Presentation

Laminaria japonica is a brown seaweed from the algae family, traditionally used in Asian cuisine, particularly Japanese.

Known for its exceptional iodine content, it also contains mineral salts (sodium, magnesium, potassium) and trace elements (manganese, selenium, chromium, molybdenum) that are valuable for the functioning of the body.

It is also rich in polysaccharides, fucans, with antioxidant, anti-inflammatory, anticoagulant and anti-tumour properties.

Benefits and virtues

Antioxidant

Fucans have been shown to have antioxidant properties, as have the various flavonoids and phenolic acids found in brown seaweed in general.

These compounds combat free radicals in two well-established ways:

• They stimulate the activity of superoxide dismutase, an enzyme that prevents the radical-induced oxidation chain reaction.
• They stimulate the activity of catalase, an enzyme that prevents the production of these radicals.

Anti-inflammatory

Two compounds from Laminaria are known for their anti-inflammatory properties: pheophorbine and pheophytin.

These two molecules, derived from chlorophyll metabolism, inhibit the action of inflammatory molecules such as prostaglandins, interleukins, cytokines and TNF-alpha.

The strong anti-inflammatory properties are particularly promising in the treatment of certain conditions:

• Inflammatory bowel disease: by reducing inflammation, it helps to restore the intestinal mucosa. It could therefore be indicated for intestinal hyperpermeability and functional colopathies.
• Asthma: a significant reduction in the inflammatory response has been observed in mice.
• Obesity: when fat accumulation is caused by an inflammatory background

Action on the thyroid

Laminaria is rich in iodine, a trace element that stimulates the production of thyroid hormones.

It is therefore of interest for hypothyroidism caused by iodine deficiency.

It can also be taken as an iodine supplement.

Its use is safe: a study on healthy people showed that 15 grams taken over 3 months (i.e. 35 mg of iodine, almost 70 times the recommended intake) did not cause hyperthyroidism.

Diabetes

Laminaria japonica has shown benefits in the fight against diabetes.

It would act directly on insulin:

• By promoting an increase in insulin production and a reduction in the glycaemic peak observed after meals. These benefits would be linked to fucoidan, a polysaccharide found in brown seaweed.
• It inhibits alpha-glucosidase, one of the enzymes responsible for transferring glucose from the intestine to the bloodstream. The inhibition of this enzyme, which makes it possible to limit the glycaemic peak, would be linked to the butyl isobutyl phthalate contained in the rhizoids of Laminaria japonica.

It would also have a positive effect on the excess fat that causes insulin resistance.

Antiviral action

Laminaria japonica polysaccharides have a positive effect on interferons, the body's defence molecules against pathogens: in the treatment of enterovirus pathologies, respiratory infections, H1N1 influenza.

Anticoagulant and antithrombotic

Studies have shown that oral supplementation with Laminaria japonica has anticoagulant and antithrombotic effects in rats.

The mode of action may involve the proteins responsible for blood clotting.

Overweight and obesity

The properties of Laminaria japonica do not stop there.

In addition to its anti-inflammatory properties, kombu has weight loss effects.

A study of 22 Korean women showed significant weight loss with Laminaria japonica consumption.

However, in this study, kombu consumption was accompanied by dietary advice and, in particular, physical activity.

The fucoxanthin would activate the membrane proteins responsible for burning abdominal fat more efficiently.

The slimming effects of brown seaweed have also been successfully studied in rats.

Kombu is also rich in fibre, which promotes slow and smooth digestion, with a role in appetite and weight.

Elimination of toxins

Laminaria japonica is rich in alginates: soluble fibres with the ability to bind heavy metals (lead, mercury, arsenic, etc.) and eliminate them in the faeces.

The different forms

Laminaria japonica contains an average of 2359 µg of iodine per gram.

This often exceeds the daily iodine limit of 600 µg set by European authorities.

Dried or fresh kombu can be found in bulk in some health food stores or on the internet.

To comply with health recommendations, you should not consume more than 500 mg.

It is very rare to find it in food supplements. In fact, there is only an extract titrated to 0.1% iodine and 10% polysaccharides.

Dosage and use

There is no official dosage for Laminaria japonica in terms of dietary intake or supplementation.

A dose of 500 mg allows you to stay below the iodine limit set by the authorities.

If therapeutically justified, it is possible to go up to 1 gram per day without risk if you have a healthy thyroid.

In fact, it adapts easily to variations in iodine intake.

Contraindications

The precautions to be taken with kombu are related to its high iodine content.

ANSES reminds us that it is advisable not to exceed 600 micrograms of iodine per day for an adult.

It advises against the consumption of seaweed by people suffering from thyroid disease, heart disease or renal failure, as well as pregnant and breastfeeding women.

Interactions with other medicines

Laminaria japonica is not recommended for people taking iodine, lithium or anticoagulants.

Side effects

No side effects are known. In people with hyperthyroidism, symptoms may worsen.

Side effects such as diarrhoea and headaches may be observed with iodine intake above 2,000 µg/d in the medium term.