In food and pharmaceutical industry, marine products are currently of considerable interest. In the marine environment, wakame seaweed is edible seaweed used as a vegetable and a traditional food item of Japan. Wakame seaweed is a type of brown seaweed which is a natural marine product. It gets the brown color from a pigment named ‘fucoxanthin’. Wakame seaweed is completely loaded with different nutrients and health-promoting compounds. Such an amazing nutrient composition has made wakame seaweed an important part of the diet in many Asian countries such as Japan, Korea, and China. It has been cultured in Japan for the past 100 years.
Wakame seaweed is a low-fat traditional food which is commonly consumed in Japan and other Asian countries. Besides this, it is a moderate to a good source of protein. Wakame seaweed is a rich source of various minerals and several health-promoting compounds that play an important role in prevention, treatment, and management of various diseases and disorders.
Nutritional Value of Wakame seaweed
Let’s have a look at the nutritional profile of wakame seaweed:
Rich in different types of nutrients
As mentioned earlier wakame seaweed is a good source of various essential minerals such as iron, calcium, zinc, iodine, potassium, and magnesium. Therefore, one can meet a part of their daily mineral requirement if they regularly eat wakame seaweed. The most abundant vitamin present in wakame seaweed is vitamin A. Besides this, wakame seaweed is a good source of carbohydrate and protein and contains essential amino acid which cannot be synthesized in the body. Its dietary fiber content is around 16.9% which makes it very beneficial in the management of diabetes and high cholesterol and triglyceride levels. (1, 2)
An abundant source of antioxidants
To fight oxidative stress, it is very important to include high antioxidant foods in the daily diet. Wakame seaweed is one such food which is very abundant in antioxidant content. Fucoxanthin and fucoidan are two main antioxidants present in wakame seaweed that are not present in any other fruits and vegetables. Phlorotannins, a group of tannins possess high antioxidant activity and are present in wakame seaweed. These antioxidants prevent the cell against oxidative damage and death. Furthermore, antioxidants present in seaweed are strong free radical scavengers. Tocopherols and carotenoids are lipophilic antioxidants present in large amounts in wakame seaweed. The presence of so many different antioxidants makes wakame seaweed a very powerful antioxidant food. (3, 4)
Wakame Seaweed Benefits
Wakame seaweed is a marine treasure that is of great importance and has a great demand in pharmaceutical and food industry. As a part of the regular diet, wakame seaweed plays a beneficial role in controlling high blood pressure, high blood glucose levels, and high triglyceride levels. Besides this, various nutrients present in wakame seaweed strengthen the immune system, help in killing cancer cells, prevents osteoporosis and is also used as a galactagogue.
Hypertension or high blood pressure
Many research studies have found that wakame seaweed plays a very beneficial role in lowering high blood pressure. It was found that wakame seaweed works by inhibiting angiotensin converting enzyme (ACE). ACE is a vasoconstrictor that constricts the arteries and raises the blood pressure. Inhibition of such an enzyme, in turn, lowers high blood pressure.
A research study was conducted in 2010 to examine the effects of wakame seaweed on high blood pressure in 37 elderly individuals with hypertension. 19 individuals were given a daily dose of 5 grams of dried wakame seaweed powder in the form of capsules while other individuals were not on wakame seaweed. After 8 weeks of the treatment period, it was found that elderly individuals on wakame seaweed had significantly lowered their systolic blood pressure by 13 mm Hg whereas, a drop of 9 mm Hg was observed in diastolic blood pressure. But no such changes were observed in elderly individuals who were not on wakame seaweed. This study clearly shows that wakame seaweed is very effective in lowering high blood pressure.
It is very well known that high blood pressure level is a great risk factor for stroke and cardiovascular diseases. Another study showed that diet containing wakame seaweed lowered the level of high blood pressure as well as delayed the risk of stroke. (5, 6, 7)
High triglyceride levels
There is a positive link between high triglyceride levels and heart diseases. Therefore, it is very important to keep triglyceride level in normal range. A very interesting rat research showed that administration with wakame seaweed powder and fish oil + wakame seaweed powder lowered the concentration of triglyceride in the liver. Enzymes are involved in the process where fat is converted and used as a source of energy. This indicates that fat is not stored in the body. The study further showed that the level of such enzymes increased in the group which was treated with wakame seaweed. Thus, less fat was stored and less cholesterol and triglyceride were formed in the body. However, such a beneficial effect was greater when rats were treated with wakame seaweed as well as fish oil.
Another study also showed that wakame seaweed is a very beneficial food in lowering high triglyceride levels and thus it helps to prevent high lipid levels in the blood. It was further showed that higher the intake of wakame seaweed greater is the reduction in triglyceride levels. Wakame seaweed modifies the rate of formation and degradation of fatty acid. (9, 10)
Type 2 diabetes mellitus
Research has found that carotenoids present in wakame seaweed play an important role in controlling high blood glucose levels. Fucoxanthin is a carotenoid (healthy compound) that is abundantly present in wakame seaweed. Studies have shown that wakame seaweed reduces insulin resistance and improves insulin sensitivity. It further improves the uptake of glucose by the cells and muscles and reduces the level of high blood glucose levels. This was possible because wakame seaweed improved the activity of glucose transporter which increases the transport of glucose to the cells and muscles, thus less of glucose will remain in the blood. It also acts as an anti-obesity agent and helps in weight loss and it is very well known that weight reduction helps to normalize blood glucose levels.
In a research trial subjects with type 2 diabetes mellitus were treated with seaweed powder which was a combination of wakame seaweed and sea tangle. Such a powder was supplemented to subjects three times a day for 4 weeks. A reduction was observed after 4 weeks in fasting blood glucose levels and post-prandial blood glucose level (after a meal). Such an effect was due to the presence of high dietary fiber content in wakame seaweed. On a dry weight basis, the total dietary fiber content in seaweed powder was 25-75% out of which 51-85% was soluble dietary fiber. Dietary fiber delays the absorption of glucose, this prevents a sudden rise in the blood glucose levels post-meal. Thus, wakame seaweed is considered as a beneficial therapeutic agent that helps in the management of uncontrolled diabetes mellitus. (11, 12)
Research has found that wakame seaweed is a great functional food that plays an important role in stimulating the immune system. Immunocompromised individuals are at a greater risk of contracting infections. Many studies have found that wakame seaweed contains immunomodulatory compounds that inhibit the factors that suppress the immunity and leads to the onset of disease. These compounds also reduce the production of pro-inflammatory markers such as TNF-alpha and IL-6. It further increases the production of anti-inflammatory markers which reduces the overall inflammation. Fucosterol is a health-promoting compound present in wakame seaweed that possesses anti-diabetic, anti-osteoporotic, antioxidant and anti-inflammatory effects. Fucosterol suppresses the activity of markers of inflammation and increases the activity of antioxidant enzymes that reduce the overload of oxidants and toxins.
A very interesting rat study showed that fucoidan, a compound present in wakame seaweed helps in the treatment of influenza. Fucoidan inhibits the multiplication of influenza virus and thus reduces the severity of the infection. Oral administration of fucoidan stimulated the immune defense function in infected rats. Treatment with fucoidan reduced the virus load, decreased weight loss, prolonged survival rate and reduced the mortality rate. It also increased antibody production in blood that further reduced infection. Thus, fucoidan can be used as a therapeutic agent in the treatment of influenza. (13)
Osteoporosis is a rising problem and the risk of osteoporosis increases with increasing age. Osteoclasts are specialized bone cells that play an important role in bone resorption and breakdown of bone matrix. Research has found that wakame seaweed contains a compound known as fucosterol that possesses anti-osteoclastic activity. Such an inhibition reduces the breakdown of bone matrix and bone resorption and thus reduces the risk of osteoporosis. Therefore, it can be concluded that wakame seaweed has anti-osteoporotic potential. (14)
Hyperphosphatemia is a condition in which the amount of inorganic phosphate increases in blood. Such a condition is more common in chronic kidney disease which is linked with abnormal bone and mineral metabolism (more of phosphate enters into the blood from bones). Research has found that rats fed with wakame seaweed had a higher amount of inorganic phosphate being excreted in the feces as compared to rats who were not treated with wakame seaweed. Such an excretion indicates lowering of high levels of inorganic phosphate in the blood. Furthermore, the research found that normal diet containing 5% wakame seaweed lowered the level of inorganic phosphate in the blood. Such a diet reduced the intestinal absorption of inorganic phosphate and even prevented progression to chronic kidney failure. Therefore, wakame seaweed can be a great food for patients with kidney problems too. (15)
Wakame seaweed is a super-food and many studies have shown that it plays a beneficial role in the treatment of cancer. A research published in 2011 showed that fucoidan, a compound present in wakame seaweed has anti-cancer activities. Fucoidan prevents the multiplication of cancer-causing cells in the body and reduces their spread. It also works by killing the cancerous cells, thus it reduces the overall population of cancerous cells. Furthermore, fucoidan suppresses the action of pro-inflammatory markers. They increase inflammation which is positively associated with the onset of lung cancer. Thus, wakame seaweed significantly reduces pro-inflammatory markers of inflammation and reduces the risk of lung cancer.
Another study published in 2012 has found that wakame seaweed plays a protective role in leukemia, lung cancer, prostate cancer and colon cancer. Compounds present in wakame seaweed are effective against tumors. It has further shown to kill tumor cells, reduce the size and rate of growth of the tumor and limit the spread of the tumor to other parts of the body. Hence, it can be said that increased wakame seaweed intake is associated with reduced risk of cancer. (16, 17)
Many scientific studies have found that wakame seaweed is considered to be an important post-pregnancy food. Wakame seaweed acts as a galactagogue that is it increases the production of breast milk in lactating mothers. In addition to this, the presence of so many nutrients in it improves the overall health of mothers post-delivery.
Brown adipose tissue is a healthy tissue that prevents accumulation of excess fat in the body whereas white adipose tissue is just the opposite. Lean individuals have more of brown adipose tissue and obese individuals have more of white adipose tissues. Scientific studies have found that lipids extracted from wakame seaweed reduce abdominal white adipose tissue. Furthermore, fucoxanthin present in wakame seaweed reduced the weight of white adipose tissue and increased the expression of a protein that causes weight loss.
In addition to this, other study showed that wakame seaweed works by reducing the action of ‘ghrelin’. Ghrelin is a hunger hormone that sends a signal to the brain to start eating or continue eating. By reducing the action of ghrelin, one may feel less hungry and lesser calories may enter into the system. This indicates that wakame seaweed plays a beneficial role in weight reduction and it can be used as an anti-obesity agent. (18, 19)
Besides being a nutritious food, wakame seaweed also has some important medicinal properties. Wakame seaweed polysaccharides gained much attention in the pharmaceutical industry as an alternative source of anticoagulants. Research has shown that wakame seaweed has anticoagulant properties that are similar to that of heparin, an anticoagulant that prevents the formation of blood clots. Such an action of wakame seaweed is attributed to the presence of fucans that inhibits thrombin (thrombin coagulates blood). Research has further found that wakame seaweed interferes with both intrinsic and extrinsic pathways of coagulation and thus inhibits clot formation.
Another research showed that polysaccharides present in wakame seaweed play an important role as an anticoagulant. It was further showed that no toxic effect was observed on human blood cells. Administration of fucoidan from wakame seaweed caused no significant difference in hematological parameters. But the prothrombin time (PT) and activated partial thromboplastin time (APTT) was prolonged after its administration. Such a prolongation indicates that coagulation is inhibited. Use of wakame seaweed extract as an anticoagulant is more beneficial and safe because its use would avoid the potential for contamination with viruses. Contamination of commercial heparin is a common problem which can be avoided if wakame seaweed is used. (20, 21)
Wakame Seaweed Toxicity
Any food consumed in excess may have a negative effect on the body or biochemical parameters. A rat study published in 2010 showed that fucoidan present in wakame seaweed, when consumed in high amount (1350 mg/ kilogram body weight/ day) for 4 weeks, had no toxic effect on the body. No changes were observed in body weight, urine and blood parameters.
Another study showed that 0 to 2000 mg/ kilogram body weight/ day of fucoidan administered to rats had no toxic effects on the rats. Thus, it can be said that wakame seaweed may have no toxicological effect. Human trials are further required to understand the effect of wakame seaweed on humans. (22, 23)
Different ways to eat and store wakame seaweed
Wakame seaweed is mostly consumed in the form of wakame salad alone or in combination with other vegetables. Another way to consume it is in the form of soups and sandwiches. In Japan and other Asian countries, wakame seaweed is added to some processed products such as noodles and bread. It can even be eaten in the dried form which is available all throughout the year.
Dried wakame seaweed can be stored for a longer period of time in an air-tight container in a dry and cool place. Cooked wakame seaweed should be stored in the refrigerator. Dried wakame seaweed can rehydrate by soaking it in water for 20 minutes followed by removing the hard parts. However fresh seaweed should be soaked for just 5 minutes before cooking it.
About wakame seaweed
Wakame seaweed is native to Japan. It is particularly found on the coasts of Japan and Hokkaido. Besides this, it is also found on the coast of Korea and Chenshan Island. It is yellowish-brown in color when harvested and it is an annual heteromorphic life-cycle plant. When preserved for a longer period of time it changes to green in color. Wakame seaweed is usually 1 to 2 meters tall but it can also grow up to 3 meters. It has a growth rate of 1 centimeter per day. It grows best in a cold climate with a temperature below 17 degrees Celsius whereas, it begins to deteriorate during summer and autumn.
The leading producers of wakame seaweed in the world are Japan, China, and Korea. Out of these, Korea has the largest production of wakame seaweed and China has recently become the main producer after 2011.