Original papers
Anti-obesity effects of two Korean whole wheat cultivars in high-fat diet-induced obese mice
2025 Volume 31 Issue 3 Pages 215-221
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2025 Volume 31 Issue 3 Pages 215-221
This study compared the anti-obesity effects of whole wheat extracts from ‘Shinmichal’ and ‘Saekeumkang’ in mice fed a high-fat diet to evaluate their potential benefits in obesity management. ‘Shinmichal’ and ‘Saekeumkang’ treatment groups showed significant reductions in body weight gain. Histological analysis revealed that ‘Shinmichal’ and ‘Saekeumkang’ reduced lipid accumulation in epididymal adipose and liver tissues, with significant decreases in levels of hepatic total cholesterol (TC) and triglycerides (TG). Both cultivars significantly improved serum levels of glucose, TC, TG, and lipoprotein. Additionally, both wheat varieties led to reductions in the atherosclerosis index and coronary risk factor, indicating a lower risk of cardiovascular problems. The ‘Shinmichal’ and ‘Saekeumkang’ Korean wheat cultivars exhibit significant anti-obesity effects, including reduced body weight gain, lipid accumulation, and improved blood biochemical parameters. Both wheat varieties may be effective dietary supplements for the prevention of obesity, underscoring the value of domestic wheat production in addressing health issues.
Obesity is a significant global health issue that arise from an imbalance between energy consumption and expenditure (Tzotzas et al., 2011). Obesity and excessive adipose tissue contribute to the development of atherosclerosis. Obesity is closely linked to numerous metabolic disorders, such as hypertension, type 2 diabetes, and cardiovascular diseases (Carbone et al., 2019). Given that obesity is often considered a lifestyle-related condition, addressing it requires comprehensive lifestyle changes, particularly dietary changes. Dietary modifications play a crucial role in the prevention and management of obesity. Foods rich in phytochemicals, such as whole grains, fruits, and vegetables, promote satiety and improve metabolic health (Eriksen et al., 2020).
Wheat is one of the most essential crops for satisfying global food needs and ranks among the most widely consumed crops globally (Hassan et al., 2021). Wheat is widely recognized for its rich content of bioactive compounds, including dietary fiber, vitamins, minerals, and various phytochemicals that have been linked to numerous health benefits (Onipe et al., 2015). South Korea relies heavily on wheat imports from the United States, Australia, and Canada, with domestic production accounting for less than 1 % of the total wheat supply in 2020 (Kim et al., 2022). To address this dependency and enhance the value of domestic grains, the National Institute of Crop Science in Rural Development Administration, developed the ‘Shinmichal’ wheat variety. This wheat cultivar is cultivated to improve the bread-making performance of white wheat flour (Choi et al., 2012). The ‘Saekeumkang’ wheat cultivar is commonly used in South Korea for making noodles or bread because of its high yield and quality (Kim et al., 2022). Our previous study, which measured the antioxidant and cytoprotective effects of 41 wheat cultivars in South Korea, revealed the distinctive advantages of the ‘Shinmichal’ and ‘Saekeumkang’ cultivars. The ‘Shinmichal’ wheat cultivar exhibited a relatively higher total polyphenol content compared to other cultivars, highlighting its potential as a superior source of antioxidants. In contrast, the ‘Saekeumkang’ cultivar demonstrated significantly higher DPPH and ABTS radical scavenging activities, emphasizing its exceptional antioxidant capacity. Antioxidants play a critical role in mitigating oxidative stress, which is closely associated with metabolic dysfunction and obesity (Khutami et al., 2022). Therefore, the abundant antioxidant compounds and strong radical scavenging abilities of these cultivars may contribute to their potential anti-obesity effects.
The development of superior wheat cultivars is crucial for improving self-sufficiency, enhancing the nutritional quality of wheat products, and supporting agricultural sustainability in South Korea. In addition, promoting the consumption of whole grains as part of a balanced diet can help manage and prevent obesity, thereby supporting overall health and well-being. Our previous research has demonstrated that wheat bran from the ‘Saekeumkang’ and ‘Shinmichal’ cultivars can inhibit non-alcoholic fatty liver disease by activating the AMPK pathway (An et al., 2023). Since wheat is commonly consumed in its whole grain form, the current study utilized whole wheat extracts from both the ‘Saekeumkang’ and ‘Shinmichal’ cultivars to compare the anti-obesity effects of the commonly used ‘Saekeumkang’ wheat variety with the newly developed ‘Shinmichal’ wheat variety in South Korea.
Materials and chemicals ‘Shinmichal’ and ‘Saekeumkang’ wheat samples were obtained from the Rural Development Administration of the Republic of Korea. Whole wheat powder (100 g each) was extracted using 1 L of methanol for 16 h at room temperature with continuous shaking. The methanol extracts were evaporated under vacuum, and the concentrates were dissolved in 0.1 % Kolliphor® EL to achieve a concentration of 50 mg/mL. The extracts were prepared in a single batch. The yield of the extracts was 3.8 % for ‘Shinmichal’ and 3.36 % for ‘Saekeumkang’, respectively. Samples were stored at –20°C until further use.
Animal experiments A schematic representation of the animal study design is shown in Fig. 1. Five-week-old male C57BL/6J mice were purchased from Central Lab Animal Inc. (Seoul, Korea). After the adaptation period, the experimental mice were randomly divided into four groups, each consisting of eight mice: normal diet (ND), high-fat diet (HFD), HFD + 100 mg/kg ‘Shinmichal’ extract in 0.1 % Kolliphor/day (HFD +‘Shinmichal’), and HFD + 100 mg/kg ‘Saekeumkang’ extract in 0.1 % Kolliphor/day (HFD+‘Saekeumkang’). Mice in the ND group were fed a standard laboratory diet (Purina 38057, Cargill Agri Purina Inc., Sungnam, Korea), Mice in the HFD groups were fed a diet with 45 % kcal of fat (TD 06415, Harlan Teklad, Indianapolis, IN, USA). Samples were administered orally once a day by oral gavage in a 0.1 % Kolliphor distilled water vehicle, whereas control mice received 0.1 % Kolliphor via oral gavage for 8 weeks. All animal experiments were approved by the Institutional Animal Care and Use Committee of Chungbuk National University (approval no. CBNUA-1751-22-01) and followed the guidelines suggested by the committee. The mice were anesthetized with diethyl ether after a 6 h fast, and blood was collected using Vacutainer serum-separating tubes (BD Biosciences, Franklin NJ, USA) for plasma biochemical analysis. Plasma was obtained by centrifuging the blood in the tubes at 10 000 rpm for 3 min at 4 °C. Organs (epididymal adipose tissue and liver) were immediately harvested, rinsed with physiological saline solution, and weighed.
Histology analysis of liver and epididymal fat tissues Liver and epididymal fat tissues were fixed in 10 % formalin buffer. Standard sections of 4 μm thickness were cut and stained with hematoxylin and eosin (H&E). The sections were viewed via optical microscopy using an Axio Imager.A2 instrument (Carl Zeiss, Oberkochen, Germany). Additionally, the stained epididymal fat tissues were analyzed for fat size using an optical microscopy image analysis system.
Measurement of plasma biochemical parameters analysis Plasma triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), aspartate transaminase (AST), alanine transaminase (ALT), blood urea nitrogen (BUN), creatinine, and glucose levels were determined using a model AU480 automated chemistry analyzer (Beckman Coulter, Munich, Germany). Non-HDL-C was calculated by subtracting HDL-C from TC. The atherogenic index (AI) and cardiac risk factor (CRF) were calculated using the following formulae:
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Statistical analysis The results are expressed as mean ± standard error. The statistical significance of the differences between the mean values of the treatment groups was determined using one-way analysis of variance (ANOVA), followed by Tukey’s test. For the body weight analysis shown in Fig. 1, statistical differences were assessed using two-way ANOVA followed by Dunnett’s test.
Effect of whole wheat on body weight in HFD-fed mice To evaluate the anti-obesity effects of whole wheat extract, mice were given the HFD with or without ‘Shinmichal’ and ‘Saekeumkang’ (administered orally at doses of 100 mg/kg daily) over 8 weeks. Weekly food intake and body weight measurements were recorded. By the end of the treatment period, the HFD group showed a mean body weight increase of 70.4 % compared with their initial weight. The ‘Shinmichal’ and ‘Saekeumkang’ treatment groups showed increases of 54.3 % and 46.6 %, respectively (Fig. 1A). Treatment with ‘Shinmichal’ and ‘Saekeumkang’ significantly decreased body weight gain in HFD mice (Fig. 1B). Additionally, there was no significant difference in food intake across the HFD and whole wheat-treated groups (Fig. 1C). However, the ‘Shinmichal’ and ‘Saekeumkang’ treatment markedly reduced food efficiency ratio, compared to that in the HFD group (Fig. 1D). These findings suggest that ‘Shinmichal’ and ‘Saekeumkang’ lead to a reduction in body weight gain and food efficiency ratio.
Effect of whole wheat on histological changes in the epididymal adipose and liver tissues Lipid accumulation in the epididymal adipose and liver tissues is commonly observed in HFD-fed mice (Im et al., 2015). H&E staining revealed that the epididymal adipose tissue in the HFD group was enlarged or hypertrophic, whereas mice supplemented with whole wheat exhibited smaller adipose tissue sizes and reduced fat weight (Fig. 2A–2C). Histological analysis revealed that, unlike the ND group, the HFD group had enlarged hepatocytes with extensive vacuolation (Fig. 2D). Treatment with whole wheat significantly reduced vacuolization and the number of lipid droplets in liver tissues of HFD mice. Hepatic steatosis assessed by measuring the hepatic TC and TG levels revealed that ‘Shinmichal’ and ‘Saekeumkang’ treatment significantly lowered HFD-induced TC and TG levels in the liver (Fig. 2E and 2F).
A recent study reported an association between whole wheat grain and lipid synthesis, showing that whole wheat significantly decreased the expression levels of 3-hydroxy-3-methylglutaryl-CoA reductase and fatty acid synthase in the mouse liver (Liu et al., 2020). The observed effects of whole wheat in inhibiting lipid synthesis and lowering cholesterol can be attributed to the presence of the bran layer, which is rich in vitamins and antioxidants. An et al. (2023) have shown that the unsaponifiable matter (USM) from the wheat bran of both the ‘Shinmichal’ and ‘Saekeumkang’ wheat cultivars effectively suppressed lipogenesis in free fatty acid-induced HepG2 cells. This suppression was mediated through the activation of the AMP-activated protein kinase signaling pathway, which subsequently resulted in a downregulation of the expression of sterol regulatory element-binding protein 1c and fatty acid synthase, key regulators of lipogenesis. Moreover, two cultivars promoted the upregulation of peroxisome proliferator-activated receptor alpha and carnitine palmitoyltransferase 1, thereby enhancing β-oxidation and mitigating lipid accumulation in hepatocytes. The USM of the ‘Shinmichal’ and ‘Saekeumkang’ wheat varieties is rich in bioactive compounds, including alkylresorcinols, carotenoids, vitamin E, policosanol, and phytosterols (An et al., 2023). However, no significant differences were observed between the two cultivars in both the USM and whole wheat powder (data not shown). Previous studies have reported that these components effectively inhibit lipid accumulation (Mounien et al., 2019; Wong et al., 2017; Zabolotneva et al., 2022). Furthermore, the most abundant compound was β-sitosterol, which has been shown to ameliorate HFD-induced hepatic steatosis (Abo-Zaid et al., 2023). These findings indicate that anti-obesity effects observed in this study following the administration of whole wheat extracts from the two varieties are likely attributable to the diverse array of bioactive compounds current in the bran layers. Therefore, the therapeutic effect of ‘Shinmichal’ and ‘Saekeumkang’ wheat extracts in mitigating HFD-induced lipid accumulation may be largely due to their rich phytochemical profile. However, a limitation of this study is the lack of direct measurement of lipid and cholesterol metabolism-related proteins in mouse adipose and liver tissues. Future research should focus on evaluating the expression of key enzymes involved in fatty acid synthesis, β-oxidation, and cholesterol metabolism to better understand the underlying mechanisms and further validate the therapeutic potential of these wheat extracts in obesity.
Effect of whole wheat on blood biochemical parameters in HFD-fed mice Elevated serum TG levels are associated with an increased risk of cardiovascular disease (Chi et al., 1982). High TG concentrations led to increases in TC and non-HDL-C, which can accumulate on arterial walls (Kwon et al., 2016). Conversely, higher levels of HDL-C can reduce non-HDL-C buildup and offer protection against heart disease by aiding in the removal of non-HDL-C, TC, and TG from the arteries (Sacks et al., 2002). In obese individuals, elevated glucose levels contribute to high TC and TG levels (Kim et al., 2015). The BUN and creatinine levels are indicators of kidney health and toxicity. ALT and AST levels are crucial for amino acid synthesis in the liver and their activities tend to increase with liver damage induced by HFD (Kim et al., 2016). Increased ALT and AST activities are linked to higher serum cholesterol levels owing to disruptions in bile acid production associated with liver disorders (Rosen et al., 2002). In the current study, ‘Shinmichal’ and ‘Saekeumkang’ treatments decreased HFD-induced serum AST and ALT levels compared to those in the HFD group (Fig. 3A and 3B). The HFD-fed mice displayed elevated serum levels of glucose, TC, TG, and non-HDL-C, whereas their creatinine and BUN levels remained unchanged. Treatment with ‘Shinmichal’ and ‘Saekeumkang’ significantly decreased glucose, TC, TG, and non-HDL-C levels, compared to those in the HFD group. Only the HDL-C level in the ‘Shinmichal’ treatment group was higher than that in the HFD group. In this study, both the AI and CRF values were calculated using TC and HDL-C values. The AI values were 0.79 for the ND group, 1.28 for the HFD group, 1.09 for the HFD + ‘Shinmichal’ group, and 1.13 for the HFD + ‘Saekeumkang’ group. The CRF values were 1.79 for the ND group, 2.28 for the HFD group, 2.09 for the HFD + ‘Shinmichal’ group, and 2.13 for the HFD + ‘Saekeumkang’ group. These findings indicate that supplementation with ‘Shinmichal’ and ‘Saekeumkang’ led to reductions in both AI and CRF values compared to those in the HFD group, suggesting a lower risk of cardiovascular problems.
In conclusion, this study evaluated the anti-obesity effects of whole wheat extracts of the ‘Saekeumkang’ and ‘Shinmichal’ varieties in HFD-fed mice. Both wheat varieties demonstrated significant anti-obesity effects by reducing body weight gain, lipid accumulation, and TC and TG levels compared to those in the HFD group. No significant difference was observed in anti-obesity effects between ‘Saekeumkang’ and ‘Shinmichal’, suggesting that both varieties provide similar health benefits. Therefore, ‘Shinmichal’, a newly developed wheat variety, can be considered a viable option with health-promoting properties similar to the widely used ‘Saekeumkang’. These findings support the potential use of both wheat varieties as dietary supplements for the prevention and management of obesity.
Acknowledgements This work was supported by Cooperative Research Program for Agriculture Science and Technology Development (Project No. RS-2020-RD009838), Rural Development Administration, Republic of Korea.
Conflict of interest There are no conflicts of interest to declare.
