Edible seaweeds, also referred to as sea plants or sea vegetables, naturally grow in the ocean and are highly mineral-rich foods. In fact, the mineral content of seaweed outperforms terrestrial, or land-grown, plants by up to 20 times the amount by weight. Importantly, these rich nutrients are those that are commonly under-consumed in the diets of Americans (Dietary Guidelines Advisory Committee, 2015; Brown et al., 2014; Pitchford, 2002).
While different species of sea vegetables have some nutrient variability, all varieties of seaweed are rich sources of essential macrominerals, such as calcium, sodium, magnesium and potassium, and trace elements, including iodine, iron, zinc and fluorine (Pitchford, 2002; Ruperez, 2002). Additionally, sea vegetables are rich in dietary fiber in the form of soluble and insoluble polysaccharides, which support overall digestive health and the gastrointestinal microbiome (Ruperez, 2002). Some population-based evidence from evaluation long-term dietary patterns in Asian cultures, has also revealed possible protective benefits for cardiovascular disease, cancer, diabetes and osteoporosis with regular consumption of edible seaweed (Brown, 2014). Taken together, even in relatively small, condiment-size amounts, seaweeds can be an excellent addition to a healthy diet.
The Whole is Greater Than its Parts
Isolated nutrient components of seaweeds are surging to the forefront for food and supplement companies interested in developing functional foods, which are foods that confer a health benefit to the consumer, and nutraceuticals, which are foods containing medicinal-like benefits (Holdt, 2011).
As with many foods, the processed components may be problematic. Extracts from sea vegetables, such as carrageenan, are now used as food additives. The most common function of carrageenan in the food supply is to act as a stabilizer in non-dairy milk alternatives, which has shown negative health-effects in animal studies (Tobacman, 2001). While consuming approved food additives in small amounts is generally recognized as safe by the Food and Drug Administration (FDA), eating sea vegetables in their whole form has a long-standing history of safety and continues to be recommended as a part of a balanced, healthy diet.
Cooking With Sea Vegetables
Traditional pairing of fermented or cultured soy products with sea vegetables relied on cultural wisdom and likely flavor. Today, scientific evidence supports the partnering of soy foods with sea vegetables that are rich in minerals to create an optimal, mineral balance (Lair, 2008). Furthermore, culinary uses of sea vegetables are now expanding beyond sushi and soy foods due to their ability to add flavor, color, texture and nutrients to a wide range of foods.
The most commonly available edible seaweeds for use in cooking include nori, wakame, kombu, dulse, arame, hijiki and agar-agar. At its most basic level, classification of seaweeds is done by color and varies between browns, reds, greens, blue-greens and yellow-greens (Pitchford, 2002).
Seaweeds are readily available for purchase in their dried from, typically in the ethnic or macrobiotic section of most natural grocery stores. A variety of other dried options can be found online, possibly at local co-ops, and in most Asian markets. These foods can be stored indefinitely in a sealed container kept in a cool, dry, dark place (Lair, 2008).
For culinary uses, most seaweed species can simply be reconstituted by soaking for a short period of time in water. The only exception is nori, which can be used in the dried state. Although arsenic is commonly found in marine foods, the most popular edible seaweeds have not been found to contain meaningfully concerning amounts. Additionally, the process of soaking seaweeds has been shown to significantly reduce possible arsenic content, and therefore not a significant health concern (Mania et al., 2015).
Three Easy Ideas for Adding Seaweed to Dishes
- Add a small amount reconstituted dulse to broth-based soups right before serving, just as you would add spinach or other leafy-green vegetables.
- Mix reconstituted wakame or arame with whole grains, noodle or mixed vegetable dishes.
- Add a 1-inch piece of dried wakame or kombu to stocks and dried-bean recipes to help break down tough plant fibers and increase digestibility. Discard seaweed before consuming beans or stock.
Three Easy Seaweed Recipes
Preheat oven to 350°F. Slice or cut sheets of nori into strips and place in a single-layer on a baking sheet. Brush with olive or sesame oil and season with sea salt. Roast in the oven for 15 minutes and eat like a chips.
Add 4 cups of plain fruit juice to a saucepan over medium heat. Add 4 tablespoons of agar-agar flakes and simmer until flakes dissolve (avoid stirring as agar-agar can be sticky). Add in 2 cups of fruit of choice and pour mixture into molds, trays or cup of choice. Refrigerate for at least 1 hour before eating.
Rinse and soak 2 ounces of hijiki or arame seaweed in 1 cup of water for 10-20 minutes. Meanwhile, heat sesame oil in a large pan (use one that has a lid) and sauté thinly sliced yellow onions, uncovered for about 2 minutes. Add 2 tablespoons mirin and reconstituted seaweed with about ½ cup of soaking water and 1 shredded carrot. Simmer for 20 minutes, covered, and then toss with tamari and cooked edamame beans. Garnish with pumpkin seeds to serve.
Brown, E.M. et al. (2014). Seaweed and human health. Nutrition Reviews, 72, 3, 205–216.
Dietary Guidelines Advisory Committee (2015). Dietary Guidelines for Americans Part D. Chapter 1: Food and nutrient intakes, and health: Current status and trends—Nutrient intake and nutrients of concern.
Holdt, S.L. and Kraan, S. (2011). Bioactive compounds in seaweed: Functional food applications and legislation. Journal of Applied Phycology, 23, 543-597.
Lair, C. (2008). Feeding the Whole Family, 3rd ed. Seattle, Wash.: Sasquatch Books.
Mania, M. et al. (2015). Total and inorganic arsenic in fish, seafood and seaweeds—exposure assessment. Annals of the National Institute of Hygiene [Poland], 66, 3, 203-210.
Pitchford, P. (2002). Healing With Whole Food, 3rd ed. Berkely, Calif.: North Atlantic Books.
Ruperez, P. (2002). Mineral content of edible marine seaweeds. Food Chemistry, 79, 23-26.
Tobacman, J.K. (2001). Review of harmful gastrointestinal effects of carrageenan in animal experiments. Environmental Health Perspectives, 109, 983–994.