Soluble Dietary Fiber Significance against Obesity in a Western China Population.

Objectives: This study aimed to investigate whether soluble dietary fibers (SDFs) could protect against obesity by influencing weight, body mass index (BMI), body fat rate (BFR), visceral fat rate (VFR), or waistline.
Methods: We examined obese adult patients from western China at 0 and 3 weeks after an SDF diet. Index assessments of obesity including height, weight, BMI, BFR, VFR, and waistline were carried out. We used the Mann-Whitney U test to examine the difference between the usual diet and the SDF group.
Results: Weight, BMI, BFR, and waistline were reduced in both the control group and the SDF group (P < 0.001). The reduction of the four indices in the SDF group was significantly higher than in the control group (P < 0.001). Higher intake of various SDFs has significantly reduced the weight, BMI, BFR, and waistline than the usual diet group in obesity.
Conclusion: Our results indicated that increased intake of SDFs in the diet of obese patients would protect against obesity in the first 3 weeks.

1. Introduction

Dietary fibers (DFs) are distinguished as complex polysaccharides from plants that escape absorption in the small intestine during digestion and serve as dietary substrates for microbial communities that colonize the human gut [1]. DFs are resistant to digestion and absorption in the small intestine while fermenting in the gut. A DF intake of 25∼30 g is recommended by the Chinese Nutrition Society [2]. Soluble dietary fibers (SDFs) are DFs that can dissolve in water, such as pectin, β-glucans, psyllium, gums, and some hemicelluloses, whereas insoluble dietary fibers (ISDFs) cannot [3]. SDFs are viscous, gel-forming, and fermented by the gut microbiota in the large colon into short-chain fatty acids (SCFAs) acetate, propionate, and butyrate [1]. In many studies, SDFs are reported to reduce obesity, diabetes, and cardiovascular disease risk [4-6]. In weight loss programs, SDFs are found to decrease body weight, adipose tissue, and organ weights [1, 3, 7, 8].

Obesity is one of the most severe global epidemics that lead to multiple etiologies including cardiovascular diseases, diabetes mellitus, and cancers [3]. Recently, obesity is supposed to be the mechanism of high-fat diet enrichment of gut microbial communities that exhibit an increased capacity for energy harvest and storage. Most interventions of SDFs treated on obesity are performed with rodents or few individuals [9]. Most studies have been focused on body weight gain, visceral adipose tissue weight, or increased adiposity [7, 10]. No studies to our knowledge have investigated more exactly objective indices in obese patients.

To study the effect of soluble dietary fiber on obesity is helpful to reduce the impact of obesity on human health. Our trial includes 50 obese patients to intake a high content of SDF diet or a usual food diet. We observe the weight, body mass index (BMI), body fat rate (BFR), visceral fat index (VFI), and waistline of subject patients. Weight, BMI, body fat rate, VFI, waistline are indices of obesity, while BMI, body fat rate, and VFI could observe obesity more exactly.

2. Method

2.1. Participants

Participants from this trial were obese patients recruited from western China. Totally, 50 patients who signed consent were enrolled in our trial. 25 participants were subject to a complex various SDFs (Magic Calorie, Du hui Health, Chen du) diet as the treatment group. The other 25 participants were subject to a usual diet as the control group. The baseline of participants was measured at the beginning (0 weeks) of the trial.

2.2. Interventions

The composite of SDFs was 3.5 g/100 ml and included various SDFs, such as konjac glucomannan and β-1,3-glucan. SDFs were added to the usual diet in the treatment group, and the control group was kept on a usual diet. Participants completed study visits at 0 and 3 weeks during the study. Indices of obesity, namely, weight, BMI, body fat rate, VFI, and waistline, were observed at the 0 and 3 weeks after SDF diet or beginning of observation in each group.

2.3. Statistics

We present descriptive statistics as means ± SDs for continuous variables and as frequency (percentage) for categorical variables. Chi-square tests, ANOVA, and Wilcoxon pair tests were used to assess differences in physical and dietary factors between 0 and 3 weeks after SDF treatment. The Mann–Whitney U test was used to assess the difference between the control group and treatment for changes in each index. Analyses were performed in R version 4.1.0. Statistical was set at P value <0.05.

3. Result

The current study comprised 50 obese patients from western China. Table 1 reports all patients' general characteristics at 0 weeks and 3 weeks. Four of the indices of obesity (weight, BMI, BFR, and waistline) had no difference at the baseline of the control group and the treatment group (P > 0.05). We excluded only one index (VFI, P < 0.05) due to imbalance between the two groups in the following analysis.

Table 1

Baseline of all obese participants.

	Overall	Con	HDF	P
Gender	50 (100%)	25 (50%)	25 (50.0%)	0.196
Female	37 (74.0%)	21 (42.0%)	16 (32.0%)
Male	13 (26.0%)	4 (8.0%)	9 (18.0%)
Age	36.74 ± 1.01	38.2 ± 1.23	34.16 ± 1.44	0.008
Height (m)	1.64 ± 0.08	1.61 ± 0.06	1.66 ± 0.10	0.032
Weight (kg)	76.09 ± 15.28	73.51 ± 8.66	78.67 ± 19.70	0.808
BMI	28.27 ± 3.99	28.37 ± 2.77	28.16 ± 4.98	0.455
BFR (%)	31.06 ± 3.56	30.49 ± 2.52	31.63 ± 4.34	0.734
VFI	12.06 ± 2.96	12.72 ± 2.46	11.40 ± 3.30	0.040
Waistline (cm)	95.19 ± 11.75	94.69 ± 9.86	95.70 ± 13.57	0.954

Values are expressed as number (percentage of patients) or mean (SD). Body mass index- BMI, body fat rate- BFR, visceral fat index- VFI.

3.1. Weight, BMI, BFR, and Waistline of Obesity Were Reduced in 3 Weeks

The four specific indices of obesity were compared between 0 weeks and 3 weeks in each patient (Table 2). In our trial, both the control group and the treatment group showed significant weight loss (P < 0.001) in 3 weeks. Both the control group and SDF group have been reduced in BMI, BFR, and waistline (all P < 0.001) in 3 weeks. The reduction of the four indices of obesity is more obvious in the SDF group (Table 3). For evaluating more exactly the effect of SDF in obese patients, we next compared the change of indices between the usual diet and the SDF diet.

Table 2

Comparison of indices between 0 weeks and 3 weeks in each obesity group.

Index	Group	0 weeks	3 weeks	P value
Weight (kg)	Con	73.51 ± 8.66	71.84 ± 8.70	<0.001
	SDF	78.67 ± 19.70	73.90 ± 18.99	<0.001
BMI	Con	28.37 ± 2.77	27.73 ± 2.84	<0.001
	SDF	28.16 ± 4.98	26.44 ± 4.83	<0.001
BFR (%)	Con	30.49 ± 2.52	29.69 ± 2.58	<0.001
	SDF	31.63 ± 4.34	29.80 ± 4.31	<0.001
Waistline (cm)	Con	94.69 ± 9.86	91.36 ± 8.97	<0.001
	SDF	95.70 ± 13.57	89.22 ± 12.58	<0.001

Values are expressed as mean (SD). Body mass index- BMI; body fat rate- BFR.

Table 3

Effect of SDFs in obese patients in 3 weeks.

Index of obesity	Overall	Control group	SDF group	P
Weight minus (kg)	3.23 ± 2.16	1.68 ± 0.57	4.77 ± 2.06	<0.001
BMI minus	1.18 ± 0.74	0.65 ± 0.22	1.72 ± 0.68	<0.001
BFR minus (%)	1.32 ± 0.69	0.80 ± 0.34	1.83 ± 0.55	<0.001
Waistline minus (cm)	4.91 ± 3.04	3.33 ± 2.22	6.48 ± 2.96	<0.001

Values are expressed as mean (SD). Body mass index- BMI; body fat rate- BFR.

3.2. SDFs Significantly against Obesity

Because both the usual diet and the SDF diet could reduce indices of obesity, we next examined the reduction of indices between the control group and the SDF group. Figure 1 illustrates the obvious reduction of the 4 indices of obesity in 3 weeks in each group. The value of the four indices at 3 weeks after an SDF diet (Figure 1, pink group) was significantly low than the value of the four indices at 0 weeks (Figure 1, blue group). The reduction between the control group and the SDF group was compared and reported in Table 3. The reduction of all indices in the SDF group was significantly higher than that in the control group (P < 0.001). The differences between the two groups reveal that SDFs can protect against obesity.

Figure 1

Comparison of weight, BMI, body fat rate, and waistline between the control group and the SDF group in 3 weeks. Black circles represent the values of the control group. Black triangles represent the values of the SDF group. The blue line represents the difference of baseline between the two groups. The pink line represents the difference of the value at 3 weeks between the two groups. (a) Weight loss between the two groups in 3 weeks. (b) Reduction of BMI between the two groups in 3 weeks. (c) Reduction of body fat rate between the two groups in 3 weeks. (d) Reduction of waistline between the two groups in 3 weeks. P value deduced the difference of the reduction in each index between the control group and the SDF group.

4. Discussion

Results from our investigation show that a soluble dietary fiber diet in the form of various compositions was significant against obesity in a China western population. Although both the control group and the treatment group have diminished obesity indices, the SDF group has a significant reduction in each index, the phenomenon which reveals that an SDF diet could protect against obesity.

These results are consistent with previous studies that suggest SDFs are associated with weight [11], waistline [12], and visceral fat [13]. Previous studies have found that DF was inversely associated with weight gain and visceral adipose tissue, respectively [14, 15]. Thus, the results of our current study are in line with previous findings and suggest that weight loss, waistline, and visceral fat may be influenced by SDFs [7, 11, 16].

To our knowledge, few studies investigated the effects of SDFs on a region of China's population with obesity [11, 17]. Most studies of SDFs in obesity focus on mammal experiments [13, 18–20]. No combination of the 5 indices of obesity would indicate obesity more exactly and objectively [12, 21]. However, the current study is limited by the enrolled patient number and may not be generalizable to other regions of China or the world. Further studies aiming at confirming our results in a large population are required.

In summary, our results indicate that SDFs have the potential to protect against obesity by contributing to weight loss, waistline loss, reduction of body fat, and visceral fat. These findings suggest that SDFs should be considered when developing preventive strategies for alleviating the burden of obesity.