Dietary lipids and risk of autoimmune disease

Abstract

In summary, it is well established that moderate calorie restriction or reduction in overall high calorie food intake prevents or forestalls the development of age-associated disease incidence such as breast cancer and renal disease in rodents. A similar approach could also readily be applied in humans for preventing the risk and rise of life-shortening diseases. Many age-associated diseases, particularly autoimmune diseases with viral etiology, appear to be exacerbated in the presence of adverse lipid intake such as an increased level of vegetable oils or trans-fatty acids from the usage of hydrogenated dietary oils. At present, nearly 35-40% of the total calories are from dietary fats and/or of lipid origin. Although usage of saturated fat, which increases cardiovascular disease, has been reduced to a large extent in the United States, consumption of both monounsaturated and polyunsaturated fats of omega-6 origin has either increased or simply been substituted in place of saturated fats. Further, for the past 50 years, a significant reduction in highly polyunsaturated fat consumption such as marine oil has also occurred specifically in the United States. The reduction in omega-3 lipids of marine or vegetable source occurs primarily because of short shelf life due to rancidity. However, the increased consumption of omega-6 or a vegetable source of oils and decreased omega-3 intake may increase in vivo the production of free radicals and higher proinflammatory cytokines. Our ongoing studies reveal that proinflammatory vegetable oil could increase autoimmune disease by increasing the free radical formation by decreasing the antioxidant enzyme mRNA levels, thereby further decreasing immune function, particularly the production of anti-inflammatory cytokines such as IL-2 and TGF beta mRNA levels. In contrast, omega-3 lipid intake in the presence of an antioxidant supplement appears to exert protection against autoimmunity by enhancing antioxidant enzymes and TGF beta mRNA levels and by preventing the rise in oncogene expression. However, detailed studies are required to establish the protective and deleterious role of different commonly consumed lipids or dietary oils by the general population, particularly during middle and aging years. Further, we also propose that combining nonsteroidal drug therapy along with moderate calorie reduction in the presence of more protective omega-3 dietary lipids of either marine or vegetable source and decreasing the levels of mono- and polyunsaturated lipids may provide additional protection against the age-associated rise in malignancy and autoimmune disorders.