Health Benefits of Kelp

Medically Reviewed by Poonam Sachdev on September 09, 2022
Written by WebMD Editorial Contributors
3 min read

If you’re a fan of Japanese cooking, you’ve probably eaten kelp. Although sometimes used as a synonym for seaweed, kelp refers to brown algae from the Laminariaceae family. The kelp most often used in Japanese dishes, including miso soup and udon, is kombu. 

Since kelp is rich in nutrients, many claims have been made about its health benefits. Scientists haven’t proven many of these claims yet, but kelp is still a tasty and nutritious addition to your diet. Kelp is rich in umami; the fifth lesser known taste alongside sweet, sour, bitter, and salty. Umami gives food a savory or meaty flavor.

Seaweed contains ten times as many minerals as plants grown in soil. People who eat seaweed seldom have mineral deficiencies. Kelp also has proven health benefits and some that scientists hope to document in the future.

Thyroid Health

Your thyroid requires iodine to function properly. Your body does not manufacture iodine, so it's important to get it through your diet. If you don’t have enough iodine, your thyroid won’t produce enough of some necessary hormones, a condition known as hypothyroidism. Kelp contains iodine, and can prevent hypothyroidism.

Be careful, though — too much iodine can cause your thyroid to malfunction. Don't eat too much kelp or take a kelp supplement without talking to your doctor.  

Diabetes Control

Kelp contains a mineral called vanadium that could help people with Type 2 diabetes. Early studies using animals and humans have shown that it can help regulate blood sugar. Researchers need to find out more about how vanadium behaves in the body before it will be available on the market.  

Scientists are also investigating fucoxanthin, a substance in brown algae that could help with weight management, which is important for people with diabetes. Researchers found that fucoxanthin increased production of omega-3 fatty acid DHA and the protein involved in fat metabolism in rodents. However, it’s not possible for humans to eat enough seaweed to experience these benefits.

Prevention of Anemia

Kelp is moderately rich in iron, which is necessary to prevent the iron deficiency known as anemia. If you have anemia, your body’s tissues don't get enough oxygen because of a shortage of red blood cells. Menstruating women are especially at risk of anemia, which can cause fatigue, weakness, dizziness, and other symptoms.

Kelp has an impressive nutritional profile. Besides iodine and iron, kelp is a rich source of: 

Nutrients per Serving

You can buy kelp fresh, dried, or in noodle form. Serving sizes are often small and may not add significant nutrition to your diet. A one-ounce serving of dried kelp (about the weight of a slice of bread) contains these nutritional values:

Things to Watch Out For

Heavy metals are a concern with kelp products. Kelp can contain aluminum, cadmium, arsenic, and lead. Kelp is more likely to contain these elements when harvested from areas with industrial development. The heavy metals in kelp are usually below toxic levels, but some people worry about exposure to them, especially to arsenic.

Before you panic, remember that arsenic is in many other foods, including rice and apple juice. Most people will never consume enough kelp to have a problem with arsenic or other heavy metals. Some people opt not to take kelp supplements because they could contain more concentrated amounts of arsenic.

Kelp is available fresh or frozen, but it can be hard to find unless you live in an area where it’s grown or harvested. Most consumers eat dried kelp or kelp noodles. Kelp is sometimes marketed under the Japanese name, kombu. Here are some ways you can use kelp:

  • Use kelp to flavor miso soup broth, called dashi
  • Use kelp flakes to give vegetarian salads the taste of the sea 
  • Combine kelp noodles with shredded vegetables to make a salad
  • Make pad thai using kelp noodles instead of traditional noodles
  • Make kombu salad by mixing: water, dried kelp carrots, cucumbers, and flavoring
  • Use kelp flakes or powder to add umami to dried beans