Conference on "Multidisciplinary approaches to nutritional problems". Postgraduate Symposium. The role of fat in gastric emptying and satiety: acute and chronic effects. Proc Nutr Soc. 2009;68:89-97. [PMID: 19126262 DOI: 10.1017/S0029665108008859]

Macronutrients effects on satiety and food intake in older and younger adults: A randomised controlled trial

Older adults are advised to increase their protein intake to maintain their muscle mass. However, protein is considered the most satiating macronutrient and this recommendation may cause a decrease in total energy intake. To date, satiety studies comparing all three macronutrients have been undertaken in young adults, and it is unclear if the same response is seen in older adults. The objective of this study was to compare the effect of preloads high in protein, fat, and carbohydrate but equal in energy (∼300 kcal) and volume (250 ml) on energy intake, perceived appetite, and gastric emptying in younger and older adults. Twenty older and 20 younger adults completed a single-blinded randomised crossover trial involving three study visits. Participants consumed a standard breakfast, followed by a preload milkshake high in either carbohydrate, fat, or protein. Three hours after the preload, participants were offered an ad libitum meal to assess food intake. Visual analogue scales were used to measure perceived appetite and gastric emptying was measured via the 13C-octanoic acid breath test. There was no significant effect of preload type or age on energy intake either at the ad libitum meal, self-recorded food intake for the rest of the test day or subjective appetite ratings. There was a significant effect of preload type on gastric emptying latency phase and ascension time, and an effect of age on gastric emptying latency and lag phase such that older adults had faster emptying. In conclusion, energy intake, and perceived appetite were not affected by macronutrient content of the preloads in both younger and older adults, but gastric emptying times differed.

The [13 C]octanoic acid breath test for gastric emptying quantification: A focus on nutrition and modeling

Gastric emptying (GE) is the process of food being processed by the stomach and delivered to the small intestine where nutrients such as lipids are absorbed into the blood circulation. The combination of an easy and inexpensive method to measure GE such as the CO₂ breath test using the stable isotope [¹³C]octanoic acid with semi‐mechanistic modeling could foster a wider application in nutritional studies to further understand the metabolic response to food. Here, we discuss the use of the [¹³C]octanoic acid breath test to label the solid phase of a meal, and the factors that influence GE to support mechanistic studies. Furthermore, we give an overview of existing mathematical models for the interpretation of the breath test data and how much nutritional studies could benefit from a physiological based pharmacokinetic model approach.

Effect of medium-chain TAG and exercise on satiety, energy intake and energy balance

The present study examined whether the combination of medium-chain TAG (MCT) along with exercise suppresses energy intake to a greater extent compared with either intervention alone. Twelve participants consumed a porridge breakfast containing 692·9 kJ of either vegetable or MCT oil on two separate occasions: one followed by rest for 240 min and another followed by rest broken up with 1 h of cycling at 65 % $\dot V$O2peak starting at 120 min. At 240 min, participants consumed a buffet lunch to satiation and recorded their food intake for the rest of the day. Expired air samples (for calculation of energy expenditure (EE)) and subjective ratings of appetite on visual analogue scales were taken every 30 min, and gastric emptying (GE) breath samples were taken every 15 min. No effect of either breakfast or exercise condition was observed on energy intake at any time point (P > 0·05) or no effect was observed on subjective appetite ratings (P > 0·05). Exercise trials resulted in significantly higher EE compared with resting trials (2960·6 kJ, 95 % CI 2528·9, 3392·2; P < 0·001), and MCT increased resting EE over 4 h compared with long-chain TAG (LCT) (124·8 kJ, 95 % CI 13·5, 236·0; P = 0·031). GE was accelerated by exercise, regardless of the breakfast consumed, but delayed by MCT in both resting and exercise trials. The results show that exercise causes energy deficits via increased EE without promoting dietary compensation. MCT has no effect on energy intake or satiety but increases EE under resting conditions. There is no additive effect of MCT and exercise on EE, intake or appetite ratings.

The Role of Dietary Protein and Fat in Glycaemic Control in Type 1 Diabetes: Implications for Intensive Diabetes Management

A primary focus of the management of type 1 diabetes has been on matching prandial insulin therapy with carbohydrate amount consumed. However, even with the introduction of more flexible intensive insulin regimes, people with type 1 diabetes still struggle to achieve optimal glycaemic control. More recently, dietary fat and protein have been recognised as having a significant impact on postprandial blood glucose levels. Fat and protein independently increase the postprandial glucose excursions and together their effect is additive. This article reviews how the fat and protein in a meal impact the postprandial glycaemic response and discusses practical approaches to managing this in clinical practice. These insights have significant implications for patient education, mealtime insulin dose calculations and dosing strategies.

Perioperative nutrition: what is the current landscape?

Poor nutrition status has long been linked to increases in postoperative complications and adverse outcomes for the patient undergoing elective surgery. While optimal planning for nutrition therapy should be comprehensive spanning throughout the perioperative period, recent advances have focused on the concept of "prehabilitation" to best prepare the patient prior to the insult of surgery. Adding immune/metabolic modulating formulas the week of surgery with carbohydrate drinks to optimize glycogen deposition immediately prior to surgery, enhances patient recovery and return to baseline function. Such nutrition strategies should now be combined with a host of other practices (such as smoking cessation, weight loss, glucose control, and specialized exercise program) as part of a structured protocol to maximize patients' chances for a full and rapid recovery from their elective surgical procedure.

The carbon dioxide production rate assumption biases gastric emptying parameters in healthy adults

RATIONALE

An altered gastric emptying (GE) rate has been implicated in the aetiology of obesity. The (13)C-octanoic acid breath test (OBT) is frequently used to measure GE, and the cumulative percentage of (13)C recovered (cPDR) is a common outcome measure. However, true cPDR in breath is dependent on accurate measurement of carbon dioxide production rate (VCO(2)). The current study aimed to quantify differences in the (13)C OBT results obtained using directly measured VCO(2) (VCO(2DM)) compared with (i) predicted from resting VCO(2) (VCO(2PR)) and (ii) predicted from body surface area VCO(2) (VCO(2BSA)).

METHODS

The GE rate of a high-fat test meal was assessed in 27 lean subjects using the OBT. Breath samples were gathered during the fasted state and at regular intervals throughout the 6-h postprandial period for determination of (13)C-isotopic enrichment by continuous-flow isotope-ratio mass spectrometry. The VCO(2) was measured directly from exhaled air samples and the PDR calculated by three methods. The bias and the limits of agreement were calculated using Bland-Altman plots.

RESULTS

Compared with the VCO(2DM), the cPDR was underestimated by VCO(2PR) (4.8%; p = 0.0001) and VCO(2BSA) (2.7%; p = 0.02). The GE T(half) was underestimated by VCO(2PR) (13 min; p = 0.0001) and VCO(2BSA) (10 min; p = 0.01), compared with VCO(2DM).

CONCLUSIONS

The findings highlight the importance of directly measuring VCO(2)production rates throughout the (13)C OBT and could partly explain the conflicting evidence regarding the effect of obesity on GE rates.

Successful development of satiety enhancing food products: towards a multidisciplinary agenda of research challenges

In the context of increasing prevalence of overweight and obesity in societies worldwide, enhancing the satiating capacity of foods may help people control their energy intake and weight. This requires an integrated approach between various food-related disciplines. By structuring this approach around the new product development process, this paper aims to present the contours of such an integrative approach by going through the current state of the art around satiety enhancing foods. It portrays actual food choice as the end result of a complex interaction between internal satiety signals, other food benefits, and environmental cues. Three interrelated routes to satiating enhancement are to change the food composition to develop stronger physiological satiation and satiety signals, anticipate and build on smart external stimuli at the moment of purchase and consumption, and improve palatability and acceptance of satiety enhanced foods. Key research challenges in achieving these routes in the field of nutrition, food technology, consumer, marketing, and communication are outlined.

Gastrointestinal transit, post-prandial lipaemia and satiety following 3 days high-fat diet in men

BACKGROUND/OBJECTIVES

High-fat (HF) diets of 2 weeks have been shown to accelerate gastric emptying (GE). To date, no studies have shown any alteration in GE following shorter HF diets. The aim of this study was to assess if an HF, high-energy diet of 3 days can adapt gastrointestinal (GI) transit, blood lipids and satiety.

SUBJECTS/METHODS

Eleven male volunteers participated in a study consisting of three, 3-day interventions each separated by a test day. During the first intervention, volunteers recorded their diet. In the second and third interventions, volunteers repeated their food diary plus either a low-fat yogurt or HF yogurt supplement in randomized order. Test days involved measurement of GE using the (13)C octanoic-acid breath-test, mouth-to-caecum transit time (MCTT) using the inulin H(2) breath test and satiety using visual analogue scales. Blood samples for measurement of lipaemia were taken using a venous cannula.

RESULTS

MCTT was different between the three test days (P=0.038), with the shortest MCTT following the HF intervention. GE was shortest following the HF intervention. There were no differences in satiety between the interventions. The HF intervention reduced triglycerides, total cholesterol and low-density lipoprotein cholesterol, and increased high-density lipoprotein cholesterol.

CONCLUSION

This study shows that changes in GI transit owing to an HF diet can occur in a time period as short as 3 days.

Characteristics of gastric emptying rate in simple obesity accompanied by bulimia

AIM: To observe gastric emptying rates in simple obesity accompanied by bulimia, simple obesity with normal diet and normal weight people, and to investigate the characteristics of gastric emptying.

METHODS: Forty two subjects with simple obesity accompanied by bulimia, 32 subjects with simple obesity and normal food intake and 40 people with normal weight were studied with SPECT. After subjects eating test meal marked 99mTc-DTPA, picture of stomach was collected, and gastric emptying rate was calculated according to a fixed formula.

RESULTS: Gastric emptying halftime of simple obesity accompanied by bulimia was shorter than that of normal control (71.21 ± 19.2 min vs 81.25 ± 14.08 min, P < 0.01). Gastric emptying halftime of normal food intake group was similar to that of normal control group. Gastric emptying rate of simple obesity with bulimia was quicker than normal control (30 min: 22.35% ± 4.53% vs 15.82% ± 4.72%; 60 min: 55.13% ± 9.21% vs 47.25% ± 8.18%; 90 min: 76.35% ± 5.76% vs 69.29% ± 8.85%; 120 min: 92.22% ± 7.41% vs 84.92% ± 6.53%, all P < 0.01). Gastric emptying rate of normal food intake group was similar to that of normal control group.

CONCLUSION: The gastric emptying rate in simple obesity with bulimia become is quicker, which may partly account for obesity.