Postprandial metabolism and inflammation: novel insights focusing on true-to-life application

Doctor of PhilosophyDepartment of Human NutritionSara RosenkranzThe aims of this dissertation were to provide innovative, applicable insights regarding the impact of single-meal consumption on metabolic and inflammatory responses in the acute post-meal (“postprandial”) period. In Chapter 2, the connection between large postprandial glucose and triglyceride (TG) fluxes and cardiovascular disease (CVD) risk were reviewed. A new marker of metabolic status, Metabolic Load Index (MLI), calculated by adding glucose and TG, was proposed based on several considerations: 1) independent associations between postprandial glucose and TG with CVD risk, although the substrates are considered to increase risk through similar mechanisms; 2) postprandial glucose and TG responses are interrelated; and 3) meals consumed in daily life typically contain both carbohydrate and fat. MLI may be useful in characterizing metabolic status/risk in both clinical and research settings. Chapter 3 was a systematic review with the purpose of objectively describing postprandial responses (i.e. magnitude and timing) to a high-fat meal (HFM) in five commonly assessed inflammatory markers: interleukin (IL)-6, C-reactive protein (CRP), tumor necrosis factor (TNF)-α, IL-1β, and IL-8. IL-6 increased in >70% of studies, starting at ~1.4 pg/mL pre-meal and peaking at ~2.9 pg/mL ~6 hours post-HFM. Other markers (CRP, TNF-α, IL-1β, and IL-8) did not change after the HFM in the majority of studies. These findings suggest that IL-6 is an inflammatory marker that routinely increases following HFM consumption. Future postprandial studies should further investigate IL-6, as well as explore novel markers of inflammation. In Chapter 4, we compared the metabolic and inflammatory responses to a HFM (17 kcal/kg, 60% fat), representative of meals used in previous postprandial studies, to two meal trials that were more reflective of typical eating patterns: a moderate-fat meal (MFM; 8.5 kcal/kg, 30% fat), and a biphasic meal (BPM), in which the MFM was consumed twice, three hours apart. The HFM elicited a greater total area-under-the-curve (tAUC) TG response (1348.8 ± 783.7 mg/dL x 6 hrs) compared to the MFM (765.8 ± 486.8 mg/dL x 6 hrs; p = 0.0005) and the BPM (951.8 ± 787.7 mg/dL x 6 hrs; p = 0.03), but the MFM and BPM were not different (p = 0.72). It appears that the large postprandial TG response observed in previous studies may not be representative of the daily metabolic challenge for many individuals. Chapter 5 assessed the impact of both aging and chronic physical activity level on postprandial metabolic responses by comparing three groups: younger active (YA), older active (OA), and older inactive (OI) adults. The TG tAUC response was lower in YA (407.9 ± 115.1 mg/dL x 6 hr) compared to OA (625.6 ± 169.0 mg/dL x 6 hr; p = 0.02) and OI (961.2 ± 363.6 mg/dL x 6 hr; p = 0.0002), while the OA group TG tAUC was lower than OI (p = 0.02). Thus, it is likely that both aging and chronic physical activity level impact the postprandial metabolic response. This series of projects provides needed clarification regarding the postprandial metabolic and inflammatory responses to single-meal intake, particularly in the context of real-life application

Making sense of heart disease risk factors

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The potential link between sugar-sweetened beverage consumption and post-exercise airway narrowing across puberty: a longitudinal cohort study

Citation: Emerson, S. R., Rosenkranz, S. K., Rosenkranz, R. R., Kurti, S. P., & Harms, C. A. (2016). The potential link between sugar-sweetened beverage consumption and post-exercise airway narrowing across puberty: a longitudinal cohort study. Public Health Nutrition, 19(13), 2435-2440. doi:10.1017/s1368980015003109Objective The prevalence of asthma is rising, presenting serious public health challenges. Recent data suggest that sugar-sweetened beverage (SSB) consumption plays a role in asthma aetiology. The purpose of the present study was to determine whether SSB consumption is linked to post-exercise airway narrowing (predictor of asthma development) across puberty. Design Participants completed pulmonary function tests, physical activity and dietary habit questionnaires, and an exercise test to exhaustion. Setting Community in Manhattan, Kansas, USA. Subjects We recruited ten boys and ten girls from an original cohort of forty participants tested in our laboratory approximately 5 years prior. Participants were aged 97 (sd 09) years at baseline and 147 (sd 09) years at follow-up. Results Pre-puberty, boys consumed 68 (sd 48) servings/week and girls consumed 69 (sd 37) servings/week, while post-puberty boys consumed 115 (sd 53) servings/week and girls consumed 77 (sd 43) servings/week. Using Pearson correlation, SSB consumption was not significantly related to post-exercise airway narrowing at pre-puberty (r=-035, P=0130). In linear regression analyses, SSB consumption was significantly related to post-exercise airway narrowing post-puberty before (standardized =-060, P=0005) but not after (standardized =-033, P=0211) adjustment for confounders. Change in SSB consumption from pre- to post-puberty was significantly associated with post-exercise airway narrowing post-puberty (r=-061, P=0010) and change in post-exercise airway narrowing from pre- to post-puberty (r=-045, P=0048) when assessed via Pearson correlations. Conclusions These findings suggest a possible link between SSB consumption and asthma development during maturation. Reduced SSB intake may be a possible public health avenue for blunting rising asthma prevalence

Is phase angle a sensitive biomarker for overall health status?

Bioelectrical impedance analysis (BIA) is used as a non-invasive method of calculating body composition, such as body fat and fat-free mass. It works by transmitting electrical currents throughout the body and assessing resistance as the current passes through different body tissues. BIA can be used to calculate Phase Angle, which is calculated using body tissue resistance and cell membrane reactance. Phase Angle is thought to be an indicator of overall cellular health and nutritional quality of cells, but it is still a relatively knew biomarker, and it is unknown whether phase angle is associated with traditional lifestyle risk factors. The purpose of this study was to determine if there is a correlation between phase angle, a potentially underutilized assessment of overall health, and behavioral markers such as diet, exercise, and stress.Lew Wentz FoundationNutritional Science

Summation of blood glucose and TAG to characterise the 'metabolic load index'

Citation: Emerson, S. R., Haub, M. D., Teeman, C. S., Kurti, S. P., & Rosenkranz, S. K. (2016). Summation of blood glucose and TAG to characterise the 'metabolic load index'. British Journal of Nutrition, 116(9), 1553-1563. doi:10.1017/s0007114516003585Research points to postprandial glucose and TAG measures as preferable assessments of cardiovascular risk as compared with fasting values. Although elevated postprandial glycaemic and lipaemic responses are thought to substantially increase chronic disease risk, postprandial glycaemia and lipaemia have historically only been considered separately. However, carbohydrates and fats can generally 'compete' for clearance from the stomach, small intestine, bloodstream and within the peripheral cell. Further, there are previous data demonstrating that the addition of carbohydrate to a high-fat meal blunts the postprandial lipaemic response, and the addition of fat to a high-carbohydrate meal blunts the postprandial glycaemic response. Thus, postprandial glycaemia and lipaemia are interrelated. The purpose of this brief review is 2-fold: first, to review the current evidence implicating postprandial glycaemia and lipaemia in chronic disease risk, and, second, to examine the possible utility of a single postprandial glycaemic and lipaemic summative value, which will be referred to as the metabolic load index. The potential benefits of the metabolic load index extend to the clinician, patient and researcher

Let’s Take A Walk: Exploring the Impact of an Inclusive Walking Program on the Physical and Mental Health of Adults with Intellectual Disability

Background: People with intellectual disabilities experience health disparities and poorer health outcomes than people without disabilities. Increased physical activity has been found to reduce the impact of chronic health conditions among people with intellectual disabilities. Method: The current study explored the impact of an inclusive walking program on the physical and mental health of adults with intellectual disabilities. Let’s Take A Walk paired adults with intellectual disabilities, hereafter referred to as Community Walkers (n = 27), with college students to walk around a college campus twice a week for 45 minutes across 10 weeks. Data on mental health outcomes, specifically depression and anxiety, were collected from 24 Community Walkers across four-time points (pre-, mid-, post-, and 3-months following intervention), and data on physical health outcomes were collected across two-time points (pre- and post-intervention). Results: Community Walkers reported significant decreases in both depression and anxiety from pre to post-implementation. Particularly promising was clinically significant decreases in anxiety symptoms over the 10-week program. No differences were noted on Community Walkers’ measures of physical health. Conclusion: Inclusive walking programs are a valuable and promising mechanism for building social connections and inclusion and improving mental health for adults with intellectual disabilities

Effects of thirty and sixty minutes of moderate-intensity aerobic exercise on postprandial lipemia and inflammation in overweight men: a randomized cross-over study

Citation: Emerson, S. R., Kurti, S. P., Snyder, B. S., Sitaraman, K., Haub, M. D., & Rosenkranz, S. K. (2016). Effects of thirty and sixty minutes of moderate-intensity aerobic exercise on postprandial lipemia and inflammation in overweight men: a randomized cross-over study. Journal of the International Society of Sports Nutrition, 13, 12. doi:10.1186/s12970-016-0137-8Background: The transient rise in blood lipids following a high-fat meal (HFM), known as postprandial lipemia, is linked to systemic inflammation and cardiovascular disease, but can be blunted by exercise. However, minimal research has investigated the effects of realistic exercise bouts on postprandial lipemia and inflammation in at-risk individuals. The purpose of this study was to assess the effects of moderate-intensity aerobic exercise lasting 30 or 60 min performed the evening before a HFM, on postprandial lipemia and inflammation in overweight, insufficiently active men. Methods: In this randomized-crossover study, twelve participants remained sedentary (CON), or performed a brisk walk on a treadmill at 60 % VO2peak for either 30 min (EX-30) or 60 min (EX-60), after which they consumed a small snack (270 kcal) to partially replace exercise energy expenditure. Following a 12-h overnight fast, participants consumed a standard HFM (1 g fat/kg; 1 g CHO/kg; 1117.8 +/- 117.0 kcal). Blood draws were performed at baseline (pre-HFM) and 1, 2, 4, 6, and 8 h post-HFM to assess glucose, insulin, lipids, and systemic inflammation. Results: There were no significant differences (p > 0.05) in fasting triglycerides between EX-60 (118.7 +/- 68.3 mg/dL), CON (134.8 +/- 66.2 mg/dL) or EX-30 (135.5 +/- 85.4 mg/dL). There were no differences in peak, time-to-peak, total or incremental area-under-the-curve between trials for triglyceride response (p > 0.05). There was no significant main effect of time (p > 0.05) in IL-1ra, IL-4, IL-5, IL-6, IL-10 or TNF-alpha from baseline to 8 h post-HFM in any trial. Conclusions: In summary, we found that in overweight, insufficiently active men, neither 30 nor 60 min of moderate-intensity exercise performed 12 h prior to a HFM attenuated postprandial lipemia or inflammation, which could potentially be explained by the partial caloric replacement of exercise energy expenditure

Household Air Pollution Exposure and Influence of Lifestyle on Respiratory Health and Lung Function in Belizean Adults and Children: A Field Study

Citation: Kurti, S. P., Kurti, A. N., Emerson, S. R., Rosenkranz, R. R., Smith, J. R., Harms, C. A., & Rosenkranz, S. K. (2016). Household Air Pollution Exposure and Influence of Lifestyle on Respiratory Health and Lung Function in Belizean Adults and Children: A Field Study. International Journal of Environmental Research and Public Health, 13(7), 12. doi:10.3390/ijerph13070643Household air pollution (HAP) contributes to the global burden of disease. Our primary purpose was to determine whether HAP exposure was associated with reduced lung function and respiratory and non-respiratory symptoms in Belizean adults and children. Our secondary purpose was to investigate whether lifestyle (physical activity (PA) and fruit and vegetable consumption (FV)) is associated with reported symptoms. Belizean adults (n = 67, 19 Male) and children (n = 23, 6 Male) from San Ignacio Belize and surrounding areas participated in this cross-sectional study. Data collection took place at free walk-in clinics. Investigators performed initial screenings and administered questionnaires on (1) sources of HAP exposure; (2) reported respiratory and non-respiratory symptoms and (3) validated lifestyle questionnaires. Participants then performed pulmonary function tests (PFTs) and exhaled breath carbon monoxide (CO). There were no significant associations between HAP exposure and pulmonary function in adults. Increased exhaled CO was associated with a significantly lower forced expiratory volume in 1-s divided by forced vital capacity (FEV1/FVC) in children. Exposed adults experienced headaches, burning eyes, wheezing and phlegm production more frequently than unexposed adults. Adults who met PA guidelines were less likely to experience tightness and pressure in the chest compared to those not meeting guidelines. In conclusion, adults exposed to HAP experienced greater respiratory and non-respiratory symptoms, which may be attenuated by lifestyle modifications

The effect of moderate intensity exercise in the postprandial period on the inflammatory response to a high-fat meal: an experimental study

Citation: Teeman, C. S., Kurti, S. P., Cull, B. J., Emerson, S. R., Haub, M. D., & Rosenkranz, S. K. (2016). The effect of moderate intensity exercise in the postprandial period on the inflammatory response to a high-fat meal: an experimental study. Nutrition Journal, 15, 13. doi:10.1186/s12937-016-0134-4Background: Consuming a high-fat meal (HFM) may lead to postprandial lipemia (PPL) and inflammation. Postprandial exercise has been shown to effectively attenuate PPL. However, little is known about the impact of postprandial exercise on systemic inflammation and whether PPL and inflammation are associated. The purpose of this study was to determine whether moderate intensity exercise performed 60 min following a true-to-life HFM would attenuate PPL and inflammation. Methods: Thirty-nine young adults (18-40 year) with no known metabolic disease were randomized to either a control group (CON) who remained sedentary during the postprandial period or an exercise (EX) group who walked at 60 % VO2peak to expend approximate to 5 kcal/kgbw one-hour following the HFM. Participants consumed a HFM of 10 kcal/kgbw and blood draws were performed immediately before, 2 h and 4 h post-HFM. Results: At baseline, there were no differences between EX and CON groups for any metabolic or inflammatory markers (p > 0.05). Postprandial triglycerides (TRG) increased from baseline to 4 h in the EX and CON groups (p 0.05). There was an increase in soluble vascular adhesion molecule (sVCAM-1) from baseline to 4 h (p = 0.027) for all participants along with a group x time interaction (p = 0.020). Changes in TRG were associated with changes in interleukin-10 (IL-10) from 0 to 2 h (p = 0.007), but were not associated with changes in any other inflammatory marker in the postprandial period (p > 0.05). Conclusions: Despite significant increases in PPL following a HFM, moderate intensity exercise in the postprandial period did not mitigate the PPL nor the inflammatory response to the HFM. These results indicate that in populations with low metabolic risk, PPL and inflammation following a HFM may not be directly related

Does moderate intensity exercise attenuate the postprandial lipemic and airway inflammatory response to a high-fat meal?

Citation: Stephanie P. Kurti, Sara K. Rosenkranz, Morton Levitt, et al., “Does Moderate Intensity Exercise Attenuate the Postprandial Lipemic and Airway Inflammatory Response to a High-Fat Meal?,” BioMed Research International, vol. 2015, Article ID 647952, 10 pages, 2015. doi:10.1155/2015/647952We investigated whether an acute bout of moderate intensity exercise in the postprandial period attenuates the triglyceride and airway inflammatory response to a high-fat meal (HFM) compared to remaining inactive in the postprandial period. Seventeen (11 M/6 F) physically active (≥150 min/week of moderate-vigorous physical activity (MVPA)) subjects were randomly assigned to an exercise (EX; 60% VO[subscript 2peak]) or sedentary (CON) condition after a HFM (10 kcal/kg, 63% fat). Blood analytes and airway inflammation via exhaled nitric oxide (eNO) were measured at baseline, and 2 and 4 hours after HFM. Airway inflammation was assessed with induced sputum and cell differentials at baseline and 4 hours after HFM. Triglycerides doubled in the postprandial period (~113 ± 18%, P < 0.05 ), but the increase did not differ between EX and CON. Percentage of neutrophils was increased 4 hours after HFM (~17%), but the increase did not differ between EX and CON. Exhaled nitric oxide changed nonlinearly from baseline to 2 and 4 hours after HFM (P < 0.05, ƞ² = 0.36) . Our findings suggest that, in active individuals, an acute bout of moderate intensity exercise does not attenuate the triglyceride or airway inflammatory response to a high-fat meal