Laminaria (Laminaria digitata) is a type of brown seaweed. It's native to Japan and is used as food in many Asian countries.
Laminaria contains iodine, an element that the body needs to make thyroid hormones. It's also a rich source of iron and potassium. Laminaria forms a thick, sticky gel when combined with water. This allows it to work as a bulk laxative in the gut.
People use laminaria for ending a pregnancy (abortion), childbirth, cancer, and many other conditions, but there is no good scientific evidence to support these uses.
Don't confuse laminaria with other types of seaweed or with chemicals found in seaweed, such as algin and carrageenan. These are not the same.
Is It Effective?
NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
- Ending a pregnancy (abortion). Applying laminaria in the vagina doesn't seem to shorten delivery time or improve the outcome of abortions. It might even worsen outcomes compared to standard care.
- Childbirth. Applying laminaria in the vagina during childbirth doesn't seem to reduce the need for a caesarean section (C-section). It actually seems to increase the risk of an infection in both the parent and infant.
There is interest in using laminaria for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.
Is it Safe?
When taken by mouth: Laminaria is commonly consumed in foods. Iodine-reduced laminaria supplements are possibly safe when used short-term. But laminaria is possibly unsafe when non-iodine reduced supplements are used as medicine. The average laminaria-based supplement might contain as much as 1000 mcg of iodine. Taking in more than 1100 mcg of iodine daily, from all foods and other sources, can cause thyroid issues. Some laminaria products also contain significant amounts of arsenic, which can be toxic.
When applied to the skin: There isn't enough reliable information to know if laminaria is safe. Some people might experience allergic reactions.
Special Precautions & Warnings:
Pregnancy: Laminaria is possibly unsafe when applied in the vagina to ripen the cervix and is likely unsafe when used to induce labor. It can cause serious side effects for both the parent and child, including infection, rupture of the cervix, and infant death. Taking laminaria by mouth as a supplement during pregnancy is unsafe. It can affect hormones. Avoid use.
Breast-feeding: Taking laminaria by mouth as a supplement while breast-feeding is likely unsafe. Laminaria might contain toxic chemicals. Avoid use.
Kidney problems: Laminaria might cause high potassium and iodine levels. Don't take laminaria if you have kidney problems.
Thyroid problems: Laminaria contains large amounts of iodine, which might make thyroid problems worse. Don't take laminaria if you have thyroid problems.
Amiodarone (Cordarone)
Interaction Rating=Moderate Be cautious with this combination.
Amiodarone contains iodine. Laminaria also contains iodine. Taking laminaria along 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.
Digoxin (Lanoxin)
Interaction Rating=Moderate Be cautious with this combination.
Laminaria contains large amounts of potassium. Large amounts of potassium can increase the effects and side effects of digoxin.
Medications for an overactive thyroid (Antithyroid drugs)
Interaction Rating=Moderate Be cautious with this combination.
Laminaria contains iodine. Iodine can increase or decrease thyroid function. Taking laminaria along with medications for an overactive thyroid might change the effects of these medications.
Medications for high blood pressure (ACE inhibitors)
Interaction Rating=Moderate Be cautious with this combination.
Laminaria contains large amounts of potassium. Some medications for high blood pressure can increase potassium levels in the blood. Taking laminaria along with some medications for high blood pressure might cause too much potassium in the blood.
Thyroid hormone
Interaction Rating=Moderate Be cautious with this combination.
The body naturally produces thyroid hormones. Laminaria might increase how much thyroid hormone the body produces. Taking laminaria along with thyroid hormone pills might increase the effects and side effects of thyroid hormones.
Water pills (Potassium-sparing diuretics)
Interaction Rating=Moderate Be cautious with this combination.
Laminaria contains large amounts of potassium. Some "water pills" can also increase potassium levels in the body. Taking some "water pills" along with laminaria might cause too much potassium to be in the body.
Iodine-containing herbs and supplements: Laminaria contains iodine. Taking laminaria 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 and sea moss.
Potassium: Laminaria contains potassium. Using it along with potassium supplements might raise potassium levels too much.
Strontium: Laminaria contains a chemical called alginate. Alginate binds to strontium in the stomach and reduces the amount of strontium that is absorbed by the body. This might lower the amount of strontium that the body gets from strontium supplements.
There are no known interactions with foods.
Laminaria is a type of seaweed that is commonly eaten in Asian countries. As medicine, there isn't enough reliable information to know what an appropriate dose of laminaria might be. Laminaria supplements are often very high in iodine. Speak with a healthcare provider before use.
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