ReviewSeaweeds: A sustainable functional food for complementary and alternative therapy
Introduction
Seaweeds are classified into Rhodophyta (red), Phaeophyta (brown) and Chlorophyta (green) marine macroalgae. They are rich in soluble dietary fibers, proteins, minerals, vitamins, antioxidants, phytochemicals, and polyunsaturated fatty acids, with low caloric value. However, like most flora their nutrient contents are affected by external factors such as the geographic location, environmental, season, sampling conditions (Khotimchenko et al., 2005, Kostetsky et al., 2004, Nelson et al., 2002, Renaud and Luong-Van, 2006). Usually they are only used as gelling agent and stabilizers in the food and pharmaceutical industries, but current research has revealed their potential medicinal uses against cancer, allergy, diabetes, oxidative stress, inflammation, thrombosis, obesity, lipidemia, hypertensive and other degenerative ailments. Although the majority of researches were on mammals, the trials on humans and epidemiological studies supported these findings. Many of the bioactive seaweed components have been identified. This review aims to boost awareness and help future functional food development from this relatively underutilized sustainable resource.
Section snippets
Antioxidant properties (in vitro and in vivo)
The most abundant terrestrial biophenols (flavonoids) have three interconnected rings. Seaweed phlorotannins have up to eight interconnected rings, making them 10–100 times more powerful and more stable as free-radical scavengers than other polyphenols (green tea catechins, have only four rings). The half-life of phlorotannins which is partially fat soluble, is up to 12 h in the body, compared to 30–180 min for water-soluble, terrestrial polyphenols (Kang et al., 2003). The total phenol contents
Nerves and brain
Peroxynitrite is amongst the most notorious of the free radicals, incriminated for neurological disorders, multiple chemical sensitivity, inflammation, fibromyalgia, chronic fatigue syndrome, post traumatic stress disorder, and many disease conditions. A 3-month, human study, on seaweeds extract supplement reported a significant improvement in well-being, sleep amelioration and skin tonicity (Gaigi, Elati, Ben Osman, & Beji, 1996). Fucoidan, a sulfated polysaccharide mainly from brown seaweeds,
Obesity
The seaweeds high soluble dietary fiber contents help slow down digestion and calorie absorption. They help moderate appetite by delaying gastric emptying and absorption in the small intestine (Paxman, Richardson, Dettmar, & Corfe, 2008) although these effects are difficult to prove in humans. Fucoxanthin (the main carotenoid in brown seaweed) showed antiobesity effects especially in obese patients with non-alcoholic fatty liver disease and elevated indices of chronic inflammation (Abidov,
Anticoagulant properties
The anticoagulant behavior of seaweeds sulfated polysaccharides depends on having preferably two sulfate groups and a glycosidic linkage on the pyranose ring (Ciancia, Quintana, & Cerezo, 2010), to enable them to interact with the basic groups in proteins. More than one protease may be targeted. However, the anticoagulant activities are mainly by antithrombin and/or heparin cofactor II mediated thrombin inhibition.
Dictyopteris delicatula sulfated polysaccharides, (heterofucans) have
Antitumor, anticancer and antiproliferative properties
Regular seaweeds consumptions were associated with lower risks of human breast cancers (Setchell, Borriello, Hulme, Kirk, & Axelson, 1984) with suppressive effects on the development of both benign and cancer neoplasis (Eskin, Grotkowski, & Connolly, 1995). Daily seaweeds intake reduces rectal (Kato et al., 1990), breast (Yoon et al., 2010), as well as benign and neoplasis cancer risks (Aceves et al., 2005, Garcia-Solis et al., 2005). Various kelps effectively reduced mammary tumors (Funahashi
Immunomodulation/inflammation /allergy
High dietary intake of seaweed, calcium, magnesium, and phosphorus was associated with a decreased prevalence of allergic rhinitis in Japanese females (Miyake et al., 2006). Seaweeds sulfolipids and fucoidans are anti-inflammatory (Berge et al., 2002). Fucoidan has anticoagulant activity similar to heparin with anti-thrombic and anti-inflammatory effects (Ruperez et al., 2002, Sezer et al., 2008). The E. cava (ECK) brown seaweed activated anti-inflammatory responses and/or suppressed the
Thyroid
Seaweed supplementation increases the thyroid stimulating hormone (TSH) in healthy postmenopausal women (Teas et al., 2009) and slightly decrease serum free thyroxine FT4 (Kiyoshi, Tomoyasu, & Masahiko, 2008). Seaweeds is a good source of iodine and iodine deficiency or excess can be detrimental to reproductive function and to the development of the fetus and newborn (Dunn & Delange, 2001). Iodine-containing tablet was effective for rapid blockage of thyroid function (Takamura et al., 2003).
Phytoestrogenic properties
Seaweed (Alaria) favorably altered estrogen and phytoestrogen metabolism (Teas et al., 2009) for women at high risk of estrogen-dependent disease or who experience fertility problems. Seaweeds have been shown to increase menstrual cycle length, stimulate ovulation and lower the estrogen/progesterone ratio in pre-menopausal women (Skibola, 2005).
Liver, kidneys, lungs
Numerous seaweeds (Halimeda monile, Porphyra spp., Ecklonia stolonifera Okamura, Ulva reticulata, E. cava, Colpomenia sinuosa, S. hemiphyllum, Myagropsis myagriodes, Sargassum henslowianum, Sargassum siliquastrum, U. pinnatifida, H. fusiformis and L. japonica) have hepatoprotective properties (Guo et al., 2007, Kim et al., 2005, Mancini et al., 2009). The compounds responsible include (i) porphyran (Guo et al., 2007, Marathe et al., 2001); (ii) free phenolic acids (Mancini et al., 2009), and
Polysaccharide, dietary fiber and gut health
The soluble dietary fibers in seaweeds are higher than terrestrial plants (up to 55% dry weight) (Wong & Cheung, 2000) especially in the red Hypnea spp. and green Ulva lactuca. Soluble fibers benefit gut health through its water binding, fecal bulking and digestive transit time decreasing effects (Matanjun, Mohamed, Mustapha, & Muhammad, 2009), which indirectly help prevent colon cancer (MacArtain, Gill, Brooks, Campbell, & Rowland, 2007). Major soluble fibers include alginate from brown
Commercialized products
Macroalgal lectins, fucoidans, kainoids and aplysiatoxins are routinely used in biomedical research (Smit, 2004). Kahalalide F produced from Bryopsis sp. has been patented for human lung carcinoma treatment (Scheuer, Haman, & Gravalos, 2000), and assimilated by the grazer Elysia rufescens for anticancer and antitumor properties (Hamann, Otto, Scheuer, & Dunbar, 1996), for controlling lung, colon and prostate cancer (Sparidans et al., 2001). This patent has entered phase II clinical studies for
Conclusion
Changes in human life style and eating habits resulted in increasing cases of obesity and chronic metabolic diseases (diabetis, heart disease, hypertension, hyperlipidemia and cancer). Research reports on the therapeutic properties of seaweeds are numerous, and the ones mentioned here are merely a representation of them. Many synthetic medicinal compounds have deterimental effects on the liver or kidneys at high doses or prolonged use. Seaweeds contain beneficial components that are a natural
References (193)
- et al.
Expression of scavenger receptors in glial cells. Comparing the adhesion of astrocytes and microglia from neonatal rats to surface-bound beta-amyloid
Journal of Biological Chemistry
(2005) - et al.
Anti-HIV-1 activity of phloroglucinol derivative, 6,6′-bieckol, from Ecklonia cava
Bioorganic & Medicinal Chemistry
(2008) Postprandial hyperglycemia and a-glucosidase inhibitors
Diabetes Research and Clinical Practice
(1998)- et al.
Carrageenans from Chilean samples of Stenogramme interrupta (Phyllophoraceae), structural analysis and biological activity
Phytochemistry
(2000) - et al.
In vitro antioxidant activities of three selected brown seaweeds of India
Food Chemistry
(2008) - et al.
Anticoagulant properties of a fucoidan fraction
Thrombosis Research
(1991) - et al.
Evaluation of antioxidant property of extract and fractions obtained from a red alga, Polysiphonia urceolata
Food Chemistry
(2006) - et al.
A polysaccharide isolated from the brown seaweed Sargassum stenophyllum exerts antivasculogenic effects evidenced by modified morphogenesis
Microvascular Research
(2008) - et al.
The structure of the agaran sulfate from Acanthophora spicifera (Rhodomelaceae, Ceramiales) and its antiviral activity. Relation between structure and antiviral activity in agarans
Carbohydrate Research
(2004) - et al.
Antiviral properties of fucoidan fractions from Leathesia difformis
Phytomedicine
(1999)