# Spirulina Supplements as a Source of Mineral Nutrients in the Daily Diet
## 4 Discussion  
Algae are no doubt the material of the future. Their production is a new branch of agriculture. They are already being used in the food, cosmetic and feed industries. They are also used in the production of fertilizers, biofuels or in wastewater treatment processes, among others. Therefore, the topic of this research is in accordance with current trends [8]. In the available literature, there are few publications on the mineral content of spirulina. Our study showed that the most abundant minerals in spirulina supplements were K and P, and the least abundant was Se. A similar trend was notified by [PERSON] et al. [25] in spirulina supplements accessible on the Slovenian market. [PERSON] et al. [30] observed a lower content of P but higher content of K. Furthermore, the authors reported that the supplements they studied were a richer source of Fe, but contained less Na, Ca and Mg than the supplements we studied. [PERSON] et al. [31] determined much higher concentrations of Na, Mg, K and Fe. Higher levels of Se, Fe, Mg and Zn, but lower amounts of Na and K, compared to those in the spirulina supplements analyzed in this study, were reported by [PERSON] et al. [32]. [PERSON] et al. [33] compared the mineral content of three algae: Spirulina, _Chlorella_ and _Isochrisis_. Two of the spirulina samples they tested had a lower Na content, and all had lower contents of P and Zn, similar amounts of K, Ca and Mg, and a higher content of Fe and Se. _Isochrisis_ samples, on the other hand, contained less K, Na, P and Zn and more Ca, Mg, Fe and Se. Microalgae of the genus _Chlorella_ were characterized by lower contents of K, Ca and Zn, similar levels of Na and Mg and higher contents of P and Se. Given the fact that selenium can be harmful in excessive amounts, spirulina is a safer choice in this respect. [PERSON] et al. [34] indicated that _Chlorella_ has a lower content of Na and Zn and a higher Fe content. [PERSON] et al. [35] in turn examined the mineral content of various algal species, though _Arthospira platensis_ was not among them. A comparison of our own findings with those of other authors regarding the mineral content of spirulina is shown in Table 7.  
Both in this study and in the research by other authors there are marked differences in mineral content between samples of individual supplements. These differences may be attributable to a multitude of reasons, including different growing conditions (under natural conditions or in media under controlled conditions) and processing methods of the microalgae. The method used to determine the mineral content, including the equipment used and the accuracy of the measurement, can also influence the results. Nevertheless, \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline  & & & & & & & & \\ \hline
**References** & **Ca** & **Fe** & **Mg** & **K** & **Na** & **Sr** & **Zn** & **P** & **Se** \\ \hline
[Our study mean] & 8554.46 & 664.8 & 3726.3 & 14,274 & 13,439.4 & 42.83 & 45.96 & 15,149.59 & 0.31 \\
[25] & 460–63,500 & 370–3480 & & 5830–26,900 & & 4.39–478 & 2.3–52.7 & 5060–14700 & 0.0–2.7 \\
[30] & 1400–3500 & 230–1200 & 1600–3100 & 13,900–21,700 & 5600–7000 & & & 1500–3200 & \\
[31] & 71,700 & 1370 & 15,500 & 110,000 & 136,000 & 60–346 & & & \\ Spirulina 2 & 29,100 & 4730 & 51,000 & 950,000 & 458,000 & & & 4.0 \\
[32] & 1.57 & 8998 & 4311 & 7680 & 1637 & & 1673 & & 1.31 \\
[33] & & & & & & & & & \\ Spirulina 1 & 8830 & 901 & 3986 & 13,269 & 18,973 & & 24.5 & 7034 & 36.8 \\ Spirulina 2 & 8930 & 924 & 3683 & 15,040 & 9886 & & 25.7 & 7460 & 1.3 \\ Spirulina 3 & 7030 & 1036 & 3997 & 14,080 & 9023 & & 30.1 & 8027 & 1.1 \\ Chlorella & 593.7 & 259 & 344.3 & 49.92 & 1346.4 & & 1.19 & 1761.5 & 0.07 \\ Isochrisis & 1081 & 228.4 & 688.6 & 1193.2 & 1109.2 & & 2.74 & 1252.4 & 1.02 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Element content of spirulina supplements—comparison of our research with data from the literature.