Rather than an exotic alpine berry or leafy garden green, the next superfood could come from the ocean – where millions of tons of it grow wild. Kelp, a seaweed that grows in cool, shallow waters, has exploded in popularity in recent years as a food that’s delicious, healthy, and surprisingly Earth-friendly.
In Japan, along with enjoying seaweeds such as nori and hijiki, roughly a fifth of the population eats one of the dozens of varieties of kelp every day (Zava and Zava, 2011). The two most popular edible kelp types are known to the Japanese – and, increasingly, to Americans – as kombu and wakame.
Some researchers say seaweed in general, and kelp in particular, are an important part of the reason people live so long in Japan (Johnson, 2011). Kelp is packed with vital nutrients and minerals, especially iodine, which is key for a healthy thyroid.
And in recent years, adventurous eaters in the West have started to embrace edible kelp. Many home cooks and chefs now prize the versatile sea vegetable (a term many prefer to the disparaging “seaweed”) for its savory, umami-rich taste, and use it in everything from kelp salads and salsas to stews, lasagne, and even pasta sauce.
What’s more, The New York Times recently called it “the climate-friendly vegetable you ought to eat.” It’s not just hype: Kelp can grow more than a foot a day while sucking greenhouse gases out of the ocean, de-acidifying the water (NOAA, 2019). Kelp forests also have some of the greatest marine biodiversity on the planet.
That’s a staggering spread of benefits for such a humble plant.
Health Benefits of Kelp
Evolutionarily speaking, kelp is more primitive than many kinds of seaweed. It is actually a kind of algae, which means it is a direct ancestor of some of the world’s oldest single-celled organisms.
It grows in dense kelp forests in places where the ocean is shallow, cold, and nutrient-rich. Thousands of fish, mammals, and invertebrates call kelp forests home, and many other microorganisms live on their leaves (NOAA, 2019). It’s a far different growing environment from other vegetables we typically eat, but the conditions are ideal for cultivating a plant that’s rich in nutrients our bodies need.
For years now, studies have pointed out that the leafy sea greens are heart-healthy, and a great source of important vitamins, minerals, and antioxidants. Beyond providing abundant iodine, seaweed is also rich in calcium, iron, magnesium, and vitamins A and K (Yu et al., 2017). Additionally, it’s a good source of fiber, and low in carbohydrates, fat, and sugar. The nutrient-dense food is also low in calories and can curb food cravings.
That burst of nutrition endows kelp with a number of health benefits, like blocking fat from forming. In studies looking at kelp’s potential to help with weight loss, scientists have shown that a compound found in the cells wall of algae, called alginate, actually hinders the absorption of fat cells in the gut (Wilcox et al., 2014). Studies of kelp also show that the plants might help keep diabetes in check (Kim et al., 2008).
It even contains a compound called fucoidan that is known to reduce inflammation and help fight the growth of cancer cells (Atashrazm et al., 2015). A study of how different types of seaweed may combat cancer showed the fucoidan in kelp can reduce the risk of colorectal and breast cancers, which commonly kill both women and men (Moussavou et al., 2014).
Kelp is also rich in a compound called astaxanthin. It’s a pigment found commonly in algae and seafood, and it’s what gives wild-caught salmon its signature pink color. Studies of astaxanthin have shown that the antioxidant improves blood circulation and fights free radicals, which are unstable atoms that can damage cells and intensify aging (Kidd 2011) (Naguib 2000).
However, if you are considering adding kelp to your diet, it’s important to remember that you can have too much of a good thing. Specifically, too much iodine can be bad for you. The Food and Drug Administration recommends that adults get 150 micrograms of iodine per day, and the amount of iodine in different types of seaweed can vary significantly (NIH, 2020). That means it’s important to check the nutrition labels. And if you’re not getting your kelp from a trusted source (as with any natural supplement), it could have harmful levels of metals and other contaminants from growing and processing the plant.
Kelp Helps Fight Climate Change
It’s not just humans whose health benefits from kelp. There’s good reason to think growing more kelp would be healthier for the planet, too.
The United Nations projects that the world’s population will surge toward 10 billion people by 2050 (UN, 2019). That will leave humans looking for ways to grow more food on the same amount of land without increasing pollution or making global warming any worse.
Kelp can help with all those problems (Hoegh-Guldberg et al., 2018). Kelp doesn’t need additional land or polluting fertilizers to grow. It can be planted (it grows from tiny spores impregnated in twine or other media) and harvested just offshore by fishermen who already live and work in the area, using little more than their existing ropes and boats. In many places, fishermen already harvest it in the off-season, adding supplemental revenue to an industry that in some areas has been hard hit by industrial overfishing.
Meanwhile, scientists are also starting to reach another startling conclusion. There’s already so much carbon dioxide in the air, we’ll need to do more than simply stop the emission of greenhouse gases. To avoid the worst impacts of climate change, we’ll actually have to start pulling CO2 out of the atmosphere (IPCC, 2018).
As it grows, kelp pulls carbon dioxide, phosphorus, and nitrogen out of the water, cleaning the ocean, and stripping it of greenhouse gasses (Duarte et al., 2017).
A healthy kelp forest also creates a cleaner ocean environment for the sea creatures that call it home. So, by planting kelp as a crop, kelp farmers are providing habitat for fish and reducing the acid in the water, which also helps shellfish form their shells and corals to grow.
Cooking With Kelp
And while scientists may be reaching a consensus on the health and climate benefits of eating sea vegetables, the key to making kelp more popular will be actually convincing people from cultures that don’t commonly eat the plant to give it a try. Typically, when most people think of eating kelp, they imagine the neon green wakame-kelp salads you’ll find in Japanese and Asian restaurants. These salads are often delicious, but can also be slimy and high in salt and sugar.
That’s because this kind of kelp has traditionally been imported from overseas, where it gets packed with preservatives and sweeteners like high-fructose corn syrup. It doesn’t have to be that way. A new movement has taken hold in the United States, with fishermen leading the charge to cultivate and harvest high-quality sea vegetables that can hold up to even the discerning palates of high-end chefs. This kind of kelp looks nothing like what most people are used to. For starters, it’s not neon green.
For example, the Wakame Seaweed Salad, with a subtle green similar to that of string beans, bursts with savory, zesty and vibrant flavors. It’s just slightly salty-sweet, and it goes great with other seafood. Or, for the adventurous, you can try adding kelp to your own cooking with frozen Sea Kelp Cubes, which are rope-line harvested by our partners at Atlantic Sea Farms during Maine’s lobster off-season. You can try your hand at dozens of recipes found on their website, from kelp pesto to kelp carrot cake.
Zava, Theodore T, and David T Zava. “Assessment of Japanese iodine intake based on seaweed consumption in Japan: A literature-based analysis.” Thyroid research vol. 4 14. 5 Oct. 2011, doi:10.1186/1756-6614-4-14
Johnson, Tiesha. “The Little-Known Longevity Factor in the Japanese Diet.” Life Extension Magazine. May 2011.
National Oceanic and Atmospheric Administration (NOAA). Ocean Facts. What is a kelp forest? National Ocean Service website, https://oceanservice.noaa.gov/facts/kelp.html, 11/14/19.
Yu, L.L., Browning, J.F., Burdette, C.Q. et al. Development of a kelp powder (Thallus laminariae) Standard Reference Material. Anal Bioanal Chem 410, 1265–1278 (2018). https://doi.org/10.1007/s00216-017-0766-z
Matthew D. Wilcox, Iain A. Brownlee, J. Craig Richardson, Peter W. Dettmar, Jeffrey P. Pearson, The modulation of pancreatic lipase activity by alginates, Food Chemistry, Volume 146, 2014, Pages 479-484, ISSN 0308-8146, https://doi.org/10.1016/j.foodchem.2013.09.075.
Kim MS, Kim JY, Choi WH, Lee SS. Effects of seaweed supplementation on blood glucose concentration, lipid profile, and antioxidant enzyme activities in patients with type 2 diabetes mellitus. Nutr Res Pract. 2008;2(2):62-67. doi:10.4162/nrp.2008.2.2.62
Atashrazm F, Lowenthal RM, Woods GM, Holloway AF, Dickinson JL. Fucoidan and cancer: a multifunctional molecule with anti-tumor potential. Mar Drugs. 2015;13(4):2327-2346. Published 2015 Apr 14. doi:10.3390/md13042327
Moussavou, G.; Kwak, D.H.; Obiang-Obonou, B.W.; Maranguy, C.A.O.; Dinzouna-Boutamba, S.-D.; Lee, D.H.; Pissibanganga, O.G.M.; Ko, K.; Seo, J.I.; Choo, Y.K. Anticancer Effects of Different Seaweeds on Human Colon and Breast Cancers. Mar. Drugs 2014, 12, 4898-4911.
Kidd P. Astaxanthin, cell membrane nutrient with diverse clinical benefits and anti-aging potential. Altern Med Rev. 2011 Dec;16(4):355-64. PMID: 22214255
Naguib YM. Antioxidant activities of astaxanthin and related carotenoids. J Agric Food Chem. 2000 Apr;48(4):1150-4. doi: 10.1021/jf991106k. PMID: 10775364.
National Institutes of Health - Office of Dietary Supplements. Iodine. Fact Sheet For Health Professionals. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/, 9/16/20.
United Nations Department of Economic and Social Affairs. “Growing at a slower pace, world population is expected to reach 9.7 billion in 2050 and could peak at nearly 11 billion around 2100.” https://www.un.org/development/desa/en/news/population/world-population-prospects-2019.html, 6/17/19.
IPCC, 2018: Summary for Policymakers. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. In Press.
Hoegh-Guldberg. O., et al. 2019. ‘‘The Ocean as a Solution to Climate Change: Five Opportunities for Action.’’ Report. Washington, DC: World Resources Institute. Available online at http://www.oceanpanel.org/climate
Duarte Carlos M., Wu Jiaping, Xiao Xi, Bruhn Annette, Krause-Jensen Dorte. Can Seaweed Farming Play a Role in Climate Change Mitigation and Adaptation? Frontiers in Marine Science. Volume 4. 2017. Page 100. https://www.frontiersin.org/article/10.3389/fmars.2017.00100