The health benefits of sea vegetables and seaweeds (aquatic plants) have been known for thousands of years, especially in Asia, where they are prized for their nutritional content.
Sea vegetables are marine algae that are simple organisms found both in marine salt waters as well in freshwater lakes and seas. They commonly grow on coral reefs or rocky landscapes and can grow at great depths provided that sunlight can penetrate through the water to reach them, and like plants, they require light for their survival. Sea vegetables are classified into three categories by color; brown, red, or green and each has a unique shape, taste, and texture.
The vast majority are edible, with only a few tropical species being poisonous. Some types are more revered for their appealing flavor, texture, and culinary versatility, which include dulse, nori, sea lettuce, kombu, wakame, arame, hijiki, and agar-agar.
Eating these vegetables is not the norm for many, but there is a long history of their use throughout history. Dulse was first used in Iceland during the 10th century to restore strength and energy by Celts and the Vikings during their long travels, and the Irish, Scottish, and British have been using it since 1200 AD. China first starting using it around 2700 BC, and Japan has used six varieties since 800 AD, and today, there are 21 species seen in their diets. When Captain Cook visited Tonga in 1777, he was given Limu Moui (algae) to restore his health and stamina. In Europe, Mediterranean seaweeds were used as food and as herbal medicines by the Greeks and Romans, and red algae were used as a drying agent and to treat parasitic worms.
Sea vegetables and seaweeds are low in fat and calories and rich in essential minerals, vitamins, and protein. Seaweeds provide all of the 56 minerals and trace minerals required for the body's physiological functions and contain approximately 15 times the minerals of land plants.
Seaweeds also contain vitamins A, B, C, and E, and nori contains vitamin D. Moreover, some seaweeds contain small amounts of vitamin B12, usually found in animal products. Seaweeds also provide 50 to 60% polysaccharides (starches), and despite this large quantity of carbohydrates, sea vegetables add few calories because their starch consists of a substance called Algin (polysaccharide found in cell walls of algae). Alginates are not easily digested by the body, acting like soft fiber, soothing, and adding bulk to the digestive tract, and are abundant in kombu, wakame, arame, and hijiki. Scientific studies have also shown that alginates inhibit the absorption of toxic metals and radioactive isotopes in the digestive tract.
Sodium intake is a health concern for many because of its link with hypertension. Still, it is important to realize the salt is an essential mineral along with potassium providing electrolytes to the cells helping to maintain proper fluid balance. If there is an imbalance, it can also affect magnesium and calcium levels, which also contribute to high blood pressure. The use of sea vegetables can provide bio-availability of essential sodium (in low amounts generally) with potassium, calcium, and magnesium for heart health.
An evolutional assumption is that dietary sodium is not easily found in our environment, and therefore the body retains sodium, but potassium (salts partner) was easily found in the evolutionary diet (vegetables, nuts, seeds, and fruits) so the body does not naturally retain potassium. Because of this assumption, humans today run into trouble because modern diets have reversed the natural availability of sodium and potassium. Potassium is leached out of processed foods, and sodium is used extravagantly as a flavor enhancer and as a preservative.
Sea vegetables have traditionally been used in Asia to treat heart disease and thyroid problems, and recent scientific research is showing positive findings related to cancer, immune function, and overall inflammation.
Today, most Westernized societies use and ingest seaweed in everyday life in the form of alginates, agars, and carrageenan's (starches and thickening agents), which are found in many foods and pharmaceuticals.
Sea vegetables are available in many food shops, usually in a dried form, which makes them ideal for long-term storage. Some sea vegetables, such as dulse, wakame, nori, and sea lettuce can be tender enough to eat raw or after a brief soaking; some such as arame need light cooking by boiling or steaming, while others such as kombu and hijiki require longer cooking times by sautéing or simmering. All sea vegetables expand after soaking, so do not use too much.
From an Ayurvedic perspective, seaweed has the energetics of being salty and warming and is reducing to especially Vata and Kapha, but the heat can increase the Pitta Dosha. Seaweeds bio-medical actions include being an anti-inflammatory, anti-cancer, anticoagulant, antithrombotic, antiviral, and are potent antioxidants. They are used for detoxification, to improve circulation, to lowers cholesterol, balance minerals deficiencies, control the growth of bacteria and candida, balance. thyroid function and promotes elimination.