eggs (76.7 % female). Therefore, all vegetarians were analyzed as one group. A total of 23.6 % of the respondents reported to eat a carnivorous diet rich in fruits and vegetables (67.2 % female); 48.5 %, a carnivorous diet less rich in meat (60.8 % female); and 25.7 %, a carnivorous diet rich in meat (30.1 % female).
Ethical approval The study was carried out in compliance with the Declaration of Helsinki. Verbal informed consent was obtained from all subjects, witnessed, and formally recorded. The ethics committee of the Medical University of Graz approved this study [EK-number: 24-288 ex11/12].
Measurements Face-to-face interviews were conducted by questioning the subjects about their sociodemographic characteristics, diseases, health-related behavior, and psychological aspects. The independent variable in this study was eating behavior. Concerning eating behavior, the respondents were given a list of six different dietary habits and asked which one described 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 habits, without interviewers giving a clear definition of the various eating categories. We created a scale that would reflect the amount of 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). The dependent variables concerning health-related behavior were smoking (number of cigarettes per day), alcohol consumption during the past 28 days (in days), and the physical exercise score (total metabolic (MET) score) [37]. The dependent variable concerning quality of life was measured using the short version of the World Health Organization Quality of Life (WHOQOL-BREF) [38]. The four domain scores (physical health, psychological health, social relationships, and environment) were calculated and transformed. The score of each domain ranged between 4 and 20. 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). The presence of 18 chronic conditions (e.g., cardiac infarction, apoplectic stroke, cancer) was also assessed. Each condition was coded as present
13
(1) or absent (0). The total frequency score was calculated by summing up the present chronic conditions (0–18, sum index). Additionally, a vascular risk score was calculated. This variable covered the presence of the following four risk factors concerning cardiovascular diseases: hypertension, enhanced blood cholesterol level, diabetes, and smoking. Each of these risk factors was coded as present (1) or absent (0). The vascular risk score was calculated by summing up the number of risk factors present in an individual (0–4, sum index). Additionally, differences in the BMI and SES of subjects were analyzed depending on the form of diet. The BMI was calculated by dividing the weight of a person in kilograms by the square of his/her height in meters (kg/m2). The SES (ranging between 3 and 15) was calculated using the variables net equivalent income, level of education, and occupation. To achieve this, net equivalent income was determined using an equivalence scale provided by the Organisation for Economic Cooperation and Development (OECD) [39], and divided based on 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-level education. Occupation was also differentiated by five different levels: (1) unskilled job, (2) apprenticeship/skilled job, (3) self-employed/middle job, (4) qualified job/academic, and (5) headship. To verify the combination of factors used for calculating the SES, reliability analyses were performed (Cronbach α = 0.596). Additionally, correlations with the different factors were calculated and ranged between R = 0.70 and R = 0.80.
Statistical analyses To analyze the differences and variation between individuals in terms of health behavior, health, and quality of life depending on their dietary habits, multivariate analyses of variance were conducted for each domain, adjusted by sex, age, and SES. Additionally, differences in the BMI and SES were analyzed performing univariate analyses of variance. p-Values
Nutrition and health: different forms of diet and their relationship with various health parameters among Austrian adults Nathalie Tatjana Burkert · Wolfgang Freidl · Franziska Großschädel · Johanna Muckenhuber · Willibald J. Stronegger · Éva Rásky
Received: 26 July 2013 / Accepted: 1 December 2013 / Published online: 17 December 2013 © Springer-Verlag Wien 2013
Summary Population-based studies report a beneficial health effect and a lower mortality rate for diets rich in fruits and vegetables. Therefore, the aim of our study was to analyze differences between various forms of diet and health-related variables. The sample for this study was taken from the Austrian Health Interview Survey 2006/07 (N = 15,474). Multivariate analyses of variance adjusted by sex, age, and socioeconomic status (SES) were conducted to examine health-related behavior, health, and quality of life depending on different forms of diet. Additionally, differences in the SES and body mass index (BMI) were analyzed. Our results show that a vegetarian diet is associated with a better health-related behavior, a lower BMI, and a higher SES. Subjects eating a carnivorous diet less rich in meat self-report poorer health, a higher number of chronic conditions, an enhanced vascular risk, as well as lower quality of life. In conclusion, our results have shown that consuming a diet rich in fruits and vegetables is associated with better health and health-related behavior. Therefore, public health programs are needed for reducing the health risks associated with a carnivorous diet. Keywords Eating behavior · Nutrition · Diet · Healthrelated behavior · Health · Quality of life
Univ.-Ass. Mag. N. T. Burkert, MA () · Prof. Dr. W. Freidl · Dr. F. Großschädel · Dr. J. Muckenhuber · Prof. Dr. W. J. Stronegger · Prof. Dr. É. Rásky Institute of Social Medicine and Epidemiology, Medical University Graz, Universitaetsplatz 6/I, 8010 Graz, Austria e-mail: [email protected]
13
Ernährung und Gesundheit – Unterschiedliche Ernährungsweisen und Zusammenhänge mit verschiedenen Gesundheitsparametern bei ÖsterreicherInnen Zusammenfassung An Populationen durchgeführte Studien zeigen, dass sich eine Ernährung, die viel Obst und Gemüse beinhaltet, vorteilhaft auf die Gesundheit und die Mortalität auswirkt. Daher war das Ziel unserer Untersuchung, Unterschiede zwischen verschiedenen Ernährungsweisen in gesundheitsrelevanten Variablen zu analysieren. Dazu wurden die Daten der österreichischen Gesundheitsbefragung (AT-HIS 2006/07; N = 15.474) analysiert. Mittels multivariater Varianzanalysen wurden Unterschiede zwischen verschiedenen Ernährungsgewohnheiten im Gesundheitsverhalten, der Gesundheit und Lebensqualität kontrolliert nach dem Geschlecht, Alter und sozioökonomischen Status (SES) berechnet. Zusätzlich wurden Unterschiede im sozioökonomischen Status (SES) und dem Body Mass Index (BMI) analysiert. Unsere Ergebnisse zeigen, dass eine vegetarische Ernährung mit einem besseren Gesundheitsverhalten, einem niedrigeren BMI und höherem SES einhergeht. Personen, die moderat Fleisch essen, haben eine schlechtere subjektive Gesundheit, leiden an mehr chronischen Krankheiten, haben ein höheres vaskuläres Risiko und eine niedrigere Lebensqualität. Zusammenfassend zeigen unsere Ergebnisse, dass der Konsum einer Ernährung mit viel Obst und Gemüse mit einer verbesserten Gesundheit und einem besseren Gesundheitsverhalten einhergeht. Daher sind Gesundheitsförderungsprogramme, die das Gesundheitsrisiko, das mit Fleischkonsum einhergeht, nötig. Schlüsselwörter Essverhalten · Ernährung · Diät · Gesundheitsverhalten · Gesundheit · Lebensqualität
Nutrition and health: different forms of diet and their relationship with various health parameters
113
original article Introduction The effect of different forms of diet on health outcome has been under research for the past decades. Studies have shown that vegetarians consume little saturated fat and cholesterol due to a higher intake of fruits, vegetables, and whole-grain products [1–3]. Overall, vegetarians have a lower body mass index (BMI) [2, 4–10], a higher socioeconomic status (SES) [11], and better health behavior, e.g., they are more physically active, drink less alcohol, and smoke less [5, 11, 12]. However, the mental health effects of a vegetarian diet or a Mediterranean diet rich in fruits, vegetables, whole-grain products, and fish are divergent [5, 13]. Moreover, these diets are associated with lower rates of hypertension, cholesterol, some chronic degenerative diseases, coronary artery disease, type 2 diabetes, gallstones, stroke, and certain cancers [1, 2, 4, 6, 8, 14–16]. Therefore, a vegetarian diet is often recommended as a method to manage weight [7] and health [17]. Even after adjustment for lifestyle factors (e.g., smoking, BMI, social class), mortality rates were lower for all causes of death, ischemic heart disease, and malignant neoplasms at a 12-year follow-up for non-meat eaters in the Oxford Vegetarian study [14]. However, other studies could show that the effect of lifestyle factors, such as physical activity, accounts for the lower disease rates, stronger than the nutritional status of the subjects [18, 19]. Moreover, convincing evidence exists that a non-meat diet is associated with lower rates of coronary heart disease, which can, at least partly, be explained by lower cholesterol levels [20]. Singh et al. [21] could show that also a diet with low meat intake is associated with lower mortality rates and increased life expectancy. Evidence concerning lower rates of cancer, colon diseases, including colon cancer, and abdominal complaints is, however, inconsistent [6, 8, 22]. Austin et al. [23] have shown that the risk to have a colorectal adenoma is significantly higher for subjects consuming a carnivorous diet, whether rich or less rich in meat. Many
studies report that consumption of red meat is associated with certain health risks, such as diabetes, colon adenomas, and colon cancer [24–28]. However, a diet that 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 [26]. Other studies report that the increased health risk is not due to consuming specific nutrients, but rather that caloric intake plays the crucial role [25, 29]. Although diets based on plant foods, such as a vegetarian diet, seem to be associated with a health benefit and a lower risk of several chronic diseases [20], and lastly, to be able to improve health [30, 31], restrictive and monotonous vegetarian diets like veganism include the risk of nutritional deficits [14, 15, 20, 26, 31]. To summarize, most studies showed a vegetarian diet to be associated with better health and lower mortality rates for specific diseases. Despite the possible overall health effects of a vegetarian diet, research about the nutritional characteristics of Austrian vegetarians is scarce and mainly focused on genetic factors [32–35]. Therefore, the aim of this study was to analyze differences in health, health-related behavior, and quality of life for various forms of diet.
Methods Study population The sample for this study was taken from the Austrian Health Interview Survey 2006/07 [36]. The analyzed data were obtained from adults aged 15 years and older (15,474 participants; 54.7 % female). The study was conducted through home-based personal interviews, with interviewees representative of the Austrian population. They were chosen from the central population register and stratified by geographic region. The age and sex distribution according to the form of nutrition for all subjects is shown in Table 1.
Table 1 Data definition and structure: number (n) and valid percentage (%) per category. (Austrian Health Interview Survey 2006/07) Sociodemographics
Vegetarian
Carnivorous diet rich in fruits and vegetables
Carnivorous diet less rich in meat
Carnivorous diet rich in meat
n
Valid %
n
Valid %
n
Valid %
n
Valid %
Men (n = 7,005)
84
24.5
1,197
32.8
2,941
39.2
2,783
69.9
Women (n = 8,469)
259
75.5
2,451
67.2
4,562
60.8
1,197
30.1
15–29 (n = 3,111)
132
38.5
682
18.7
1,191
15.9
1,106
27.8
30–44 (n = 3,979)
89
25.9
966
26.5
1,771
23.6
1,153
29.0
45–59 (n = 3,759)
66
19.2
914
25.1
1,810
24.1
969
24.3
60 or older (n = 4,625)
56
16.3
1,086
29.8
2,731
36.4
752
18.9
Total
343
2.2
3,648
23.6
7,503
48.5
3,980
25.7
Sex
Age
N = 15,474
114 Nutrition and health: different forms of diet and their relationship with various health parameters
13
original article
Overall, only 0.2 % of the interviewees were pure vegetarians (57.7 % female), 0.8 % were vegetarians consuming milk and eggs (77.3 % female), and 1.2 % were vegetarians consuming milk and fish and/or eggs (76.7 % female). Therefore, all vegetarians were analyzed as one group. A total of 23.6 % of the respondents reported to eat a carnivorous diet rich in fruits and vegetables (67.2 % female); 48.5 %, a carnivorous diet less rich in meat (60.8 % female); and 25.7 %, a carnivorous diet rich in meat (30.1 % female).
Ethical approval The study was carried out in compliance with the Declaration of Helsinki. Verbal informed consent was obtained from all subjects, witnessed, and formally recorded. The ethics committee of the Medical University of Graz approved this study [EK-number: 24-288 ex11/12].
Measurements Face-to-face interviews were conducted by questioning the subjects about their sociodemographic characteristics, diseases, health-related behavior, and psychological aspects. The independent variable in this study was eating behavior. Concerning eating behavior, the respondents were given a list of six different dietary habits and asked which one described 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 habits, without interviewers giving a clear definition of the various eating categories. We created a scale that would reflect the amount of 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). The dependent variables concerning health-related behavior were smoking (number of cigarettes per day), alcohol consumption during the past 28 days (in days), and the physical exercise score (total metabolic (MET) score) [37]. The dependent variable concerning quality of life was measured using the short version of the World Health Organization Quality of Life (WHOQOL-BREF) [38]. The four domain scores (physical health, psychological health, social relationships, and environment) were calculated and transformed. The score of each domain ranged between 4 and 20. 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). The presence of 18 chronic conditions (e.g., cardiac infarction, apoplectic stroke, cancer) was also assessed. Each condition was coded as present
13
(1) or absent (0). The total frequency score was calculated by summing up the present chronic conditions (0–18, sum index). Additionally, a vascular risk score was calculated. This variable covered the presence of the following four risk factors concerning cardiovascular diseases: hypertension, enhanced blood cholesterol level, diabetes, and smoking. Each of these risk factors was coded as present (1) or absent (0). The vascular risk score was calculated by summing up the number of risk factors present in an individual (0–4, sum index). Additionally, differences in the BMI and SES of subjects were analyzed depending on the form of diet. The BMI was calculated by dividing the weight of a person in kilograms by the square of his/her height in meters (kg/m2). The SES (ranging between 3 and 15) was calculated using the variables net equivalent income, level of education, and occupation. To achieve this, net equivalent income was determined using an equivalence scale provided by the Organisation for Economic Cooperation and Development (OECD) [39], and divided based on 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-level education. Occupation was also differentiated by five different levels: (1) unskilled job, (2) apprenticeship/skilled job, (3) self-employed/middle job, (4) qualified job/academic, and (5) headship. To verify the combination of factors used for calculating the SES, reliability analyses were performed (Cronbach α = 0.596). Additionally, correlations with the different factors were calculated and ranged between R = 0.70 and R = 0.80.
Statistical analyses To analyze the differences and variation between individuals in terms of health behavior, health, and quality of life depending on their dietary habits, multivariate analyses of variance were conducted for each domain, adjusted by sex, age, and SES. Additionally, differences in the BMI and SES were analyzed performing univariate analyses of variance. p-Values
