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Background: The maximal calcium absorption in response to vitamin D has been proposed as a biomarker for vitamin D sufficiency. Objective: The objective was to determine whether there is a threshold beyond which increasing doses of vitamin D, or concentrations of serum 25-hydroxyvitamin D [25(OH)D], no longer increase calcium absorption. Design: This was a placebo-controlled, dose-response, randomized, double-blind study of the effect of vitamin D on calcium absorption in healthy postmenopausal women. Seventy-six healthy postmenopausal women were randomly assigned to placebo or 800 IU (20 mg), 2000 IU (50 µg), or 4000 IU (100 µg) vitamin D3 for 8 wk. The technique of dual isotopes of stable calcium was used with a calcium carrier to measure calcium absorption at baseline and after 8 wk. Results: Seventy-one women with a mean ± SD age of 58.8 ± 4.9 y completed the study. The mean calcium intake was 1142 6 509 mg/d and serum 25(OH)D was 63 ± 14 nmol/L at baseline. A statistically significant linear trend of an increase in calcium absorption adjusted for age and body mass index with increasing vitamin D3 dose or serum 25(OH)D concentration was observed. A 6.7% absolute increase in calcium absorption was found in the highest vitamin D3 group (100 µg). No evidence of nonlinearity was observed in the dose-response curve. Conclusions: No evidence of a threshold of calcium absorption was found with a serum 25(OH)D range from 40 to 130 nmol/L. Calcium absorption in this range is not a useful biomarker to determine nutritional recommendations for vitamin D. This trial was registered at clinicaltrials. gov as NCT01119378. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Subjects with restrictive anorexia nervosa (AN) display increased basal plasma levels of ghrelin that normalize after refeeding. The mechanism responsible for increased ghrelin levels in AN is unknown. We studied if changes of ghrelin reactive autoantibodies (autoAbs) could explain elevated plasma ghrelin in AN. Methods: Plasma levels of autoAbs reactive with ghrelin and des-acyl ghrelin were measured by enzyme-linked immunosorbent assay in subjects with AN before and 1 mo after hospitalization (refeeding) and compared with healthy controls and with plasma levels of ghrelin peptides. Results: Decreased levels of immunoglobulin (Ig) G, IgM, and IgA classes of autoAbs reacting with acyl ghrelin were found in patients with AN. Addition of des-acyl ghrelin but not of acyl ghrelin peptides at 10−8 M to plasma before enzyme-linked immunosorbent assay showed in patients with AN but not in controls high levels of IgG autoAbs reacting with des-acyl ghrelin as a result of dissociation of des-acyl ghrelin autoAbs in immune complexes. Plasma levels of acyl and des-acyl ghrelin peptides correlated negatively with des-acyl ghrelin IgG autoAbs. Body mass index, which improved after refeeding, correlated with an increase of acyl ghrelin IgM autoAbs. Conclusion: These results show that in patients with AN, ghrelin IgG autoAbs exist mainly as immune complexes with des-acyl ghrelin accompanied by a decrease of a free fraction of these autoAbs binding acylated and des-acyl ghrelin. This decrease of bioavailable ghrelin autoAbs may underlie a long-term elevation of plasma ghrelin levels and the resulting phenomenon of ghrelin resistance in malnourished patients with AN. [Copyright &y& Elsevier]

Using content and interpretative phenomenological analysis, we explored the meaning of food and eating from the perspective of adults receiving home parenteral nutrition (PN). The aim of this research was to obtain a deeper understanding of how issues related to food and eating influence quality of life (QOL). Semistructured telephone interviews were conducted between May 2006 and January 2007 with 24 adults with intestinal failure and home PN dependency. The analysis revealed themes relevant to eating behaviors, hunger and thirst, strategies for dining in restaurants, and a perception of wasting money because of malabsorbed food. Three patterns of eating emerged: eating for survival, eating for health benefits, and eating for socialization. A proposed model illustrates how these eating patterns are linked to QOL. Being able to eat and enjoy food is an important ingredient for good self-reported QOL. Measurements of QOL for this population may be enhanced with inclusion of a food and eating domain. The social and emotional context of food and mealtimes is an important component to address in the nutrition care plan for PN-dependent adults. [Copyright &y& Elsevier]

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) both play a role in the control of glucose homeostasis, and GIP is implicated in the regulation of energy storage. The capacity of carbohydrates to induce secretion of these incretin hormones could be one of the factors determining the metabolic quality of different types of carbohydrates. We analyzed the correlation between the rate of intestinal absorption of (starch-derived) glucose and plasma concentrations of GLP-1 and GIP after ingestion of glucose and starchy foods with a different content of rapidly and slowly available glucose. In a crossover study, glucose, insulin, GLP-1, and GIP concentrations were monitored for 6 h after consumption of glucose, uncooked cornstarch (UCCS) or corn pasta in 7 healthy men. All test meals were naturally labeled with 13C. Using a primed, continuous D-[6,6-2H2]glucose infusion, the rate of appearance of exogenous glucose (RaEx) was estimated, reflecting the rate of intestinal glucose absorption. GLP-1 concentrations increased significantly from 180 to 300 min after ingestion of UCCS, the starch product with a high content of slowly available glucose. A high GIP response in the early postprandial phase (15-90 min) occurred after consumption of glucose. There was a strong positive within-subject correlation between RaEx and GIP concentrations (r = 0.73, P < 0.01) across the test meals. Rapidly and slowly digestible carbohydrates differ considerably in their ability to stimulate secretion of incretin hormones; the metabolic consequences of such differences warrant exploration. [ABSTRACT FROM AUTHOR]