Benefits of dietary fiber in clinical nutrition.

Dietary fiber is widely recognized as an important part of a healthy diet and is a common addition to enteral nutrition (EN) formulas. Fiber sources differ in characteristics such as solubility, fermentability, and viscosity, and it is now well known that different types of fiber exert varying physiological effects in the body. Clinical studies suggest fiber can exert a wide range of benefits in areas such as bowel function, gut health, immunity, blood glucose control, and serum lipid levels.

Reported zinc, but not copper, intakes influence whole-body bone density, mineral content and T score responses to zinc and copper supplementation in healthy postmenopausal women.

A supplementation trial starting with 224 postmenopausal women provided with adequate vitamin D and Ca was conducted to determine whether increased Cu and Zn intakes would reduce the risk for bone loss. Healthy women aged 51-80 years were recruited for a double-blind, placebo-controlled study. Women with similar femoral neck T scores and BMI were randomly assigned to two groups of 112 each that were supplemented daily for 2 years with 600 mg Ca plus maize starch placebo or 600 mg Ca plus 2 mg Cu and 12 mg Zn.

Inhibitory effects of dietary calcium on the initial uptake and subsequent retention of heme and nonheme iron in humans: comparisons using an intestinal lavage method.

Background: Calcium is the only reported dietary inhibitor of both heme- and nonheme-iron absorption. It has been proposed that the 2 forms of iron enter a common pool in the enterocyte and that calcium inhibits the serosal transfer of iron into blood.

Objectives: We aimed to ascertain whether the inhibitory effect of calcium occurs during initial mucosal uptake or during serosal transfer and to compare the serosal transfer of heme and nonheme iron, which should not differ if the 2 forms have entered a common mucosal iron pool.

Increased contractility of cardiomyocytes from copper-deficient rats is associated with upregulation of cardiac IGF-I receptor.

Hearts from severely Cu-deficient rats show a variety of pathological defects, including hypertrophy and, in intact hearts, depression of contractile function. Paradoxically, isolated cardiomyocytes from these rats exhibit enhanced contractile properties. Because hypertrophy and enhanced contractility observed with other pathologies are associated with elevation of insulin-like growth factor-I (IGF)-I, this mechanism was examined for the case of dietary Cu deficiency.

Controlled substitution of soy protein for meat protein: effects on calcium retention, bone, and cardiovascular health indices in postmenopausal women.

In a controlled feeding study, the effects of substituting 25 g soy protein for meat on calcium retention and bone biomarkers were determined. Postmenopausal women (n = 13) ate two diets that were similar, except that, in one diet, 25 g high-isoflavone soy protein (SOY) was substituted for an equivalent amount of meat protein (control diet), for 7 wk each in a randomized crossover design. After 3 wk of equilibration, calcium retention was measured by labeling the 2-d menu with (47)Ca, followed by whole-body counting for 28 d.

Controlled high meat diets do not affect calcium retention or indices of bone status in healthy postmenopausal women.

Calcium balance is decreased by an increased intake of purified proteins, although the effects of common dietary sources of protein (like meat) on calcium economy remain controversial. We compared the effects of several weeks of controlled high and low meat diets on body calcium retention, using sensitive radiotracer and whole body scintillation counting methodology. Healthy postmenopausal women (n = 15) consumed diets with similar calcium content (approximately 600 mg), but either low or high in meat (12 vs.

Increases in insulin-like growth factor-1 level and peroxidative damage after gestational ethanol exposure in rats.

Ethanol exposure during pregnancy elicits profound detrimental developmental and behavioral effects such as reduced levels of insulin-like growth factor-1 (IGF-1) in the fetus. However, few reports have addressed its impact on postpartum dams. This study was designed to examine the influence of gestational ethanol exposure on postpartum maternal organ oxidative damage and IGF-1 level.

Inadequate copper intake reduces serum insulin-like growth factor-I and bone strength in growing rats fed graded amounts of copper and zinc.

This study examined the effects of graded intakes of zinc (Zn) and copper (Cu) on serum insulin-like growth-factor-I (IGF-I) concentration and bone quality in growing rats. Using a 3 x 4 factorial design, weanling male Sprague-Dawley rats were randomly assigned to 12 groups (n = 7 per group) and were fed one of nine modified AIN-93G basal diets with varying amounts of Cu (0.3, 3 and 10 micro g/g) and Zn (5, 15 and 45 micro g/g) for 6 wk.

Impact of estrogen replacement on ventricular myocyte contractile function and protein kinase B/Akt activation.

Women with functional ovaries have a lower cardiovascular risk than men and postmenopausal women. However, estrogen replacement therapy remains controversial. This study examined the effect of ovarian hormone deficiency and estrogen replacement on ventricular myocyte contractile function and PKB/Akt activation.

Initial uptake and absorption of nonheme iron and absorption of heme iron in humans are unaffected by the addition of calcium as cheese to a meal with high iron bioavailability.

Background: Quantitative data on the mucosal uptake and serosal transfer of nonheme-iron absorption in humans and the effects of calcium on these components are limited.

Objective: Our objective was to measure the initial mucosal uptake and the subsequent serosal transfer of nonheme iron and to determine the effects of adding calcium to a meal on both heme- and nonheme-iron retention.

Design: Whole-gut lavage and whole-body scintillation counting methods were applied to determine the 8-h uptake of nonheme iron and the 2-wk retention (absorption) of heme and nonheme iron in healthy adults (n = 17) after the consumption of meals of radiolabeled food.

Mucosal uptake and whole-body retention of dietary manganese are not altered in beta2-microglobulin knockout mice.

To further examine the interrelationships between manganese and iron absorption, the mucosal uptake, initial rate of loss, whole-body retention, and tissue distribution of an orally administered 54Mn radiotracer were compared between normal and beta2-microglobulin knockout [beta2m(-/-)] mice. These mutant mice are commonly used as a model for the study of human hemochromatosis, a hereditary iron-overload disease. Initial uptake of 54Mn by the intestinal mucosa, the liver, and the brain was not different between the two strains.

Adaptation in iron absorption: iron supplementation reduces nonheme-iron but not heme-iron absorption from food.

Background: Results of cross-sectional studies suggest that in healthy people, iron absorption adapts to meet physiologic needs and stabilize iron stores, but this has not been adequately tested in longitudinal studies.

Objective: We tested whether heme- and nonheme-iron absorption decrease in response to increased iron intake and whether iron stores reach a steady state.

Design: In a randomized, placebo-controlled trial, heme- and nonheme-iron absorption by healthy men and women (n = 57) were measured before and after 12 wk of supplementation with 50 mg Fe/d as ferrous sulfate.

Adaptation of iron absorption in men consuming diets with high or low iron bioavailability.

Background: Short-term measurements of iron absorption are substantially influenced by dietary bioavailability of iron, yet bioavailability negligibly affects serum ferritin in longer, controlled trials.

Objective: Our objective was to test the hypothesis that in men fed diets with high or low iron bioavailability, iron absorption adapts to homeostatically maintain body iron stores.

Design: Heme- and nonheme-iron absorption from whole diets were measured in 31 healthy men at 0 and 10 wk while the men consumed weighed, 2-d repeating diets with either high or low iron bioavailability for 12 wk.

Dietary copper primarily affects antioxidant capacity and dietary iron mainly affects iron status in a surface response study of female rats fed varying concentrations of iron, zinc and copper.

This study was designed to examine the interactions among dietary iron (Fe), copper (Cu), and zinc (Zn) and their effects on Fe status and oxidative stress in female rats. In a three-factor central composite response surface design, rats were assigned to 15 groups and fed modified AIN-93G basal diets with varying amounts of Fe and Zn (7.0, 15.

Nonheme-iron absorption, fecal ferritin excretion, and blood indexes of iron status in women consuming controlled lactoovovegetarian diets for 8 wk.

Background: The characteristics of vegetarian diets suggest that these diets would have lower dietary iron bioavailability than nonvegetarian diets, but there is no evidence of iron deficiency in vegetarians.

Objective: We evaluated the responsiveness of serum and fecal ferritin to differences in iron absorption from controlled lactoovovegetarian and nonvegetarian diets.

Design: Twenty-one women aged 20-42 y with serum ferritin concentrations from 6 to 149 microg/L consumed lactoovovegetarian and nonvegetarian weighed diets for 8 wk each (crossover design).

Urinary riboflavin and its metabolites: effects of riboflavin supplementation in healthy residents of rural Georgia (USA).

The following study was designed to provide a comprehensive assessment of urinary riboflavin and flavin metabolites before and after ingestion of a riboflavin load in normal human volunteers. With respect to riboflavin, the total flavin excretion, the flavin-to-creatinine ratio, and the response of the flavin catabolites to the supplement indicate a well-nourished population. Differences in the effects of supplementation on the specific flavin catabolites across sex and age groups are included in detail for the first time.

Effect of diet on bone matrix constituents.

Bone formation occurs in an integrated, highly ordered manner, beginning in the embryonic period. Nutrients may affect bone formation by delaying cellular differentiation, altering responses to bone growth factors, affecting supply of needed nutrients, and/or affecting rates of synthesis of the matrix constituents. Several growth factors, both systemic and local, are being identified which affect bone formation.

Flavin composition of human milk.

The identity and quantity of greater than 95% of the flavins present in human milk were assessed by acid-phenol extractions followed by high-performance liquid chromatography. Flavin adenine dinucleotide (FAD) and riboflavin were the predominant flavins, followed by 10-(2'-hydroxyethyl)-flavin. In addition, traces of 7 alpha- and 8 alpha-hydroxyriboflavins (7-hydroxymethylriboflavin and 8-hydroxymethylriboflavin, respectively) were detected.

Qualitative and quantitative assessment of flavins in cow's milk.

Although milk is one of the primary sources of riboflavin in the North American diet, the amounts of riboflavin and other flavin derivatives in milk have not been accurately quantified. In this study, a comprehensive assessment of milk was performed to identify and quantify greater than 95% of the flavins in this food. Riboflavin and flavin adenine dinucleotide (FAD) were the predominant flavins in all milk samples; 10-(2'-hydroxyethyl)flavin was next most common.

The effects of dietary acid stress on bone metabolism in young ovariectomized and intact rats.

1. Two studies were performed to determine the effects of acid stress and ovariectomy on bone metabolism in young rats. In Expt 1, eighteen female weanling Sprague-Dawley-descended rats were ovariectomized, placed in one of three dietary groups and given a diet containing (g/kg): 6 calcium and 3, 6 or 12 phosphorus for 10 weeks.