European journal of nutrition
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Review
Selenium and cancer: biomarkers of selenium status and molecular action of selenium supplements.
The relationship between selenium and cancer involves many different aspects. These include the forms of selenium present in the diet and in the body, their functions and mechanisms of action, and methods employed in assessing an individual's selenium nutritional status-both in general, and in epidemiological studies of the risk of cancer in relation to diet, as well as in connection with long-term trials for investigating the disease-preventive potential of selenium supplementation. ⋯ The rapid advance in the knowledge of different selenoproteins and their biological functions has opened up new possibilities for the understanding of the biological effects of selenium supplementation. A wide variety of effects of different forms and doses of selenium has been observed in a number of experimental systems, and it is at present difficult to pinpoint the mechanism that may explain the positive preventive effects of selenium supplementation observed in some human long-term trials. Moreover, additional such trials are needed to define the benefits and risks of different types and doses of selenium supplements which in the future may be implemented for public health reasons. Another necessary focus for future research is a better understanding of the mechanisms by which selenium interferes with the carcinogenesis process.
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Mediterranean diets are characterized by olive oil, as the dominant fat source and a high to moderate consumption of fruit and vegetables, cereal products, fish, legumes, in combination with little meat and wine with meals. The "reference" Mediterranean diet seems to differ according to country, but is associated with good health and a long life expectancy. From the Seven Countries Studies, it has been shown that especially the traditional Cretan diet was associated with very low 25-year mortality rates for coronary heart disease, cancer and all-causes. ⋯ Intervention studies in East Finland and Southern Italy have convincingly shown that the coronary risk profile (lower LDL cholesterol and blood pressure levels) is improved by a Mediterranean diet. Moreover, the Cretan diet was tested in cardiac patients and showed a 70 % lower cardiac and all-causes mortality compared to the control diet. In conclusion, epidemiological studies and intervention trials suggest that the Cretan Mediterranean diet lowers the risk of coronary heart disease.