Patients that were undergoing Protecton® Zellactiv (Smith Kline Beecham, Fink Naturarznei GmbH, Bühl, Germany) chemotherapy and that ingested selenium daily experienced significantly higher levels of serum selenium, enhanced glutathione peroxidase 1 (GPX1) activity in their erythrocytes, higher levels of malondialdehyde (MDA), increased white blood cells counts, reduced neutropenia, and a reduction in the negative side effects induced by chemotherapy (e.g., hair loss, abdominal pain, weakness, malaise, and loss of appetite) [152]. This evidence concerns the gene GPX1 and neutropenia.