Nutrition reviews
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Review Randomized Controlled Trial Clinical Trial
Zinc lozenges reduce the duration of common cold symptoms.
A randomized, double-blind, placebo-controlled clinical trial has shown that treatment of the common cold with zinc gluconate lozenges resulted in a significant reduction in duration of symptoms of the cold. Patients received zinc-containing lozenges or placebo lozenges every 2 hours for the duration of cold symptoms. The median time to complete resolution of cold symptoms was 4.4 days in the zinc group compared with 7.6 days in the placebo group. The mechanism of action of zinc in treating the common cold remains unknown.
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Mice were made deficient in transthyretin (TTR), the protein that normally transports plasma retinol complexed with retinol-binding protein (RBP), by targeted mutagenesis (TTR-knockout mice). The TTR- mice were healthy and fertile, despite extremely low plasma retinol and RBP levels (6% of wild type). Circulating retinoic acid was 2.3 times that of wild-type controls. Liver levels of RBP were 60% higher in the TTR-mutants compared to wild-type mice, suggesting that lack of TTR may block secretion of RBP-retinol from liver.
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Fluid and electrolyte homeostasis depend on a balance between the intake and output of water. Aging is characterized by reduced homeostatic capacity. Changes in the control of both water intake and excretion accompany aging and may predispose the elderly to disturbances in sodium and water balance. ⋯ The elderly have a reduced capacity to excrete a water load, which means they are predisposed to water overload and hyponatremia. Furthermore, various neuroendocrine changes in the elderly affect fluid and electrolyte homeostasis. More studies are needed to understand the etiology of the disturbances of fluid intake and output so that they can be better prevented and treated.