Minerals in human nutrition are basically required for electrolytes in extracellular and intracellular fluids. Particularly intracellular fluid, the site of major metabolic activities, needs more the maintenance of optimal amount and concentration of minerals [1]. As the life expectancy increase, some chronic diseases are epidemic all around world. Especially, cardiovascular disease, arthritis and diabetes mellitus type II are prevalent in young people as well as in elderly. In recent, these diseases are referred being related with mineral status in the body through immune system [2].

Even though the trace amount of minerals which exist under 100 mg in the body, they perform vital roles for metabolic functions. For example, microminerals such as zinc (Zn), copper (Cu) and iron (Fe) are important for enzyme cofactors, stabilizers of organic molecules or participants in redox reactions. Therefore either a deficit or excess of any of them should be harmful for health [3]. In addition, interaction between minerals may influence their bioavailability, although they are not serious in physiological level. These interactions could lead to nutrient imbalance and increase the need for balanced intake of minerals. For example, intake of Fe and calcium (Ca) represses the absorption of Zn, while Cu intake does not [4,5]. As a matter of fact, a good source of one mineral may be a poor source of another, e.g. meats are rich of Fe, but deficit of Ca [6]. Some studies suggested that Fe, Zn as well as ascorbic acid and carbohydrates influenced Cu bioavailability [7]. Moreover according to species manganese (Mn) could decrease Fe absorption in animals but not humans [8].

Generally Korean ordinary diets are referred to be good for human health in worldwide. However it is uncertain whether they provide microminerals enough for growth and health of teenagers. The aim of this research is to identify the contents of Fe, Zn, Cu and Mn of cuisines and relationship between these microminerals in school meals around Changwon area.

The amount of microminerals was expressed with unit as ug per one serving size of cuisine categorized into four groups as cooked-rice, soup, kimchi and side-dish (Table 1, Fig. 1).

The quantitative contribution of minerals to school meal and %DRI of each microminerals were obtained (Fig. 2). Linear regression showing for relationship between microminerals in all cuisines was expressed in Fig. 3.

During the past century researchers had focused on the effect of nutrition on the control of diseases induced from malnutrition involving the immune response and its modifying agents [9,10]. In recent several studies have reported that the some relationship between minerals, vitamins or phytochemicals and development of some chronic diseases such as cardiovascular disease and diabetes mellitus are intimately existed [11,12,13]. These two diseases are associated with obesity which is referred a stimulator to produce and secret pro-inflammatory cytokines TNF-a, IL-6, but to reduce anti-inflammatory cytokines like adiponectin.[14]. Inflammation is a kind of catabolic mechanism to keep body weight within acceptable range [6] or a kind of immune responses against obesity [15]. In immune system, relations between Fe, Zn, Cu and Mn are interconnected primarily through antioxidant function. In general these microminerals are important for enzyme cofactors, stabilizers of organic molecules or participants in redox reactions [16]. Fe is existed under 100 mg in the body, and one of the antioxidants which function to make metabolite being reduced states [17]. Zn is needed for enzymes as many two hundred or more to function in the body [18]. Those functions are related to DNA or RNA synthesis, cell growth and development, antioxidants defenses, immune function and acid-base balance for maintaining optimal health. And Cu is essential for energy metabolism, neurotransmitter regulation, collagen synthesis, and for antioxidant defense against free radicals. Deficiencies of Cu are associated with accelerated bone mineral loss and increased blood pressure and cholesterol levels. Higher doses of Cu may lead liver damage, coma and death. Mn is a cofactor for many enzymes with importance for carbohydrate metabolism, protein digestion and metabolism, biotin function, cartilage regeneration, and free radical defense. Mn deficiency causes decreased fertility, higher susceptibility to seizures, and bone fractures. The toxicities of ingested Mn result in tremor, delayed movement, and rigidity due to nervous damage [17].

Still there are some informational gaps about the role of micronutrients in human health and lacks of studies on biological endpoints that reflect sufficient or insufficient body stores of them. In addition there should be needed to identify and quantify the effects of interactions between micronutrients and interactions between micronutrients and other food components, the food matrix, food processing such as cooking [19,20,21,22].

In this study Fe and Zn contents in soups were almost double of those in kimchies and side-dishes, and that of cooked rice with grains was the lowest among all foods. The Mn content was also higher in kimchies and side-dishes than in cooked rice with grains as well as in soup. In side-dishes, Mn content was high, but Cu content was relatively low. However comparing to Korean Dietary Reference Intakes (KDRI) level of microminerals, average school meal as a lunch set provided insufficient supply (< 25% DRI) of Fe, Zn or Mn, but did excess (> 125% DRI) of Cu, especially from kimchies. All these results could be applicable as a fundamental data estimating optimal micromineral contents and their relative ratios in typical school meals for healthy adolescents.

In conclusion, the contents of Fe, Zn and Mn provided from school meals were not sufficient for teenagers in Gyeongnam area. In contrast Cu contents were excess when compared with KDRI for both 9-11 year-old and 12-14 year-old students. Moreover the results showed that students consumed twelve folds of Cu and four folds of Fe as their intake of Zn increase. Therefore in the field of school meal, substantial alterations to the menus should be considered to ensure the nutrient value of cuisines in the future. At the same time, it should be the right time to think over on determining the dietary reference intakes of microminerals as well as their relative ratios for Korean teenagers.