Evidence suggests that plant foods have beneficial health effects. In particular, plants contain a number of phytonutrients that may be beneficial to the health. These phytonutrients include the polyphenols and carotenoids, two groups of chemicals that may play an important role in our defence against disease. In addition, plants contain essential nutrients including vitamins, minerals and essential fatty acids, a variety of plant fibres that are important for gastrointestinal health as well as other accessory nutrients. The evidence that plant foods are beneficial to the health is extensive, but it is unclear if vegetarians benefit from their almost exclusive reliance on such foods. Certainly some studies show that certain meats, particularly preserved meats, may be detrimental to the health because they increase rates of gastrointestinal cancers. Also meats have been shown to contain pesticide residues and toxin that may have synergistic effects as disease causing agents. Vegetarianism is often therefore considered a more healthy way of life.
However, studies have compared the all-cause mortality of individuals from vegetarian and non-vegetarian groups. Such studies generally show that vegetarianism does not confer benefits against all-cause mortality. For example, in one large scale prospective study, a group of over 60,000 individuals living in the United Kingdom were followed to assess the benefits of vegetarian versus nonvegetarian diets1. The results of the study showed that there was no significant difference in the overall mortality of the two groups, However heterogeneity did exist within subgroups of the study. For example, fish eater had a greater risk of circulatory death but a lower risk of death from malignant cancer, including pancreatic cancer and cancer of the lymph tissue. Meat eater has a lower risk of respiratory disease compared with vegetarians and a lower risk of all cause mortality. However, the all cause mortality between vegetarians and nonvegetarians was similar suggesting that healthy diets may include meat and fish.
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