单项选择题

Fish Oil Much has been made of the benefits of oil derived from fish. It is claimed that people with a diet rich in fish oil have a greatly reduced chance of heart disease and arteriosclerosis. In addition, it has been shown conclusively that people suffering from elevated blood lipids react positively to treatment using fish oils. limits’’ Diet and Diseases The advantages of fish oil became apparent after studies some two decades ago of the diet of the Inuit, or Erkimo, populations of Greenland. It was found that the Inuit, with their traditional diet of seal, whale and Arctic fish — a diet very high in fat — suffered practically no heart disease, had near zero incidence of diabetes, and enjoyed a comparatively low rate of rheumatoid arthritis. (Interestingly, incidence of cancer, equal to that found in most other parts of the world, appeared unaffected by the traditional Inuit diet.) Few Heart Attack Deaths Until the work of Dyberg and Bang in the 1970s, little attention was paid to the implications of a fish-rich diet, despite a centuries-old knowledge of Inuit customs. The two researchers noted that in one community of 1,800 people there were only three heart attack deaths between 1950 and 1974. To understand why, they examined the Inuits’’ blood lipids and diet. Omega-3 fatty acids featured strongly in the bloodstream of the research subjects, directly attributable to diet. A Comparison between the Inuits in Greenland and those in Denmark In order to rule out genetic or racial factors from their findings, Dyberg and Bang went on to compare the Greenland Inuit communities with those Inuit residing in Denmark who consumed a diet almost identical to that of the Danes. The Inuit in Denmark, particularly those who had been there for longer periods, were shown to have higher blood cholesterol levels and significantly higher serum triglyceride levels than their Greenland counterparts. In fact, the levels of the Westernized Inuits matched those of the Danes themselves, who consume mainly meat, milk products and eggs. As would be expected, levels of heart disease and arteriosclerosis of the Inuit well-established in Denmark were far closer to those of the Danes man those of the Greenland Inuit. The findings, according to the researchers, indicated an Omega-3 deficiency in the Danish diet compared with the Greenland diet. Findings in Japan Similar findings come from Japan. A comparison of the diets of farmers and fishermen, together with an examination of health records and death rates of the two groups, has shown a link between the health of the human heart and fish oil. Whereas the average Japanese farmer has 90 grams of fish a day, the average fisherman has 250 grams. In all other respects, their diets are similar. Correspondingly, fishermen have lower blood pressure and lower rates of heart disease and rheumatoid arthritis. This compares with the 20 grams eaten daily by the average person in the US, where rates of heart disease and arteriosclerosis are five to seven times higher than in Japan. Fish Oil’’s Effects in the Treatment of Hyperlipidaemic Patients Its high Omerga-3 content and easy digestibility make fish oil particularly useful in the treatment of hyperlipidaemic patients. Studies have shown an inverse relationship between dosage of salmon oil and plasma triglyceride concentrations. Specifically, it has been found that the consumption of three grams of salmon oil per day by such patients reduces their plasma triglyceride levels some 32 per cent. For patients given six grams, the levels fall by 41 per cent, and for those taking nine grams, concentrations dropped an average of 52 per cent. The table below gives the Omega-3 contents of several fish varieties as compared with a selection of vegetable-based oils and butterfat. Diabetes is rare among the Greenland Inuit.