In elementary school, I remember being interrupted one day by a friend shouting “there’s seaweed in your milk!” as I happily sipped on my chocolatey drink. At the time, I dismissed the idea, thinking that my friend had been tricked into believing some silly story. There couldn’t possibly be seaweed in my chocolate milk–the idea was absurd! Decades later, I realized that not only was my childhood friend right about seaweed products in chocolate milk, but that the role of seaweed in our food system goes far beyond just this one tasty drink.

The popularity of seaweed farming has been on the rise in recent years, and mariculture enthusiasts are clamoring for permits to farm within U.S. state waters. With emerging studies suggesting that seaweed has the ability to promote healthy digestion, aid weight loss, and even stave off cancer, it’s no wonder that people are intrigued. Health brands offer seaweed in their skincare, supplements, and recipes, making an understated alga into the luxury “it” additive. While seaweed is enjoying its moment in the sun (pun intended), it’s been a production staple for centuries. 

The use of seaweed in the food system can be traced back thousands of years. In Ancient Roman times, farmers harvested seaweed and used it as mulch for their fields, especially when planting new seedlings. Similarly, evidence dating back to the Neolithic era in Ireland shows seaweed being collected and then burned before the ash was spread across farmlands (Pereira, 2019). The nitrogenous and phosphoric compounds found in seaweed are an impressive natural fertilizer, and archaeological evidence shows that these nutrients have been used to power food production for millennia. 

Today, seaweed-derived fertilizers are widely available on the open market and their benefits to crop yield have been widely tested. A 2006 study conducted in India highlighted these benefits by assessing how different concentrations of seaweed fertilizer impacted soybean plant growth and yield. The researchers found that the plants that received the highest concentration of seaweed fertilizer yielded the largest crops, with treated plants producing over 57% more soybeans than the control group. Seaweed-derived fertilizers show promise as an alternative to traditional fertilizers as our food systems transitions away from chemical additives. 

While seaweed has been used as a soil supplement and fertilizer for years, scientific advancements are allowing it to play a novel role in mitigating the methane emissions from livestock production. Agriculture is one of the largest single contributors to methane emissions, with global estimates suggesting that over 145 million tons of methane are emitted by agricultural production annually. This emissions estimate is daunting, but feed that includes red algae derivatives have been found to reduce these emissions in feedlot and dairy cows by up to 80% (Roque, 2021). There are still debates as to whether the impacts of growing, processing, and transporting the amount of seaweed needed cancels out the positive benefits of seaweed’s methane-reducing powers, but it is still an interesting area of exploration. While focusing on cow burps to reduce climate change-causing emissions may seem silly, studies suggest that feeding cows seaweed could be a piece of the climate puzzle.

While seaweed has been used in food throughout history, recent studies have brought up some concerns about its effects. Carrageenan, a food additive derived from red seaweed, has had its share of controversy. This algal compound can be found in everything from meat products to the beloved chocolate milk of my childhood. Its ability to thicken and bind food has made it a popular part of the food system for decades, yet recent health concerns have chipped away at its popularity. In Europe, it has even been banned from infant formula over concerns that it leads to intestinal inflammation and other health problems.

Whether or not the popularity of carrageenan is in decline, algae are far from uncommon in our food. Agar–an ingredient likely familiar to many, from bakers to vegans–is a frequent silent star of our food. The darling of Michelin chefs across the world, agar’s ability to turn any food into a boba-like sphere of flavor makes it exciting. Like carrageenan, it is derived from seaweed and can be used as a thickener. Unlike its controversial cousin, agar is being celebrated as a heart-healthy and low-calorie option. 

Other algae derivatives are more easily recognizable in our pantries. Seaweed snacks are widely available, with major brands developing seaweed puffs, crackers, or the tried and true seaweed paper. Many recipes will even call for seaweed flakes or roasted seaweed to add umami flavor to a dish. For many, the most immediately identifiable form of edible seaweed is found in sushi restaurants–rolls are often wrapped in a seaweed paper, and seaweed salad is frequently offered up as a side. Whatever your diet, there’s a good chance that seaweed is present somewhere in it.

We don’t often think of seaweed as a part of our daily diets, yet it plays a role in every step of food production. Seaweed is involved in enriching soil to grow crops, managing our livestock emissions, creating stability in food products, and is an ingredient in many of our foods. The role that seaweeds play in every step of our food production demonstrates what a powerful force it is in our food system. So next time you’re enjoying sushi, a steak, a salad, or some delicious chocolate milk, give a little thank you to the silent heroes of our food cycle: algae. 

Author’s Note:

I believe information should be as accessible as possible. I personally strive to cite as much open source material as possible in my work. Unfortunately, some information discussed in this article is behind paywalls. In an attempt to make the sources cited in this article accessible, a copy of the sources will be provided upon request. I encourage you to reach out.

Contact Currents’ Editor-in-chief for access to the following publications cited in this piece:

Pereira, L. (2019, October). Historical Use of Seaweed as an Agricultural Fertilizer in the European Atlantic Area. ResearchGate. Retrieved November 11, 2022, from https://www.researchgate.net/publication/336878973_Historical_Use_of_Seaweed_as_an_Agricultural_Fertilizer_in_the_European_Atlantic_Area

Roque BM, Venegas M, Kinley RD, de Nys R, Duarte TL, Yang X, Kebreab E. Red seaweed (Asparagopsis taxiformis) supplementation reduces enteric methane by over 80 percent in beef steers. PLoS One. 2021 Mar 17;16(3):e0247820. doi: 10.1371/journal.pone.0247820. PMID: 33730064; PMCID: PMC7968649.