## 1 Introduction  
Excessive body mass is an emerging global problem causing multiple health complications. Hypercaloric diet, improper dietary patterns, and low physical activity are the main factors leading to excessive fat tissue accumulation. The main parameter used for nutritional status assessment in this context is body mass index (BMI) which is the body mass in kilograms divided by the square of height in meters. BMI values serve also as the cut-off points for diagnosing overweight and obesity according to the World Health Organization (WHO). The normal range of BMI is 18.5-24.99 kg/m\({}^{2}\), overweight is defined as BMI 25.00-29.99 kg/m\({}^{2}\), and obesity is diagnosed when BMI is 30 kg/m\({}^{2}\) or higher. During the course of adipose tissue accumulation, it enables the immune system cells to be infiltrated, thus its excess results in oxidative stress and chronic low-grade inflammation. Chronic inflammation of adipose tissue called adjositis can lead to insulin resistance resulting in elevated glucose levels and endothelium dysfunction leading to elevated blood pressure and atherosclerosis due to atherogenic dyslipidemia [1]. These aspects are important healthcare problems as they are the main cardiovascular disease risk factors and cardiovascular diseases are the leading cause of death worldwide [2]. That is why counteracting obesity and its accompanying metabolic disorders is crucial in terms of public health [3]. As mentioned above, obesity can lead to metabolic syndrome which according to the International Diabetes Federation, apart from central obesity, diagnosis requires fulfilling two out of four metabolic criteria [4]. They include a triglyceride (TG) level of 150 mg/dL (1.7 mmol/L) or higher; a high-density lipoprotein (HDL) level lower than 40 mg/dL (1.03 mmol/L) in males, or lower than 50 mg/dL (1.29 mmol/L) in females; a fasting glucose level of 100 mg/dL (5.6 mmol/L) or higher, or previously diagnosed type 2 diabetes; and a systolic blood pressure level of 130 or higher, or diastolic blood pressure level 85 mmHg or higher [4]. Treatment of each specific metabolic disorder is also treated as a fulfilled criterion. As mentioned above, excessive fat tissue content leads to chronic inflammation. One of the most important features on the path between obesity and the development of its complications acknowledged as metabolic syndrome is oxidative stress. The excessive production of reactive oxygen leads to tissue damage including insulin resistance and endothelium dysfunctions, and finally, it results in chronic inflammation [5]. That is why antioxidant compounds, that could potentially reduce these processes, are possible agents that could be supplemented to prevent overweight and obesity metabolic complications [6]. Fruits are very good sources of natural antioxidants which is why their consumption is advised as a part of a healthy diet [3]. Nonetheless, fruit consumption is often non-satisfactory. In such cases, dietary supplements based on natural products could serve as a form of introduction of more fruits into everyday dietary patterns. Nutraceuticalals are such products, as they are derived from natural foods that are generally suggested to provide health benefits. Apples and dwarf kiwis are examples of them. Their higher concentration in the nutraceuticalals compared to habitual intake can possibly increase their metabolic potential observed in terms of the typical diet. Apples are one of the most popular fruits in Poland. They are low-caloric (52 kcal/100 g) and cost-affordable for most of the Polish population. Apples are high in carbohydrates (13.8 g/100 g) and dietary fiber (2.4 g/100 g) and low in protein (0.26 g/100 g) or fat (0.17/100 g) [7]. They also contain other bioactive compounds, e.g., flavonoids [8]. Different parts of the fruit are characterized by different concentrations of antioxidants and fiber, however; apple skin and seed core are the best sources of them [9]. The recommended daily fiber consumption should be 35-45 g [3; 10].