Antioxidative potential and origin of algae based food supplements are relatively
unknown, as food supplements do not have strict regulation compared to food and
medicinal drugs. Our goal was to evaluate different samples of food supplements that
are based on Aphanizomenon flos-aquae – AFA, Spirulina sp., Chlorella sp. and
brown algae, by determining antioxidative potencial - AOP (methods DPPH and
Folin-Ciocalteu), elemental composition analysis (XRF and ICP-MS) and ratios of
stables isotopes of light elements (C, N and S; EA-IRMS method). AFA samples
have 4.4 higher AOP compared to Chlorella sp. and 2,7 higher compared to Spirulina
sp., while AOP in brown algae is negligible. Manufacturer's suggested doses of
samples do not exceed upper intake level of essencial elements. Concentrations of
toxic elements (arsenic, cadmium, mercury and lead) are low and do not represent
risk to consumer's health. Few samples have increased silicon content, which could
mean addition of undeclared additive SiO2. Statistical analysis (principal component
analysis and cluster analysis) has confirmed that AFA samples originate from the
same source, which is supposedly lake Klamath. Hawaiian S. pacifica can also be
differentiated from other samples, due to characteristic elemental composition.
Different isotopic ratios of stable elements (C, N and S) of Spirulina sp. and Chlorella
sp. samples are consequence of using different nutrient sources and algae growing
techniques.
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