Background

Ascophyllum nodosum is a type of brown seaweed. It is found along the shorelines in cold areas of the world, such as Northern Canada and Iceland.

Ascophyllum nodosum is now protected in many countries because of over-harvesting for a chemical called alginate. It also contains nutrients such as carbohydrates, iodine, and fatty acids such as oleic acid.

People use Ascophyllum nodosum for tooth plaque, gum disease, iodine deficiency, weight loss, and many other conditions, but there is no good scientific evidence to support these uses.

Don't confuse Ascophyllum nodosum with other types of seaweed, such as blue-green algae, dulse, Ecklonia cava, Fucus vesiculosus, laminaria, or sea moss. These are not the same.

Safety Safety definitions

When taken by mouth: Ascophyllum nodosum is possibly safe when used for up to 6 months. It's usually well-tolerated. But seaweeds such as Ascophyllum nodosum can accumulate high levels of heavy metals such as arsenic. Purchasing a product that is certified as being free of heavy metals can reduce the risk of heavy metal exposure.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There isn't enough reliable information to know if Ascophyllum nodosum is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Thyroid disorders: Ascophyllum nodosum contains iodine. Long-term use or high doses of iodine might make certain thyroid disorders worse. Also, people with autoimmune thyroid disease might be especially sensitive to the harmful effects of iodine.

Effectiveness

Dosing & administration

Ascophyllum nodosum has most often been used by adults as a dried powder at doses of 500 mg by mouth daily for up to 6 months. Speak with a healthcare provider to find out what dose might be best for a specific condition.

Interactions with pharmaceuticals

Amiodarone (Cordarone)

Interaction Rating=Moderate Be cautious with this combination.

Ascophyllum nodosum and amiodarone both contain iodine. Taking Ascophyllum nodosum with amiodarone might increase the levels of iodine in the blood. Too much iodine in the blood can cause side effects that affect the thyroid.

Medications for an overactive thyroid (antithyroid drugs)

Interaction Rating=Moderate Be cautious with this combination.

Ascophyllum nodosum contains iodine. Iodine can increase or decrease thyroid function. Taking Ascophyllum nodosum along with medications for an overactive thyroid might change the effects of these medications.

Thyroid hormone

Interaction Rating=Moderate Be cautious with this combination.

Ascophyllum nodosum contains iodine. Iodine can increase or decrease thyroid function. Taking Ascophyllum nodosum along with thyroid hormone medications might increase the effects of these medications.

Interactions with herbs & supplements

Iodine-containing herbs and supplements: Ascophyllum nodosum contains iodine. Taking Ascophyllum nodosum with other products that contain iodine might cause iodine levels to go too high. This can cause side effects, such as changes in thyroid function. Examples of supplements that contain iodine include seaweed products, such as dulse, laminaria, and sea moss.

Interactions with foods

There are no known interactions with foods.