To answer your first question: yes, there are several types of seaweed.

But in general, seaweeds are pretty much the same.

Algae, the fancy city name for seaweed, are a group of photosynthetic, non-flowering, plant-like organisms (called macroalgae) that live in the sea.

They are not plants, but members of the Protista kingdom. This partly explains why they do not have roots, stems, leaves, flowers or cones. Technically they are not vegetables either, but are often described as sea vegetables due to their edibleness and yumminess.

Find more in-depth information about four diverse types of algae (green, red, brown and blue Microalgae) in this article.

Four Types of Seaweed

Green algae are mostly made of chlorophyll (the same substance that allows for photosynthesis) and storage polysaccharides (energy units).

However, the bits not made of chlorophyll and energy are also rich in magnesium, calcium, iodine, and phosphorus (Jaspars & Folmer, 2013). The main carotenoids (or antioxidants) present in these algae are β-carotene (Burtin, 2003).

Would you like to know more about Carotenoids?  Check out this article we have on them. If you do not want to know, check it out all the same, you will not regret it.

Red seaweed get their color from phycoerythrin and phycocyanin. These two are actually like little cousins of chlorophyll, and they overshadow all other pigments, including a number of unique xanthophylls (http://www.seaweed.ie) that are in the seaweed’s composition.

Also, red seaweed has protein levels comparable to those found in high-protein vegetables, such as soybeans. However, red algae see those protein levels and contains around 100-800 mg of vitamin C per kilogram, beating soybeans to oblivion with their added value.  

Brown algae get their color from the dominance of a xanthophyll pigment named fucoxanthin (a very fancy word for the color yellow). They have also lots of phlorotannins, which give them anti-obesity and anti-diabetic properties (Jaspars & Folmer, 2013).

In addition to all that, brown seaweeds are rich in carotenes (precursors of vitamin A) and vitamin C.

Now, blue seaweed, also known as microalgae, are the largest primary biomass in the world. They cover 70% of the earth’s surface to a depth of up to 200 m, meaning they have been our overlords all along, and we have just begun embracing them.

Until recently, microalgae have been an untapped resource. However, some have recognized their potential application for biofuel and human food supplementation. This has led to a boom in the microalgae culture industry (Jaspars & Folmer, 2013) that perhaps you were not aware of, but should probably pay attention to.

The Four Types in Depth

Types of Seaweed: Green, Red, Brown and Blue

Seaweeds are not all birds of a feather, mostly because they are not birds. They might look similar, but each type has unique compositions and attributes. To get you acquainted with them, we will discuss four specific types: red, brown, green, and blue.

Now, red, brown and green algae are marine algae that are large enough to be seen by the naked eye. Some can grow to up to 60 meters  in length (for my Liberian, Burmese and American friends, that is somewhere around 65 yards – I know you appreciate the conversion. Wait – you do, do you not? Just checking.)

Algae are not vegetables nor plants, which only goes to show Mother Nature has a nice sense of humor in making them edible and plant-like. Ironically enough, blue-green algae are not marine algae either, but cyanobacteria.

Green Algae

Found towards the top of bodies of water, green algae mostly contain chlorophyll and storage polysaccharides, otherwise known as the substance providing photosynthesis and energy bars.

They are also rich in magnesium, calcium, iodine, and phosphorus (Jaspars & Folmer, 2013), which makes them really nutritious for a human diet.  

Colored by chlorophyll a and b, the carotenoid composition of green algae is similar to that of higher plants (here is where Mother Nature chuckles). The main carotenoids present in these algae are β-carotene (Burtin, 2003).

Would you like to know more about Carotenoids? As in information on what they are? Check out this article we have on them and why they are important.

Green Algae and Vitamin C

In green and brown algae, the levels of Vitamin C average between 500 to 3000 mg/kg of dry weight, comparable with that of parsley, blackcurrant, and peppers. Yet, they have not achieved the same status as parsley, blackcurrant or pepper in Western civilization.

Also, green algae show interesting levels of alpha linolenic acid (Burtin, 2003), one of two essential fatty acids, which have the cutest name ever.

Red Algae

Red algae also have a good composition for a human diet. It is just that phycoerythrin and phycocyanin give them their red color.

What these two do is they actually mask the other pigments in the red algae’s internal structure. It even outcolors the unique xanthophylls, which is just a fancy name for the color yellow.

Is There Protein in Red Seaweed?

Well…red seaweeds contain about 10-30% of their dry weight in protein, which is comparable to high-protein vegetables, such as soybeans (and Mother Nature smirks again).

One thing that the red seaweed does better than its other colorful counterparts is that it has a higher score of amino acids (at 91 and 100 in particular kinds). In a last brushstroke from Mother Nature, some of these scores are similar to those present in animal-derived foods (Rajapakse & Kim, 2011).

How are Vitamins and Red Algae Related?

Glad you asked!

Red algae contain the ABC of vitamins: they have large amounts of vitamin A, significant quantities of vitamins B and B2, and around 100 to 800 mg of vitamin C per kg.

Brown Algae

Brown algae are a bit special. They get their color from a dominance of a xanthophyll pigment named fucoxanthin, AKA the color yellow.

Used as dried sheets, flakes, or ground seaweed flour (Jaspars & Folmer, 2013), people tend not to consume this alga as a fresh “vegetable” like its differently colored cousins.  

One of their most particular uses is that, due to their composition (phlorotannins + carotenoid fucoxanthin), brown algae bear anti-obesity and anti-diabetic properties (Jaspars & Folmer, 2013).

How Do Iodine and Magnesium Compare in Brown Seaweed?

Since iodine and magnesium are so important for human life in general, it is important to know the differences between each color. Like Power-Rangers, each alga has different properties and amounts of minerals.

In this case, brown algae have the highest content of iodine in seaweed, which for brown algae ranges at a concentration of 1500–8000 ppm. This means that for each million parts of alga, you get between 1500 to 8000 parts of iodine.

Bear in mind that the magic minimum intake recommendation for iodine is just 150 mg a day. Also, a normal portion size of brown seaweed provides more than 50% of the recommended daily allowance of magnesium (Rajapakse & Kim, 2011).

How Do Vitamins and Brown Algae Compare?

To B or not to B? We said brown algae were special.

Even if most land plants do not have it, brown seaweeds provide vitamin B12, which is found in considerable amounts only in a few vegetables (Bender, 1980).

In addition, brown seaweeds are rich in carotenes (precursor to vitamin A) and vitamin C.

Blue Seaweed (Microalgae)

Blue seaweed may not be algae, but they are definitely prosperous.

Also known as microalgae, blue seaweed are the largest primary biomass in the world. They cover 70 percent of the earth’s surface to a depth of up to 200 m. Given their potential, I, for one, welcome our new overlords. (Oh! Sorry – for our feet-measuring buddies, 200 m would equal an approximate of 650 feet, as well).

Until recently, microalgae have been an untapped resource. Some have discovered in recent years that they can be used in different fields, including applications in biofuel production and extraction of proteins and essential fatty acids. This has sparked an interest (Jaspars & Folmer, 2013), and it has led to people growing blue seaweeds like they were mushrooms.

Today, microalgae are cultured in large-scale open systems and in closed fermenters to contain their potential from taking over the world.

REFERENCES

Bender, A. E. (1980). Dictionary of Nutrition and Food Technology. Butterworths, London.

Jaspars, M., & Folmer, F. (2013). Sea vegetables for health. Food and Health Innovation Service Service, 4-19.

Rajapakse, N., & Kim, S. K. (2011). Nutritional and digestive health benefits of seaweed. In Advances in food and nutrition research (Vol. 64, pp. 17-28). Academic Press.

Selmi, C., P. Leung, et al. (2011). “The effects of Spirulina on anemia and immune function in senior citizens.” Cellular and Molecular Immunology 8: 248-254.

Small, E. (2018). 56. Kelps: the key to sustainable harvest of marine biodiversity. Biodiversity, 1-13.