The Benefits of Seaweed Supplements: A Nutrient-Rich Addition For Your Wellness Routine
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Medically reviewed by Barbie Cervoni MS, RD, CDCES, CDN
People have been eating seaweed for thousands of years. But seaweed in supplement form? That's a new one. Or is it? If you've been using a super greens product containing spirulina, kelp, or other algae, you've been consuming seaweed. Here is what you need to know about seaweed, including the types available, health benefits, and more.
Types of Seaweed
Seaweed can be classified into three groups: red, brown, and green. Brown algae, or seaweed, is categorized into subgroups including kelps and fucales. Meanwhile, red algae is the largest group, and green algae, or sea lettuce, is the most common.
Seaweeds contain protein and healthy fatty acids, primarily omega-3 and omega-6 polyunsaturated fatty acids. Both red and green algae have more protein than brown varieties. In addition, algae or seaweeds are rich sources of soluble fiber, providing about 24 grams per 100-gram serving.
The incredible essential mineral content of seaweed makes it an ideal addition to a supplement. Because of this, seaweed and algae can be used to help you reach your daily recommended mineral needs.
Seaweed also is packed with fat-soluble and water-soluble vitamins A, B1, B12, D, E, pantothenic acid, riboflavin, and folic acid. They're also rich in carotenoids and polyphenols that have powerful antioxidant, anti-inflammatory, and anticancer properties. The most common form of seaweed used in supplements includes kelp, spirulina, nori, and wakame.
Spirulina
Spirulina is a freshwater blue-green algae that are abundant in B vitamins, vitamin E, beta-carotene, chlorophyll, and iron. Spirulina provides vibrant blue color to smoothies and smoothie bowls, yet is mostly undetectable in flavor.
Kelp
In a small, randomized clinical control trial, 50 Japanese people were given either tablets that contained kelp powder or kelp-free tablets for 8 weeks. The group that was given the kelp supplement experienced significant decreases in in body fat percentage, body weight, and BMI. Larger and longer studies is diverse populations are needed to determine the exact implications of supplementing with kelp. Kelp powder can be used in salad dressings or sprinkled on top of vegetables. It provides an earthy, yet slightly sweet and salty flavor.
Nori
Nori is dried seaweed commonly used in Japanese cooking. Nori has a sweet and salty flavor and can be eaten both fresh and dried. Some research performed among Japanese children suggests that nori may help reduce blood pressure and hypertension risk factors.
Wakame
Wakame is a brown seaweed rich in dietary fiber. One in vitro study shows that wakame has positive effects on insulin resistance and metabolic syndrome.
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Potential Health Benefits of Seaweed Supplements
Not surprisingly, seaweed offers a number of health benefits. It boosts thyroid function, improves cardio-protective properties, and supports the immune system. Here is a closer look at some of those benefits.
Boosts Thyroid Function
Algae is an excellent source of iodine, an essential micronutrient important for the synthesis of thyroid hormones. Research suggests consuming algae regularly is particularly beneficial for those with an underactive thyroid.
On the other hand, excessive consumption of seaweed and iodine-rich foods may increase your risk of developing a thyroid disorder. The upper limit of iodine is 1,100 mcg for adults. While it is tough to estimate how much seaweed is too much, it is likely safe to eat small amounts (one or two tablespoons a few times per week). Pregnant people, especially, should avoid excessive use of seaweed products or choose ones labeled low-iodine. If you are pregnant or lactating, discuss your iodine needs with your physician. Your needs will increase during pregnancy but there is a delicate balance between having too little and too much.
Impacts Heart Health
Heart health is largely associated with a diet rich in fiber, vitamins, and minerals. These nutrients have a positive effect on blood pressure, cholesterol, blood sugar levels, and body weight. Seaweed is rich in all of the above. Thus, it may make sense that including seaweed in your diet or in supplemental form would provide cardiovascular benefits.
The only challenge is that the research on this subject is scarce. That said, several cohort studies on Japanese individuals found that seaweed intake was inversely associated with the risk of coronary heart disease and stroke.
Supports Immune Function
Seaweeds have developed strong anti-inflammatory properties to protect them from the environment in which they are exposed to. Because of this, supplement use of seaweed products provides an abundance of polyphenols, polysaccharides, and carotenoids that function as powerful antioxidants and anti-inflammatory agents.
May Help with Weight Management
While there are no magic pills for weight management, some research suggest that supplementing with seaweed may increase the ability to burn fat. However, the review evaluated studies done in animals and test tubes and more research is needed in humans to determine the effects of seaweed supplementation on weight.
May Improve Gut Health
Poor gut health is associated with an increased risk of inflammatory bowel disease, hypertension, type 2 diabetes, and obesity. But seaweed is a rich source of soluble fiber and prebiotics—both of which have a beneficial effect on the gut microbiome. In fact, unique polysaccharides found in seaweed have been shown to positively change the gut microbiome.
Meanwhile, soluble fiber in seaweed makes it a great option for balancing gut health, especially because fiber is one of the most important nutrients for a healthy gut microbiome. In fact, soluble dietary fibers provide the main fuel source for gut bacteria.
Considerations and Precautions
Iodine is an essential nutrient responsible for the synthesis of thyroid-stimulating hormones. Without enough iodine, you increase your risk for hypothyroidism; and in pregnancy, it can lead to fetal brain damage. But, like other marine nutrient sources, including fish and shellfish, seaweed is high in iodine, so balance is key.
In fact, a diet with excessive iodine can be risky. While iodine toxicity is rare, it can lead to thyroid dysfunction in people with pre-existing thyroid disorders or who are pregnant. It also can be risky for the elderly and premature infants. Fortunately, there are seaweed products available with low-iodine that are within safe levels.
You also need to be aware of the risk of heavy metals in seaweed especially because the accumulation of these metals could lead to potential health risks. More research is needed to better understand these risks associated with consuming seaweed, considering the abundance of nutritional benefits.
In the meantime, choosing high-quality seaweed supplements from reputable manufacturers will help to prevent unnecessary risk factors. Look for products marked with third-party certifications to ensure they contain what is marketed on the label.
Also consult with a healthcare provider such as a registered dietitian before using seaweed supplements, especially if you are pregnant, taking medications, or have an underlying health issue.
Bottom Line
Seaweed is a rich source of dietary fiber, vitamins, minerals, healthy fats, and amino acids. Regular use of a seaweed supplement may have positive effects on your health and quality of life. The dietary fiber, prebiotics, and anti-inflammatory effects provided by algae may boost heart health, promote a healthy body weight, and provide immune system support.
If you are thinking about supplementing with seaweed talk to a medical professional first and look for third-party tested supplements. Seaweed supplements are a nutrient-rich complement to a balanced diet, but should not replace a varied and whole-foods based diet.
