Manuel Ruz

Iron absorption and iron status are reduced after Roux-en-Y gastric bypass

BACKGROUND Iron deficiency and iron deficiency anemia are common in patients who undergo gastric bypass. The magnitude of change in iron absorption is not well known. OBJECTIVE The objective was to evaluate the effects of Roux-en-Y gastric bypass (RYGBP) on iron status and iron absorption at different stages after surgery. We hypothesized that iron absorption would be markedly impaired immediately after surgery and would not improve after such a procedure. DESIGN Anthropometric, body-composition, dietary, hematologic, and iron-absorption measures were determined in 67 severe and morbidly obese women [mean age: 36.9 +/- 9.8 y; weight: 115.1 +/- 15.6 kg, body mass index (BMI: in kg/m(2)); 45.2 +/- 4.7] who underwent RYGBP. The Roux-en-Y loop length was 125-150 cm. Determinations were carried out before and 6, 12, and 18 mo after surgery. Fifty-one individuals completed all 4 evaluations. RESULTS The hemoglobin concentration decreased significantly throughout the study (repeated-measures analysis of variance). The percentage of anemic subjects changed from 1.5% at the beginning of the study to 38.8% at 18 mo. The proportion of patients with low serum ferritin increased from 7.5% to 37.3%. The prevalence of iron deficiency anemia was 23.9% at the end of the experimental period. Iron absorption from both a standard diet and from a standard dose of ferrous ascorbate decreased significantly after 6 mo of RYGBP to 32.7% and 40.3% of their initial values, respectively. No further significant modifications were noted. CONCLUSION Iron absorption is markedly reduced after RYGBP with no further modifications, at least until 18 mo after surgery.

Inhibition of iron and copper uptake by iron, copper and zinc

Interactions of micronutrients can affect absorption and bioavailability of other nutrients by a number of mechanisms. In aqueous solutions, and at higher uptake levels, competition between elements with similar chemical characteristics and uptake process can take place. The consequences of these interactions may depend on the relative concentrations of the nutrients. In this work, we measure the effects of increasing concentrations of iron, zinc, and copper on iron and copper uptake in Caco-2 cells. Intracellular Fe or Cu levels were affected by incubating with increased concentrations of metals. However, when the cells already had different intracellular metal concentration, the uptake of Fe or Cu was nor affected. In competition studies, we showed that Cu and Zn inhibited Fe uptake, and while Fe inhibited Cu uptake, Zn did not. When the three metals were given together (1:1:1 ratio), Fe or Cu uptake was inhibited approximately 40%. These results point to a potential risk in the absorption and bioavailability of these minerals by the presence of other minerals in the diet. This aspect must be considered in food supplementation and fortification programs.

Iron, Copper, and Zinc Transport: Inhibition of Divalent Metal Transporter 1 (DMT1) and Human Copper Transporter 1 (hCTR1) by shRNA

Iron (Fe), copper (Cu), and zinc (Zn) fulfill various essential biological functions and are vital for all living organisms. They play important roles in oxygen transport, cell growth and differentiation, neurotransmitter synthesis, myelination, and synaptic transmission. Because of their role in many critical functions, they are commonly used in food fortification and supplementation strategies globally. To determine the involvement of divalent metal transporter 1 (DMT1) and human copper transporter 1 (hCTR1) on Fe, Cu, and Zn uptake, Caco-2 cells were transfected with four different shRNA plasmids to selectively inhibit DMT1 or hCTR1 transporter expression. Fe and Cu uptake and total Zn content measurements were performed in shRNA-DMT1 and shRNA-hCTR1 cells. Both shRNA-DMT1 and shRNA-hCTR1 cells had lower apical Fe uptake (a decrease of 51% and 41%, respectively), Cu uptake (a decrease of 25.8% and 38.5%, respectively), and Zn content (a decrease of 23.1% and 22.7%, respectively) compared to control cells. These results confirm that DMT1 is involved in active transport of Fe, Cu, and Zn although Zn showed a different relative capacity. These results also show that hCTR1 is able to transport Fe and Zn.

Zinc absorption and zinc status are reduced after Roux-en-Y gastric bypass: a randomized study using 2 supplements

BACKGROUND Micronutrient deficiencies are common in patients undergoing gastric bypass. The effect of this type of surgery on zinc absorption and zinc status is not well known. OBJECTIVE The objective was to evaluate the effects of Roux-en-Y gastric bypass (RYGBP) on zinc status and zinc absorption at different stages after surgery. We hypothesized that zinc status would be significantly impaired after surgery and that this impairment would be less severe in subjects receiving increased supplemental zinc. We also hypothesized that zinc absorption would be lower after surgery. DESIGN Anthropometric and body-composition variables and dietary and biochemical indexes of zinc status and zinc absorption were determined in 67 severe and morbidly obese women [mean (±SD) age: 36.9 ± 9.8 y; BMI (in kg/m(2)): 45.2 ± 4.7] who underwent RYGBP. The subjects were randomly assigned to 1 of 2 vitamin-mineral supplementation groups. Measurements were made before and 6, 12, and 18 mo after surgery. Fifty-six subjects completed the 18-mo follow-up. RESULTS Mean plasma zinc, erythrocyte membrane alkaline phosphatase activity, and the size of the rapidly exchangeable zinc pool decreased after RYGBP. Percentage zinc absorption decreased significantly from 32.3% to 13.6% at 6 mo after RYGBP and to 21% at 18 mo after surgery. No effect of supplement type was observed. CONCLUSIONS Zinc status is impaired after RYGBP, despite the finding that dietary plus supplemental zinc doubled recommended zinc intakes in healthy persons. Zinc absorption capacity is significantly reduced soon after RYGBP, with no major changes until 18 mo after surgery.

Zinc inhibits nonheme iron bioavailability in humans

There is increasing concern about potential negative interactions in combined iron and zinc supplementation. The aim of the present study was to determine the dose-response effect of zinc, given as a solution, on iron bioavailability. Twenty-two healthy adult women were selected to participate in the study. Iron, with or without zinc was given as an aqueous solution on d 1,2,14, and 15 of the study. Iron bioavailability was measured on the basis of erythrocyte incorporation of55Fe or59Fe 14 d after administration. Subjects received 0.5 mg of iron together with graded zinc concentrations (0-11.71 mg). No significant effect of zinc on iron absorption was found at Zn : Fe molar ratios up to 2 :1. At 5:1,10:1, and 20 :1 molar ratios, a dose-dependent inhibitory effect on iron absorption was observed (28-40% of iron absorption inhibition; one-way repeated-measures ANOVA, F = 4.48,p = 0.02). In conclusion, zinc administration combined with iron in an aqueous solution leads to the inhibition of iron bioavailability, which occurs in a dose-dependent way. This negative interaction should be considered for supplementation programs with both microminerals.

Controlled trial of zinc supplementation in Chilean pregnant adolescents

Objective. The aim of this study was to analyze the effect of zinc supplementation on pregnancy outcome of Chilean adolescents from low socio-economic status (LSES); they often have low zinc intakes which may affect normal growth. Study design. A double blind randomised zinc supplementation trial was conducted with 804 healthy pregnant adolescents of LSES (age 16 ± 1.3 y.). Individuals were randomly assigned to Zn supplemented (S, n = 401) or Placebo (P, n = 403) groups. During the follow-up 297 were excluded. The S group received 20 mg Zn/d and the P group received a placebo, starting before 20 weeks of gestation. Results. On admission, both groups were comparable in age, rate of underweight, gestational age (12.5 vs 12.8 weeks), and dietary zinc intakes (7.3 vs 7.6 mg/d). At delivery, the S group presented a birthweight of 3,319 ± 460 g compared with 3,250 ± 514 g in the P group (NS). The proportion of low birthweight (<2,500 g) in the S group was significantly lower than in the P group (6/249 vs 16/258, p = 0.036). Prematurity rate was lower in S than P (14/249 vs 30/258, p = 0.016). Multiple regressions found a significant effect of maternal nutritional status (p = 0.011) and zinc supplementation (p = 0.05) on birthweight. No effects on pregnancy complications, RBC or plasma alkaline phosphatase were found. Conclusions. Oral zinc supplementation affects favourably the pregnancy outcomes in Chilean adolescents from low socio-economic status.

Trace element requirements in humans: An update

Concepts about nutrient intake requirements and recommendations have emerged from a period of relative consensus about concepts and goals to one of vertiginous shifts of paradigms and a proliferation of agendas, often competing, for making nutrient and dietary recommendations in public policy. The recommendations for intakes of those trace elements considered to be essential in human nutrition are updated in the context of the ferment and controversy regarding how to establish a recommended intake. It is our contention that making universal recommendations for the intake of trace elements to cover all societies among the diverse geographic and ecological settings of the world is a futile effort. Differences in ethnicity, body size, traditional diets, genetics, and environmental stressors condition distinct needs at distinct locations. It is speculated that lower than “usual” body stores of certain trace elements may be adaptive, i.e., to improve human survival under certain adverse and challenging environmental conditions. Additionally, gaps in our knowledge regarding the bases for nutrient recommendations in the very old and the impact of new, engineered foods and dietary guidelines for intake regimes that prevent chronic diseases need to be filled. As trace elements are inorganic and can accumulate in tissues, recommendations for usual intakes confront the issue of the upper limits of tolerance and potential toxic consequences. Iron, copper, and manganese are among the trace elements for which this consideration is ever latent. The community of scientists involved in trace element biology must follow closely the chaotic situation regarding changing paradigms and agendas of oral intake recommendations, participate in the discussions when called upon, but continue to produce new findings. J. Trace Elem. Exp. Med. 11:177–195, 1998.

Rural‐urban variation in limed maize use and tortilla consumption by women in Guatemala

The tortilla, a flat‐cake made of alkali‐treated maize, is an important traditional staple of the Guatemalan diet and a particularly important source of dietary calcium. This cross‐sectional study examined rural‐urban variation in tortilla size and limed maize use in 60 households of Kekchi indigenous people from three rural, two semi‐urban and one very low‐income urban community of Guatemala. The mean weight ± SEM of tortillas from rural areas (53.1 ± 1.8) was significantly (p < .0001) greater than that of semi‐urban (40.9 ± 2.2) and urban (27.9 ± 4.2) tortillas. Tortillas prepared for sale (34.0 ± 2.9) were significantly (p < .0001) smaller than those prepared exclusively for home consumption (50.3 ± 1.7). Thus, size differences in tortillas may confound quantitative estimation of tortilla intake. More limed maize per person was prepared in semi‐urban than rural households whereas less tortilla was consumed by urban than semi‐urban adult women. In this study, womens tortilla intake did not characterize...

Changes in ghrelin concentrations one year after resective and non-resective gastric bypass: Associations with weight loss and energy and macronutrient intakes

OBJECTIVE Ghrelin is a potent stimulator of appetite and synthesized in the stomach. Its role in weight loss after gastric bypass (GBP) is still controversial. The aim of this study was to evaluate the relation between weight loss and food intake and between weight loss and changes in serum ghrelin concentrations 1 y after GBP with resection of the bypassed stomach (R-GBP) and without resection (NR-GBP). METHODS Of 50 women (37.6 ± 10.2 y old, body mass index 43.8 ± 4.8 kg/m²) with GBP, 26 had R-GBP and 24 had NR-GBP. Body weight, body composition (dual energy x-ray absorptiometry), food intake, and serum ghrelin at baseline and 12 mo after GBP were measured. RESULTS The percentage of excess weight loss was 68.9 ± 12.8% at 12 mo after GBP. At 12 mo, the decrease of serum ghrelin was greater in the R-GBP group (-25.3 ± 22.5%) compared with the NR-GBP group (+11.2 ± 50.9%, P < 0.005). After adjustment by the baseline excess of body weight, there was a greater percentage of excess weight loss in the R-GBP group only at 6 mo (61.8% versus 54.9%, P = 0.011). After controlling for the baseline intake, a significant lower carbohydrate intake was observed in the R-GBP group 6 mo after surgery (P < 0.05). CONCLUSION A greater decrease in ghrelin levels was observed only in patients who underwent R-GBP at 12 mo after surgery. This difference was not associated with differences in dietary intakes or weight loss at the same time point. Therefore, the small gastric pouch is probably more important than decreased ghrelin levels in producing long-term weight loss after R-GBP.

Dietary supplementation with selenomethylselenocysteine produces a differential proteomic response

Organic forms of selenium offer important health benefits including cancer prevention. Selenium intake has been traditionally quantified as glutathioneperoxidase activity or selenium concentration in blood or tissues. However, these indexes do not reflect organic selenium intake. Effect of dietary supplementation of rats with selenomethylselenocysteine on the blood plasma proteome was investigated in order to detect protein abundance differences between experimental (supranutritional selenium supplementation) and control [minimum selenium dose and sodium selenate instead of selenomethylselenocysteine (SeMSeCys)] groups. Four experimental groups and six control groups consisting of six rats each were fed with base diet supplemented with SeMSeCys or sodium selenate in different concentrations for different periods of time. A proteomic approach, comprising two-dimensional gel electrophoresis and mass spectrometry, was used to assess protein abundance in blood plasma. Statistically significant differences in the abundance of some proteins were detected in all the experimental groups. Four proteins were found to increase their abundance in response to the experimental conditions: apolipoprotein E, haptoglobin and alpha-1-antitrypsin abundance was related to the extent of supplementation period and transthyretin in response to SeMSeCys dose. Apolipoprotein E and transthyretin were not differentially expressed when diets were supplemented with sodium selenate instead of SeMSeCys. We postulate that these proteins are potential biomarkers of chemoprotective selenium intake.