Densely nutritious and sustainably grown, seaweed is finally getting the recognition it deserves as a superfood.
It’s early morning on a Mendocino County beach in Northern California, the sun still below the horizon as Cole Meeker and his crew of seaweed harvesters make their way to the shoreline. The tide is just pulling away, laying bare the bounty of the ocean.
“When you walk into the tidal zone, you’re looking down at a micro-landscape — at this wild, rugged, rocky country,” Meeker says. “It’s an abundant, harmonious ecological system. It is a forest of food.”
Meeker is CEO of The Great and Wonderful Sea of Change Trading Company, which transforms its seaweed harvest into seasonings and snacks, including seaweed chocolate bars. He’s inspired by the oceans’ prolific production of sea vegetables, which, unlike terrestrial vegetables, require no land or fresh water.
Indeed, seaweed is one of the world’s most environmentally friendly crops. Harvested or farmed, it is easier on the planet than conventional farming, and it represents a largely uncharted frontier in Western agriculture. Seaweed captures and stores carbon from its environment more efficiently than terrestrial trees and plants, and researchers are investigating its potential role in countering the effects of climate change.
Seaweed is also one of the world’s most nutritious foods. Grown in the ultimate mineral bath, sea vegetables are rich in iodine, iron, and calcium, as well as a host of vitamins, including A, B, and C. They’re also packed with protein (a similar amount to eggs, though it varies by species), omega-3 fatty acids (which give the fish that eat them their high omega-3 content), and soluble fiber (great for boosting satiety and promoting gut health).
Known biologically as marine algae, seaweeds are identified by color — brown, red, and green — and many of the 10,000 different species are edible. Brown algae, including kombu (a variety of kelp), wakame, and arame, are known for their high iodine content. Red seaweeds include dulse and nori, a favorite of sushi fans (don’t be fooled by its green–black hue); some of these species deliver as much protein as legumes. Green seaweeds include unicellular microalgae called chlorella, prized for their antioxidant properties and typically consumed in powder form.
Seaweed’s nutritional profile is so distinctive that some scientists believe it played a crucial role in the evolution of Homo sapiens. Researchers hypothesize that early humans evolved in coastal communities where they got a steady supply of iodine from seaweed. Iodine is crucial for brain development, and it’s used by the thyroid to produce hormones that regulate metabolism and help with weight control. A 2008 study showed that the form of iodine in kelp can detox free radicals — those reactive molecules that accelerate aging.
As the foundational food source for marine life, seaweed sustains everything from sea urchins to fish. And with the help of nutrition and health researchers, environmental activists, innovative chefs, and harvesters like Cole Meeker, it is becoming more widely recognized as an important food source for humans, as well.
Seaweed’s Healing Power
Beyond its nutritional bounty, seaweed contains specific chemicals that scientists have found prevent and relieve a number of chronic ailments. “The benefits of eating seaweed include not only the nutritional value, but also the bioactive compounds they contain that are unique to a marine environment,” explains Emeir McSorley, PhD, a nutrition professor in the School of Biomedical Sciences at Ulster University in Northern Ireland. Researchers are actively investigating seaweed’s potential for fighting these and other chronic conditions:
Brown seaweed contains several compounds that play a strong protective role against cancer, according to a 2013 study by Jane Teas, PhD, research assistant professor at the University of South Carolina’s Cancer Center. These include alginate fiber; fucoxanthin, a carotenoid; the polysaccharides fucoidan and laminarin; and polyphenol defense compounds.
Another study showed reduced estrogen levels associated with lower breast-cancer rates in laboratory mice that were fed kelp at levels typical in the traditional Japanese diet.
No other food delivers this cancer-fighting combination, says Teas. “Brown seaweeds have no land equivalents in terms of their specific components.”
Teas doesn’t recommend taking a purified capsule of fucoidan, however. This unique polysaccharide in brown seaweed may be protective against breast cancer, but it won’t confer the same health benefits in supplement form. “You can separate any one of the components of seaweed, but it doesn’t work as well as consuming the seaweed whole,” she says. “The whole is more than the sum of its parts.”
McSorley and her team recently completed a study that demonstrated a shift in gut bacteria in mice that ate seaweed. “After feeding obese mice kelp, the composition of their gut microflora changed to a composition that was associated with better health, including a better lipid profile,” McSorley says. Other studies suggest that polysaccharides in seaweed may function as prebiotics — foods that fuel healthy gut bacteria.
Researchers have observed that seaweed may mitigate some biological processes related to metabolic syndrome.
- Insulin resistance. A 2011 Japanese study concluded that the alginic acid in kombu may prevent type 2 diabetes by blocking the absorption of triglycerides — fat molecules that, at high levels in the bloodstream, can indicate insulin resistance. And fucoxanthin, a compound in brown seaweeds, has been found to lower blood glucose and insulin levels.
- Obesity. In laboratory studies on rats, fucoxanthin has also been shown to hinder the accumulation of abdominal fat — a symptom of metabolic syndrome — and inhibit overall weight gain. Scientists in the United Kingdom found that people who consumed alginate, a fiber in brown seaweed, ate fewer calories at subsequent meals. Some participants in a related study published in the journal Nutrition Research registered lower blood-cholesterol and glucose levels while on a diet that included alginate.
5 Seaweeds to Try
Rich in vitamins, minerals, healthy fats, protein, and fiber, seaweed is considered by many to be a superfood. Here are five varieties to look for in your local natural-food store.
Nutrient Power: Wakame is packed with calcium, as well as fucoxanthin, found to improve insulin resistance.
Cook It Up: This seaweed has a deep-green hue, long and wide leaves, a salty–sweet flavor, and a soft texture. It’s great for seaweed salads or tossed with soba noodles. Chef Crystal June Maderia, author of The New Seaweed Cookbook, recommends sautéing wakame with green beans and topping it with tamari and sesame seeds.
Nutrient Power: A variety of kelp, kombu offers a wealth of minerals, including iodine, magnesium, potassium, folate, iron, and calcium. A 1⁄3-cup serving of kelp provides more iron than 31/2 cups of spinach.
Cook It Up: Next time you make a savory soup, broth, or pot of beans, toss in a leaf of kombu — a giant among kelp with a rich, salty taste. Also, look for kombu noodles and other kelp noodles, which have a cooked texture similar to al dente pasta. Toss them with a peanut sauce for a variation on pad thai or try them with your favorite pasta sauce.
Nutrient Power: The ocean flavor of this familiar seaweed is mild.
While it offers little in terms of protein or fat, nori does deliver on vitamins A and C, as well as potassium and magnesium.
Cook It Up: Once harvested, nori is chopped, dried, and formed into thin sheets used for sushi and snacking. Try making your own sushi, or simply wrap nori paper around some sliced avocado, julienned cucumber, and grated carrot; drizzle with tamari and sesame oil. Nori flakes are also great sprinkled onto a salad and tossed with a mild vinaigrette.
Nutrient Power: Researchers have found that arame, rich in potassium, possesses antiobesity and antiviral properties.
Cook It Up: This large sea vegetable is typically cut into long, thin strands for drying. It’s tender in texture and mild in flavor, with a hint of sweetness. Maderia suggests tossing it into a slaw with carrots, cabbage, ginger, and rice-wine vinegar.
Nutrient Power: This pinkish-red seaweed is an excellent source of minerals; a 1⁄3-cup serving of dulse has more potassium than a large banana. It’s also rich in vitamins and antioxidants.
Cook It Up: Eaten raw, dulse has an intense ocean flavor (try it with a rice-wine vinaigrette), though it mellows when it’s cooked. Dulse’s naturally occurring glutamates give it a bacon-like flavor when it’s fried. You can also sauté it with your favorite seasonal vegetables, such as carrots, broccoli, or bok choy.
Seaweed plays a vital role in marine habitats, filtering the oceans by absorbing heavy metals, carbon dioxide, and even radiation. A variety called hijiki is particularly good at sopping up arsenic, and many food-safety agencies around the world advise against consuming more than small amounts of it.
So how can you know you’re getting all of seaweed’s myriad benefits without the risk?
“You want your seaweed to come from a really clean body of water,” says Jane Teas, PhD, of the University of South Carolina’s Cancer Center. To feel confident about the purity of your seaweed, read packaging and websites, or even call seaweed farmers and harvesters and ask where they source their product and whether they test for pollutants. Harvester Cole Meeker says he keeps close track of the state of the water in which his seaweed grows; he even tests for radioactive isotopes.
Teas recommends avoiding seaweed imported from China, since the government does not consistently enforce food-safety regulations.
Photography by Terry Brennan
Food styling by Lara Miklasevics
Sautéed Wakame and Green Beans
Excerpted from The New Seaweed Cookbook, by Crystal June Maderia
Makes two to four servings
Prep time: 30 minutes, including soaking
4 cups dried wakame
1 lb. green beans
4 tbs. cooking oil or fat
1 tsp. wheat-free tamari
2 tbs. prepared sesame seeds
Soak wakame in enough water to cover. When the wakame is soft, remove the water and slice into long, thin strips, discarding the center rib. Trim the green beans and place in a large pot of boiling water for two minutes. Drain and run under cold water until cool to retain crispness and color.
Heat a large cast-iron skillet on medium-high heat. Sauté the green beans for three minutes. Add the cooking oil and wakame. Continue to sauté for three to four minutes. Remove from the heat and toss with the tamari and sesame seeds. Serve hot or cold.
Basic Arame Slaw
Excerpted from The New Seaweed Cookbook, by Crystal June Maderia
Makes four to six servings
Prep time: 40 minutes, including soaking
2 cups dried arame
1 1/2 cups water
1/4 cup mirin
1 cup purple cabbage, shredded
1 tsp. grated gingerroot
1/4 cup flat parsley, minced
1 tbs. lemon juice
1 tbs. prepared sesame seeds
Cayenne to taste
Soak the arame in water for 30 minutes, and then drain. In a large bowl, mix together the remaining ingredients. Add the arame and season with cayenne to taste.