Effects of Chocolate Containing D-allulose on Postprandial Lipid and Carbohydrate Metabolism in Young Japanese Women

Abstract

D-allulose is an almost zero calorie sweetener with 70% sweetness of sucrose, and has some health benefits. Here, we conducted a small-scale human trial with a single blind cross over design in 8 young healthy Japanese women to assess the utility of D-allulose as a low-calorie and functional sweetener, using chocolates as the test food. Subjects were asked to consume 50 g of chocolate containing no D-allulose (placebo), 1.8 g D-allulose, 3.6 g D-allulose, or 12.5 g D-allulose, and blood samples were collected at 0, 1, 2, 4, and 6 h after intake. The levels of postprandial free fatty acid increased and blood glucose and insulin levels decreased in the D-allulose group compared with those in the placebo group. These changes may be related to the enhanced GLP-1 secretion observed after the D-allulose intake. Our findings suggest that D-allulose can be a healthy alternative low-calorie sweetener for use in confectioneries.

Introduction

Metabolic syndrome is a major health problem affecting the world, and there has been an increase in number of cases in Japan in the past few decades. According to the 2017 National Nutritional and Health Survey, the prevalence of metabolic syndrome was estimated at 27.8% for men and 12.9% for women in Japanⁱ⁾. Metabolic syndrome is commonly recognized as a condition associated with increased visceral fat accumulation and risk factors (hyperglycemia, dyslipidemia, and hypertension). As these factors are closely related to lifestyle, correcting an individual's lifestyle habits such as those related to diet and exercise is important to prevent metabolic syndrome. In relation to diet, lower amounts of calorie, sugar, and fat in foods have been proposed to avoid excessive energy intake, and there has been an impetus for the development of healthier food ingredients such as low-calorie sweeteners, resistant starches, and fat replacement foods.

Rare sugars are monosaccharides that occur less frequently in nature, and some of them were recently found to have various health benefits in addition to low calories (Chattopadhyay et al., 2014). D-allulose, a rare sugar, is an almost zero calorie sweetener with 70% of the sweetness of sucrose, and is naturally contained in Itea plants (Poonperm et al., 2007). Many reports have indicated the suppressing effects of D-allulose on postprandial blood glucose and insulin levels (Hayashi et al., 2010; Hossain et al., 2015; Iida et al., 2008; Matsuo, 2013). Long-term D-allulose intake reduces fat mass (Han et al., 2018) and body weight (Han et al., 2016), and increases energy expenditure (Ochiai et al., 2014). Furthermore, it decreases hepatic enzyme activities and improves fatty liver (Itoh et al., 2015; Tanaka et al., 2019; Tanaka et al., 2020). Additionally, Iwasaki et al. (2018) reported that D-allulose intake promotes secretion of glucagon like peptide-1 (GLP-1) and restricts the level of food consumption by activation of vagal afferent signaling. The effective dose of D-allulose to enhance secretion of GLP-1 in humans was reported as more than 0.07 g per kg body weight (Yada et al., 2017). Further, the safety of D-allulose has been substantially confirmed by several studies in both animals (Matsuo et al., 2002; Matsuo et al., 2012; Yagi and Matsuo, 2009) and humans (Hayashi et al., 2010; Tanaka et al., 2019; Tanaka et al., 2020). D-allulose is also generally recognized as safe (GRAS) by the Food and Drug Administration in USA. The maximum non-effective level of D-allulose that did not cause diarrhea in human subjects was reported to be approximately 0.50–0.60 g per kg body weight (Iida et al., 2007). D-allulose is contained in some dairy foods like corn-snacks, fried dough cakes, and Worcester sauce (Oshima et al., 2006), and is regarded as an isomerized product of fructose in the manufacturing process. Miyoshi et al. (2019) reported that D-allulose was a more stable rare sugar than other rare sugars under various manufacturing conditions. These facts together support the potential application of D-allulose as a healthier sweetener than the common sweeteners.

Chocolate is a craved food among young Japanese women (Komatsu and Aoyama, 2014). The annual consumption of chocolates has been increasing in Japan, and per-capita consumption in 2017 was reported to be 2.16 kg/person according to the data provided by the Chocolate and Cocoa Association of Japanⁱⁱ⁾. Chocolates contain a high amount of sugar and fat. According to standard tables of food composition in Japan, 100 g of milk chocolate contains 59.3 g of monosaccharides and 34.1 g of fat (The Subdivision on Resources The Council for Science and Technology Ministry of Education, Culture, Sports, Science and Technology [MEXT] Japan, 2015). The postprandial blood sugar status after chocolate intake can be worsened easily. Hence, dark chocolate has become popular among people who like chocolates but also want to acquire health benefits and reduce sugar intake. However, dark chocolates are too bitter for consumption for some people. As mentioned above, D-allulose can be a potential alternative to sucrose as a low-calorie sweetener and is also expected to have beneficial effects on carbohydrate and lipid metabolism. Therefore, we carried out a small-scale trial in young Japanese women to assess the effects of chocolates containing D-allulose on postprandial plasma parameters related to lipid and carbohydrate metabolism.

Materials and Methods

Participants    The subjects were 8 young healthy Japanese women with regular ovarian cycles and apolipoprotein E phenotype 3/3. Subject characteristics were as follows: age, 21.0 ± 0.3 years; height, 160.2 ± 1.2 cm; body weight, 53.0 ± 1.6 kg; body mass index, 20.6 ± 0.5 kg/m² (values are the means ± standard errors [SE]). All subjects were nonsmokers without apparent acute or chronic illnesses, and did not have any medications and dietary supplements. This experiment conformed with the Helsinki Declaration (adopted in 1964 and amended in 2013) and Ethical Guidelines for Epidemiological Research in Japan. The protocol was approved by the Institutional Review Board of Sugiyama Jogakuen University School of Life Studies (approval date, March 24, 2017; approval no., 2016-26). Subjects were given full information about the importance, purpose, and contents of the experiment, and informed consent was obtained from each of them. This study was registered in the University Hospital Medical Information Network clinical trial registry (registration number: UMIN000039769).

Test foods    Four types of chocolates were used as test foods, and the nutrient composition of each test food is shown in Table 1. D-allulose amounts of 1.8 g and 3.6 g acted as substitutes for 10% and 20% sucrose, respectively, which was in the placebo chocolate. The utilizable amount of D-allulose in a 50 g chocolate was fixed as 12.5 g, based on GRAS Notice 498. All test foods were manufactured by NISSHIN KAKO Co., Ltd (Tokyo). D-allulose was supplied by Matsutani Chemical Industry Co., Ltd. (Itami). Appearance of these test foods did not differ.

Table 1. Nutrient composition in 50 g test foods

	Placebo	1.8 g D-allulose		3.6 g D-allulose	12.5 g D-allulose
Calorie (kcal)	316	309		302	266
Protein (g)			2.4
Fat (g)			24.2
Carbonhydrate (g)			20.0
Serose (g)	18.2	16.4		14.6	5.7
D-allulose (g)	0.0	1.8		3.6	12.5
Others (g)			1.8
Fiber (g)			2.7
Ash (g)			0.7

Experimental design    A randomized, single-blinded, crossover study was conducted, and each subject participated in four trials wherein the following were given: placebo, 1.8 g of D-allulose, 3.6 g of D-allulose, 12.5 g of D-allulose. Each trial had a 4-week interval between the trials to minimize effects on metabolism by the menstrual status. Subjects abstained from intake of caffeine and alcohol, and had predesignated lunch and dinner during the previous day of the experiment. Dinner of the previous day of the experiment was completely finished by 21:00, and then subjects were not allowed to eat and drink anything other than water. Subjects consumed the different test foods (50 g chocolate) with 200 mL of water after fasting blood collection on the experiment day. Blood samples were collected from a brachial vein at 0, 1, 2, 4, and 6 h after consumption of the test food. After blood collection at the 2 h-timepoint, subjects performed light exercise for 30 min on a treadmill (AF-1700; ALINCO, Osaka or TRUE600; True fitness technology, USA) to reflect a daily amount of exercise. Eating food and exercise, except walking on the treadmill, were prohibited until the end of blood collection, but subjects could drink water freely after the 1 h-timepoint of blood collection.

Biochemical analysis    The following parameters were measured in all trials: triglyceride (TG), total cholesterol (T-Cho), free fatty acid (FFA), glucose, insulin, lactic acid, pyruvic acid, total ketone body, acetoacetic acid (AcAc), and 3-hydroxybutyric acid (BOH). Detailed analyses as follows were made only in the placebo and the 12.5 g-D-allulose groups to evaluate exogenous lipid metabolism: apolipoproteins (apoA-I, apoA-II, apoB48, apoB, apoC-II, apoC-III, and apoE), subfractions of TG and cholesterol in lipoproteins [chylomicron (CM), very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL)] measured by gel filtration high-performance liquid chromatography, remnant like particles cholesterol (RLP-C), pre-heparin lipoprotein lipase mass (LPL). Incretin hormones [GLP-1 and gastric inhibitory peptide (GIP)] were measured only in the placebo and the 12.5 g-D-allulose groups because only the 12.5 g-D-allulose chocolate contained the effective dose mentioned in a previous report (Yada et al., 2017). Blood samples were immediately centrifuged at 3 500 rpm for 15 min and then stored at 4 °C for insulin, TG, T-Cho, RLP-C, and apolipoprotein measurements or at −80 °C for the other parameters until analysis. The glucose levels were determined using glucose assay kits (FUJIFILM Wako Pure Chemical Corporation, Osaka). Apolipoproteins (except apoB48) and subfractions levels of TG and cholesterol were measured by Skylight Biotech Inc. (Akita). The FFA levels were measured by New Drug Research Center Inc. (Tokyo). The other parameters were determined by SRL, Inc. (Tokyo). The incremental area under the curves (IAUC) for blood glucose and insulin were calculated by the trapezoidal method generally used in the calculation of glycemic index.

Statistical analysis    Each value is expressed as the mean ± SE. Data were statistically analyzed to compare between the placebo and D-allulose groups. The Dunnett's test was used for the data measured in all trials, and a paired t-test was used for the data measured only in the placebo and 12.5 g-D-allulose groups. Statistical analyses were performed using SPSS version 26 (IBM Japan, Ltd., Tokyo), and a p-value below 0.05 was considered statistically significant.

Results

Results measured in all test groups are shown in Figs. 1–4 and Table 2. With respect to lipid metabolism, postprandial TG levels were not significantly different between the placebo and all the D-allulose groups (Fig. 1A). In contrast, significant increases were observed in the FFA levels at 1 and 2 h in the 12.5 g-D-allulose group compared with those in the placebo group (Fig. 1B). The levels of total ketone body, AcAc, and BOH did not show significant differences between the placebo and all D-allulose groups (Fig. 2). No significant changes in T-Cho levels were observed after test food consumption (data not shown). Measured parameters related to carbohydrate metabolism are shown in Figs. 3 and 4 and Table 2. Postprandial blood glucose and insulin levels significantly decreased in the 12.5 g-D-allulose group at 1 h compared to those in the placebo group (Fig. 3). IAUC of blood glucose and insulin for 2 h were significantly lower in the 12.5 g-D-allulose group than in the placebo group (Table 2). Levels of pyruvic acid and lactic acid decreased in the D-allulose groups at 1 h in a dose-dependent manner (Fig. 4).

Fig. 1.

Levels of TG and FFA after each test food consumption.

A: Triglycerid (TG) levels, B: Free fatty acid (FFA) levels.

Each value shows mean ± SE (n=8). Significant differences compared with the placebo group were observed, as determined by the Dunnett's test (*p < 0.05).

Fig. 2.

Levels of ketone bodies after each test food consumption.

A: Total ketone body levels, B: Acetoacetic acid (AcAc) levels, C: 3-hydroxybutyric acid (BOH) levels.

Each value shows mean ± SE (n=8). No significant differences compared with the placebo group were observed, as determined by the Dunnett's test.

Fig. 3.

Levels of blood glucose and insulin after each test food consumption.

A: Glucose levels, B: Insulin levels.

Each value shows mean ± SE (n=8). Significant differences compared with the placebo group were observed, as determined by the Dunnett's test (*p < 0.05).

Fig. 4.

Levels of pyruvin acid and lactic acid after each test food consumption.

A: Pyruvin acid levels, B: Lactic acid levels.

Each value shows mean ± SE (n=8). Significant differences compared with the placebo group were observed, as determined by the Dunnett's test (*p < 0.05, **p < 0.01).

Table 2. IAUC of blood glucose and insulin for 2 h after each test food consumption

	Placebo	1.8 g D-allulose	3.6 g D-allulose	12.5 g D-allulose
Glucose (mg·h/dL)	9.58 ± 2.23	6.76 ± 1.82	8.17 ± 1.53	1.51 ± 0.873*
Insulin (µU·h/mL)	14.8 ± 3.18	13.6 ± 2.17	9.90 ± 1.97	3.97 ± 1.33*

Each value shows mean ± SE (n=8).

Significant differences in the 12.5 g D-allulose group compared with the placebo group were observed, as determined by the Dunnetf s test (*p<0.05).

Results of detailed analyses are shown in Tables 3 and 4 and Fig. 5. No significant changes in TG and cholesterol subfractions levels were observed (Table 3). Levels of ApoB48 at 1 h and LPL mass at 6 h indicated significant decreases in the 12.5 g-D-allulose group compared with those in the placebo group (Table 4). RLP-C levels did not change after test food consumption (data not shown). Fig. 5 demonstrates the levels of incretin hormones after each test food consumption. GLP-1 levels tended to increase (p = 0.078), while those of GIP were significantly low in the 12.5 g-D-allulose group at 1 h after the consumption compared with those in the placebo group.

Table 3. Triglyceride and cholesterol subfractions in lipoproteins after each test food consumption

	(mg/dL)		0 h	1 h	2 h	4 h	6 h
Triglyceride	CM	Placebo	7.73 ± 2.59	9.93 ± 3.04	11.0 ± 2.87	19.0 ± 5.99	15.3 ± 5.15
		12.5 g D-allulose	5.96 ± 1.87	6.60 ± 1.93	8.06 ± 2.12	16.9 ± 5.55	10.1 ± 3.49
	VLDL	Placebo	40.4 ± 6.11	45.7 ± 6.14	51.4 ± 6.63	57.7 ± 7.30	52.3 ± 8.77
		12.5 g D-allulose	41.1 ± 3.90	44.3 ± 5.19	47.7 ± 5.26	60.9 ± 7.19	51.4 ± 8.22
	LDL	Placebo	16.8 ± 0.995	16.1 ± 0.807	15.9 ± 0.761	16.1 ± 0.697	15.6 ± 0.720
		12.5 g D-allulose	17.4 ± 0.809	17.1 ± 0.667	17.2 ± 0.686	17.3 ± 0.561	17.4 ± 0.881
	HDL	Placebo	14.8 ± 0.663	14.6 ± 0.622	15.2 ± 0.554	16.5 ± 0.387	15.4 ± 0.775
		12.5 g D-allulose	16.2 ± 1.38	15.9 ± 1.43	16.2 ± 1.37	18.4 ± 1.63	17.2 ± 1.46
Cholesterol	CM	Placebo	2.53 ± 0.762	2.65 ± 0.727	2.75 ± 0.688	4.10 ± 1.17	3.77 ± 1.26
		12.5 g D-allulose	2.08 ± 0.590	1.97 ± 0.499	2.16 ± 0.533	3.81 ± 1.08	2.42 ± 0.709
	VLDL	Placebo	32.6 ± 3.42	32.3 ± 3.22	33.2 ± 3.65	33.7 ± 4.14	35.9 ± 4.88
		12.5 g D-allulose	31.6 ± 2.56	32.0 ± 2.66	33.0 ± 2.81	34.5 ± 2.94	35.3 ± 3.12
	LDL	Placebo	88.0 ± 5.63	86.7 ± 4.89	85.9 ± 5.21	85.1 ± 5.29	85.9 ± 4.55
		12.5 g D-allulose	83.3 ± 6.29	83.3 ± 5.74	83.7 ± 6.06	80.8 ± 6.21	82.7 ± 6.21
	HDL	Placebo	54.3 ± 2.42	54.0 ± 2.49	53.4 ± 2.40	52.4 ± 2.64	53.3 ± 2.84
		12.5 g D-allulose	52.9 ± 2.61	53.5 ± 2.72	53.6 ± 2.60	51.2 ± 2.33	52.0 ± 2.24

Each value shows mean ± SE (n=8).

No significant differences in the 12.5 g D-allulose group were observed compared with the placebo group, as determined by a paired t-test.

Table 4. Apolipoproteins and LPL mass levels after each test food consumption

		O h	1 h	2 h	4 h	6 h
ApoA-I (mg/dL)	Placebo	144 ± 3.51	144 ± 3.68	144 ± 3.72	143 ± 3.56	144 ± 3.46
	12.5 g D-allulose	141 ± 4.74	142 ± 5.33	145 ± 4.93	142 ± 4.77	144 ± 4.47
ApoA-II (mg/dL)	Placebo	28.1 ± 0.847	27.6 ± 0.778	27.9 ± 0.756	27.6 ± 0.966	28.4 ± 1.01
	12.5 g D-allulose	27.0 ± 0.886	27.3 ± 0.950	27.5 ± 1.04	27.0 ± 0.965	27.4 ± 0.888
ApoB48 (pg/mL)	Placebo	2.01 ± 0.492	3.31 ± 0.547	4.33 ± 0.944	4.30 ± 0.511	4.11 ± 0.724
	12.5 g D-allulose	1.73 ± 0.151	1.93 ± 0.200*	2.98 ± 0.226	5.29 ± 0.670	3.89 ± 0.555
ApoB (mg/dL)	Placebo	87.7 ± 5.56	85.4 ± 5.43	86.3 ± 5.64	86.9 ± 6.17	90.1 ± 6.52
	12.5 g D-allulose	84.3 ± 4.55	84.4 ± 4.44	86.0 ± 4.55	85.1 ± 4.60	86.8 ± 4.57
ApoC-II (mg/dL)	Placebo	3.03 ± 0.419	3.03 ± 0.407	2.99 ± 0.440	2.58 ± 0.458	2.65 ± 0.450
	12.5 g D-allulose	3.01 ± 0.338	3.00 ± 0.353	2.99 ± 0.374	2.63 ± 0.379	2.69 ± 0.355
ApoC-III (mg/dL)	Placebo	8.29 ± 0.566	8.14 ± 0.575	7.98 ± 0.613	7.40 ± 0.699	7.58 ± 0.681
	12.5 g D-allulose	8.21 ± 0.723	7.94± 0.834	7.58 ± 0.802	7.41 ± 0.817	7.39 ± 0.741
ApoE (mg/dL)	Placebo	4.44 ± 0.167	4.34 ± 0.134	4.39 ± 0.127	4.41 ± 0.147	4.41 ± 0.143
	12.5 g D-allulose	4.60 ± 0.197	4.63 ± 0.239	4.70 ± 0.214	4.71 ± 0.213	4.56 ± 0.150
LPL (ng/mL)	Placebo	45.6 ± 7.24	-	-	-	39.5 ± 6.37
	12.5 g D-allulose	38.5 ± 5.53				34.3 ± 5.58*

Each value shows mean ± SE (n=8).

Significant differences in the 12.5 g D-allulose group compared with the placebo group were observed, as determined by a paired t-test (*p<0.05).

Fig. 5.

Levels of incretin homones after each test food consumption.

A: Glucagon like peptide-1 (GLP-1) levels, B: Gastric inhibitory peptide (GIP) levels.

Each value shows mean ± SE (n=8). A significant difference and tendency compared with the placebo group were observed, as determined by a paired t-test (†p < 0.1, **p < 0.01).

Discussion

In this study, we assessed the effects of chocolate containing D-allulose as a low-calorie sweetener on postprandial metabolism. With regards to lipid metabolism, while postprandial TG and ketone bodies levels did not show significant differences in all test groups, postprandial FFA levels significantly increased in the 12.5 g-D-allulose group compared with that in the placebo group (Figs. 1 and 2). Elevation of FFA levels implies an enhancement of fat oxidation derived from FFA. Increases in fat oxidation by D-allulose consumption were previously reported in humans during rest (Kimura et al., 2017) and exercise (Yamaguchi et al., 2019). Kimura et al. (2017) showed elevated fat oxidation during rest after consumption of high-fat breakfast with a drink containing 5 g of D-allulose, and Yamaguchi et al. (2019) demonstrated similar results during exercise after consumption of a drink containing 5 g of D-allulose. In this study, we used chocolates containing D-allulose as test foods. It is expected from these results that D-allulose could enhance fat oxidation in various types of food like sports drinks, drinks with a meal, and confectioneries. Kuzawa et al. (2019) also evaluated postprandial metabolism after intake of fat only or fat with D-allulose, fructose or sucrose. In this report, D-allulose intake with fat significantly increased FFA levels compared to combinations with sucrose or fructose. Other indicators related to lipid metabolism (TG, RLP-C, and apoB100) after intake of D-allulose and fat showed similar responses to combinations of fat with fructose or sucrose, which agreed with our results. Postprandial TG, cholesterol subfraction (CM, VLDL, LDL, and HDL) and apolipoproteins levels also showed no clinically significant changes upon intake of chocolates containing D-allulose (Tables 3 and 4).

With respect to carbohydrate metabolism, postprandial blood glucose and insulin levels were lower in the D-allulose groups than in the placebo group (Fig. 3), and IAUC for blood glucose and insulin in the 12.5 g-D-allulose group was significantly reduced compared with that for the placebo group (Table 2). Many previous reports indicated suppressing effect of D-allulose on postprandial blood glucose and insulin levels by inhibition of the α-glucosidase activity in the small intestine and the facilitation of glycogen synthesis due to the enhancement of glucokinase translocation in liver cells (Hayashi et al., 2010; Hossain et al., 2011; Iida et al., 2008; Matsuo and Izumori, 2006). Moreover, levels of the glycolysis metabolites pyruvic acid and lactic acid also significantly decreased in the D-allulose groups compared with those in the placebo group (Fig. 4). These results indicate that carbohydrate oxidation may be low after intake of chocolate containing D-allulose, and might thereby facilitate fat oxidation. The differences in nutrient composition of the test foods could also contribute to these effects on carbohydrate and fat metabolism, because amounts of sucrose were less in the D-allulose groups than in the placebo group (Table 1). Additionally, it is also reasonable to suppose that enhancing the glucokinase translocation and subsequent synthesis of glycogen in the liver suppressed energy production derived from the glycolytic pathway, leading to the induction of FFA from abdominal fat as an alternative source.

In this study, changes in incretin hormones levels were observed (Fig. 5). Blood GLP-1 levels tended to increase in the 12.5 g-D-allulose group compared with that in the placebo group at 1 h (Fig. 5A). Hence, another hypothesis could be that the enhancement of GLP-1 secretion might be involved in the postprandial increase in fat oxidation and improvement in carbohydrate metabolism by the consumption of chocolate containing D-allulose. Previous studies also revealed that D-allulose stimulated GLP-1 secretion from L cell in the lower part of the small intestine in the animal experiments, where improvements in carbohydrate and lipid metabolism were observed (Hayakawa et al., 2018; Iwasaki et al., 2018). GLP-1 has also been reported to suppress feeding and improve glucose tolerance and lipid metabolism (Campbell and Drucker, 2013). Moreover, high plasma GLP-1 levels or a GLP-1 receptor agonist were reported to enhance fat oxidation, causing increases in a set of oxidation factors including uncoupling protein-1 (UCP-1), peroxisome proliferation activated receptor α (PPARα), and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) (Pannacciulli et al., 2006; Xu et al., 2016). Upregulation of UCP-1 and PPARα expression were reported simultaneously with increase in fat oxidation in D-allulose-fed rats (Iwasaki et al., 2018; Nagata et al., 2015). These results together suggest that consumption of chocolates containing D-allulose could promote postprandial fat oxidation through increases in GLP-1 secretion. On the other hand, the significant decrease in GIP levels was considered to be due to differences in baseline values (Fig. 5B). The variations in GIP (ΔGIP) levels were actually not significant between the placebo and the 12.5 g -D-allulose groups (data not shown).

The level of LPL, which catalyzes TG hydrolysis along with production of FFA for tissue utilization (Mead et al., 2002), significantly decreased in the 12.5 g-D-allulose group compared with that in the placebo group at 6 h (Table 4). The adipose tissue and blood LPL levels are reportedly stimulated by insulin, while the muscle LPL level is known to be downregulated by insulin (Inadera et al., 1992; Kiens et al., 1989). Therefore, the low blood LPL levels after intake of chocolates containing D-allulose in this study may be attributed to considerably low levels of insulin. Matsuo et al. (2001) showed increases in soleus muscle LPL level in rats fed D-allulose. Meanwhile, as the hormone sensitive lipase in adipose tissues is suppressed by insulin (de Graaf et al., 2002), the fat oxidation in adipose tissues might enhance via decreases in insulin levels by D-allulose, and consequently FFA derived from adipose tissues might increase. Though there seems to be a positive correlation between LPL mass levels in post-heparin and pre-heparin blood (Kobayashi, 2003), further investigation of the exact effect of D-allulose intake on LPL will be required. Moreover, the small sample size is also a limitation in this study; therefore, further studies with larger sample size will be needed.

In conclusion, we demonstrated that intake of chocolates containing D-allulose promoted postprandial fat oxidation, and reduced blood glucose and insulin levels compared with common chocolates containing sucrose. Although functional food ingredients provide health benefits, some of them often become compromised in their taste. However, approximately 80% of consumers assessed the taste and flavor of chocolates containing D-allulose as good as common chocolates in a survey. Therefore, D-allulose can be an effective low-calorie sweetener for both health benefits and good taste. Our findings could support the worldwide use of D-allulose in the near future.

Acknowledgements    The authors gratefully acknowledge all participants in this study. We also thank NISSHIN KAKO Co., Ltd for manufacturing the test chocolates containing D-allulose for this study. MT, HN, and TI are employees of Matsutani Chemical Industry Co., Ltd, which provided funding for this study.

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