Have you eaten seaweed? A traditional food in many cultures, seaweed and other algae are still a novelty to many Americans. That may be changing. From microscopic phytoplankton to large seaweed like kelp, the commercial market for many varieties has been growing dramatically. Seaweed’s nutrition profile, sustainability, low environmental impact, and deep umami flavor are some of the reasons it is popping up in everything from packaged snacks to pasta sauces.
Nutritional Benefits. There are three main types of seaweed—brown, red, and green. Exact nutrient content varies by color and species, but some key attributes are consistent.
➧ Snack on seaweed sheets. Crunchy, roasted seaweed is a popular snack enjoyed for its savory, umami flavor. ➧ Swap in kelp noodles. Try this neutral flavored noodle with marinara or pesto sauce, in stir-fries, soups, or any noodle recipe. ➧ Try seaweed broth. Dashi, or seaweed broth, is the base for dishes like miso soup and ramen. It can be homemade from simmered dried kelp or prepared using dashi granules or powder. Use it as you would other broths in soups, noodle dishes, and stews. ➧ Season with seaweed. Seaweed seasonings like furikake are found in the Asian section of many markets. Sprinkle on any dish for a new, savory, and sometimes spicy, twist.
The protein in seaweed is complete. This means it is one of the few plant foods that, like animal proteins, contains all nine essential amino acids. It is also high in fiber. Seaweed-derived fibers like carrageenan and agar have been used to thicken, stabilize, and emulsify processed foods and cosmetic products for decades.
While nutrient content varies by variety, most seaweeds contain a variety of minerals, including iodine, calcium, magnesium, and potassium. The most common vitamins found in significant quantities in seaweeds are A, C, K, and folate.
While some plant foods (notably soybean and canola oils, nuts, and seeds) contain omega-3 fatty acids in the form of ALA (alpha-linolenic acid), some seaweeds contain an essential fatty acid found in fish and seafood—EPA (eicosapentaenoic acid). Higher blood levels of EPA (typically along with the essential fatty acid DHA) have been associated with lower risk for cardiovascular disease, chronic kidney diseases, and risk of death from all causes. Seaweeds also contain sterols, a plant form of cholesterol that has been shown to help lower blood levels of cholesterol when consumed in foods.
Seaweed has attracted attention from the food manufacturing and nutraceutical industries due to the presence of other bioactive compounds like flavonoids. These compounds are being actively studied for their health effects, although there has been no definitive human research proving that extracting these compounds from their natural sources and adding them to foods or supplements is beneficial.
Recently, two large studies conducted in Japan reported an association between seaweed intake and lower risk of cardiovascular diseases.
Potential Risks. Seaweed is a natural source of iodine, without which the body can’t make thyroid hormone. Too much iodine, however, can cause thyroid problems. Eating very large quantities of seaweed has the potential to lead to excessive iodine intake.
Seaweed accumulates heavy metals from the environment. While these metals, like arsenic and cadmium, are associated with adverse effects on health, concentrations in edible seaweeds are generally below levels considered harmful to human health. Heavy metal and iodine levels in seaweeds vary depending on the type of seaweed, how and where it is grown, and even what part of the seaweed is eaten. It therefore seems prudent to avoid daily intake of large amounts of these otherwise nutritious foods.
Environment. Seaweed’s reputation as a sustainable food is a key driver of its growing popularity. Unlike other crops, algae don’t require land, fertilizer, or fresh water to grow. Seaweed can be harvested in the wild, but seaweed farming is currently the fastest growing sector of American aquaculture (the controlled cultivation of aquatic organisms). It is grown on long lines suspended below the water.
Adding to its sustainability, seaweed is very fast growing and it helps improve water quality. It uses carbon dioxide to grow, which helps balance nutrient levels in surrounding waters, creating favorable conditions for fish to thrive.
Dried seaweed snacks, sheets of nori for sushi rolls, and seaweed-based seasonings are available in the international foods section of many markets. For a wider selection, look for Asian specialty markets in your area or order online.