Determinação da bioacessibilidade de metais em suplementos alimentares por espectrometria de emissão óptica após protocolos in vitro

Abstract

Dietary supplements are defined as products to supplement the diet and provide essential nutrients for the humans. They can contain vitamins, minerals, botanical products, amino acids, or any combination of these. The large consumption of dietary supplements can be associated with several factors, as awareness of the people with health care, higher consumption by athletes and bodybuilding exercises practitioners for better performance and gain of muscle mass, among others. Among the nutrients provided by dietary supplements, there are the essential and non-essential elements and the evaluation of their bioaccessibility is crucial. Bioaccessibility is defined as the fraction of a nutrient that is released from its matrix in the gastrointestinal tract, making it available for efficient absorption by intestine. Different methodologies can be applied to determine the bioaccessibility of elements, and the in vitro methods have been widely used, mainly due to their lower cost and easier application. The Bioaccessibility Research Group of Europe (UBM BARGE) developed a unified bioaccessibility method (UBM) in order to produce a validated and standardized in vitro procedure. Another bioaccessibility in vitro method was also established in a consensus by the COST (European Cooperation in Science and Technology) INFOGEST international network. Thus, in this work the bioaccessibility of some essential (Co, Cu, Fe, Mg, Mn, Mo, Ni, Zn, V) and non-essential elements (Al, As, Ba, Be, Bi, Cd, Cr, La, Pb, Sr) was determined by using the UBM BARGE and COST INFOGEST protocols, and further determination by inductively coupled plasma optical emission spectrometry (ICP OES) and the interference was evaluated by microwave-induced plasma optical emission spectrometry (MIP OES). Four samples of dietary supplements of different classes (vitamins and minerals, minerals, and botanicals) were used. Total concentration of the essential and non-essential elements was determined by ICP OES after microwave-assisted wet digestion. The UBM BARGE procedure consisted of a three-stage process, simulating the digestive processes of the mouth, stomach, and small intestine, where the first stage simulates the gastric phase (saliva + gastric fluid), and the second stage simulates the gastrointestinal phase (duodenal fluid + bile). On the other hand, the COST INFOGEST method produces the gastric and the gastrointestinal phase in only one stage (saliva + gastric fluid + intestinal fluid). All extractions were performed at 37 °C as suggested by both protocols, because the enzyme activity and chemical characteristics, such as solubility, are affected by the temperature. The total concentration for Ag, As, Be, Cd, Co, La, Ni, Pb, and V were below the limits of quantification (LQ) of the method in all samples, and these elements were not considered for the bioaccessiblity study. The bioaccessible fractions using the UBM BARGE method were low for some elements, as Al, Ba, Cr, Fe, Sr and Zn (up to 34% depending on the sample), and higher for others, like Cu, Mg, Mn and Mo (above 98% for some elements). Considering the COST INFOGEST method, the bioaccessible fractions for Ba, Fe, Mg, Mn, V and Zn were up to 39%, depending on the sample. On the other hand, higher bioaccessible fractions were found for Cu, Mo (above 77% depending on the sample). The results obtained for the bioaccessible fractions of the essential and non-essential elements in the dietary supplements samples showed differences depending on the method used, requiring a careful evaluation for each matrix and analyte.