The Journal of nutrition
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The Journal of nutrition · May 2003
ReviewSelenoprotein metabolism and function: evidence for more than one function for selenoprotein P.
Biological functions of selenium are exerted by selenoproteins that contain selenocysteine in their primary structure. Selenocysteine is synthesized and inserted into proteins cotranslationally by a complex process. Families of selenoproteins include the glutathione peroxidases, the iodothyronine deiodinases and the thioredoxin reductases. ⋯ Brain tissue did not begin accumulating (75)Se until (75)Se-labeled selenoprotein P had begun appearing in the plasma after 30 min. These results suggest that tissues like liver can take up small-molecule forms of selenium whereas presence of the element in selenoprotein P facilitates uptake by tissues like brain. Thus, there is evidence for both antioxidant and selenium transport functions of selenoprotein P.
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As incomes rise, the share of income spent on food decreases. To Engel's law should be added the observation that the diet structure changes as well. Incomes and the macronutrient composition of the diet are linked at the aggregate and-most likely-the individual level. ⋯ The lowering of energy costs ($/MJ) through technological innovation has been most marked for foods containing added sugars and fat. Although wealthier persons in poor nations are more likely to be overweight, obesity in the United States is associated with lower incomes. Obesity in the United States and similar societies may be a socioeconomic, as opposed to a medical, problem and one that is related to diet structure and diet costs.
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The Journal of nutrition · Jun 2002
ReviewLiving fast, dying when? The link between aging and energetics.
The idea that aging should be linked to energy expenditure has a long history that can be traced to the late 1800s and the industrial revolution. Machines that are run fast wear out more quickly, so the notion was born that humans and animals might experience similar fates: the faster they live (expressed as greater energy expenditure), the sooner they die. Evidence supporting the "rate-of-living" theory was gleaned from the scaling of resting metabolism and life span as functions of body mass. ⋯ However, the link between energetics and aging across species is reconcilable within the framework of the "free-radical damage hypothesis" and the "disposable soma hypothesis." Within species one might anticipate the rate-of-living model would be more appropriate. We reviewed data generated from three different sources to evaluate whether this were so, studies in which metabolic rate is experimentally increased and impacts on life span followed, studies of caloric restriction and studies where links between natural variation in metabolism and life span are sought. This review reveals that there might be contrasting effects of resting and nonresting energy expenditure on aging, with increases in the former being protective and increases in the latter being harmful.
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The Journal of nutrition · Nov 2001
ReviewThe Mediterranean diets: What is so special about the diet of Greece? The scientific evidence.
The term "Mediterranean diet," implying that all Mediterranean people have the same diet, is a misnomer. The countries around the Mediterranean basin have different diets, religions and cultures. ⋯ Analyses of the dietary pattern of the diet of Crete shows a number of protective substances, such as selenium, glutathione, a balanced ratio of (n-6):(n-3) essential fatty acids (EFA), high amounts of fiber, antioxidants (especially resveratrol from wine and polyphenols from olive oil), vitamins E and C, some of which have been shown to be associated with lower risk of cancer, including cancer of the breast. These findings should serve as a strong incentive for the initiation of intervention trials that will test the effect of specific dietary patterns in the prevention and management of patients with cancer.