Guest post by Johanna Mirenda, Technical Director at Organic Materials Review Institute. If you have questions pertaining to this article, please contact the author.

Seaweed is a general term for a broad range of marine plants and macroscopic algae, of which there are over 20,000 species worldwide. Seaweeds are distinct from terrestrial plants, not just because they grow underwater, but also because they lack true roots. Instead of being rooted in soil, seaweeds are free-floating or attached to hard surfaces. Seaweeds are multicellular, making them distinct from microscopic single-celled algae.

Commercially, seaweeds can be wild harvested or intentionally cultivated or farmed. Seaweeds themselves can be certified organic either as crops or as wild crops¹, or they can be used as input materials in an organic system of production and processing. They are taxonomically classified into three broad groups based on pigmentation: Phaeophyceae (brown seaweeds), Rhodophyceae (red seaweeds), and Chlorophyceae (green seaweeds).

Permitted uses in organic production and processing

Crop Production

Seaweed extracts are widely used in crop production for a variety of benefits. Naturally occurring proteins, lipids, sugars, amino acids, nutrients, vitamins, plant hormones, and other biochemicals present in the seaweeds can provide fertility and soil conditioning functions. As fertilizers, seaweeds can provide a natural form of potash (soluble potassium).

Nonsynthetic forms of seaweeds products (such as liquids, soluble powders, and meals) are permitted in organic crop production. Extraction or other processing is allowed using water, heat, pressure, or nonsynthetic materials.

Commercial seaweed and other aquatic plant extracts may be prepared using synthetic alkali extraction. The National Organic Program (NOP) regulations at §205.601(j) allow for synthetic extracts of aquatic plants for use as fertilizers, provided that the extraction process uses only potassium hydroxide or sodium hydroxide in the amount necessary for extraction. This restriction is intended to prevent alkali substances from contributing to nutrient fortification in the resulting seaweed extract. OMRI does not consider products to be fortified as long as they have at least 2.5 times as much aquatic plant material as synthetic extractant. Potassium carbonate, a common extractant, is prohibited as an extractant.

Livestock Production

In livestock production, seaweed products are commonly added to feed to provide natural minerals and trace elements. When used in livestock feed, seaweeds including kelp must be certified organic. The NOP considers kelp to be an agricultural substance (see NOP Guidance 5027), and all agricultural ingredients in livestock feed must be organic in accordance with §205.237. OMRI interprets this to mean that any seaweeds, not just those specifically identified as “kelp,” must be organic when used in livestock feed.

Processing and Handling

Nonorganic ingredients and processing aids used in products labeled as “organic” must be specified on the National List; there are eight listings on the National List that pertain to seaweeds and seaweed derivatives that may be used in organic processing and handling.

Alginates and alginic acids, both sourced from the cell walls of brown seaweeds, are permitted. Alginic acid occurs naturally in brown seaweeds. It is isolated through a series of extractions and is permitted as a nonsynthetic substance at §205.605(a). During the extraction process, salts of alginic acid are temporary formed and, if isolated, are permitted as synthetic substances under the listing of alginates at §205.605(b).

Agar-agar, sourced from red seaweed, is permitted at §205.605(a) for use in organic food processing, primarily as a gelling agent. Carrageenan is also sourced from red seaweed and permitted at §205.605(a), although the National Organic Standards Board (NOSB) recommended removing it from the National List because of available alternatives and concerns about compatibility with organic production and processing. Carrageenan is a derivative of red seaweed through a series of extraction and isolation methods. It is used as a stabilizer and texturizer in a wide range of foods.

Agricultural substances including kelp, Pacific kombu seaweed, and wakame seaweed are listed at §205.606. They may be used in organic foods, and organic forms are required when they are commercially available. These materials are derived from brown seaweeds, although the listing for “kelp” is nonspecific in its taxonomic limitations. Beta-carotene derived from algae is permitted at §205.606 as a color, provided that organic forms are not commercially available. It is typically sourced from green algae species.

NOSB activity to address nomenclature and sustainability concerns

The NOSB has identified a need to improve the consistency and clarity of the taxonomic nomenclature used across the nine individual listings of aquatic plant materials and their derivatives on the National List. In fall 2016, the NOSB Handling Subcommittee published a discussion document² to bring attention to this issue and solicit public comments. At the spring 2017 meeting, the subcommittee presented a recommendation³ to amend these listings and clarify the taxonomic identities of each listing. However, public comment indicated that additional consideration was needed, so the recommendation was sent back to subcommittee for further deliberation. The previously published discussion document and recommendation will be considered again at the upcoming NOSB meeting, which occurs on October 31 – November 2, 2017 in Jacksonville, FL. More information on the NOSB meeting is available here:

Concerns about impacts of seaweed harvesting on the environment are also being considered by the NOSB. There are potentially serious conservation issues for some types of algae species in some areas, resulting from overharvesting of wild species and/or destructive harvest methods. The NOSB Crops Subcommittee is considering options for ensuring that harvesting of seaweed for use in input materials does not negatively impact the environment. A recommendation or discussion document may be presented at a future meeting.

¹ Certifying agents will consider whether certification as a crop or wild crop is more. More information on wild crop harvesting is available in the NOP Guidance on Wild Crop Harvesting:

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