Is Eating Seaweed Safe?

Eating fresh seaweed is considered to be safe for most people.

That said, consuming it regularly or in high amounts may cause some side effects.

It May Contain High Levels of Heavy Metals

Depending on where they’re grown, some varieties of seaweed can contain high levels of mercury, cadmium, lead and arsenic.

The US Food and Drug Administration (FDA) regulates the levels of these chemicals and heavy metals in fresh seaweed. However, supplements are not regulated and may contain levels that are detrimental to health.

A High Intake May Interfere With Kidney Function and Blood Thinners

Certain varieties of seaweed may contain high levels of sodium and potassium, which can be harmful to individuals suffering from kidney disease.

Seaweed also contains vitamin K, which may interfere with blood-thinning medications. Those taking blood thinners should make sure to check with a doctor before making it a regular part of their diet.

Some Are Very High in Iodine and May Interfere With Thyroid Function

While iodine is necessary for proper thyroid function, getting too much iodine can be harmful.

Kelp, dulse and kombu are types of seaweed with the tendency to contain very high levels of iodine. For instance, 25 grams of fresh kombu can contain close to 22 times more iodine than the safe daily limit.

Therefore, these varieties should not be consumed too often, nor in large quantities.