Abstract only
Background
Dietary protein and fiber independently influence insulin‐mediated glucose control. However, the potential additive or synergistic effects of higher protein and fiber intake ...on postprandial insulin and glucose responses are not known.
Purpose
This study assessed the effects of protein and fiber intakes at breakfast on postprandial insulin and glucose responses.
Methods
Men and women n = 20; age: 26 ± 5 y; body mass index: 26.1 ± 0.2 kg/m
2
; means ± SEM consumed provided breakfast meals with varying protein (high = 25 g vs. normal =12.5 g) and fiber (high= 8 g vs. normal = 3 g) amounts during 4, 2‐week interventions (randomized crossover experimental design). Each 2‐week period was separated by a 2‐week washout period. The breakfast variations included: normal protein and fiber (NPNF), normal protein and high fiber (NPHF), high protein and normal fiber (HPNF), or high protein and fiber (HPHF). Breakfast was provided with fixed energy (400 kcal) and digestible carbohydrate (50 g) on each day, and the remainder of daily energy intake was self‐selected. On the last day of each intervention period, a meal tolerance test was completed to assess serum glucose and insulin concentrations at fasting and hourly for 4 hours (240 min). Repeated measures ANOVA was applied for data analyses.
Results
There were no differential responses among breakfast meals on composite postprandial insulin and glucose (240‐min total areas under the curve (AUC)) after adjusting for fasting values, sex, and breakfast treatment order. Analysis of the 0–120 min and 120–240 min AUCs supported that higher protein and/or fiber did not influence glucose responses. Further, differential responses were not observed for insulin AUC at 0–120 min but were for 120–240 min. The 120–240 min insulin AUC was numerically lowest after NPHF (880 ± 103 μU/mL) and was statistically different from HPNF (1228 ± 104 μU/mL) but not HPHF (1004 ± 104 μU/mL) or NPNF (1049 ± 108 μU/mL).
Conclusion
Doubling the amount of protein from 12.5 g to 25 g/meal and increasing fiber from 3 to 8 g/meal did not additively or synergistically affect postprandial insulin and glucose responses. These results do not support increasing dietary protein and fiber at breakfast as an effective strategy for modulating insulin‐mediated glucose responses in young, overweight adults.
Support or Funding Information
Support: American Egg Board‐ Egg Nutrition Center; NIH UL1TR0001108; USDA‐NIFA 2011‐38420‐20038
Background: Hypertension is a major, modifiable risk factor for cardiovascular and kidney disease and premature mortality that is improved by the DASH (Dietary Approaches to Stop Hypertension) diet. ...The DASH diet emphasizes increased consumption of fruit and vegetables, whole grains, low-fat dairy, nuts, and poultry and fish and reduced intakes of fats, red meats (including pork), sodium, and added sugars.
Objective: We sought to evaluate whether the consumption of lean pork compared with the consumption of chicken and fish as the predominant protein source in a DASH-style diet affected blood pressure (BP) control in men and women with elevated BP.
Design: In a randomized crossover study, 13 women and 6 men mean ± SEM age: 61 ± 2 y; BMI (in kg/m2): 31.2 ± 1.4 with elevated BP systolic blood pressure (SBP)/diastolic blood pressure (DBP): 130 ± 2/85 ± 2 mm Hg consumed a DASH-style diet for two 6-wk controlled dietary interventions (with a 4-wk diet washout between interventions) with either lean pork DASH diet with pork (DASH-P) or chicken and fish DASH diet with chicken and fish (DASH-CF), the control diet as the major protein source (55% of total protein intake). SBP and DBP were measured manually and with a 24-h BP monitoring system on 3 d before and 3 d at the end of each diet intervention.
Results: Preintervention manual BP (DASH-P: 130/84 ± 2/1 mm Hg; DASH-CF: 129/84 ± 2/1 mg Hg) and postintervention manual BP (DASH-P: 122/79 ± 2/1 mm Hg; DASH-CF: 123/78 ± 3/1) were not different between the DASH-P and DASH-CF. Consumption of these DASH-style diets for 6 wk reduced all measures of BP (P < 0.05) with no differences in responses between the DASH-CF and DASH-P.
Conclusion: The results indicate that adults with elevated BP may effectively incorporate lean pork into a DASH-style diet for BP reduction. This trial was registered at clinicaltrials.gov as NCT01696097.
Abstract only
The brain's reward system influences ingestive behavior and subsequently obesity risk. Functional magnetic resonance imaging (fMRI) is a common method for investigating brain reward ...function. We sought to assess the test‐retest reliability and postprandial time course of neural responses to visual food cues using fMRI.
A priori
brain regions of interest included bilateral insula, amygdala, orbitofrontal cortex, caudate, and putamen. Fasting‐state fMRI and appetite assessments were completed by 29 overweight or obese women (n=17) and men (n=12) on 2 days for test‐retest reliability analyses determined by intraclass correlation coefficient. A subset of 3 women and 4 men completed postprandial fMRI and appetite assessments 0, 90, 180, and 270 min after consuming a 300 kcal meal to document the postprandial time course of responses. Mean fasting‐state neural responses on Day 1 and Day 2 were not different in 8 of 10 regions of interest. However, test‐retest reliabilities of neural responses were mostly poor or unreliable. Only the left orbitofrontal cortex response demonstrated fair test‐retest reliability. Furthermore, neural responses to visual food stimuli were largely unaffected by meal consumption. In conclusion, fMRI‐measured responses to visual food cues in overweight and obese adults show relatively good group‐level reproducibility but considerable within‐subject variability and are insensitive to meal consumption.
Support or Funding Information
American Egg Board, NIH UL1 TR001108, USDA‐NIFA 2011‐38420‐20038, Purdue University Ingestive Behavior Research Center
Abstract only
Increasing either protein or fiber at mealtimes has relatively modest effects on satiety and ingestive behavior. Whether increasing protein and fiber in the same meal has additive or ...interactive effects on ingestive behavior is not known. Five female and 10 male overweight (BMI: 27.1 ± 0.2 kg/m
2
) young adults (26 ± 1 y) were provided with breakfast meals of varying protein and fiber amounts (normal protein 12.5 g + normal fiber 3 g, normal protein 12.5 g + high fiber 8 g, high protein 25 g + normal fiber 3 g, high protein 25 g + high fiber 8 g) during 4, 2‐week interventions in a randomized crossover manner. At the end of each intervention, fasting and postprandial appetite ratings, neural responses to visual food stimuli, and
ad libitum
energy intake at lunch were collected.
A priori
reward‐related brain regions of interest included bilateral insula, amygdala, orbitofrontal cortex, caudate, and putamen. Fiber intake at breakfast did not affect ingestive behavior outcomes. Higher protein intake at breakfast transiently decreased desire to eat 60 minutes after breakfast, but did not influence hunger, fullness, or energy intake at lunch. Compared to fasting‐state, right insula responses to visual food stimuli were decreased 180 min after consuming normal protein, but not high protein, breakfasts. In conclusion, these data do not support increasing dietary protein and fiber at breakfast as effective strategies for modulating neural reward processing and ingestive behavior in overweight adults.
Support or Funding Information
American Egg Board, NIH UL1 TR001108, USDA‐NIFA 2011‐38420‐20038, Purdue University Ingestive Behavior Research Center
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