Nutritional Content Of Seaweed

Seaweeds include thousands of different species of red, brown and green algae that live in the sea or brackish water. Some types of seaweed are edible and are considered a delicacy in Asian countries, but seaweed is also harvested for industrial purposes. Seaweed is a low-calorie source of nutrition, including iodine. It naturally contains widely different amounts of iodine and some products may have toxic levels, so talk to your health care provider before using seaweed supplements.

Basic Nutrition

There are about 10,000 species of seaweeds, according to the Seaweed Site, and the U.S. Department of Agriculture Nutrient Database provides nutritional information for just a few of them, including edible kelp and wakame. A 100-gram serving of raw kelp has 43 calories and 2 grams of protein, while wakame is almost identical with 45 calories and 3 grams of protein in a 100-gram serving. They only have a small amount of fiber, but with 1.3 grams, kelp has double the amount of wakame. Both types of seaweed have 0.6 grams of fat in a 100-gram serving.

Vitamins

Both kelp and wakame provide 3 percent of the recommended daily value of antioxidant vitamin C in a 100-gram serving, according to the Institute of Medicine. They also have about 4 percent of the daily value of thiamin and 12 percent of riboflavin -- B vitamins needed for the production of energy and a healthy nervous system. Both seaweeds are rich sources of folate, providing 45 percent of the recommended daily value. Folate is so vital for the creation of new cells that taking supplements may prevent birth defects. Wakame provides 12 percent of the recommended daily value of both niacin and vitamin A, which is four times more niacin and three times more vitamin A, than you’ll get from kelp. Like other B vitamins, niacin converts food to energy, while vitamin A is necessary for vision and bone growth.

Minerals

One hundred grams of kelp and wakame provides 15 to 17 percent of the recommended daily value of bone-building calcium. Kelp has 121 milligrams, or 29 percent of the daily value of magnesium, and wakame has 107 milligrams, or 26 percent. Magnesium is needed for strong bones, and it also helps regulate your heartbeat. Both types of seaweed have 1 to 2 percent of the daily value of potassium. Your body must have this important mineral for muscle contraction and nerve signal transmission. Wakame has 80 milligrams of phosphorus, or twice the amount that’s found in kelp. Wakame also has more than three times the amount of salt, containing 872 milligrams of sodium, compared with 233 milligrams in kelp.

Considerations

Seaweed contains iodine, which it naturally absorbs from seawater. We need iodine for thyroid functioning, and seaweed supplements are marketed for that purpose. However, the amount of iodine varies from one type of seaweed to the next and the USDA Nutrient Database does not include nutritional values for iodine. The recommended dietary intake for iodine is 150 micrograms a day, and you shouldn’t have more than 1,100 micrograms. Just 1 gram of dried seaweed can have 16 to 2,984 micrograms of iodine, according to the Office of Dietary Supplements.