The American journal of clinical nutrition
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Nuts are energy-dense foods, rich in total fat and unsaturated fatty acids. The favorable fatty acid profile probably contributes to the beneficial effects of nut consumption observed in epidemiologic studies (prevention of coronary heart disease and diabetes) and feeding trials (cholesterol lowering). Besides fat, the complex matrices of nuts contain many bioactive compounds: vegetable protein, fiber, minerals, tocopherols, and phenolic compounds. ⋯ Walnut consumption also reduced expression of endothelin 1, a potent endothelial activator, in an animal model of accelerated atherosclerosis. Beneficial effects on vascular reactivity may be ascribed to several constituents of walnuts: l-arginine, the precursor of nitric oxide, alpha-linolenic acid, and phenolic antioxidants. Although more studies are warranted, the emerging picture is that nut consumption beneficially influences cardiovascular risk beyond cholesterol lowering.
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This article reviews recent epidemiologic evidence on nut intake and health outcomes. It focuses on studies in which nut consumption is directly assessed or when nuts are included in a dietary score or pattern. Epidemiologic studies have been remarkably consistent in showing an association between nut consumption and a reduced risk of coronary heart disease (CHD). ⋯ Long-term nut consumption is linked with lower body weight and lower risk of obesity and weight gain. A dietary pattern or score that includes nuts is consistently related with beneficial health outcomes, and this provides an indirect evidence of the salutary benefits of nut consumption. More longitudinal studies are needed to clarify the possible effects of nuts on diseases other than CHD.
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The World Health Organization (WHO) recently increased their recommended iodine intake during pregnancy from 200 to 250 microg/d and suggested that a median urinary iodine (UI) concentration of 150-249 microg/L indicates adequate iodine intake in pregnant women. Thyrotropin concentrations in blood collected from newborns 3-4 d after birth may be a sensitive indicator of even mild iodine deficiency during late pregnancy; a <3% frequency of thyrotropin values >5 mU/L indicates iodine sufficiency. New reference data and a simple collection system may facilitate use of the median UI concentration as an indicator of iodine status in newborns. ⋯ Whether mild-to-moderate maternal iodine deficiency produces more subtle changes in cognitive function in offspring is unclear; no controlled intervention studies have measured long-term clinical outcomes. Cross-sectional studies have, with few exceptions, reported impaired intellectual function and motor skills in children from iodine-deficient areas, but many of these studies were likely confounded by other factors that affect child development. In countries or regions where <90% of households are using iodized salt and the median UI concentration in school-age children is <100 microg/L, the WHO recommends iodine supplementation in pregnancy and infancy.
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Review
Regulation of skeletal muscle mitochondrial fatty acid metabolism in lean and obese individuals.
A reduction in fatty acid (FA) oxidation has been associated with lipid accumulation and insulin resistance in skeletal muscle of obese individuals. Numerous reports suggest that the reduction in FA oxidation may result from intrinsic mitochondrial defects, although little direct evidence has been offered to support this conclusion. This brief review summarizes recent work from our laboratory that reexamined whether this decrease in skeletal muscle FA oxidation with obesity was attributable to a dysfunction in FA oxidation within mitochondria or simply to a reduction in muscle mitochondrial content. ⋯ However, this did not result from decreased protein contents of various transcription factors, because peroxisome proliferater-activated receptor gamma coactivator 1alpha (PGC1alpha), PGC1beta, peroxisome proliferator-activated receptor alpha (PPARalpha), and mitochondrial transcription factor A (TFAM) were not reduced with obesity. In contrast, it appears that obesity is associated with altered regulation of cofactors (PGC1alpha and PGC1beta) and their downstream transcription factors (PPARalpha, PPARdelta/beta, and TFAM), because relations among these variables were present in muscle from lean individuals but not from obese individuals. These findings imply that obese individuals would benefit from interventions that increase the skeletal muscle mitochondrial content and the potential for oxidizing FAs.
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Review Meta Analysis
Glycemic response and health--a systematic review and meta-analysis: the database, study characteristics, and macronutrient intakes.
Reduction of dietary glycemic response has been proposed as a means of reducing the risk of diabetes and coronary heart disease. Its role in health maintenance and management, alongside unavailable carbohydrate (eg, fiber), is incompletely understood. ⋯ Among GI studies, observed reductions in glycemic load are most often not solely due to substitution of high for low glycemic carbohydrate foods. Available carbohydrate intake is a confounding factor. The role of unavailable carbohydrate remains to be accounted for.