8. Fish

Early observations have concluded that there are fewer incidences of coronary heart diseases in populations where fish is a major component of the diet. The health benefits of dietary fish are due mainly to the presence of high levels of polyunsaturated fatty acids, mainly the omega-3 fatty acids. For example, fish oil-supplemented diet can reduce the disease symptoms associated with ventricular arrhythmias and, in some cases, lead to normalized heart beats. Fish oil also reduces the levels of blood clotting factors, cholesterol, and low-density lipoproteins, which reduces the risk of blood coagulation within the circulatory system. The high contents of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in fish oil contribute to increase memory performance by maintaining a high cellular fluidity in the brain. Increased cell fluidity provides for easy and regular translocation of signaling molecules. By increasing calcium accumulation in the mitochondria, DHA enhances apoptosis of cancer cells, though this effect is greater in the presence of butyrate. High levels of dietary DHA and EPA from fish can lead to increased incorporation of these fatty acids into immune cells, which displaces the proinflammatory omega-6 fatty acids and promotes production of anti-inflammatory cytokines. For example, fish oil-supplemented diet reduced the degree of inflammation in chronic kidney disease, especially the level of monocyte chemoattractant protein 1. Fish protein (e.g., salmon calcitonin) attenuates weight gain, especially dietary fat-mediated increase in white adipose tissue (WAT) weight, a known risk factor for obesity-linked insulin resistance. Weight-reducing effect of salmon calcitonin is due to upregulation of energy expenditure and decreased fat storage.