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Phaeophyta (Brown Algae) – Interesting Facts

What is Phaeophyta (Brown Algae)?


Brown algae is a type of seaweed that can be found growing along some coastal areas which are very rocky. They play an important role both as habitat and as food.

Scientific Name


Interesting Facts & Characteristics

Phaeophyta is mainly marine in distribution, with fewer than 1 percent of the species are found in freshwater.

The brown color in brown algae results from the large amounts of fucoxanthin, a type of carotenoid that masks other pigments.

With the help of fucoxanthin, Phaeophyta can also utilize green and yellow light for assimilation.

The algae vary from very small thread-like algae to giants of over 50 meter in length. Giant kelp supports a large variety of marine animals and grows in large forests along the coastline.

Growth in most Phaeophyta occurs as a result of divisions in a single apical cell or in a row of such cells at the tips of structures.

Phaeophyta is one of the largest and most complex types of algae. They are one of only 5 eukaryotic lineages to have independently evolved complex multicellularity. Genetic studies show their closest relatives to be the Xanthophyceae (yellow-green algae).

There are approximately 1500 to 2000 species of brown algae worldwide. The majority of the species occur in temperate regions.

These algae are distinguished by chloroplasts which have:

  • thylakoids (a membrane-bound compartment inside cyanobacteria and chloroplasts) in stacks of 3;
  • 4 surrounding membranes;
  • laminarin (a water-soluble polysaccharide) as the photosynthetic reserve;
  • fucoxanthin which masks chlorophyll a and c;
  • alginates as the wall matrix component.

Phaeophyta also exhibits some remarkable traits regarding its cell biology. For instance, cytokinesis has characteristics typical of both green plants (centrifugal cell plate formation) and centrosomes (animals).

They are tough and easily withstand lots of wave motion.

Some types of brown algae have adaptive bladders, which are designed for floating photosynthetic parts near or on the water surface for harvesting light.

The best known Phaeophyta is most likely Laminaria saccharina of the family Laminariacea.

Other well-known brown algae are the Sargassum and Fucus which floats in a thick, tangled mass through the Sargasso Sea, a region of the North Atlantic Ocean which is surrounded by four ocean currents. The sea area is 2000 miles long and 700 miles wide.

Life Cycle

The life cycle of most Phaeophyta is a Haploid/Diploid life cycle.

Uses & Health Benefits

Certain species are eaten as a vegetable (e.g., Laminaria) in East Asia, and several are used as fertilizer.

They are also used to produce alginates, a biomaterial that has a variety of uses, especially in industrial manufacturing (as a stable component of a battery anode) and as a food additive.

Commercial alginates are primarily extracted from species of Macrocystis, Laminaria, Eclonia, Ascophyllum, Durvillea, Lessonia, and Sargassum.

Moreover, brown algae fix a substantial portion of the earth’s carbon dioxide (CO2) yearly through photosynthesis. This is important since CO2 levels today are significantly higher than at any point in at least the past 800,000 years, according to research.


It is a brown seaweed pigment that is found in most brown algae. It is a xanthophyll (yellow pigments which occur widely in nature), a molecule that is structurally similar to beta-carotene (a precursor of vitamin A). But, the structure of this plant pigment makes it different from other plant carotenoids.

There is strong evidence that fucoxanthin may promote healthy functioning of the blood vessels, liver, bones, brain, eyes, and skin. Plus, it may reduce inflammation levels in the human body.


These algae are a good source of iodine. The body needs iodine in trace amounts for development, growth, and to produce thyroid hormones. Thyroid hormones play an essential role in numerous important bodily functions, such as:

  • development of the central nervous system;
  • immune response;
  • bone health;
  • metabolism.

According to statistics, around 40% of the world’s population is at risk of iodine deficiency. Symptoms of an iodine deficiency include:

  • constipation;
  • poor cognition, especially in children;
  • cold intolerance;
  • forgetfulness;
  • weight gain;
  • depression;
  • dry skin;
  • hair loss;
  • hair weakness;
  • fatigue.

ALSO READ: Plants Used In Phytoremediation


It is a type of dietary fiber which is found in Phaeophyta. Fucoidan benefits the human body by burning fatty lipids such as triglycerides and cholesterol. According to a 2012 study that was issued in the journal “PLoS One,” fucoidan may help prevent metastasis of lung cancer.

Moreover, this fiber has been shown to help aging stem cells (the foundation for every tissue and organ in the body) which are vital for rebuilding the inner walls of damaged blood vessels.

Fucoidan has also been proven in clinical studies to have apoptotic (programmed cell death) and suppressive effects on enveloped viral diseases, like – HIV, genital and oral herpes, and hepatitis C (a disease that causes infection and inflammation of the liver).

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Antioxidant Properties

Phaeophyta contains a few chemicals that work as antioxidants. These potent substances can slow or prevent damage to cells that is caused by free radicals.

Processes and activities which can lead to oxidative stress include:

  • ozone;
  • mitochondrial activity;
  • inhaling or the intake of industrial solvents;
  • excessive physical exercise;
  • chemotherapy;
  • exposure to chemicals, like – pesticides;
  • radiation;
  • tissue trauma, due to injury and inflammation;
  • environmental pollution;
  • ischemia (a restriction in blood supply to tissues);
  • smoking and second-hand smoking;
  • consumption of certain foods, particularly foods that contain trans fats (anything fried in oil), processed foods, artificial sweeteners, and foods and drinks with food additives.

ALSO READ: Is Dicalcium Phosphate vegan?

Side Effects Of Brown Algae

Brown algae are usually safe, but, at high doses of several grams per day, they may cause temporary diarrhea.

According to a 2003 study that was issued in the journal “Endocrine Practice,” supplementing with Phaeophyta may substantially increase the levels of thyroid-stimulating hormone.

However, the biggest side effect of eating too much Phaeophyta is ingesting too much iodine.

Consuming too much iodine has been associated with the development of subclinical hypothyroidism (also known as mild thyroid failure), which may increase the risk of heart issues.

Additionally, in some individuals, a high intake of iodine can cause an acneiform eruption (skin problems such as acne rosacea, acne vulgaris, perioral dermatitis, and folliculitis).

Groups at the highest risk for iodine toxicity are seniors, people with thyroid disease, and developing babies.