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Soluble corn fiber increases bone calcium retention in postmenopausal women in a dose-dependent manner: a randomized crossover trial.
Jakeman, SA, Henry, CN, Martin, BR, McCabe, GP, McCabe, LD, Jackson, GS, Peacock, M, Weaver, CM
The American journal of clinical nutrition. 2016;(3):837-43
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Abstract
BACKGROUND Dietary soluble corn fiber (SCF) significantly improves calcium absorption in adolescents and the bone strength and architecture in rodent models. OBJECTIVE In this study, we aimed to determine the skeletal benefits of SCF in postmenopausal women. DESIGN We used our novel technology of determining bone calcium retention by following the urinary appearance of (41)Ca, a rare long-lived radioisotope, from prelabeled bone to rapidly and sensitively evaluate the effectiveness of SCF in reducing bone loss. A randomized-order, crossover, double-blinded trial was performed in 14 healthy postmenopausal women to compare doses of 0, 10, and 20 g fiber from SCF/d for 50 d. RESULTS A dose-response effect was shown with 10 and 20 g fiber from SCF/d, whereby bone calcium retention was improved by 4.8% (P < 0.05) and 7% (P < 0.04), respectively. The bone turnover biomarkers N-terminal telopeptide and osteocalcin were not changed by the interventions; however, a significant increase in bone-specific alkaline phosphatase, which is a bone-formation marker, was detected between 0 and 20 g fiber from SCF/d (8%; P = 0.035). CONCLUSION Daily SCF consumption significantly increased bone calcium retention in postmenopausal women, which improved the bone calcium balance by an estimated 50 mg/d. This study was registered at clinicaltrials.gov as NCT02416947.
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Resistant starch from high-amylose maize increases insulin sensitivity in overweight and obese men.
Maki, KC, Pelkman, CL, Finocchiaro, ET, Kelley, KM, Lawless, AL, Schild, AL, Rains, TM
The Journal of nutrition. 2012;(4):717-23
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Abstract
This study evaluated the effects of 2 levels of intake of high-amylose maize type 2 resistant starch (HAM-RS2) on insulin sensitivity (S(I)) in participants with waist circumference ≥89 (women) or ≥102 cm (men). Participants received 0 (control starch), 15, or 30 g/d (double-blind) of HAM-RS2 in random order for 4-wk periods separated by 3-wk washouts. Minimal model S(I) was assessed at the end of each period using the insulin-modified i.v. glucose tolerance test. The efficacy evaluable sample included 11 men and 22 women (mean ± SEM) age 49.5 ± 1.6 y, with a BMI of 30.6 ± 0.5 kg/m2 and waist circumference 105.3 ± 1.3 cm. A treatment main effect (P = 0.018) and a treatment × sex interaction (P = 0.033) were present. In men, least squares geometric mean analysis for S(I) did not differ after intake of 15 g/d HAM-RS2 (6.90 × 10⁻⁵ pmol⁻¹ · L⁻¹ × min⁻¹) and 30 g/d HAM-RS2 (7.13 × 10⁻⁵ pmol⁻¹ · L⁻¹ × min⁻¹), but both were higher than after the control treatment (4.66 × 10⁻⁵ pmol⁻¹ · L⁻¹ × min⁻¹) (P < 0.05). In women, there was no difference among the treatments (overall least squares ln-transformed mean ± pooled SEM = 1.80 ± 0.08; geometric mean = 6.05 × 10⁻⁵ pmol⁻¹ · L⁻¹ × min⁻¹). These results suggest that consumption of 15-30 g/d of HAM-RS2 improves S(I) in men. Additional research is needed to understand the mechanisms that might account for the treatment × sex interaction observed.
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Yellow maize with high β-carotene is an effective source of vitamin A in healthy Zimbabwean men.
Muzhingi, T, Gadaga, TH, Siwela, AH, Grusak, MA, Russell, RM, Tang, G
The American journal of clinical nutrition. 2011;(2):510-9
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Abstract
BACKGROUND The bioconversion efficiency of yellow maize β-carotene to retinol in humans is unknown. OBJECTIVE The objective of this study was to determine the vitamin A value of yellow maize β-carotene in humans. DESIGN High β-carotene-containing yellow maize was grown in a hydroponic medium with 23 atom% (2)H(2)O during grain development. Yellow maize β-carotene showed the highest abundance of enrichment as [(2)H(9)]β-carotene. Eight healthy Zimbabwean men volunteered for the study. On day 1 after a fasting blood draw, subjects consumed 300 g yellow maize porridge containing 1.2 mg β-carotene, 20 g butter, and a 0.5-g corn oil capsule. On day 8, fasting blood was drawn, and subjects consumed 1 mg [(13)C(10)]retinyl acetate in a 0.5-g corn oil capsule and 300 g white maize porridge with 20 g butter. Thirty-six blood samples were collected from each subject over 36 d. Concentrations and enrichments of retinol and β-carotene in labeled doses and serum were determined with the use of HPLC, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry. RESULTS The area under the curve (AUC) of retinol from 1.2 mg yellow maize β-carotene was 72.9 nmol · d, and the AUC of retinol from 1 mg retinyl acetate (13)C(10) was 161.1 nmol · d. The conversion factor of yellow maize β-carotene to retinol by weight was 3.2 ± 1.5 to 1. CONCLUSION In 8 healthy Zimbabwean men, 300 g cooked yellow maize containing 1.2 mg β-carotene that was consumed with 20.5 g fat showed the same vitamin A activity as 0.38 mg retinol and provided 40-50% of the adult vitamin A Recommended Dietary Allowance. This trial was registered at clinicaltrials.gov as NCT00636038.
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Zinc absorption from low-phytate hybrids of maize and their wild-type isohybrids.
Hambidge, KM, Huffer, JW, Raboy, V, Grunwald, GK, Westcott, JL, Sian, L, Miller, LV, Dorsch, JA, Krebs, NF
The American journal of clinical nutrition. 2004;(6):1053-9
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Abstract
BACKGROUND Identification of allelic variants in a single gene that determine the phytate content of maize kernels and the subsequent breeding of low-phytate maize have facilitated studies designed to determine quantitatively the effects of maize phytate on the bioavailability of minerals in maize. OBJECTIVE The objective was to determine the relation between the fractional absorption of zinc (FAZ) and the phytate content and phytate:zinc molar ratios of maize tortillas prepared from hybrids with different phytate contents. DESIGN Six healthy adults were fed, as the only food for 2 d, maize tortillas prepared from 1 of 2 low-phytate mutants: lpa1-1 (lpa1-1-LP) or Nutridense Low Phytate (ND-LP), which have phytate reductions of approximately 60% and approximately 80%, respectively, compared with their respective wild-type isohybrids. Four additional subjects were fed tortillas prepared from the corresponding wild-type isohybrids (lpa1-1-WT and ND-WT) according to the same study design. Meals were extrinsically labeled with zinc stable isotopes, and FAZ was determined with a dual-isotope-tracer ratio technique. Overall FAZ values were examined in relation to dietary phytate and phytate:zinc molar ratios by using a mixed nonlinear regression model. RESULTS The mean (+/-SD) FAZ values from tortillas prepared from ND-LP, lpa1-1-LP, lpa1-1-WT, and ND-WT were 0.38 +/- 0.07, 0.28 +/- 0.04, 0.15 +/- 0.07, and 0.13 +/- 0.05, respectively. A negative relation (P < 0.001) was found between FAZ and both dietary phytate and the phytate:zinc molar ratio. The effect of dietary zinc (8-14 mg Zn/d) under these experimental conditions was not significant. CONCLUSIONS FAZ from maize tortillas is positively related to the extent of phytate reduction achieved with low-phytate hybrids.