El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Background & aims: Several studies have examined the effect of vegetarian diets (VD) on metabolic syndrome (MetS) or its components, but findings have been inconsistent. The aim of this study was to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies to assess the association between VD and MetS or its components (systolic blood pressure [SBP], diastolic blood pressure [DBP], fasting glucose triglycerides, waist circumference [WC], HDL-cholesterol (HDL-C)) in adults. Methods: The Cochrane Library, EMBASE, PubMed, Web of Science, and Scopus were searched. RCTs, cohort studies and cross-sectional studies evaluating the effects of VD on MetS or its components in adults, with omnivore diet as control group, were included. Random effects meta-analyses stratified by study design were employed to calculate pooled estimates. Results: A total of 71 studies (n = 103 008) met the inclusion criteria (6 RCTs, 2 cohorts, 63 cross-sectional). VD were not associated with MetS in comparison to omnivorous diet (OR 0.96, 95% CI 0.50–1.85, p = 0.9) according to meta-analysis of five cross-sectional studies. Likewise, meta-analysis of RCTs and cohort studies indicated that consumption of VD were not associated with MetS components. Meta-analysis of cross-sectional studies demonstrated that VD were significantly associated with lower levels of SBP (mean difference [MD] −4.18 mmHg, 95%CI −5.57 to −2.80, p < 0.00001), DBP (MD −3.03 mmHg, 95% CI −4.93 to −1.13, p = 0.002), fasting glucose (MD −0.26 mmol/L, 95% CI −0.35to −0.17, p < 0.00001), WC (MD −1.63 cm, 95% CI −3.13 to −0.13, p = 0.03), and HDL-C (MD −0.05 mmol/L, 95% CI −0.07 to −0.03, p < 0.0001) in comparison to omnivorous diet. Heterogeneity of effects among cross-sectional studies was high. About, one-half of the included studies had high risk of bias. Conclusions: VD in comparison with omnivorous diet is not associated with a lower risk of MetS based on results of meta-analysis of cross-sectional studies. The association between VD and lower levels of SBP, DBP, HDL-C, and fasting glucose is uncertain due to high heterogeneity across the cross-sectional studies. Larger and controlled studies are needed to evaluate the association between VD and MetS and its components. / Revisión por pares

A random population survey (n=601) and a survey of vegetarians (n=106) were conducted to examine South Australians' beliefs about meat and vegetarianism. Meat beliefs, barriers and benefits of vegetarianism, meat consumption, personal values, use of and trust in sources of food/nutrition/health information and demographic variables were measured via a written questionnaire. There were differences in the responses of vegetarians, semi-vegetarians, and non-vegetarians. For example, vegetarians were more likely than non-vegetarians to use and trust unorthodox information sources and to hold universal values (e.g. 'equality'). The factors associated with meat consumption and four sets of health-related beliefs about meat and vegetarianism (Meat is Necessary, Vegetarianism Health Concerns and Appreciates Meat, Meat is Unhealthy, Health Benefits of Vegetarianism) were examined. Other (health and non-health) beliefs, barriers and benefits of vegetarianism were the most important factors overall to be associated with these beliefs and with meat consumption. Information sources were also associated (particularly orthodox, unorthodox, mass media, advertising, and social sources). Together, these results provided insight into how consumption of meat and plant foods might be influenced. Finally, the proportion of prospective vegetarians was gauged. Approximately 15% of non-vegetarians were found to hold similar beliefs about vegetarianism as vegetarians. Prospective vegetarians were distinct from vegetarians and the remaining omnivores. For example, they were less likely than the remaining omnivores to eat red meat as frequently or to be Anglo-Australian. The research suggested that a significant portion of the population is interested in vegetarian diets, but that certain barriers need to be overcome if this is to increase and lead to dietary change; in particular, the beliefs that vegetarian diets are nutritionally inadequate and that meat is essential for health. Tailored communications about how to prepare healthy, tasty vegetarian meals may also be useful. The results indicated the sources of food/nutrition/health information that may be most appropriate to disseminate such messages. Additionally, it was found that ethical (e.g. environmental, animal welfare) issues were linked to health and dietary behaviour. They may need to be more fully addressed by health professionals if the public is to obtain maximum benefit from plant-based diets, with minimum risk. / Thesis (Ph.D.)--Department of Public Health, 2001.

A random population survey (n=601) and a survey of vegetarians (n=106) were conducted to examine South Australians' beliefs about meat and vegetarianism. Meat beliefs, barriers and benefits of vegetarianism, meat consumption, personal values, use of and trust in sources of food/nutrition/health information and demographic variables were measured via a written questionnaire. There were differences in the responses of vegetarians, semi-vegetarians, and non-vegetarians. For example, vegetarians were more likely than non-vegetarians to use and trust unorthodox information sources and to hold universal values (e.g. 'equality'). The factors associated with meat consumption and four sets of health-related beliefs about meat and vegetarianism (Meat is Necessary, Vegetarianism Health Concerns and Appreciates Meat, Meat is Unhealthy, Health Benefits of Vegetarianism) were examined. Other (health and non-health) beliefs, barriers and benefits of vegetarianism were the most important factors overall to be associated with these beliefs and with meat consumption. Information sources were also associated (particularly orthodox, unorthodox, mass media, advertising, and social sources). Together, these results provided insight into how consumption of meat and plant foods might be influenced. Finally, the proportion of prospective vegetarians was gauged. Approximately 15% of non-vegetarians were found to hold similar beliefs about vegetarianism as vegetarians. Prospective vegetarians were distinct from vegetarians and the remaining omnivores. For example, they were less likely than the remaining omnivores to eat red meat as frequently or to be Anglo-Australian. The research suggested that a significant portion of the population is interested in vegetarian diets, but that certain barriers need to be overcome if this is to increase and lead to dietary change; in particular, the beliefs that vegetarian diets are nutritionally inadequate and that meat is essential for health. Tailored communications about how to prepare healthy, tasty vegetarian meals may also be useful. The results indicated the sources of food/nutrition/health information that may be most appropriate to disseminate such messages. Additionally, it was found that ethical (e.g. environmental, animal welfare) issues were linked to health and dietary behaviour. They may need to be more fully addressed by health professionals if the public is to obtain maximum benefit from plant-based diets, with minimum risk. / Thesis (Ph.D.)--Department of Public Health, 2001.