Recently, studies on medical products, dietary supplements, and natural foods that help in reducing abdominal fat and various blood lipids have been actively conducted due to the increasing incidence of metabolic disorders. Based on the National Nutrition Survey in South Korea, dietary habits have gradually changed to the western style according to rapid economic growth and family types. Therefore, there is an increasing trend in the incidence of cardiovascular disease caused by increased animal product consumption and excessive sodium intake much more than recommended daily allowance compared to the 20^th century in South Korea [1]. Moreover, it has been reported that obese people have 2 times higher risk of developing hypertension, diabetes, and hyperlipidemia compared to the normal population based on The National Nutrition Survey in 2010 [2]. Abdominal obesity, hyperlipidemia, and insulin resistance lead to the development of metabolic syndrome, and the metabolic syndrome is mainly caused by obesity [3]. Due to obesity, adipocyte accumulation and metabolic disorder in adipocytes can occur and this can increase the risk of chronic inflammation and insulin resistance, which may cause type-2 diabetes, cardiovascular disease, and hyperlipidemia [4]. Lifestyle factors may have an impact on these diseases.

Dietary treatment, exercise therapy, psychotherapy, and surgery have been used for treating obesity; however, the drugs used to treat obesity may cause serious side effects such insomnia, rash, nausea, and headache. Therefore, it seems that reasonable dietary habits and regular physical activity based on the daily energy expenditure would be the optimal fundamental treatment for obesity [5]. In addition, there is an urgent need to develop dietary supplements derived from natural plants for treating obesity.

Since the 1970s, the daily activity of people has decreased and carbohydrate (CHO) intake has also decreased; on the other hand, lipid intake has increased due to an increase in national income and simplification of living and dietary life [6,7]. CHOs have been considered as a major energy source in the human body; however, recent studies have reported that CHOs have various effects on physiological metabolism, which are more than that of a macronutrient [8]. Especially, potato starch has been widely used in industries to increase solubility, viscosity, and processability [9]. Moreover, the worldwide production of potatoes is 350 million tonnes per year9) and they have excellent eating quality with medicinal effects and various food ingredients [10]. Potatoes have been considered as a good food source because they contain high quality protein, minerals such as calcium and magnesium, and vitamin C [11]. It is also known that potatoes can reduce the sense of hunger and they are used in treatment of cancer, hypertension, atherosclerosis, cardiovascular disease, and liver disease [12].

Lotus (Nelumbo nucifera Gaertner) is commonly found in South Korea and Japan. It is a plant from the Paleozoic era, belongs to the Nymphaeaceae family, and is a perennial herb [13]. Lotus flowers have been used for ornamental purposes, and tea ingredients and their leaves and roots have been used for edible purposes. Nelumbo nucifera leaves considered as lotus leaves have been used for treatment of diarrhea, edema, and bleeding disorders caused by hot and humid weather because they have been known to be effective in reducing heat, maintaining moisture inside the body, and achieving hemostasis [14]. Thus, the pharmacological action of lotus leaves has been investigated nationally and internationally. Especially, its anti-obesity action, effect on the endocrine system, and effect on the lipid metabolism have been reported in previous studies. Lotus extract has been reported to have an effect of reducing fasting blood glucose, total cholesterol, and triglyceride in diabetic animals, thus showing anti-diabetic and antilipid effects [15]. In addition, it has been reported that lotus extract has an effect of improving obesity and hyperlipidemia [16], reducing blood glucose [17], anti-oxidation, and protecting neurons [18] in animals with high fat diet-induced obesity. Also, it has been known that long-term use of lotus leaves might exert a suppressive effect on adipose tissue differentiation at the cellular level [19]. Although we can assume that lotus leaf intake may have a direct positive effect on lipid metabolism, it is still unclear whether lotus leaf consumption has an effect of reducing the food intake. Recently, proteinase inhibitor 2 (PI2), found in potatoes, has received great attention for effectively controlling cholecystokinin [20]; therefore, it can be expected that PI2 combined with lotus leaf intake will be able to induce cholecystokinin secretion and subsequently reduce body fat. Based on the previous reports, the purpose of this study was to investigate the effects of potato and lotus leaf extract intake on body composition, abdominal fat, and blood lipid concentration in female university students.

Studies with the use of plants focusing on the anti-oxidant effect have been conducted in South Korea [21,22]; however, there are few systematic studies assessing the effects of physiological intake of natural plant ingredients. Therefore, this present study investigated the physiological effects on body composition and blood lipid changes in female university students following potato and lotus leaf extract intake.

Total cholesterol plays an important role in formation of the cell membrane and production of hormones; however, an excessive amount of total cholesterol may cause hypercholesterolemia and it is an important risk factor for coronary heart disease (CHD). Lowering TC concentration would be effective in decreasing the incidence of CHD according to several previous studies, and a decrease in TC concentration by 1% has been known to decrease the incidence of CHD by 2% [23,24]. Results of the present study showed that there was a significant interaction of TC in the SKG and PG with regard to groups and treatment period. Moreover, values of TC in the SKG showed a decreasing tendency and this confirms the positive effect of potato and lotus leaf extract intake. This result was similar to that in previous studies, which showed positive effects of lotus leaf intake on obesity, endocrine system, and lipid metabolism [25].

Lotus leaves (Nelumbo nucifera) are commonly found in South Korea and have been used as a natural remedy. Lotus flowers have been used for ornamental purposes, and tea ingredients and their leaves and roots have been used for edible purposes [26]. Dried lotus leaves have a bitter taste and have healing effects on bleeding stomach ulcer, gastritis, hemorrhoids, diarrhea, headache, hemoptysis, gynecological blood stasis after delivery, nocturia, and deintoxication [27]. However, few studies on lotus have been conducted so far. Recent research on lotus by Bhat and Sridhar [28] reported about the nutrients present in lotus seeds, Rai and colleagues [29] showed the anti-oxidant effect of lotus seeds, and Chiang and Luo [30] reported on changes in lotus root components while cooking. Most of these recent studies focused on lotus seeds and roots. Currently, most of the lotus leaves are usually discarded, and thus, studies on lotus leaves would provide information on new bioactive substances, which would be useful for developing natural dietary supplements.

Moreover, Rha and colleagues [31] reported that small colored potato extract intake in rats caused a significant decrease in TC compared to that in controls, which supports the results of the present study. The present study showed that there was a significant difference in android and gynoid fat distribution between the two groups; however, there was no significant interaction between the groups and there were no trend changes in the groups. Also, there was no significant difference in the interaction effect, group difference effect, and periodic changes in HDL-C, LDL-C, and TG between the two groups.

Similar to the results of the present study, the animal study by Cha and Cho [32] reported that potato extract added by 0.5% level of the meal caused no changes in body weight during 2 weeks. The study by Lee and Lee [33] reported that there was a decreased trend of body weight gain in the lotus leaf extract intake group compared to the high fat diet group. In other words, potato and lotus leaf extract intake might have caused a decreased trend of body weight gain in participants of this present study without controlling the dietary habit and daily activity. To obtain more accurate and basic study results, further studies are needed for evaluating different doses of potato and lotus leaf extract intake combined with a diet program and a physical activity program. Such studies might show more definite effects of potato and lotus leaf extract intake.

The purpose of this study was to investigate the effects of potato and lotus leaf extract intake on body composition, abdominal fat, and blood lipid concentration in female university students. Eight-week intake of potato and lotus leaf extract had a positive effect of decreasing TC. This study confirmed a positive trend in lowering blood lipids following potato and lotus leaf extract intake. Therefore, a further similar study is needed to obtain more detailed effects of potato and lotus leaf extract intake by considering the effective dose condition such as minimum dose, administration period, and administration type.