Kelp Nutrition Facts

Calories, Carbs, and Health Benefits of Kelp

Kelp, annotated

Verywell / Alexandra Shytsman 

Kelp (Laminaria) is a word used to describe a type of brown seaweed that usually grows in large underwater forests. While seaweed can grow in nearly any type of saltwater or freshwater, kelp is found only in saltwater, typically along nutrient-rich, cold, rocky coastlines. There are about 30 different varieties of kelp.

Kelp provides nutrition for a wide range of sea life. People also consume this leafy seaweed because it is widely promoted as a health food due to the high nutritional value of kelp.

Nutrition Facts

The following nutrition information is provided by the USDA for 1/2 cup (40g) of raw kelp.

  • Calories: 17.2
  • Fat: 0.2g
  • Sodium: 93mg
  • Carbohydrates: 3.8g
  • Fiber: 0.5g
  • Sugars: 0.3g
  • Protein: 0.7g

Kelp—along with other types of edible seaweed—has been a staple in the Japanese diet for hundreds of years. This food has become common in other parts of the world, due in part to the popularity of kelp noodles.

Raw kelp provides very few calories at 17.2 calories per 1/2 cup. However, kelp is not usually consumed raw as a stand-alone food.

For example, if you eat kelp noodles, the nutrition facts will vary based on the product that you buy and the recipe you use. If you find a brand with just kelp, water, and sodium alginate (a natural hydration agent that is extracted from brown seaweed), there should be fewer than 10 calories per serving.

Carbs in Kelp

The carb content of kelp is very low at just 3.8 grams of carbs per 1/2 cup serving of raw kelp. It also contains about 0.5 gram of fiber and less than 1 gram of sugar.

Fats in Kelp

There is very little fat in raw kelp. Any fat consumed from kelp will likely be from added fat during cooking or from other kelp products.

Protein in Kelp

Kelp is not a good source of protein. There are about 0.7 grams of protein per 1/2 cup of raw kelp.

Micronutrients in Kelp

Kelp contains many important vitamins and minerals. Vitamins in kelp include vitamin K, vitamin A, vitamin C, folate, vitamin E, vitamin B12, and vitamin B6. It also contains small amounts of thiamin, riboflavin, niacin, and pantothenic acid.

Iodine is a mineral that's present in high amounts in kelp. Other minerals include calcium, magnesium, iron, sodium, phosphorus, and small amounts of zinc, copper, manganese, and selenium.

Health Benefits

Kelp is considered to have a high nutritional value because it's very low in calories but is packed with fiber, vitamins, and minerals.

  • Vitamin K: Essential for blood clotting
  • Folate: Important for blood cell formation and may help maintain healthy blood pressure
  • Vitamin C: An antioxidant that may help prevent illness or disease
  • Calcium: Aids in bone health
  • Iron: Important for healthy blood and disease resistance
  • Magnesium: Essential for hundreds of biochemical reactions in your body
  • Iodine: Necessary for the production of thyroid hormones and to maintain a healthy metabolism

Additional reported health benefits include weight loss, cancer prevention, management of high blood pressure, constipation relief, and radioactive intoxication treatment. However, there is not enough high-quality clinical evidence to support the use of kelp for these purposes.

Common Questions

Where do you buy kelp?

Kelp and kelp noodles are found in many specialty markets. Kelp noodles can also be found in some grocery stores and supermarkets in the Asian food section. You can also buy kelp and kelp noodles online.

How do I store kelp and how long is it good for?

If you purchase dried kelp or kelp noodles it is usually packaged so that you can keep it in your cupboard for about six months, unopened.

What is kombu? Is it the same as kelp?

There are different varieties of kelp, one of which is kombu. Kombu is the Japanese word for kelp, usually the Saccharina japonica species.

Recipes and Preparation Tips

Raw kelp can be used in stir-fry dishes, in soups, added to salads, or included in smoothies. Dried kelp can be added to the pot when cooking dried beans to enhance flavor and make them less gas-causing. It can also be used to add flavor to soups and broths.

Kelp noodles can be consumed cold or heated. Rinse kelp noodles before consuming. Try adding them to green salads, using them as a pasta alternative, or tossed with sauteed veggies and a protein. There is also an abundance of kelp noodle recipes online.

Allergies and Interactions

Kelp is likely safe when consumed in amounts typically found in food. However, the high amount of iodine and potentially heavy metals in kelp can be detrimental to your health if you consume too much, especially in the form of supplements.

Your recommended daily intake of iodine depends on your age and gender. Most adults need 150 micrograms per day. The upper limit (the most that should be consumed in a day) is 1,100 micrograms.

Since kelp nutrition varies, it can be unclear how much iodine you will consume when you eat it. Consuming too much iodine can cause serious negative health effects, such as goiter, thyroid gland inflammation, and, in severe cases, thyroid cancer. Exposure to heavy metals can also harm thyroid function.

Health experts advise that pregnant or breastfeeding women and those with kidney or thyroid disorders, such as hyperthyroidism, avoid consuming laminaria (kelp).

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Article Sources

Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Cherry P, O’Hara C, Magee P, McSorley E, Allsopp P. Risks and benefits of consuming edible seaweedsNutr Rev. 2019;77(5):307-329. doi:10.1093/nutrit/nuy066

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