Kelp and spirulina are two different types of seaweed that are good for human consumption. They can be eaten both raw or dried; they can be blended into smoothies, mixed into salads, or included in many other baked or cooked dishes. The two seaweeds contain different quantities of various nutrients, so in many cases a mix of both provides the most complete nutrition.
Calories, Fat, Cholesterol and Sodium
One 100 gram serving of raw kelp contains 43 calories, while the same serving of raw spirulina contains only 26 calories. There are 0.56 grams of total fat and 0.25 grams of saturated fat in the kelp, and 0.39 grams of total fat and 0.14 grams of saturated fat in the spirulina. The kelp contains 233 milligrams of sodium, while the spirulina contains 98 milligrams of sodium. Consumption of more than 2,300 milligrams of sodium per day can lead to an increased risk of high blood pressure complications, according to University of Maryland Medical Center.
Carbohydrates, Fiber and Protein
Each serving of kelp contains 9.57 grams of carbohydrates, 1.3 grams of dietary fiber and 1.68 grams of protein; each serving of spirulina contains 2.42 grams of carbohydrates, no fiber and 5.92 grams of protein. According to the Harvard School of Public Health, your body uses protein to repair and maintain itself; for example, when you work out your muscles, your body needs protein to rebuild them.
The raw kelp contains 116 International units of vitamin A, while the raw spirulina contains only 56 International units. Similarly, the kelp contains 180 micrograms of folate, while the spirulina contains only 9 micrograms. However, the kelp contains only 0.05 milligrams of thiamin, 0.15 milligrams of riboflavin, and 0.47 milligrams of niacin; the spirulina is richer in all these nutrients, with 0.222 milligrams of thiamin, 0.342 milligrams of riboflavin and 1.196 milligrams of niacin. The kelp does contain 0.642 milligrams of pantothenic acid -- the spirulina only contains 0.325 milligrams.
The raw kelp contains 168 milligrams of calcium, 121 milligrams of magnesium and 42 milligrams of phosphorus; the raw spirulina contains much less, with only 12 milligrams of calcium, 19 milligrams of magnesium and 11 milligrams of phosphorus. However, the kelp contains 89 milligrams of potassium, while the spirulina contains even more, with 127 milligrams. The kelp's zinc content is 1.23 milligrams, while the spirulina's zinc content is 0.2 milligrams.