Irish moss: What is it and how does it stack up in terms of nutritional value?

Sea moss was always spoken of very highly by Dr. Sebi and for those of us that follow his diet it's pretty much a staple food that is part of our everyday lives. 

That said, there still seems to be a lot of confusion surrounding which type (species) of seaweed is actually "Irish moss" as well as the nutritional value it possess.

What is Irish sea moss?

The name “Irish moss” originally comes from the historical use of Chondrus crispus by the Irish. 

However, today, depending on where you are in the world, “Irish sea moss”, “Irish moss” or simply “sea moss” may refer to a number of different seaweeds including (but possibly not limited to) Chondrus crispus, Kappaphycus alvarezii (a.k.a Eucheuma Cottonii) as well as various species within the Gracilaria genus.

Despite being called a “moss”, all of these seaweeds are actually types of red algae of which there are 1000s of species.

Edible red algae, or Rhodophyta, are known to possess high amounts of protein, minerals, vitamins, essential fatty acids and are typically rich sources of antioxidants. [3]

Scientific classification of seaweeds

The taxonomies used in the scientific classification of seaweeds is a hierarchy as follows
Division > Class > Order > Family > Genus > Species

The division for all of these “Irish moss” seaweeds is Rhodophyta (red algae), of the Florideophyceae class (the same as 95% of all red algae). 

But the order, family, genus and species, is where things start to differ.

Chondrus crispus and Kappaphycus alvarezii belong to the same order, Gigartinales, but Gracilaria belongs to the Gracilariales order

K. alvarezii belongs to the Solieriaceae family, while Chondrus crispus belongs to the Gigartinaceae family and Gracilaria belongs to the Gracilariaceae family.

The naming convention of seaweeds uses binomial nomenclature, a "two-term naming system".

Understanding this helps to identify the genus a particular species belongs to from the name alone. The first part of the name identifies the genus to which the species belongs, while the second part identifies the species within the genus, i.e. Chondrus crispus is a species belonging to the Chondrus genus.

Chondrus crispus

Chondrus crispus grows in cooler waters and appears in abundance around the rocky parts of the Atlantic coasts of Europe, especially Ireland and the UK as well as Iceland, the Faroe Islands western Baltic Sea to southern Spain. It can also be found on the Atlantic coasts of Canada and North America. [1]

In it’s moist, natural state, it possesses a soft and cartilaginous consistency and can have varying colors from a greenish-yellow, through red, to a dark purple or purplish-brown. 

When washed and sun-dried it has a yellowish and translucent appearance, which, if you purchase the dried herb is usually how it will look.

History & Traditional Use of Irish Moss (Chondrus crispus)

Traditionally thought of as a “poverty food” during the potato famine of 1846-48, Irish moss has been used as a cold remedy and treatment for respiratory ailments such as tuberculosis and pneumonia since 1810.


Gracilaria is a genus within the Gracilariaceae family, and is “the third largest genus of red algae with over 150 species worldwide”. Nearly 28 species of Gracilaria have been reported from the Indian coast. [39]

Gracilaria is noted for its economic importance and is mainly cultivated and harvested in Asia, South America, Africa and Oceania for the production of Agar, providing more than 50% of the world’s supply. [39]

Agar is used as “a laxative, an appetite suppressant, a vegetarian substitute for gelatin, a thickener for soups, in fruit preserves, ice cream, and other desserts”. [2]

Additionally, various species of Gracilaria are used in soups and salads in several countries such as Korea, Thailand, China, and Japan where it is known as ogonori or simply “ogo”. 

Kappaphycus alvarezii (Eucheuma Cottonii)

This species was initially named Eucheuma Cottinii until the 1980s when the Kappaphycus genus was created and a few of the Eucheuma species were renamed according to the type of carrageenan they produce. [41] Commercially, however, it is still known as “cottonii”. [40]

Similar to the Gracilaria genus, it grows in warmer waters with an “optimum temperature between 27–30 degrees Celsius” and is usually found just below the shore line of reef areas on sandy-corally to rocky surfaces where the water flow is slow to moderate. [38][40]

As you can see, the name “Irish moss” is applied almost interchangeably across a number of species of red algae from different parts of the world. 

While the aforementioned seaweeds are all red algae that share some of the same taxonomic groups, with all of them except for Gracilaria belonging to the same order  – it is important to remember that they are different species and therefore the mineral and vitamin content for them is likely different.

In regards to the nutritional values and health benefits, I will only consider Chondrus crispus going forward.

Not only is it the original “Irish moss”, but Chondrus crispus is the exact species spoken of and used by Dr. Sebi. Furthermore, nutritional data and studies are much more readily available for it allowing us to back up claims surrounding its potential health benefits. 

That said, I have come across people buying, selling and consuming other species of “Irish moss”. If there is a demand for more information regarding those I will surely look into them at some point and potentially update this article.

Nutritional content (Chondrus crispus)

Focusing on the vitamins and minerals of which Chondrus crispus provides over 15% of the daily recommended value – I will give an overview of why these nutritional elements are important as well as draw comparisons between Irish moss and more mainstream sources of the respective vitamin or mineral.

Hopefully this will give you more perspective into the kind of nutrients you can expect from consuming it.

The nutritional data I am using for Chondrus crispus comes from the USDA database. I will report and compare on the nutritional value of sources using 100g quantities as standard.

Vitamin content

Riboflavin (B2)

Vitamin B2, otherwise known as Riboflavin, is essential for absorbing nutrients from food. B2 deficiencies are extremely common amongst the general population; dry skin, white spots on the inside of the lips, cracked skin around the mouth are a few symptoms. 

We are often told that milk and bread are strong sources of B2. (WebMD) Whole cow’s milk contains 0.13mg of B2 per 100g/100ml. [4] 

Most bread that you buy in the store will usually contain no natural Riboflavin yet the ingredients for the flour will likely include Riboflavin. [5] This is because it must be artificially added to the flour used to bake bread due to the milling process of the grain, specifically the degermination of the kernel.

Irish moss has 0.4mg of B2 per 100g. [6] That’s approximately 40% of your recommended daily intake! 

Degerminated grains

Degerminating the kernel of a grain removes basically all of the vitamin content, i.e. B2 and B3. In the early 1900s a lack of B3 in the population resulted in the great pellagra epidemic in which it is estimated that 100,000 Americans died due to malnutrition attributed primarily to degerminated flours.

Folate (B9)

Vitamin B9, otherwise known as folate, is important when the body is undergoing periods of cell division and growth. Infancy and pregnancy, for example. A lack of B9 can hinder DNA synthesis and cell division. [7]

The recommended daily intake for most adults is around 0.4mg. 0.6mg for pregnant or lactating women. [8]

You may have heard of folic acid. This is manufactured and used to “enrich” foods. The body then converts this folic acid into folate. [8]

In order to better reflect the “higher bioavailability of folic acid than that of food folate”, the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine have developed a new dietary reference intake system for folate known as Dietary folate equivalents or DFE. [8] 

This may be worth noting as it was rolled out very recently (January 2020). The folate content in the foods below do not consider these recent changes.

Broccoli is said to be a good source of folate (WebMD), 100g raw uncooked broccoli contains 0.06mg. [9]

Irish moss contains 0.18mg per 100g, almost half of the recommended daily value. [6]


Irish moss really comes into a league of its own when mineral content is considered. Honestly. you would be hard pushed to find a plant with a more readily available source of essential minerals than this.

According to Bergner, no land plant even comes close to seaweeds as sources of metabolically-required minerals. [10]


About 99% of the calcium in our bodies exists within our bones and teeth. Aside from building bones and ensuring they remain strong and healthy, calcium enables our blood to clot, muscles to contract and our heart to beat.

To some people it almost defies belief that you can get calcium from anything but milk. Well, Irish moss is actually a fantastic, and an arguably more natural source of calcium at 70mg per 100g. [6]

The calcium content of 100ml/100g of whole cow’s milk can range from anywhere between 90mg to 125mg. [4]

Although milk technically has more calcium, the reasons you may want to avoid cow’s milk in your diet are numerous but that goes beyond the scope of this article.

If you're interested in learning more about the potential dangers of cow's milk, this article is worth a read.


Iron is vital to the proper function of hemoglobin – a protein needed to transport oxygen in the blood. It is also important for the metabolism as an essential component of some proteins and enzymes.

The recommended daily intake of iron for children is approx 9mg, slightly more in the teenage years, girls more so than boys. An adult male requires 8mg, a female 18mg, and a pregnant woman requires a staggering 27mg. [12]

As gross as it may seem, nutritionists often claim organ meats are one of the best sources of iron. An article published by Healthline states that “a 3.5-ounce (100-gram) serving of beef liver contains 6.5mg of iron”. [11]

Recommended alternatives for vegans include things like spinach and quinoa, which offer 2.7mg and 2.8mg of iron per 100g respectively. [11]

There is 8.9mg of iron per 100g of Irish moss. [6]

It’s worth noting that you don’t run the risk of iron poisoning from plants as you may from iron supplements. [13]

Iron levels for vegans

Because non-heme iron (contained in plants) is typically harder for the body to absorb than heme iron (contained in fish and meat). If you’re following a vegan diet it is especially important that you are mindful of your iron levels. More so than if your diet included fish for example.

To maximize iron absorption be sure to keep your vitamin C levels topped up. [14]


Iodine is an essential mineral in the production of thyroid hormones which control the body’s metabolism among other functions. For instance, bone and brain development during pregnancy and infancy.

Low iodine foods as a consequence of iodine-deficient soils and water, often result in “chronic low iodine consumption” in adult humans.

This iodine deficiency initially presents itself as goiter – a swelling in front of the neck, followed by various “manifestations of hypothyroidism”. [15]

This “swelling” in the neck is actually the thyroid gland becoming enlarged by TSH (thyroid-stimulating Hormone) in order to increase the cell surface area as a means of “trapping” more iodine. [15]

Unfortunately, the USDA database does not list the iodine content of foods. However, according to Algae: An Introduction to Phycology, “a single gram of red algae”, such as Irish moss, is enough to meet the 0.15mg/day iodine requirement for (non-pregnant) adults. [3]

Pregnant women (teens and adults) need the most iodine at approximately 0.22mg per day and 0.29mg per day when breastfeeding.

Infants aged 7-12 months need 0.13mg, children 1 - 8 years need 0.09mg and 0.12mg when going through puberty. 14 year olds right through to adults need 0.15mg per day. [16]

Can I take too much iodine?

If you’re taking iodine supplements, yes, it is possible to take much resulting in iodine poisoning. However, “it’s very hard to get iodine poisoning from food alone, adults can tolerate up to 1.1mg a day”. [13]

That said, some individuals are extremely sensitive to iodine. Too much in their diet and they begin to exhibit “hyperthyroid signs and symptoms, i.e. nervousness, heart palpitations, sleeplessness, irritability and even iodine-induced goiter”. [15]


Magnesium is an instrumental mineral for maintaining good cardiovascular health. It helps to regulate muscle functionality throughout the body, including the heart.

Green leafy vegetables are touted as a good source of magnesium, namely spinach and kale. Raw spinach contains 79mg per 100g. Raw kale, 32.7mg. [17]

Which, although isn't bad, is not on par with the 144mg per 100g contained in Irish moss. [6]


While at high levels manganese can be toxic, it is still an essential human dietary element. [18]

It exists as a coenzyme in several biological processes including, macronutrient metabolism, bone formation, and free radical defense systems. [19]

Irish moss contains 0.37mg [6], which is about 18% of the daily value. Pecan nuts are an exceptionally good source of manganese containing 4.5mg per 100g. [20]


As the second most plentiful mineral in the body, we need phosphorus for many functions including filtering waste as well as repairing tissue and cells.

Health conditions like diabetes and alcoholism as well as some medications can cause phosphorus levels in the body to drop too low.

Cooked chicken is one of the best sources of phosphorus at around 214mg per 100g. [21] For vegans, whole wheat is also relatively high in phosphorus at 150mg per 100g (cooked). [22]

By comparison, Irish moss contains 157mg per 100g. [6]


When it comes to essential minerals for the immune system and combating disease, there aren’t many that top the importance of zinc.

Not only is it essential for immune cell function and cell signaling but zinc’s ability to function as an “anti-oxidant and stabilize membranes suggests that it has a role in the prevention of free radical-induced injury during inflammatory processes”. [23]

Interestingly, the essentiality of zinc in the human body was not recognized by modern science until the 1960s. [24]

Generally speaking, “fruits and vegetables are poor sources of zinc”. [25] Kale, for example, contains about 0.2mg per 100g, just 2% of the daily value. [26]

Irish moss is an exception, however, and contains a massive 1.95mg per 100g, which is about 21% of your daily recommended amount. [6]

Health benefits of Irish moss

So, how does all that nutritional goodness translate into improving our overall health and well-being?

Well, providing you've read through everything above it should be abundantly clear by now that the benefits this incredible superfood has to offer are plentiful, here are a few of the highlights:

  • Can help maintain bone strength, nourish the skin and improve its elasticity.
  • Topically applied it has a soothing effect and can be used to treat Eczema, rashes and burns.
  • Marked improvement to thyroid function (high iodine content)
  • Improvements to immune system response (high zinc content)

If you're still not convinced or simply want to learn more take a look at my article on the benefits of Irish moss for a full and detailed breakdown along with some suggestions on how to consume it.


[1] ‘Chondrus crispus’ (2020) Wikipedia. Available at: (Accessed: 5 March 2020)

[2] ‘Gracilaria’ (2020) Wikipedia. Available at: (Accessed: 5 March 2020)

[3] ‘Red algae’ (2020) Wikipedia. Available at: (Accessed: 8 March 2020)

[4] U.S. Department of Agriculture 2019, Milk, whole, 3.25% milkfat, with added vitamin D, 746782, viewed 5 March 2020, <>

[5] U.S. Department of Agriculture 2019, BREAD (BRANDED), 566368, viewed 10 March 2020, <>

[6] U.S. Department of Agriculture 2019, Seaweed, irishmoss, raw, 11444, viewed 5 March 2020, <>

[7] ‘Folate’ (2020) Wikipedia. Available at: (Accessed: 23 March 2020)

[8] Office of Dietary Supplements 2020, Folate, National Institutes of Health, viewed 21 March 2020, <>

[9] U.S. Department of Agriculture 2020, Broccoli, raw, 787465, viewed 23 March 2020, <>

[10] Bergner, P. 1997. Healing Power of Minerals. P.13

[11] Franziska Spritzler, RD, CDE, 2020, 12 Healthy Foods That Are High in Iron, Healthline, 20 March 2020, <>

[12] Office of Dietary Supplements 2020, Iron, National Institutes of Health, viewed 21 March 2020, <>

[13] Judith Marcin, MD, 2017, Iron Poisoning, Healthline, 20 March 2020, <>

[14] Verena Tan, RD, PhD, 2017, How to Increase the Absorption of Iron From Foods, Healthline, 15 March 2020, <>

[15] Ryan Drum, PhD 2008, Medicinal Uses of Seaweeds, viewed 30 March 2020,

[16] Office of Dietary Supplements 2020, Iodine, National Institutes of Health, viewed 21 March 2020, <>

[17] U.S. Department of Agriculture 2019, Kale, raw, 323505, viewed 19 March 2020, <>

[18] Jill Seladi-Schulman, PhD, 2018, Manganese Deficiency, Healthline, 20 March 2020, <>

[19] ‘Manganese’ (2020) Wikipedia. Available at: (Accessed: 23 March 2020)

[20] U.S. Department of Agriculture 2019, Nuts, pecans, 170182, viewed 15 March 2020, <>

[21] Erica Julson, MS, RDN, CLT, 2018, Top 12 Foods That Are High in Phosphorus, Healthline, 15 March 2020, <>

[22] U.S. Department of Agriculture 2019, Spelt, cooked, 169746, viewed 15 March 2020, <>

[23] Prasad, A 2008, ‘Zinc in Human Health: Effect of Zinc on Immune Cells’, Molecular Medicine, vol. 14, no.5-6, pp. 353–357

[24] Gibson R. S. (2012). A historical review of progress in the assessment of dietary zinc intake as an indicator of population zinc status. Advances in nutrition (Bethesda, Md.), 3(6), 772–782.

[25] Helen West, RD, 2018, The 10 Best Foods That Are High in Zinc, Healthline, 20 March 2020, <>

[26] U.S. Department of Agriculture 2019, Kale, raw, 11233, viewed 5 March 2020, <>