Bladder Wrack or Black tang, Fucus vesiculosus, is a very common brown algae found in cold and temperate waters of coastal and sublittoral regions along the rocky coasts of the northern hemisphere (Atlantic and Pacific Oceans, Channel, North Sea and Baltic Sea) (CATARINO & al., 2018).
It is part of the Fucaceae family. It grows half of its time out of the water. It is therefore subject to strong variations in temperature and salinity. It carries airy vesicles or floats called aerocysts which allow it to maintain a certain buoyancy to capture light while remaining attached to its substrate.
It contains various chemical components including polyphenols with antibiotic activity such as fucols and fucophloretols; polysaccharides and mucilages (12% alginic acid); minerals such as iodine (0.05-0.1%), bromine, sodium and magnesium; proteins (10%); all amino acids (including tryptophan, phenylalanine and leucine); carotenoids; vitamins A, B1, B2, B6, B12, PP, C, D3, E and K; and phytohormones (gibberellins). This composition provides bladder wrack with many health benefits.
First of all, its high polysaccharide content gives it a particularly interesting antioxidant activity (RUPEREZ & al., 2002). It has an inhibitory effect on proteases, which is shown to be beneficial for health given their role in deleterious tissue remodeling in various inflammatory diseases. It exhibits anti-collagenase (25% inhibitory activity) and anti-elastase (50% inhibitory activity) activities (THRING & al., 2009).
In addition, it has protective effects on the stomach. Indeed, the fucoidan polysaccharides contained in bladder wrack inhibit the attachment of Helicobacter pylori to gastric epithelial cells in vitro. In addition, bladder wrack extracts have a cytotoxic effect on gastric carcinoma cells (CHUA & al., 2015).
It contains numerous polysaccharides, including fucoidans, which have an immunostimulatory role (KIM & al., 2011) and an antitumor effect in vitro on human lung cancer cells, via the inhibition of ERK1/2, Akt-mTOR and NF-kB signaling pathways (LEE & al., 2012).
Bladder Wrack has the particularity of containing a high content of alginates which are polysaccharides with multiple benefits. The accumulation of alginates in this algae strongly depends on seasonality: the contents are on average 3 times higher in summer (23.97% of dry matter) than in spring (8.40%) (OBLUCHINSKAIA & al., 2002 ; CATARINO & al., 2018).
These polysaccharides show beneficial effects in the gastrointestinal tract, helping to regulate intestinal flow while stimulating the growth of microbial species beneficial for intestinal homeostasis (BROWN & al., 2014).
They turn into gel on contact with acidic gastric juice, thus forming a floating mechanical barrier preventing acid reflux into the esophagus (KIM, 2016). A meta-analysis of fourteen placebo-controlled studies including 2,095 patients showed that alginate-based therapies effectively reduce symptoms in patients with gastroesophageal reflux disease and erosive esophagitis (LEIMAN & al., 2017).
In addition, they increase the feeling of fullness after a meal, reduce the feeling of hunger and food intake, helping to fight obesity (JENSEN & al., 2011 ; 2012). The alginates also have antihyperglycemic and anti-hypercholesterolemic effects, which is beneficial in the context of the prevention and management of type 2 diabetes, cardiovascular diseases and metabolic syndrome (TORSDOTTIR & al., 1991 ; WOLF & al., 2002 ; PAXMAN & al., 2008).
