Natural mineral bottled waters available on the Polish market as a source of minerals for the consumers. Part 2: The intake of sodium and potassium.

Background: Natural mineral waters are purchased and consumed according to consumer preferences and possible recommendations. The choice of appropriate water should take into account not only the general level of mineralization but also the content of individual components, including electrolytes such as sodium and potassium. Sodium is necessary to ensure the proper physiological functions of the body. It is defined as a health risk factor only when its excessive intake occurs. Potassium acts antagonistically towards sodium and calcium ions, contributes to a reduction of the volume of extracellular fluids and at the same time reduces muscle tension and permeability of cell membranes. The demand for sodium and potassium is of particular importance in people expending significant physical effort, where an increased electrolyte supply is recommended.

Objective: The aim of the study was to estimate the content of sodium and potassium in natural mineral waters available in the Polish market and to evaluate the intake of those components with the commercially available mineral waters by different groups of consumers at the assumed volume of their consumption.

Material and Methods: The research material consisted of natural mineral waters of forty various brands available on the Polish market. The examined products were either produced in Poland or originated in other European countries. Among the products under examination, about 30% of the waters were imported from Lithuania, Latvia, the Czech Republic, France, Italy and Germany. A sample for analyses consisted of two package units of the examined water from different production lots. Samples for research were collected at random. The study was conducted with the same samples in in which calcium and magnesium content was determined, which was the subject of the first part of the study. The content of sodium and potassium was determined using the emission technique (acetylene-air flame), with the use of atomic absorption spectrometer – ICE 3000 SERIES – THERMO – England, equipped with a GLITE data station, with wavelengths of 589.0 nm and 766.5 nm, respectively.

Results: The obtained research results indicate a high differentiation of the content of both sodium and potassium in natural mineral waters available on the Polish market, particularly in medium- and highly-mineralized waters. The consumption of 1 liter of low-mineralized natural mineral water ensures recommendations concerning the amount of sodium intake only in a limited scope, while in case of products of medium and high level of mineralization, it is much diversified. On the other hand, potassium supply with one liter of natural mineral water may ensure no more than several percent of the recommended daily intake of this component.

Conclusions: The high diversification of sodium content in natural mineral waters available on the Polish market should encourage the analysis of their composition to avoid health disorders in a given group of consumers. The natural mineral waters examined in the study, at the assumed volume of their daily consumption, are not a good source of potassium for the population groups under analysis.