Understanding the gastrointestinal tract in obesity: From gut motility patterns to enzyme secretion.

BACKGROUND AND PURPOSE: The pathophysiology of obesity has been the product of extensive research, revealing multiple interconnected mechanisms contributing to body weight regulation. The regulation of energy balance involves an intricate network, including the gut-neuroendocrine interplay. As a consequence, research on the gut-brain-microbiota axis in obesity has grown extensively. The physiology of the gastrointestinal tract, far from being underexplored, has significant implications for the development of specific complications in people living with obesity across the fields of gastroenterology, nutrition, and pharmacology. Clinical research indicates higher fasting bile acids serum levels, and blunted postprandial increases in bilious secretions in people living with obesity. Findings are less straightforward for the impact of obesity on gastric emptying with various studies reporting accelerated, normal, or delayed gastric emptying rates. Conversely, the effect of obesity on gastrointestinal pH, gastrointestinal transit, and gastric and pancreatic enzyme secretion is largely unknown. In this review, we explore the current evidence on the gastrointestinal physiology of obesity.

Physiological and muscle histochemical assessment of men and women 10 km runners matched for race performance or training volume.

Women have a disadvantage for performance in long-distance running compared with men. To elaborate on inherent characteristics, 12 subelite women were matched with 12 men for training volume (M-Tm) (56.6 ± 18 vs. 55.7 ± 17 km/wk). The women were also matched to other men for a 10 km staged outdoor time trial (M-Pm) (42:36 min:s) to determine which factors could explain equal running performance. Anthropometry and treadmill tests were done. Fiber type (% Type I and Type IIA) and citrate synthase activities were analyzed in muscle biopsy samples. Consistent sex differences for both comparisons included height, weight, % body fat (P < 0.01), and hematocrit (P < 0.05). Women had lower V̇o2max and peak treadmill speed (PTS) compared with both M-Tm and M-Pm (P < 0.01). Training matched pairs had no sex difference in % PTS at race pace but compared with M-Pm women ran at a higher % PTS (P < 0.05) and %HRmax (P < 0.01) at race pace. On average, the women trained 22.9 km/wk more than M-Pm (+67.5%, P < 0.01). This training was not associated with higher V̇o2max or better running economy. Muscle morphology and oxidative capacity did not differ between groups. Percentage body fat remained significantly higher in women. In conclusion, women matched to men for training volume had slower 10 km performance (-10.5% P < 0.05). Higher training volume, more high-intensity sessions/wk, and time spent training in the 95%-100% HRmax zone may explain the higher % PTS and %HRmax at race pace in women compared with performance-matched men.NEW & NOTEWORTHY When subelite women 10 km runners were matched with male counterparts for 10 km race performance, inherent differences in % body fat, V̇o2max, Hct, and peak treadmill speed were counteracted by significantly higher training volume, more time training at higher %HRmax and consequently, higher %HRmax and %PTS at race pace. Citrate synthase activity and muscle fiber types did not differ. When women and men matched for training, 10 km performance of men was 10.5% faster.

Dietary Patterns, Socio-Demographic Predictors Thereof, and Associations of Dietary Patterns with Stunting and Overweight/Obesity in 1-<10-Year-Old Children in Two Economically Active Provinces in South Africa.

A review of the literature showed that there were only a few studies that reported on the dietary patterns of children in South Africa. The aim of the present study was to characterise the dietary patterns of children aged 1-<10 years who were studied during the Provincial Dietary Intake Survey (PDIS) in 2018 and to investigate the socio-demographic predictors thereof, as well as the associations with stunting and overweight/obesity. Dietary pattern analysis was conducted within three age groups, namely 1-<3-year-olds, 3-<6-year-olds, and 6-<10-year-olds using iterated principal factor analysis with varimax rotation and 24 h recall data from the PDIS. The dietary patterns that emerged seem to be far from ideal. Energy-dense, nutrient-poor patterns were included in the top three strongest patterns in all three age groupings that were investigated. Few of the dietary patterns included vegetables other than starchy vegetables, fruit, dairy, quality proteins, and unrefined carbohydrates. There were no associations between any of the dietary patterns and stunting or overweight/obesity in the children. Key predictors of greater adherence to the mostly unhealthy patterns included indicators of a higher socio-economic status in all three age groups, as well as having an obese mother in the 6-<10-year-old group. Key predictors of greater adherence to the mostly healthy patterns were a higher wealth index and having an obese mother in the two younger groups, with no predictors in the 6-<10-year-old group. We conclude that the dietary patterns of children in the Western Cape contain strong elements of the energy-dense, nutrient-poor dietary patterns. Interventions to improve the dietary intake of children should be directed at both poorer and higher income communities.

The impact of advanced age on gastrointestinal characteristics that are relevant to oral drug absorption: An AGePOP review.

The purpose of this review is to summarize the current knowledge on three physiological determinants of oral drug absorption, i.e., gastric emptying, volumes and composition of luminal fluids, and intestinal permeability, in the advanced age population, so that potential knowledge gaps and directions for further research efforts are identified. Published data on gastric emptying rates in older people are conflicting. Also, there are significant knowledge gaps, especially on gastric motility and emptying rates of drugs and of non-caloric fluids. Compared with younger adults, volumes of luminal contents seem to be slightly smaller in older people. Our understanding on the impact of advanced age on luminal physicochemical characteristics is, at best, very limited, whereas the impact of (co)morbidities and geriatric syndromes in the advanced age population has not been addressed to date. The available literature on the effect of advanced age on intestinal permeability is limited, and should be approached with caution, primarily due to the limitations of the experimental methodologies used.

The Food Environment of Primary School Learners in a Low-to-Middle-Income Area in Cape Town, South Africa.

Rapid changes in food environments, where less nutritious foods have become cheaper and more accessible, have led to the double burden of malnutrition (DBM). The role food environments have played in shaping the DBM has attained global interest. There is a paucity of food environment research in low-to-middle-income countries. We conducted a case study of the food environments of school aged learners. A primary school in Cape Town was recruited. A multi-method design was used: a home food and eating behaviours questionnaire completed by 102 household respondents and four questions completed by 152 learners; learner participatory photography; a semi-structured school principal interview; a tuckshop inventory; observation of three-day tuckshop purchases. Foods that were commonly present in households: refined carbohydrates, fats/oils, chicken, processed meats, vegetables, fruit, legumes, snacks/drinks. Two thirds of households had rules about unhealthy drinks/snacks, ate supper together and in front of the TV, ate a home cooked meal five-seven times/week and ate breakfast together under two times/week. Vegetables were eaten under two times/week in 45% of households. A majority of learners (84%) took a lunchbox to school. Twenty-five learners photographed their food environment and 15 participated in semi-structured interviews. Six themes emerged: where to buy; what is available in the home; meal composition; family dynamics; peer engagement; food preparation. Items bought at informal food outlets included snacks, drinks and grocery staples. The principal interview revealed the establishment of a healthy school food environment, including a vegetable garden, although unhealthy snacks were sold at the tuckshop. Key dimensions of the food environment that require further investigation in disadvantaged urban and informal settlement areas include the home availability of unhealthy foods, eating behaviours in households and healthfulness of foods sold by informal food outlets.

Mean ± Standard Deviation Intake Values for 1-<10-Year-Old South African Children for Application in the Assessment of the Inflammatory Potential of Their Diets Using the DII® Method: Developmental Research.

This study aimed to develop a set of mean ± standard deviation (SD) intake values for South African (SA) children for 36 of the 45 food parameters included in the original Dietary Inflammatory Index (DII®) tool. The SA food composition database contains 30 of the 45 food parameters included in the original DII®, and a supplementary database was developed for six of the food parameters not included in the SA database. The SA child mean ± SD intake of macronutrients, micronutrients and select flavonoids was calculated by age in years, using eight data sets from dietary surveys conducted in SA in the last three decades. A total sample of 5412 children was included in the calculation of the mean ± SD. The current study sample was determined to be representative of 1-<10-year-old children in SA, and the plausibility of the mean intake values was confirmed by being in line with age-appropriate recommendations. Furthermore, an increase in energy, macronutrient, and most micronutrient intakes with increase in age was evident. The generated mean ± SD values for SA children can be used for calculation of the inflammatory potential of the dietary intake of SA children in the age range of 1-<10-year-old children.

Measurement Methods Used to Assess the School Food Environment: A Systematic Review.

Children consume approximately half of their total daily amount of energy at school. Foods consumed are often energy-dense, nutrient-poor. The school food environment represents an effective setting to influence children's food choices when dietary habits are established and continue to track into adulthood. The aim of this review was to: (1) group methods used for assessing the school food environment according to four food environment dimensions: Physical, economic, socio-cultural and policy and (2) assess the quality of the methods according to four criteria: Comprehensiveness, relevance, generalizability and feasibility. Three databases were searched, and studies were used to assess food and beverages provided at school canteens, tuck shops or cafeterias were included. The review identified 38 global studies (including 49 methods of measuring the food environment). The physical environment was the primary focus for 47% of articles, aspects of policy environment was assessed by 37% articles and a small number of studies assessed the economic (8%) and socio cultural (8%) environment. Three methods were rated 'high' quality and seven methods received 'medium' quality ratings. The review revealed there are no standardized methods used to measure the school food environment. Robust methods to monitor the school food environment across a range of diverse country contexts is required to provide an understanding of obesogenic school environments.

Assessment of the Dietary Intake of Schoolchildren in South Africa: 15 Years after the First National Study.

There has not been a national dietary study in children in South Africa since 1999. Fortification of flour and maize meal became mandatory in October 2003 to address micronutrient deficiencies found in the national study in 1999. The purpose of this review was to identify studies done after 1999 in schoolchildren, 6-15 years old, in order to determine whether dietary intakes reflected improvements in micronutrients, namely: iron, zinc, vitamin A, folate, thiamine, riboflavin, vitamin B6, and niacin. An electronic and hand search was done to identify all studies complying with relevant inclusion criteria. The search yielded 10 studies. Overall, there is a paucity of dietary studies which have included the fortified nutrients; only four, of which only one, reported on all micronutrients; making it difficult to determine whether fortification has improved the micronutrient intake of schoolchildren. This is further complicated by the fact that different dietary methods were used and that studies were only done in three of the nine provinces and thus are not generalizable. The results of these studies clearly point to the importance of doing a national study on the dietary intake of schoolchildren in order to confirm the outcomes of the fortification process.