What is Seaweed?

Seaweeds - marine macroalgae - are packed with beneficial nutrients, from minerals to fiber to unique polysaccharides that aren’t found in land plants or in sea animals. Humans, plants, and other animals can benefit from the nutritional abundance that seaweeds offer.


Seaweeds live and grow awash in the mineral richness of the ocean, and they are especially good at extracting and in some cases, accumulating, the ocean’s dissolved minerals and trace elements. This includes a wide range of minerals such as calcium, magnesium, and potassium, and trace elements (micronutrients) such as chromium, vanadium, and boron.

According to some sources, seaweeds provide all of the dozens of minerals and trace elements needed for human health. The minerals in seaweeds also tend to be in chelated or colloidal forms that are easier to absorb and assimilate.




Iodine is one of the minerals that is abundant in the ocean, and is accumulated to varying degrees by seaweeds. Some kelps, for example, can concentrate iodine up to 100,000 times that of surrounding seawater. Iodine is crucial for human health, and not found in substantial amounts in many foods. Iodine is essential for thyroid functioning, and also for the health of many other parts and systems of our bodies—from breasts to skin. Many sources recognize that seaweeds are one of the best food sources of iodine on the planet.

The salty taste of seaweed comes not just from sodium but a range of other mineral “salts,” particularly potassium. Intake of higher amounts of potassium than of sodium is recommended for good health, but modern diets, heavy in processed rather than fresh or whole foods, tend to be heavy on sodium and light on potassium. Seaweeds generally contain more potassium than sodium, and in some cases have comparable potassium levels to foods such as bananas that are recognized as good potassium sources.

Seaweeds also provide vitamins (A, Bs, C, E, K, possibly D), essential fatty acids such as omega-3s, and high-quality proteins, in many cases with all or most of the essential amino acids. In fact, the amino acid glutamate might sound familiar. It is the natural form that synthesized monosodium glutamate (MSG) was created to mimic, and helps to impart the “umami” taste of seaweed—also called the “fifth taste,” and similar but so much more complex than “savory.”


Seaweeds may be a rare non-animal source of Vitamin B12, though it isn’t yet clear if the B12 they contain is true B12 or an “analogue” form that looks like B12 but doesn’t act the same or have the same benefits. One view is that the B12 in seaweeds actually comes from microbes associated with the seaweed.