Complex seaweed-derived compounds known as fucoidans support immune function and longevity

A Seaweed’s biochemical solutions that they have crafted to survive the salty, turbulent seas, at times swarming with microorganisms, offer surprising help for some of our own health challenges.²

Seaweeds contain large amounts of uniquely structured long chain sugars, or polysaccharides, with many immune benefits.³ Seaweed polysaccharides come in a variety of arrangements and molecules, varying by seaweed type, and each appears to have its own set of healing properties.⁴

Fucoidans constitute up to 30% of the dry weight of seaweed, an important component of the Okinawan diet – one of the healthiest diets in the world.⁵

Nearly 1,500 peer-reviewed studies have been published on fucoidans, half of those in the last decade alone.⁶Interest in fucoidans surged when scientists began to study the world’s longest living people on the island of Okinawa, some of whom were over a century old.^7,8 The Okinawan diet, which includes more than a dozen varieties of seaweed, is now considered one of the healthiest diets in the world.⁹ A survey of more than 100,000 participants across Japan showed that the consumption of seaweed and several other traditional foods – such as rice and tofu – is correlated with lower all-cause mortality.¹⁰

Fucoidans have been called “a treasure trove of physiologically active polysaccharides,”¹¹ with biological effects including immune modulation,¹² antibacterial and antiviral properties,^13,14 anti-inflammatory activity,¹⁵ modulation of gut flora,¹⁶ and even antithrombotic (anti-clotting) and anticancer properties.^17,18 

Fucoidans enhance immune function and stimulate both innate and adaptive immunity.¹⁹ Specifically, fucoidans modulate two prominent classes of T-cells: Th1 cells, which attack intracellular bacteria and viruses, and Th2 cells, which fight helminths (worms) and other extracellular pathogens.²⁰ Fucoidans also downregulate excessive Th2 responses, which can lead to allergies and inflammation. And they work not only when taken orally, but also topically for skin irritation.²¹

Fucoidans may protect the brain and nervous system from chronic inflammation, particularly supporting specialized cells called microglia.

Fucoidans also increase natural killer cell activity, stimulate immune cells called macrophages, and promote the maturation of specialized immune cells (dendritic cells).^22,23 Some fucoidans also mobilize stem cells and increase their numbers in the blood.²⁴

Finally, fucoidans are potent anti-inflammatory molecules.²⁵ Fucoidans may protect the brain and nervous system from chronic inflammation, particularly supporting specialized cells called microglia.²⁶

Fucoidans as antibacterial agents

Helicobacter pylori (H. pylori) colonizes the stomach of half the world’s humans, and can cause chronic gastritis, peptic ulcer disease, gastric (stomach) cancer, and gastric MALT lymphoma.²⁷Unfortunately, the efficacy of standard triple antibiotic combination therapy has declined in recent years to only 70%, despite the use of these multiple medications simultaneously.^28,29 Growing evidence suggests that fucoidans may boost antibiotic efficacy in resolving H. pylori infection.

Antiviral effects of fucoidans

Just as fucoidan inhibits bacteria from attaching to cells, it can bind to cell surface proteins that viruses use to enter cells, including herpes simplex viruses (HSV), which cause oral and genital herpes. Many herpes strains are now resistant to acyclovir, the most common antiviral drug used to combat infection.³⁰ Therefore, a natural product that could protect against infection or reduce the viral burden would be of great interest.

Fucoidan exhibited “excellent in vitro antiviral activity,” the researchers concluded, and was “significantly more active against clinical strains of HSV-2 than HSV-1.”

Fucoidans also may protect against potentially deadly viruses such as hepatitis C,³¹ which can cause liver cancer, and a retrovirus known as HTLV-I,³² which has been implicated in several diseases including T-cell lymphoma.