A Systematic Review and Meta-Analysis of Randomized Controlled Trials on the Effects of Oats and Oat Processing on Postprandial Blood Glucose and Insulin Responses.

BACKGROUND: Oats are a whole grain cereal with potentially favorable effects on the postprandial glycemic response; however, the effects of oat processing on these glycemic benefits are not well understood. OBJECTIVES: The study objective was to determine the effects of differently processed oats on the postprandial blood glucose and insulin responses relative to refined grains. METHODS: Eleven electronic databases were systematically searched to identify studies published up to and including May 2019. Randomized controlled trials comparing the postprandial blood glucose and insulin responses to oats compared with any refined grain were included, so long as the available carbohydrate content of the test meals was similar. Pooled effect sizes were computed using the difference in incremental area under the curves for blood glucose and insulin following the consumption of oats compared with the refined grain control. RESULTS: Ten publications were included, with intact oat kernels studied in 3 comparisons, thick oat flakes (>0.6 mm) in 7 comparisons, and thin/quick/instant oat flakes (≤0.6 mm) in 6 comparisons. Compared with the consumption of the refined grain control, the consumption of intact oat kernels was associated with significant reductions in postprandial blood glucose (-45.5 mmol x min/L; 95% CI: -80.1, -10.9 mmol x min/L; P = 0.010) and insulin (-4.5 nmol x min/L; 95% CI: -7.1, -1.8 nmol x min/L; P = 0.001) responses; the consumption of thick oat flakes was associated with significant reductions in postprandial blood glucose (-30.6 mmol x min/L; 95% CI: -40.4, -20.9 mmol x min/L; P < 0.001) and insulin (-3.9 nmol x min/L; 95% CI: -5.3, -2.5 nmol x min/L; P < 0.001) responses; but, the consumption of thin/quick/instant oat flakes was not associated with any effects on the postprandial blood glucose and insulin responses. CONCLUSIONS: A disruption in the structural integrity of the oat kernel is likely associated with a loss in the glycemic benefits of oats.

The effects of whole-grain compared with refined wheat, rice, and rye on the postprandial blood glucose response: a systematic review and meta-analysis of randomized controlled trials.

Background: Whole grains are often referred to collectively, despite differences in their composition, physical structure, processing, and potential health benefits. Objective: The aim of this study was to compare the postprandial blood glucose response of whole-grain with refined wheat, rice, or rye, while controlling for the food delivery matrix and the processing of the grain (e.g., grinding, germination). Design: Eleven electronic databases were systematically searched to identify studies published up to and including November 2017. Randomized controlled trials comparing the effects of whole-grain wheat, rice, or rye with those of each grain's refined counterpart on postprandial blood glucose area under the curve (AUC) were included. Pooled effect sizes were computed by using the difference in the blood glucose AUC after the consumption of the whole compared with the refined grain. Results: Twenty publications were included, with 10, 14, and 5 strata (or active-control comparisons) on whole-grain wheat, rice, and rye, respectively. The consumption of ground (wholemeal) wheat, compared with white wheat, was not associated with a significant reduction in blood glucose AUC (-6.7 mmol/L ⋅ min; 95% CI: -25.1, 11.7 mmol/L ⋅ min; P = 0.477). The consumption of wholemeal rye, compared with endosperm rye, was not associated with a significant reduction in blood glucose AUC (-5.5 mmol/L ⋅ min; 95% CI: -24.8, 13.8 mmol/L ⋅ min; P = 0.576). The consumption of intact (whole-grain) rice, compared with white rice, was associated with a significant reduction in blood glucose AUC (-40.5 mmol/L ⋅ min; 95% CI: -59.6, -21.3 mmol/L ⋅ min; P < 0.001). Conclusions: Compared with white rice, whole-grain rice significantly attenuates the postprandial blood glucose response. In most of the studies on wheat and rye, the postprandial blood glucose responses to foods formulated with wholemeal compared with refined flours were compared. Whether reductions in the blood glucose AUC can be achieved with whole-grain (as opposed to wholemeal) wheat and rye requires further investigation.

Consuming Lower-Protein Nutrition Bars with Added Leucine Elicits Postprandial Changes in Appetite Sensations in Healthy Women.

BACKGROUND: Higher-protein meals (>25 g protein/meal) have been associated with enhanced satiety but the role of amino acids is unclear. Leucine has been proposed to stimulate satiety in rodents but has not been assessed in humans. OBJECTIVE: We assessed the acute effects of lower-protein nutrition bars, enhanced with a leucine peptide (LP), on postprandial appetite sensations in combination with plasma leucine and peptide YY (PYY) in healthy women. METHODS: Utilizing a double-blind randomized crossover design, 40 healthy women [28 ± 7.5 y; body mass index (BMI, in kg/m2): 23.5 ± 2.4] consumed the following isocaloric (180 kcal) pre-loads on 3 separate visits: control bar [9 g protein with 0 g added LP (0-g LP)] or treatment bars [11 g protein with 2 g added LP (2-g LP) or 13 g protein with 3 g added LP (3-g LP)]. Pre- and postprandial hunger, desire to eat, prospective food consumption (PFC), fullness, and plasma leucine were assessed every 30 min for 240 min. Plasma PYY was assessed hourly for 240 min (n = 24). RESULTS: Main effects of time (P < 0.0001) and treatment (P < 0.03) were detected for postprandial hunger, desire to eat, PFC, and fullness. Post hoc analyses revealed that the 2-g and 3-g LP bars elicited greater increases in fullness and greater decreases in PFC compared with 0-g LP (all, P < 0.05) with no differences between the 2-g and 3-g LP bars. The 2-g bar elicited greater decreases in hunger and desire to eat compared with the 0-g LP bar (both, P ≤ 0.01), whereas 3-g LP did not. Appetite incremental areas under the curves (iAUCs) and PYY outcomes were not different between bars. A treatment × time interaction was detected for plasma leucine with increases occurring in a leucine-dose-dependent manner (P < 0.0001). CONCLUSION: Despite the dose-dependent increases in plasma leucine following the consumption of lower-protein bars enhanced with LP, only the 2-g LP bar elicited consistent postprandial changes in select appetite sensations compared with the 0-g LP bar. This study was registered on clinicaltrials.gov as NCT02091570.

Daily intake of dairy products in Brazil and contributions to nutrient intakes: a cross-sectional study.

OBJECTIVE: Dairy products are sources of protein and micronutrients important in a healthy diet. The purpose of the present analysis was to estimate consumption of dairy products by Brazilians and identify contributions of dairy products to nutrient intakes. DESIGN: Dairy consumption data were obtained from 24 h dietary records. Dairy products were defined as milk (including flavoured), cheese and yoghurt. Estimates of dairy product intakes were generated for all individuals, individuals in urban and rural households and for age groups 10-18 years, 19-59 years and ≥60 years. Contributions to nutrient intakes were estimated for the total sample and sub-populations. SETTING: Nationwide cross-sectional survey, 2008-2009. SUBJECTS: Nationally representative sample of individuals aged ≥10 years in the Individual Food Intake survey, a component of the Brazilian Household Budget Survey (n 34 003). RESULTS: Among individuals aged ≥10 years, per capita intake of dairy products was 142 (se 2.1) g/d. Dairy product intake was higher among individuals in urban compared with rural areas and among groups 10-18 years and ≥60 years compared with adults aged 19-59 years. Dairy products accounted for 6.1% of daily energy intake, 7.3% of protein, 16.9% of saturated fat, 11.1% and 4.3% of total and added sugars, respectively, and 10.2-37.9% of daily Ca, vitamin D, P, vitamin A and K. CONCLUSIONS: Dairy products were substantial contributors to daily intakes of selected nutrients of concern in Brazil, although mean daily dairy product consumption was less than a typical portion. Education efforts in Brazil to raise awareness about the nutritional role of dairy foods may serve to improve overall diet quality.

Depot medroxyprogesterone acetate: implications for weight status and bone mineral density in the adolescent female.

Depot medroxyprogesterone acetate (DMPA) is an effective and easy-to-use contraceptive method for adolescents. However, recent literature suggests that overweight teens may be at increased risk for weight gain while on this contraceptive method, and decreases in bone mineral density have been documented in adolescents on DMPA, particularly with longer duration of use. Consideration of this new literature on DMPA and its implications for clinical practice must be done in the context of the United States having the highest adolescent pregnancy rate in the industrialized world. Hence, potential DMPA risks need to be weighed against the risk of unintended pregnancy in an adolescent.

Vitamin D deficiency in adolescent females.

PURPOSE: The purpose of this study was to estimate the incidence of low serum 25-hydroxyvitamin D [25(OH)D] levels in adolescent girls and across racial groups and seasons. METHODS: Healthy postmenarcheal girls (12-18 years of age) were recruited for the study. Serum samples were assayed for 25(OH)D with a competitive protein binding assay (CPB) (Nichols Institute, San Clemente, California). RESULTS: The study included 370 girls (mean age, 15.5 +/- 1.6 y), with a mean serum 25(OH)D level of 53.7(29.0) nmol/L. Seventeen percent of the girls were found to be vitamin D deficient (serum 25(OH)D

Decreased bone resorption with soy isoflavone supplementation in postmenopausal women.

OBJECTIVE: To investigate the effect of soy isoflavone supplementation on bone mineral density (BMD) and markers of bone turnover in postmenopausal women. METHODS: In this randomized, placebo-controlled clinical trial, we used a crossover design to test the effect of soy isoflavone (110 mg/day) (1.3:1.0:0.22 ratio of genistein/daidzein/ glycitein) on bone formation, bone resorption, bone mineral content (BMC), and BMD for 6 months. RESULTS: Postmenopausal women (n = 19), mean age 70.6 +/- 6.3 years and mean time since menopause 19.1 +/- 5.5 years, were given isoflavone supplements for 6 months. There was a 37% decrease in urinary concentrations of type 1 collagen alpha1-chain helical peptide (HP), a marker of bone resorption, during the isoflavone supplementation compared with baseline (p < 0.05) and a significant difference in mean (SE) HP excretion levels when isoflavone was compared with placebo (43.4 +/- 5.2 vs. 56.3 +/- 7.2 microg/mmol creatinine [cr], p < 0.05). With isoflavone supplementation, mean spine BMD at L2 and L3 was significantly greater when treatment was compared with control, with a difference between means of 0.03 +/- 0.04 g and 0.03 +/- 0.04 g (p < 0.05), respectively. There were nonsignificant increases from baseline for total spine BMC (3.5%), total spine BMD (1%), total hip BMC (3.6%), and total hip BMD (1.3%) with the isoflavone treatment. CONCLUSIONS: Soy isoflavone, in isolated form, was effective in this study to significantly decrease bone resorption in postmenopausal women. Further investigation needs to be done to evaluate the long-term effects of soy isoflavone on bone mass and fracture risk.