Effect of Corn Peptides in Combination with Exercise on Weight Reduction, Plasma Lipid, Chemerin and...

Yin Wu, Liang Yin, Xiaohui Wang, Shujie Lou

  Open Access OPEN ACCESS  Peer Reviewed PEER-REVIEWED

Effect of Corn Peptides in Combination with Exercise on Weight Reduction, Plasma Lipid, Chemerin and Lp-PLA2 in Overweight and Obese Females

Yin Wu1, Liang Yin2, Xiaohui Wang2,, Shujie Lou2

1Department of Computer and Statistics, Shanghai University of Sport, Shanghai, China

2Department of Sport Science, Shanghai University of Sport, Shanghai, China

Abstract

Our previous work has demonstrated better weight reduction and plasma lipid improvement roles of corn peptides (CP) in combination with aerobic exercise than aerobic exercise in obese rats, the purpose of this paper is to explore if the better effectiveness of CP combined with exercise also exist in overweight and slight obese young females and to determine the possible role of adipokine chemerin and inflammation factor lipoprotein-associated phspholipase A2 (Lp-PLA2). Twenty-six young female (18-21 years old, body fat percentage: 29.15%±2.71% and body mass index (BMI): 23.92±1.78) were allocated randomly to four groups: exercise 1 group (E1, n=6), CP+E1 group (n=7), E2 group (n=6) and CP+E2 group (n=7). The females in E1 and CP+E1 groups did 1 hour aerobics 3 times a week, while the same aerobics were done but 5 times a week by E2 and CP+E2 groups. The exercise lasts for four weeks and 10 g of CP were taken orally by the females in the two CP groups every night after meal. Similar power placebo was administered to the non-CP treated females. The diet of these females kept unchanged during the 4 weeks. The body weight, BMI, body fat percentage and plasma lipid parameters including triglyceride (TG), total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), apolipoprotein a (Apo-A), apolipoprotein b (Apo-B) and the ratios of LDL-C/HDL-C and Apo-B/Apo-A as well as plasma levels of chemerin and Lp-PLA2 were determined pre and post 4 weeks. Compared to E1 group, all the above parameters did not change in CP+E1 group after 4 weeks. Except for an obvious reduction of body fat percentage (from 29.44%±2.65% to 27.93%±2.56% vs from 27.95%±3.38% to 27.47%±3.88%, p<0.05) were found in CP+E2 group, other changes were still not observed compare with that of E2. It’s worth noting that obvious reduction of chemerin was found in individuals with abnormal lipid parameters return to normal and no change of chemerin was showed in a female whose abnormal lipid index kept stable after treatment with CP combined with exercise. In conclusion, only when frequent aerobic exercise was performed did CP in combination with aerobic exercise promote significantly the decrease of body fat percentage in overweight and slight obese females. The fat loss resulted from CP in combination with exercise is not related to the plasma levels of chemerin and Lp-PLA2, which might be attributed to no change of blood lipid parameters within normal ranges in overweight and slight obese females. Although no difference of chemerin between groups, changes of plasma chemerin in individual females with abnormal lipid parameters suggested that CP in combination with exercise might reverse the abnormal plasma levels of TG, TC and LDL-C by decreasing the plasma levels of chemerin.

Cite this article:

  • Wu, Yin, et al. "Effect of Corn Peptides in Combination with Exercise on Weight Reduction, Plasma Lipid, Chemerin and Lp-PLA2 in Overweight and Obese Females." Journal of Food and Nutrition Research 2.8 (2014): 485-490.
  • Wu, Y. , Yin, L. , Wang, X. , & Lou, S. (2014). Effect of Corn Peptides in Combination with Exercise on Weight Reduction, Plasma Lipid, Chemerin and Lp-PLA2 in Overweight and Obese Females. Journal of Food and Nutrition Research, 2(8), 485-490.
  • Wu, Yin, Liang Yin, Xiaohui Wang, and Shujie Lou. "Effect of Corn Peptides in Combination with Exercise on Weight Reduction, Plasma Lipid, Chemerin and Lp-PLA2 in Overweight and Obese Females." Journal of Food and Nutrition Research 2, no. 8 (2014): 485-490.

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1. Introduction

Obesity is one of the main human epidemics today, leading to several chronic obesity-associated diseases such as hyperlipidemia, coronary atherosclerosis, diabetes and hypertension. The cause of obesity is very complicated results from interactions among a variety of factors, in which over-nutrition and insufficient energy consumption are the two main causes. Therefore diet control and aerobic exercise are emphasized to prevent and treat obesity, which are difficult to persist for obese persons because of tedious, time consuming and weak willpower. Therefore, specific nutrients and substances possessing weight reduction effects are becoming a focus of functional foods recently.

Corn is a major cereal crop throughout the world. Corn gluten meal containing approximately 60% protein is difficult to utilize in the food industry because of its low water solubility and amino acid imbalance [1]. Recently, corn gluten meal was hydrolyzed with a biochemical grade alcalase and the derived hydrolysates were purification to produce CP. Corn peptides (CP) is less than 2000 Da molecular weight and absorbed easily by digestive system. As bioactive peptides, CP attracts growing attention for its multiple functions such as angiotensin-converting enzyme inhibitor [2], alcohol metabolism enhancer [3] and antioxidant capacity [4]. Bong H.Y. reported the effect of CP on body weight reduction and improvement of lipid metabolism in obese rats [5], which makes CP an interesting area for further investigation. Our previous work has demonstrated that CP in combination with aerobic exercise could reduce the body weight, perirenal fat and plasma levels of triglyceride (TG), total cholesterol (TC) and LDL-C while no roles were found when only supplement of CP without exercise [6].

Chemerin is an adipose-derived signaling protein (adipokine) that regulates adipocyte differentiation and lipolysis as well as glucose homeostasis. Recent experimental and clinical data indicated that circulating chemerin expression and activation were elevated in numerous metabolic and inflammatory diseases including obesity [7, 8, 9, 10], metabolic syndrome [10, 11, 12], type 2 diabetes [12, 13, 14] and coronary artery disease [15]. Chemerin significantly decreased after bariatric surgery in obese patients undergoing bariatric surgery, accompanied by pronounced weight loss and improvements in parameters of lipid and glucose metabolism [16]. So chemerin may be a promising new target for the treatment of obesity, metabolic syndrome and type 2 diabetes [10, 12]. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an inflammatory mediator involved in atherosclerosis [17]. Elevated levels of Lp-PLA2 appear to be a strong risk factor for the severity of coronary atherosclerosis [18] and cardiovascular events in patients with coronary heart disease [19]. 4 months of low-calorie diet associated with weight loss in obese women resulted in the significant reduction of the plasma levels of Lp-PLA2 [20].

Therefore the present study is to explore the effect of CP in combination with aerobic exercise on weight reduction, plasma lipid as well as plasma Lp-PLA2 and chemerin in overweight and slight obese young females.

2. Material and Methods

2.1. Subjects

The criteria of overweight and obesity in adult females of Chinese were 24-27.9 kg/m2 and ≥28 kg/m2 by BMI or 25%-29.9% and ≥ 30% by body fat percentage, respectively. The body fat percentage of our twenty-six female subjects (18-21 years old) were 29.15% ± 2.71% and BMI were 23.92±1.78 kg/m2. The discrepancy of the two indicators was found in some female subjects, whose lower BMI might be result from less muscle mass. Considering the more concise in reflecting the fat mass or obesity, the body fat percentage criteria was selected in choosing subjects and our subjects were described as overweight or slight obese females. They were random divided into four groups: E1 group (n=6), CP+E1 group (n=7), E2 group (n=6) and CP+E2 group (n=7).

2.2. Analysis and Supplement of CP

CP was purchased from Ruibang biological technology co., ltd. (China). The molecular weight distribution and amino acid composition of CP were analyzed by test and analysis center of Jiangnan University (Jiangsu, China). 10 g of CP was taken orally by females in the two CP groups every night after meal. Similar power placebo was administered to the non-CP treated females.

2.3. Exercise Protocol and Diet

The females in E1 and CP+E1 groups did aerobics for 1 hour, 3 times a week and last for 4 weeks, while the same aerobics were done but 5 times a week by E2 and CP+E2 groups. The intensity of this aerobics are moderate and the heart rates of these females were monitored and controlled at the range of 40%-60% heart rate reserve (about 125-150 beats/min) during doing aerobics, representing moderate aerobic exercise. The diet of these females kept unchanged during the 4 weeks.

2.4. Determination of Body Weight, BMI and Body Fat Percentage

The body weights and heights of these females at pre and post 4 weeks were detected by a scale and their BMI was calculated as the body weight divided by the squared height. Body fat percentages of these females were determined by body fat measuring instrument (Omron HBF-701, China).

2.5. Blood Assay

Blood samples of these four groups females were collected pre- and post- 4 weeks aerobics for detecting the plasma levels of TG, TC, HDL-C, LDL-C, Apo-A and Apo-B by Shanghai Adicon clinical laboratories Inc (Shanghai, China) by Beckman Coulter AU 680, and the ratios of LDL-C/HDL-C and Apo-B/Apo-A were calculated. The plasma levels of chemerin and Lp-PLA2 (RD systems Inc, USA) were detected by ELISA according to the protocol.

2.6. Statistical Analysis

Data were analyzed using SPSS 18.0 for windows. Mean values of body weight, BMI and body fat percentage were compared using analysis of covariate (ANCOVA), and the post-pre difference of other data were analyzed using one-way ANOVA.

3. Results

3.1. Molecular Weight Distribution and Amino Acid Composition of CP

As shown in Table 1, the most component of our CP is the part of 500-180 Da molecular weight, holding 65.72% of total components, and the number and weight average molecular weights are 277 and 301 respectively. The part of 1000-500 Da molecular weight is in the second (17.65%), whose number and weight average molecular weights are 277 and 301 respectively. According to the results of the proportion (83.37%) of oligopeptides under 1000 Da as well as the number and weight average molecular weight, a conclusion was drawn that the CP we used are high quality products.

Table 1. Molecular weight distribution of CP

In addition, the total amino acid of our CP reach 62.47g per 100g CP, among which the most two amino acids are glutamic acid and leucine, accounting for 15.79g and 9.07g in 100g CP respectively (Table 2).

3.2. Influence of CP in Combination with Exercise on Body Weight, BMI and Body fat Percentage

The decreases of body weight, BMI and body fat percentage were no significant difference between CP+E1 group and E1 group. More obvious reduce of body fat percentage (from 29.44%±2.65% to 27.93%±2.56% vs from 27.95%±3.38% to 27.47%±3.88%, p<0.05) and no difference of decreased body weight and BMI were shown in CP+E2 group compare to E2 group. In addition, the above three indicators declined more remarkably in CP+E2 group than that of CP+E1 group (Table 3).

Table 3. Effect of CP in combination with exercise on body weight, BMI and body fat percentage of overweight and slight obese females

3.3. Influence of CP in Combination with Exercise on Plasma Lipid and Plasma Levels of Chemerin and Lp-PLA2

As shown in Table 4, no difference were found among the four groups in plasma levels of TG, TC, LDL-C, HDL-C, Apo-A and Apo-B as well as LDL-C/HDL-C and Apo-B/Apo-A. The above indicators of most of the overweight and slight obese subjects were normal (normal plasma levels of TG, TC, LDL-C, HDL-C as well as Apo-A and Apo-B in human were less than 1.7 mmol/L, 5.2 mmol/L and 3.37 mmol/L and more than 1.04 mmol/L as well as 1.03-2.03 g/L and 0.42-1.26 g/L, respectively). In addition, the post-pre difference of the plasma levels of chemerin and Lp-PLA2 kept unchanged among the four groups.

3.4. Influence of CP in Combination with Exercise on the above Blood Indicators of Some Individuals

Although no difference of the above indicators among groups was found, there were considerable variations among individuals. Only one of the two abnormal subjects were found to improve plasma indicator in CP+E1 group while both of the two abnormal females returned to normal plasma indicators in CP+E2 group (Table 5). What interesting was that the decrease of plasma TG, TC and LDL-C were accompanied with the downregulation of plasma chemerin in the three females with abnormal plasma lipid (No.7, 22 and 23) and unimproved plasma lipid concomitant with slight enhancement of plasma chemerin (No.8), which suggested that there might be a relation between the improved plasma lipid index and the reduction of the plasma level of chemerin. Similary results were not shown in plasma levels of Lp-PLA2.

Table 4. Effect of CP in combination with exercise on plasma lipid and plasma levels of chemerin and Lp-PLA2 of overweight and slight obese females

Table 5. Abnormal plasma lipid index and plasma levels of chemerin and Lp-PLA2 in some females

4. Discussion

Our previous work has demonstrated that CP only when combined with aerobic exercise decreased the body weight, body fat and improved the plasma lipid of high fat induced obese rats [6], while the present study indicated that only frequent exercise (5 times a week, 1 h per time) did exert fat reduction effect on overweight and slight obese females when combined with CP.

It has been demonstrated that leucine, a branched chain amino acid, decreased body weight and food intake [21] and play an important role in treatment of obesity and metabolic syndrome [22]. CP we used has a high amount of leucine (9.07g/100g CP). Whether the role of CP is through some oligopeptides, leucine or both need further investigation.

As shown in results, the plasma levels of TG, TC, LDL-C, HDL-C as well as Apo-A and Apo-B in most of the overweight and slight obese subjects were normal, which may be contributed to the steadiness of the above indicators after treatment with CP combined with exercise. Although no differences of the above indicators among groups were found, there were considerable improvements of the above parameters in some abnormal individuals which restored to normal such as increased TC, TC and LDL-C.

A significant positive correlation was found between chemerin and BMI, TC, TC and LDL-C levels, and chemerin showed a significant negative correlation with the level of HDL-C [7, 8, 9]. Ress C et al. demonstrated that bariatric surgery resulted in the decrease of circulating chemerin level, which may be related to the weight loss and improvements of lipid and glucose metabolism [16]. Except bariatric surgery, 6-month combined strength and endurance exercise led to a significant reduction in serum chemerin in overweight or obese, non-diabetic individuals [23]. The effect of 8-week lifestyle intervention (a home-based diet and exercise program) on the decrease of circulating chemerin was also demonstrated in young obese adults [24] and a 12-week exercise significantly decreased serum chemerin level in overweight and obese adults with type 2 diabetes [25]. In our study, no difference of plasma chemerin was found in CP combined with exercise groups compared with their respective exercise control groups, suggested that the fat reduction role of CP combined with exercise on overweight and slight obese females was not related to plasma chemerin. We speculated that the discrepancy between our results with others might be resulted from no change of blood lipid parameters which were within normal ranges, but it needs further study. It's worth noting that there were obvious decreases of chemerin in three females who were accompanied with the return of abnormal TG, TC and LDL-C, and no change of chemerin in a female whose upregualted TG, TC and LDL-C kept stable after treatment with CP in combination with exercise. The data make us speculated that the improvement of abnormal blood lipid parameters might be associated with decreased plasma chemerin, thus achieving blood lipid improvement of CP in combination with exercise on overweight and slight obese females, but it needs verification.

As a good biomarker of cardiovascular risk in obese adults, Lp-PLA2 is strongly associated with stroke and many others cardiovascular events, which can be seen in obesity. Weight loss by diet control in obese women resulted in the significant reduction of the plasma levels of Lp-PLA2 [20]. In our study, plasma Lp-PLA2 kept unchanged after CP combined with exercise treatment compared with exercise control, suggested that the fat loss resulted from CP combined with exercise was not related to plasma Lp-PLA2 in overweight and slight obese females. Lp-PLA2 were negatively related to Apo-A and strongly positively associated with Apo-B and Apo-B/Apo-A ratio [26, 27]. So we speculated that unchanged plasma Lp-PLA2 levels might be attributed to no changes of Apo-A, Apo-B and Apo-B/Apo-A ratio in our study, it also needs further exploration.

5. Conclusions

In conclusion, only when frequent aerobic exercise was performed did CP in combination with aerobic exercise promote significantly the decrease of body fat percentage in overweight and slight obese females. The fat loss resulted from CP in combination with exercise is not related to the plasma levels of chemerin and Lp-PLA2, which might be attributed to no change of blood lipid parameters within normal ranges in overweight and slight obese females. Although no difference of chemerin between groups, changes of plasma chemerin in individual females with abnormal lipid parameters suggested that CP in combination with exercise might reverse the abnormal plasma levels of TG, TC and LDL-C by decreasing the plasma levels of chemerin.

Acknowledgement

This work was supported by Capacity Progress Project of Science and Technology Commission of Shanghai Municipality (NO.11290503000).

List of Abbreviations

TG: triglyceride; TC: total cholesterol; HDL-C: high density lipoprotein-cholesterol; LDL-C: low density lipoprotein-cholesterol; Apo-A: apolipoprotein a; Apo-B: apolipoprotein b; Lp-PLA2: Lipoprotein-associated phospholipase A2; BMI: body mass index; CP: CP; E: exercise.

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