Sea moss has become extremely popular over the past few years, as celebrities and influencers have claimed the supplement cleared their acne, reduced their anxiety, and boosted their energy levels. 

According to Catherine Gervacio, RND, a consultant for WOWMD, sea moss is considered a superfood because it’s packed with nutrients and antioxidants. “It also has iron for red blood cell production and energy levels, magnesium for muscle function, nerve signaling, and cardiovascular health, calcium for bones and teeth, and omega-3 fatty acids for cardiovascular health,” she says.

 Here’s what to know about the risks and benefits of sea moss supplementation:

How sea moss impacts thyroid function

One of the main benefits people are talking about is the plant’s impact on thyroid function. Sea moss is a great source of iodine—a trace element that the thyroid gland uses to produce hormones that help regulate metabolic function, according to the National Institutes of Health (NIH).

Smyth PPA. Iodine, seaweed, and the thyroid. European Thyroid Journal. 2021;10(2):101-108.

Without iodine, the thyroid gland would not function optimally.

ATA statement on the potential risks of excess iodine ingestion and exposure. American Thyroid Association.

It’s worth noting that the claims linking sea moss to improved thyroid function are based on studies evaluating iodine—not sea moss, says Chris Mohr, PhD, RD, a fitness and nutrition advisor for Fortune Recommends. “There isn't direct evidence linking sea moss to improved thyroid function,” Dr. Mohr said. 

The Food and Nutrition Board of the Institute of Medicine of the National Academies recommends that adults consume 150 micrograms (μg) of iodine each day.

Darias-Rosales J, Rubio C, Gutiérrez ÁJ, Paz S, Hardisson A. Risk assessment of iodine intake from the consumption of red seaweeds (Palmaria palmata and Chondrus crispus). Environ Sci Pollut Res. 2020;27(36):45737-45741.

The maximum tolerable daily intake, or the amount of iodine an adult could safely consume in one day, is 1,100 μg. 

But what happens if you have more than this? Research suggests too much iodine could lead to thyroids function and trigger health conditions like hyperthyroidism or hypothyroidism.

Smyth PPA. Iodine, seaweed, and the thyroid. European Thyroid Journal. 2021;10(2):101-108.

“While iodine is very important, more is not always better,” says Gervacio. Kayleigh Harrison, ND, LMT, an associate staff physician at Sonoran University, says that high levels of sea moss may cause antibody production in the thyroid, which can disrupt thyroid function. In the case of hypothyroidism, it can lead to symptoms like weight loss, sweating, nervousness, and increased heart rate, she says. 

According to the American Thyroid Association (ATA), pregnant people are more susceptible to the effects of excess iodine exposure.

ATA statement on the potential risks of excess iodine ingestion and exposure. American Thyroid Association.

Individuals who are breastfeeding, have a shellfish allergy, or have been diagnosed with hyperthyroidism, Hashimoto’s thyroiditis, autoimmune thyroiditis, autoimmune conditions, or kidney disease as well as people who take medications that affect your thyroidshould avoid sea moss, says Harrison.  

So, who might sea moss make the most sense for? According to Dr. Mohr, people who have abnormally low levels of iodine. “The benefits are from correcting [a] deficiency or optimizing an insufficiency, rather than simply adding more of any nutrient with the intention of a benefit,” he said. 

What to consider when treating patients interested in sea moss

According to The Department of Defense Dietary Supplement Program, sea moss’s nutrient composition depends on the environment it comes from.

Smyth PPA. Iodine, seaweed, and the thyroid. European Thyroid Journal. 2021;10(2):101-108.

The season and geographic

al location of the plant, for example, can impact the plant’s makeup. Consequently, some nutrients, including iodine, may exceed the tolerable upper intake level, or the greatest amount a person could consume before it becomes dangerous, as laid out by the Institutes of Medicine. The amount of iodine varies from product to product, says Gervacio. According to the ATA, many supplements contain far too much iodine. 

Lastly, be mindful of how much sea moss your patients take. “It’s important not to exceed the recommended daily iodine intake, which is around 150 micrograms per day for adults,” says Gervacio. But even then, most people likely do not need to boost their iodine levels by taking sea moss every day, she adds. “I advise against long-term, high-dose use unless supervised by a healthcare provider,” she said. This is especially true for people with hyperthyroidism or hypothyroidism, as taking sea moss could exacerbate these conditions.

It’s crucial to evaluate each patient’s medical history, allergies, and other medications and supplements to appropriately weigh the pros and cons. “Sea moss may be beneficial in certain cases but can also cause harm,” Harrison said.