Postprandial Glycaemic Responses of Dried Fruit-Containing Meals in Healthy Adults: Results from a Randomised Trial

Short-term effects of sugar-free apricot jam, cocoa powder and dried cranberry cereal bar on glycaemic responses in healthy adults: a randomised clinical trial

High sugar intake has been associated with adverse effects on health, with some types of breakfast being highly linked to overweight and obesity. The aim was to compare the effects of four sugar-free breakfast items, apricot jam with white bread (JWB), white bread (WB), cocoa with fat-free milk (CM), and dried cranberry cereal bar (CB), compared to d-glucose on the glycaemic responses. Using a cross-over design, twelve healthy individuals (25 ± 4 years; BMI 22 ± 2 kg/m²) received isoglucidic test meals (25 g of available carbohydrate) and 25 g glucose reference, in random order. Glycaemic index/load (GI/GL) were calculated, and capillary blood glucose samples were collected at 0–120 min after meal consumption. Subjective appetite was assessed with visual analogue scales. Sugar-free apricot jam and cocoa powder contained traces of available carbohydrates and were consumed along with bread and fat-free milk, respectively. JWB and WB were classified as medium GI, low-to-medium GL; CM as medium GI, low GL; and CB as high GI, low-to-medium GL. Subjective hunger was lower after JWB, fullness was higher after CM and pleasure was higher after CB (P for all < 0⋅05). In conclusion, sugar-free apricot jam with and without WB and cocoa powder with fat-free milk are suitable healthy breakfast options leading to improved glycaemic and subjective appetite responses.

Extended Inter-Meal Interval Negatively Impacted the Glycemic and Insulinemic Responses after Both Lunch and Dinner in Healthy Subjects

This study aimed to investigate the glycemic and insulinemic effects of lunch timing based on a fixed feeding window, and the effects of apple preload on postprandial glucose and insulin responses after nutrient-balanced lunch and the subsequent high-fat dinner in healthy participants. Twenty-six participants completed four randomized, crossover experimental trials: (1) early standardized lunch at 12:00 (12S); (2) apple preload to 12S (12A+S); (3) late standardized lunch at 14:00 (14S); and (4) apple preload to 14S (14A+S); wherein twenty participants’ blood samples were collected for insulin analysis following the lunch trails. In each experimental trial, each participant equipped with a continuous glucose monitor (CGM) was provided with a standardized breakfast and a high-fat dinner to be consumed at 8:00 and 18:00, respectively. The late lunch (14S) resulted in significantly elevated glucose peak, delayed insulin peak time, decreased insulin sensitivity, and increased insulin resistance following the lunch; also decreased glycemic response following the subsequent dinner and larger blood glucose fluctuation over the 24-h period compared with the 12S. The 14A+S significantly reduced the glucose peak, the insulin peak time and the glycemic variability following the lunch, also the 24-h glycemic variability compared with the 14S. The insulin sensitivity was significantly improved in the 12A+S, compared with that of the 12S. In conclusion, the present study found that an extra 2-h inter-meal fasting before and after lunch resulted in elevated glycemic response in both macronutrient-balanced meal and high-fat meal in healthy subjects. The negative impact of a late lunch could be partly reversed by the apple preload, without a trade-off of insulin secretion.

Both Isocarbohydrate and Hypercarbohydrate Fruit Preloads Curbed Postprandial Glycemic Excursion in Healthy Subjects

This study aimed to investigate the impact of fruit preloads on the acute postprandial glycemic response (PGR) and satiety response of a rice meal in healthy female subjects based on iso-carbohydrate (IC) and hyper-carbohydrate (HC) contents, respectively. The IC test meals including (1) rice preload (R + 35R), (2) orange preload (O + 35R), (3) apple preload (A + 35R) and (4) pear preload (P + 35R), contained 50.0 g available carbohydrates (AC) where the preload contributed 15.0 g and rice provided 35.0 g. The HC meals included (1) orange preload (O + 50R), (2) apple preload (A+50R) and (3) pear preload (P + 50R), each containing 65.0 g AC, where the fruits contributed 15.0 g and rice provided 50.0 g. Drinking water 30 min before the rice meal was taken as reference (W + 50R). All the preload treatments, irrespective of IC or HC meals, resulted in remarkable reduction (p < 0.001) in terms of incremental peak glucose (IPG) and the maximum amplitude of glycemic excursion in 180 min (MAGE_0–180), also a significant decrease (p < 0.05) in the area of PGR contributed by per gram of AC (AAC), compared with the W + 50R. Apple elicited the lowest PGR among all test meals, as the A + 35R halved the IPG and slashed the incremental area under the curve in 180 min (iAUC_0–180) by 45.7%, while the A + 50R reduced the IPG by 29.7%, compared with the W + 50R. All the preload meals and the reference meal showed comparable self-reported satiety in spite of the difference in AC. In conclusion, pre-meal consumption of three fruits effectively curbed post-meal glycemia even in the case of a 30% extra carbohydrate load.

Is sugar extracted from plants less healthy than sugar consumed within plant tissues? The sugar anomaly

There are dilemmas in the minds of consumers with respect to sugar consumption - they would like to consume sugars for sweetness, but in a healthy (and perhaps guilt free!) way. In a sense, consumers believe that if sugar does not appear as an ingredient on the product label, but is intrinsic in the food (and will appear as a nutrient), it is 'good'. As an ingredient, however, it is viewed as a 'bad chemical' associated with tooth decay and obesity. The reality is that unless processing induced modifications have occurred, the sugar molecule within a plant tissue is the same molecule structure as present in purified sugar. The same calorific value. However, there is an argument that humans eat too refined food and that if sugars were eaten in their natural context (e.g. within a fruit), their presence and concentration would be in harmony (where different nutrients complement and balance the sugar concentration) with the human body. This reflects the process of eating, satiety, presence of other nutrients (including water) and the associated impact of the indigestible components of plant foods on the transit/nutrient bioavailability control and thus benefits through the gut. The authors explore these issues in this article and seek to provide a scientific basis to different sides of the argument - sugar is good or bad depending on how (in which format and how much/how concentrated) it is consumed. More importantly perhaps, how should sugar consumption - an important nutrient - be managed to optimize the benefits but reduce the disadvantages? © 2020 Society of Chemical Industry.

Potential contributions of the methodology to the variability of glycaemic index of foods

Glycaemic index (GI) testing provides a useful point of comparison between carbohydrate sources. For this comparison to be meaningful, the methods used to determine GI values need to be rigorous and consistent between testing events. This requirement has led to increasing standardization of the GI methodology, with an international standard developed in joint consultation with FAO/WHO (ISO 26642:2010) currently the most up to date document. The purpose of this review is to compare the international standard to methods of published studies claiming to have performed a GI test. This analysis revealed that the international standard permits a wide range of choices for researchers when designing a GI testing plan, rather than a single standardized protocol. It has also been revealed that the literature contains significant variation, both between studies and from the international standard for critical aspects of GI testing methodology. The primary areas of variation include; what glucose specification is used, which reference food is used, how much reference food is given, what drink is given during testing, the blood sampling site chosen and what assay and equipment is used to measure blood glucose concentration. For each of these aspects we have explored some of the methodological and physiological implications of these variations. These insights suggest that whilst the international standard has assisted with framing the general parameters of GI testing, further stan-dardization to testing procedures is still required to ensure the continued relevance of the GI to clinical nutrition.

Mediterranean Raisins/Currants as Traditional Superfoods: Processing, Health Benefits, Food Applications and Future Trends within the Bio-Economy Era

This review elaborates on the significance of Mediterranean raisins, focusing particularly on indigenous Greek varieties (e.g., Zante currants) as a previously overlooked traditional food, currently brought on the spotlight, resulting from the increased consumers’ awareness to improve wellness through diet modification. Recent studies on the effect of processing steps on final quality, along with findings on the potential health benefits raisins and currants elicit, are also presented. The development of novel functional food products to further exploit the nutritional value and the bioactive compounds of raisins is evidenced in view of indicating potential food industry applications. Moreover, valorization options of waste and by-product streams obtained from processing facilities are also proposed. Conclusively, raisins and currants should be further enhanced and incorporated in a balanced diet regime through the inclusion in novel foods formulation. Evidently, both the processing of the onset material and side-streams management, are essential to ensure sustainability. Hence, the article also highlights integrated biorefinery approaches, targeting the production of high-value added products that could be re-introduced in the food supply chain and conform with the pillars of bio-economy.

A glycaemic index compendium of non-western foods

Current international tables published on the glycaemic index (GI) of foods represent valuable resources for researchers and clinicians. However, the vast majority of published GI values are of Western origin, notably European, Australian and North American. Since these tables focus on Western foods with minimal inclusion of other foods from non-Western countries, their application is of limited global use. The objective of this review is to provide the GI values for a variety of foods that are consumed in non-Western countries. Our review extends and expands on the current GI tables in an attempt to widen its application in many other regions of the world.

A Review of Edible Jujube, the Ziziphus jujuba Fruit: A Heath Food Supplement for Anemia Prevalence

The fruits of Ziziphus jujuba, commonly known as jujube, red date or Chinese date, are taken as fresh or dried food, and as traditional medicine worldwide due to high nutritional and health values. Traditionally in China, jujube is considered as a medicinal fruit that is being used in treating blood deficiency. In this review, the beneficial effects of jujubes on the hematopoietic functions are summarized and discussed. As illustrated in cell and animal models, the application of jujube extract possessed beneficial effects, including regulation of erythropoiesis via activation of hypoxia inducible factor-induced erythropoietin, potential capacity in recycling heme iron during erythrophagocytosis and bi-directional regulation of immune response. Thus, the blood-nourishing function of jujube is being proposed here. Flavonoid, polysaccharide and triterpenoid within jujube could serve as the potential active ingredients accounting for the aforementioned health benefits. Taken together, these findings provide several lines of evidence for further development of jujube as supplementary products for prevention and/or treatment of anemia.

Dried fruit consumption and cardiometabolic health: a randomised crossover trial

Fruit intake is associated with lower risk of cardiometabolic diseases. However, effects of dried fruits on cardiometabolic health are not well researched. We investigated the effect of daily dried fruit consumption compared with a carbohydrate-rich snack on cardiometabolic disease risk factors in adults with increased cardiometabolic risk. A two-period randomised crossover trial was conducted in adults (n 55) with elevated BMI and at least one additional risk factor for cardiometabolic disease to compare the effects of consuming 3/4 cup/d mixed dried fruits (plums, figs, dates and raisins) or an energy- and carbohydrate-matched control snack for 4 weeks. The primary outcome was LDL-cholesterol; secondary outcomes included other lipids and lipoproteins, glucose and insulin, C-reactive protein, blood pressure and vascular stiffness. Linear mixed models were used for data analysis. Lipid and lipoprotein concentrations did not differ between conditions; however, dried fruit increased LDL-cholesterol (0·10 mmol/l, 95 % CI 0·01, 0·20) compared with baseline. Compared with the control, dried fruit increased mean fasting glucose (0·08 mmol/l, 95 % CI 0·005, 0·16; P = 0·038). Vascular outcomes, fasting insulin and C-reactive protein did not differ between conditions. Mean weight changes did not differ (P = 0·55) but tended to increase after both conditions (dried fruit 0·3 kg, 95 % CI -0·09, 0·65; control 0·4 kg, 95 % CI 0·01, 0·75). Thus, short-term daily consumption of a large portion of mixed dried plums, figs, dates and raisins, without structured dietary guidance, did not improve cardiometabolic risk factors, compared with carbohydrate-rich snacks, in adults with increased baseline cardiometabolic risk.

Co-ingested vinegar-soaked or preloaded dried apple mitigated acute postprandial glycemia of rice meal in healthy subjects under equicarbohydrate conditions

This study investigated 2 possible approaches to dietary control of acute postprandial responses to a rice-based meal under equicarbohydrate conditions: (1) a dried apple (DA) preload and (2) co-ingestion of vinegar-soaked DA. We hypothesized that both approaches would counteract hyperglycemia with no negative effect on satiety, possibly explained by an inhibitory effect on digestive enzyme activity and/or the effect of the sugar component of the DA. Fifteen healthy female subjects consumed (1) rice, (2) co-ingestion of DA and rice (DA + R), (3) DA preload and rice (PDA + R), (4) rice with sugar solution (same sugar profile as in DA) preloaded (PSS + R), or (5) co-ingestion of rice with vinegar-soaked DA (VDA + R) in a randomized crossover trial. Acute postprandial glycemic response tests and subjective satiety tests were conducted for each test meal. Compared with rice reference, the PA + R and PSS + R achieved 31.4% and 36.3% reduction of the incremental area under the curve_0-120, 24.3% and 27.0% decreases in the average glucose peak, along with 21.6% and 27.0% decreases in glycemic excursion in 240 minutes, whereas the VDA + R resulted 42.4%, 27.0%, and 29.7% reductions in the incremental area under the curve_0-120, peak, and glycemic excursion, respectively. The DA-containing meals had no effect or a favorable effect on satiety. The in vitro assay found larger resistant starch and smaller rapid digestible starch fractions in DA + R and VDA + R meals compared to those of the rice reference (P < .001). The result of this study supported the research hypothesis, and the DA-containing meals could be considered as a potential dietary approach for glycemic management.

Apple Preload Halved the Postprandial Glycaemic Response of Rice Meal on in Healthy Subjects

This study aimed to investigate the possible glycemic effect of apple preload on acute postprandial glycemic responses (GRs) of a following rice meal, comparing with its co-ingestion counterpart and an apple sugar solution preload, based on equal carbohydrates intake. In a randomized crossover trial, 18 healthy female subjects consumed (1) rice, (2) co-ingestion of apple and rice (A+R), (3) apple preload and rice (PA+R), and (4) rice with sugar solution preload (same sugar profile as in apple) (PSS+R). Acute postprandial GR tests and subjective satiety tests were carried out for each test food. Compared with rice reference, the PA+R achieved a 50% reduction of the iAUC_0-120, a 51.4% reduction of the average peak value, and a 52.6% reduction of glycemic excursion in 240 min, while the PSS+R showed 29.7% and 31.6% reduction of peak value and glycemic excursion, respectively. No significant differences were found between R and PA+R in any of the satiety characteristics. Compared with rice control, apple preload of 15 g available carbohydrates remarkably lowered the acute postprandial GR without negative effect on satiety. The sugar component may partly contribute to the glycemic suppressing effect of the apple preload.

The Postprandial Appearance of Features of Cardiometabolic Risk: Acute Induction and Prevention by Nutrients and Other Dietary Substances

The purpose of this review is to provide an overview of diets, food, and food components that affect postprandial inflammation, endothelial function, and oxidative stress, which are related to cardiometabolic risk. A high-energy meal, rich in saturated fat and sugars, induces the transient appearance of a series of metabolic, signaling and physiological dysregulations or dysfunctions, including oxidative stress, low-grade inflammation, and endothelial dysfunction, which are directly related to the amplitude of postprandial plasma triglycerides and glucose. Low-grade inflammation and endothelial dysfunction are also known to cluster together with insulin resistance, a third risk factor for cardiovascular diseases (CVD) and type-II diabetes, thus making a considerable contribution to cardiometabolic risk. Because of the marked relevance of the postprandial model to nutritional pathophysiology, many studies have investigated whether adding various nutrients and other substances to such a challenge meal might mitigate the onset of these adverse effects. Some foods (e.g., nuts, berries, and citrus), nutrients (e.g., l-arginine), and other substances (various polyphenols) have been widely studied. Reports of favorable effects in the postprandial state have concerned plasma markers for systemic or vascular pro-inflammatory conditions, the activation of inflammatory pathways in plasma monocytes, vascular endothelial function (mostly assessed using physiological criteria), and postprandial oxidative stress. Although the literature is fragmented, this topic warrants further study using multiple endpoints and markers to investigate whether the interesting candidates identified might prevent or limit the postprandial appearance of critical features of cardiometabolic risk.

Effect of dried fruit on postprandial glycemia: a randomized acute-feeding trial

Background/Objectives

To investigate the effect of dried fruit in modifying postprandial glycemia, we assessed the ability of 4 dried fruits (dates, apricots, raisins, sultanas) to decrease postprandial glycemia through three mechanisms: a glycemic index (GI) effect, displacement effect, or ‘catalytic’ fructose effect.

Subjects/Methods

We conducted an acute randomized, multiple-crossover trial in an outpatient setting in 10 healthy adults. Participants received 3 white bread control meals and 12 dried fruit test meals in random order. The test meals included each of 4 dried fruits (dates, apricots, raisins, sultanas) alone (GI effect), 4 of the dried fruits displacing half the available carbohydrate in white bread (displacement effect), or 4 of the dried fruits providing a small ‘catalytic’ dose (7.5 g) of fructose added to white bread (‘catalytic’ fructose effect). The protocol followed the ISO method for the determination of GI (ISO 26642:2010). The primary outcome was mean ± SEM GI (glucose scale) for ease of comparison across the three mechanisms.

Results

Ten healthy participants (7 men, 3 women; mean ± SD age and BMI: 39 ± 12 years and 25 ± 2 kg/m²) were recruited and completed the trial. All dried fruit had a GI below that of white bread (GI = 71); however, only dried apricots (GI = 42 ± 5), raisins (GI = 55 ± 5), and sultanas (51 ± 4) showed a significant GI effect (P < 0.05). When displacing half the available carbohydrate in white bread, all dried fruit lowered the GI; however, only dried apricots (GI = 57 ± 5) showed a significant displacement effect (P = 0.025). None of the dried fruits showed a beneficial ‘catalytic’ fructose effect.

Conclusions

In conclusion, dried fruits have a lower GI and reduce the glycemic response of white bread through displacement of half of the available carbohydrate. Longer-term randomized trials are needed to confirm whether dried fruit can contribute to sustainable improvements in glycemic control.

Trial registration

ClinicalTrials.gov identifier, NCT02960373