Seaweed salad and the interesting properties of wakame

Seaweed saladThis tasty and healthy seaweed salad is made with wakame. Wakame is the common name for the seaweed species Undaria pinnatifida. Wakame is one of the most commonly eaten edible brown seaweeds in Japan, Korea and China. It is actually the sterile leaf from the asexual generation that is consumed (1). In Korea, most mothers are given a U. pinnatifida soup after birth because it is believed that this soup aids postnatal recovery and cleanses the blood (2).

The scientific study of algae (seaweed is a type of algae) is termed phycology and there has been quite a bit of research into wakame as it contains a number of interesting compounds that have a range of physiological and biological properties.

Fucoxanthin

Fucoxanthin, a major marine carotenoid, is found in the chloroplasts of brown seaweed, including wakame (3). Fucoxanthin has a unique structure and shows strong antioxidant properties (4). Interestingly, fucoxanthin reportedly has anti-obesity and anti-diabetic effects.

Studies have shown that fucoxanthin up-regulates energy expenditure in abdominal white adipose tissue (WAT) and reduces excess lipid in WAT. It is thought that one of the mechanisms by which fucoxanthin mediates this anti-obesity effect is via induction of uncoupling protein 1 (UCP1) in abdominal WAT. This induction has been shown in rats and in mice (5, 6). UCP1 is normally expressed only in brown adipose tissue (BAT) where it plays a role in energy and heat production. Results have also shown that fucoxanthin up-regulates expression of the β3-adrenergic receptor in WAT, which is responsible for lipolysis (the breakdown of fats) (7).

Additionally, supplementation of obese mice with 0.1% or 0.2% purified fucoxanthin showed anti-diabetic effects. It is thought that these anti-diabetic effects are due to the suppression of inflammation in adipocytes (fat cells) and the restoration of the glucose transporter 4 (GLUT4) activities in skeletal muscle. GLUT4 allows muscle cells to utilize glucose and is reduced in insulin-resistance diabetes (8).

Is fucoxanthin bioavailable from the consumption of wakame? One study showed that in 5 healthy subjects consuming 6 grams (dry weight) of cooked wakame daily for one week, which contained 6.1mg of fucoxanthin, fucoxanthinol, an intestinal metabolite of fucoxantin, was increased in plasma to a concentration of 0.8nmol/l (9). However, the authors noted that this concentration was low.

Fucoidans

Brown algae, including wakame, contain sulfated polysaccharides, predominantly sulfated L-fucose, which are called fucoidans (10). This feature of wakame is of particular interest to me as one of my current areas of research involves fucose containing glycans and the interactions of these glycans. As I started reading the literature on the fucoidans and the biological effects that these sulfated fucose containing polysaccharides have, it made perfect sense to me as these fucoidans mimic the ligands or the receptors for a range of biological systems.

Studies have shown that fucoidans isolated from wakame can have antiviral and antiparasitic effects. One study treated groups of 10 mice orally with 1mg or 5mg of fucoidans isolated from wakame twice per day for 7 days before and 7 days after these mice were infected with the two different subtypes of avian influenza virus A (H5N3 and H7N2). A control group was also included. These mice were not given the fucodians but were dosed with distilled water. The results showed that those mice given both doses of the fucodians had significantly lower viral loads in the lungs compared to the control group, with the higher dose of 5mg reducing the viral load more than the 1mg dose. It was also found that those mice given the fucodians displayed greater production of neutralizing antibody and anti-influenza virus specific IgA antibody (11). A number of other studies have found that the fucodians can prevent replication of the herpes simplex virus type 1 (HSV-1) and protect mice from infection with this virus (12, 13). My interpretation is that the fucodians inhibit viral loads by mimicking the receptors that these viruses typically bind to mediate entry into host cells. It is interesting that the isolated fucodians appear to also stimulate the host immune response to these viruses. Again, I would think that this is because these polysaccharides mimic the ligands involved in these immune pathways.

The fucoidans have also been shown to have anti-inflammatory effects. This is because they can act as the ligands for the receptors on the surface of leukocytes or white blood cells, the E-, P- and L- selectins, and inhibit selectin-mediated leukocyte migration and infiltration, thus leading to the decrease in systemic inflammation (14, 15). Additional mechanisms of action for the anti-inflammatory effects of fucodian have also been reported (16, 17).

Undariase

The fucoidans from wakame have been shown to have anticoagulant and antithrombotic effects. One recent study identified a direct-acting fibrinolytic serine protease in U. pinnatifida, which also displayed anticoagulant and antiplatelet properties. This enzyme was named “undariase” by the researchers. Thrombosis (the formation of a clot within a blood vessel) plays a major role in circulatory diseases such as myocardial infarction, deep vein thrombosis and pulmonary embolism. Current treatments for thrombosis have some drawbacks including complications with hemorrhaging. “Undarise” isolated from U. pinnatifida may offer a safe and effective alternative for thrombolytic therapy (18).

Seaweed salad

These properties of wakame are very interesting, however, it is impossible that you could obtain a sufficient amount in a seaweed salad made with wakame to actually elicit the biological responses described above. All these studies are conducted using the extracted and concentrated compounds from wakame. Nevertheless, providing your body with all of the building blocks that it requires to carry out these biological processes, in my view, is optimal for overall good health. Plus U. pinnatifida is rich in polyunsaturated fatty acids and water and fat-soluble vitamins, including vitamins A, B, C and E (19, 20). So try this seaweed salad for something different. You can get dried wakame from your local Asian supermarket. Remember wakame increases substantially in size when rehydrated.

WakameSeaweed salad

Makes 1 large salad

Ingredients

25 grams dried wakame seaweed

3 tablespoons rice vinegar

3 tablespoons soy sauce

1 tablespoon sesame oil

1 teaspoon honey

1 clove garlic, minced

2 cm fresh ginger, finely grated

¼ teaspoon dried chilli

1 cup cucumber, chopped

¼ teaspoon salt

1 carrot, grated

1 tablespoon sesame seeds, roasted

Method

  • Sprinkle the cucumber with salt and allow to sit for 10 – 15 minutes. Squeeze out the water from the cucumber.
  • Cover the wakame seaweed with water and allow the seaweed to hydrate for about 10 minutes (it will be obvious when it has hydrated as it will swell considerably). Drain the seaweed and squeeze out the excess water.
  • Combine the rice vinegar, soy sauce, honey, garlic, ginger and chilli into a small bowl and mix well.
  • Add the seaweed, cucumber and carrot into a salad bowl. Pour over the dressing and mix well. Top with the roasted sesame seeds to serve.Wakame dehydrated
  1. Murata, M., Ishiharo, K. and Saito, H. (1999). Hepatic Fatty Acid Oxidation Enzyme Activities Are Stimulated in Rats Fed the Brown Seaweed, Undaria pinnatifida (wakame). Nutr. 129: 146–51.
  2. Moon, S., & Kim, J. (1999). International Journal of Food Sciences and Nutrition. 50: 165–171.
  3. Matsuno, T. (2001). Aquatic animal carotenoids. Fisheries Science. 67: 771-783.
  4. Sachindra, N., Sato, E., Maeda, H., Hosokawa, M., Niwano, Y., Kohno, M. and Miyashita, K. (2007). Radical scavenging and singlet oxygen quenching activity of marine carotenoid fucoxanthin and its metabolites. Agric. Food Chem. 55: 8516-8522.
  5. Maeda, H., Hosokawa, M., Sashima, T., Funayama, K. and Miyashita, K. (2005). Fucoxanthin from edible seaweed, Undaria pinnatifida, shows antiobesity effect through UCP1 expression white adipose tissues. Biophys. Res. Commun. 332: 392-397.
  6. Woo, M., Jeon, S., Shin, Y., Lee, M., Kang, M and Choi, M. (2009). Anti-obese property of fucoxanthin is partly mediated by altering lipid-regulating enzymes and uncoupling proteins of visceral adipose tissues in mice. Nut Food Res. 53: 160-1611.
  7. Maeda, H., Hosokawa, M., Sashima, T., Murakaimi-Funayama, K. and Miyashita, K. (2009). Anti-obesity and anti-diabetic effects of fucoxanthin on diet-induced obesity conditions in a murine model. Med. Report. 2: 897-902.
  8. Maeda, H., Hosokawa, M., Sashima, T. and Miyashita, K. (2007). Dietary combination of fucoxanthin and fish oil attenuates the weight gain of white adipose tissue and decreases blood glucose in obese/diabetic KK-Ay mice. Agric. Food. Chem. 55: 7701 – 7706.
  9. Asai, A, Yonekura, L, Nagao, A. (2008). Low bioavailabiliy of dietary epoxyxanthophylls in humans. J. Nutr. 100: 273-277.
  10. Berteau, O. and Mulloy, B. (2003). Review: Sulfated fucans, fresh perspectives: structures, functions, and biological properties of sulfated fucans and an overview of enzymes active toward this class of polysaccharide. Glycobiology. 13: 29R-40R.
  11. Synytsya, A., Bleha, R., Synytsya, A., Pohl, R., Hayashi, K., Yoshinaga, K., Nakano, T. and Hayashi, T. (2014). Mekabu fucoidan: structural complexity and defensive effects against avian influenza A viruses. Carbohydrate Polymers, 111: 633-644.
  12. Hayashi, K., Nakano, T., Hashimoto, M., Kanekiyo, K. and Hayashi, T. (2008). Defensive effects of a fucoidan from brown alga Undaria pinnatifida against herpes simplex virus infection. International Immunopharmacology. 8: 109-116.
  13. Hemmingson, J., Falshaw, R., Furneaux, R. and Thompson, K. (2006). Structure and Antiviral Activity of the Galactofucan Sulfates Extracted from Undaria Pinnatifida (Phaeophyta). Journal of Applied Phycology. 18: 185-193.
  14. Carvalho, A., Sousa, R., Franco, A., Costa, J., Neves, L., Ribeiro, R., Sutton, R., Criddle, D., Soares, P. and de Souza, M. (2014). Protective effects of fucoidan, a P- and L-selectin inhibitor, in murine acute pancreatitis. Pancreas. 43: 82-87.
  15. Li, C., Gao, Y., Xing, Y., Zhu, H., Shen, J. and Tian, J. (2011). Fucoidan, a sulfated polysaccharide from brown algae, against myocardial ischemia-reperfusion injury in rats via regulating the inflammation response. Food Chem. Toxicol. 49: 2090-2095.
  16. Park, H., Han, M., Park, C., Jin, C., Kim, G., Choi, I., Kim, N., Nam, T., Kwon, T., and Choi, Y. (2011). Anti-inflammatory effects of fucoidan through inhibition of NF-kB, MAPK and Akt activation in lipopolysaccharide-induced BV2 microglia cells. Food Chem. Toxicol. 49: 1745-1752.
  17. Cui, Y., Jia, Y., Zhang, T., Zhang, Q., and Wang, X. (2012). Fucoidan protects against lipopolysaccharide-induced rat neuronal damage and inhibits the production of proinflammatory mediators in primary microglia. CNS Neurosci. Ther. 8: 827-833.
  18. Choi, J-C., Sapkota, K., Kim, M-K., Kim, S., and Kim, S-J. (2014). Undariase, a Direct-Acting Fibrin(ogen)olytic Enzyme from Undaria pinnatifida, Inhibits Thrombosis In Vivo and Exhibits In Vitro Thrombolytic Properties. Appl Biochem Biotechnol.173: 1985–2004.
  19. Kumari, P., Kumar, M., Gupta, V., Reddy, C. R. K., & Jha, B. (2010). Tropical marine macroalgae as potential sources of nutritionally important PUFAs. Food Chemistry. 120: 749–757.
  20. MacArtain, P., Gill, C. I. R., Brooks, M., Campbell, R., & Rowland, I. R. (2007). Nutritional value of edible seaweeds. Nutrition Reviews. 65: 535–543.

5 thoughts on “Seaweed salad and the interesting properties of wakame

  1. Pingback: Spinach, dill and feta crustless quiche | I can't believe that's healthy

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