Health Benefits of Seaweed

Seaweed has antioxidants and vitamins but also offers possible benefits like blood sugar stability and healthy gut promotion.

Seaweed, also known as algae, is an aquatic plant without flowers that is mainly produced for humans to eat. It has long been a staple food of many Asian diets, particularly in Japanese cuisine. You may find seaweed, also known as algae, most commonly in sushi, salads, soups, and on their own as snacks.

Also, some seaweed benefits include healthy gut promotion, blood sugar regulation, and vitamin content. Here's more about seaweed, including its benefits, nutrition, risks, and ways to enjoy it.

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Supports Thyroid Function

Your thyroid gland in the neck produces and releases thyroid hormone, which controls your metabolism.

One of the causes of hypothyroidism, or an underactive thyroid, is a lack of iodine. Hypothyroidism causes symptoms like:

  • Developing a goiter, which is a large growth on your neck and near your thyroid gland
  • Feeling fatigued
  • Gaining weight

Adding seaweed to your diet is a great way to increase your intake of iodine if you have an underactive thyroid. In one study, researchers found that some types of seaweed can provide rich amounts of iodine.

Has Antioxidants

Vitamins A, C, and E, all present in seaweed, are excellent sources of antioxidants.

Antioxidants help prevent cell damage by decreasing the effects of free radicals. Free radicals are substances that contribute to chronic diseases, like cardiovascular diseases, diabetes, and certain types of cancer. Antioxidants can also boost your immune system.

Promotes a Healthy Gut

Fiber helps promote a healthy gut by increasing bowel regularity. Seaweed is a great source of fiber. Researchers reported that 23% to 64% of dried seaweed is fiber.

May Support Weight Management

Adding seaweed to your diet may help you carefully manage your weight. Seaweed has few calories, which can help keep your calorie intake lower.

Brown algae, which includes kelp, wakame, kombu, and arame, contain fucoxanthin. Fucoxanthin is a chemical that has antioxidant properties and also helps reduce your risk of obesity.

Could Decrease Risk of Cardiovascular Disease

Seaweed may also help decrease your risk of developing cardiovascular disease—the most common cause of death in the United States.

One of the factors contributing to your risk of developing cardiovascular disease is high cholesterol. Researchers explained in one study that the vitamins and minerals found in seaweed, particularly fiber, can help reduce cholesterol.

Keeps Blood Sugar Levels Stable

It's possible that seaweed could decrease your risk of developing type 2 diabetes. Among its antioxidant properties, fucoxanthin also helps regulate your blood sugar by reducing the amount of sugar your bloodstream absorbs.

Nutrition of Seaweed

Seaweed, also known as algae, packs antioxidants—including vitamins A, C, and E—and is a great source of iodine. One cup, or 15 grams, of dried seaweed contains:

  • Calories: 44.7 calories
  • Protein: 4.77 grams
  • Fat: 0.601 grams
  • Carbohydrates: 7.86 grams
  • Fiber: 0.84 grams
  • Sugars: 0.456 grams
  • Vitamin A: 2.1 micrograms
  • Vitamin C: 0.75 milligrams
  • Vitamin E: 0.75 milligrams

However, the amounts of vitamins and minerals in seaweed vary slightly depending on the type of algae. There are different classes of algae, such as:

  • Brown algae, like kelp, wakame, kombu, and arame
  • Red algae, like dulse and nori
  • Green algae, like sea lettuce

Risks of Seaweed

Although seaweed has several health benefits, ensure you don't have too much of the tasty marine plant.

However, it's essential to proceed with caution while reviewing the iodine content of your seaweed. Too little or too high amounts of iodine can adversely affect your thyroid function.

Also, some types of seaweed have a lot of heavy metals, like arsenic and lead. If you're taking seaweed supplements, double-check the ingredients. The Food and Drug Administration (FDA) does not regulate the amounts of those heavy metals in seaweed supplements.

Standard Disclaimer: Dietary supplements are minimally regulated by the FDA and may or may not be suitable for you. The effects of supplements vary from person to person and depend on many variables, including type, dosage, frequency of use, and interactions with current medications. Please speak with your healthcare provider or pharmacist before starting any supplements.

Tips for Consuming Seaweed

Some of the most popular types of edible seaweed include nori, kelp, wakame, and dulse. Look for varieties of seaweed online or at Asian supermarkets, natural-food stores, and well-stocked grocery stores.

Most seaweed is sold, dried, consumed, or reconstituted in warm water. Some seaweed, like kelp, is also available frozen, which means it doesn't need to be reconstituted.

Executive chef Jeremy Rock Smith, a faculty member at the Kripalu Center for Yoga & Health in Stockbridge, Mass., recommended:

  • Adding kombu when preparing dried beans
  • Sneaking kelp into slaws for a great depth of flavor
  • Shaking store-bought furikake (a topping that includes sesame seeds and nori) onto popcorn, roasted vegetables, cooked fish, or omelets

Think of nori as the gateway seaweed. You can find it in sushi rolls and sheets as "seaweed snacks." Kelp is the primary ingredient in dashi, a Japanese stock that forms the base of miso soup. Also, kelp noodles are a staple dish in Korean cuisine. You can even add kelp powder to smoothies.

Wakame is the main component of most seaweed salads and the wide, slippery seaweed you often find in miso soup. Usually sold dried, dulse is available whole, flaked, or powdered. Some people say it tastes like bacon when they fry dulse.

You can also:

  • Add seaweed to chicken bone broth
  • Snack on nori and dulse right out of the bag
  • Whip up a seaweed salad with sesame oil and garlic

A Quick Review

Seaweed has many possible benefits, from blood sugar regulation to decreased heart disease risk. The plant is available in various types and has vitamins and antioxidants. There are risks to eating seaweed, such as its iodine content's potential to cause thyroid problems. Still, the different types of seaweed make the plant versatile, as you can eat seaweed as a snack or as part of meals.

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  1. Lozano Muñoz I, Díaz NF. Minerals in edible seaweed: health benefits and food safety issuesCritical Reviews in Food Science and Nutrition. 2022;62(6):1592-1607. doi:10.1080/10408398.2020.1844637

  2. Shahid MA, Ashraf MA, Sharma S. Physiology, thyroid hormone. In: StatPearls. StatPearls Publishing; 2023.

  3. MedlinePlus. Hypothyroidism, also called: underactive thyroid.

  4. Aakre I, Solli DD, Markhus MW, et al. Commercially available kelp and seaweed products – valuable iodine source or risk of excess intake? Food Nutr Res. 2021;65:10.29219/fnr.v65.7584. doi:10.29219/fnr.v65.7584

  5. American Academy of Family Physicians. Antioxidants: what you need to know.

  6. US Department of Agriculture FoodData Central. Seaweed, dried.

  7. Centers for Disease Control and Prevention. Fiber: the carb that helps you manage diabetes.

  8. Wells ML, Potin P, Craigie JS, et al. Algae as nutritional and functional food sources: revisiting our understandingJ Appl Phycol. 2017;29(2):949-982. doi:10.1007/s10811-016-0974-5

  9. Zhang H, Tang Y, Zhang Y, et al. Fucoxanthin: a promising medicinal and nutritional ingredientEvidence-Based Complementary and Alternative Medicine. 2015;2015:e723515. doi:10.1155/2015/723515

  10. Centers for Disease Control and Prevention. Leading causes of death.

  11. de Jesus Raposo M, de Morais A, de Morais R. Emergent sources of prebiotics: seaweeds and microalgaeMarine Drugs. 2016;14(2):27. doi:10.3390/md14020027

  12. Merck Manual Professional Version. Iodine deficiency.

  13. Merck Manual Professional Version. Iodine toxicity.

  14. US Food and Drug Administration. Testing results for arsenic, lead, cadmium and mercury.

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