Ambiguities in dietary antioxidant supplementation compared to calcium channel blockers therapy

Antioxidants are widely considered as being essential for an optimal health so that supplementation with natural antioxidants is advised for cancer, cardiovascular diseases and other various pathologies, whereas supplementation with vitamin pills may not be advised, as discussed below. By clicking “antioxidant miracle” on a web search engine one gets about 2 million results. This mainly relates to vitamin E and C, the former being lipid-soluble and the latter being water-soluble, which are best known by laypeople. Antioxidants neutralize the harmful effects of excessive formation of reactive oxygen species (ROS) (Godfraind, 2004). They share this quality with major therapeutic agents such as dihydropyridine-type calcium channel blockers (Godfraind, 2004) that are established drugs for treating cardiovascular diseases. In this opinion paper, we intend to compare some cardiovascular outcomes of dietary antioxidant supplements versus calcium channel blockers (CCBs). Both clinical and experimental evidences indicate that ROS play an important role in the development of several diseases including cancer (Chandel and Tuveson, 2014) and hypertension (Godfraind, 2004). The mitochondrial electron transport chain and NADPH oxidases (NOXs) localized to the plasma membrane and the membrane of cellular organelles are producers of reactive oxygen species. NOXs enzymes are a family of heme-containing transmembrane proteins (Bedard and Krause, 2007). These enzymes transport electrons across the membrane from a cytosolic electron donor to an electron acceptor located in the extracellular or in the luminal space. NADPH serves as electron donor and oxygen as electron acceptor for the production of reactive oxygen species (Bedard and Krause, 2007). ROS comprise superoxide anion (O2·−), hydroxyl radical (HO·), peroxyl radical (RO·2), alkoxyl radical (RO·) (Dunford, 1987). The highly reactive hydroxyl radical can react with molecules in cells, including DNA, proteins and lipids (Girotti, 1998). In the process of peroxidation, hydroxyl radical reaction with phospholipids is forming water (Girotti, 1998). For example, assuming that LH represents the lipid and OH· the hydroxyl radical (the · representing an electron):