Irish Moss Uses and Plant Monograph
I first met Chondrus crispus when I moved from Florida to Massachusetts for college and was studying marine biology. Irish moss is a seaweed that you don’t always see at first, much in the same way that you might not see plantain at first when you look at a field, and then you realize it’s all over under your feet.
Irish moss is a short and stubby seaweed with craggy edges, growing tight and close to the rocks, just like moss on land. But when you get close, you realize they have this deep brown burgundy color and shimmer with silvery iridescence in the sunlight.
I love their fierce tenacity, living in the intertidal zone where winter storm waves crash and daily tides sweep in and out. For me, as a white person descended from coastal European countries, seaweed is deep ancestral medicine. Irish moss is a food that sustained my ancestors and nourished the soil for their crops. Every time that I interact with Irish moss, and any of the North Atlantic seaweeds, it feels like a homecoming, and an honoring of the mysterious and mundane ways that we connect to the sea.
Irish Moss Uses & Plant Profile Summary:
- Botanical Name: Chondrus crispus
- Other Common Names: Irish moss, carrageen moss, carragheen, carraigín (*not to be confused with Jamaican/Caribbean sea moss, Gracilaria spp. + Eucheuma spp., though the medical and culinary applications are interchangeable)
- Family: Gigartinaceae
- Parts Used: whole plant, which for seaweeds is called the thallus. Generally available in commerce as whole leaf, flakes, and powder
- Energetics: Neutral to cool, moistening
- Taste: salty, minerally, a little bitter
- Plant Properties: antioxidant, anti-inflammatory, antiviral, demulcent, emollient, hypoglycemic, hypolipidemic, nutritive, tonic, bulking laxative (mild)
- Plant Uses: Vitamin and mineral dense food, antiviral for a wide range of pathogens, soothing therapeutic for GI and respiratory tract, skin support for rashes, burns, and other irritations
- Plant Preparations: food, powder, cream/lotion, infusion, tincture
Applications
The most distinctive feature of Irish moss, and the source of most of its medicinal benefits, is the presence of polysaccharides called carrageenan. Carrageenan is extracted from seaweed by heating it in water and forms a luscious, gooey gel. The Latin name “chondrus” actually comes from the Greek “khóndros” meaning cartilage, which is a reference to that gelatinous carrageenan. Depending on the water to seaweed ratio, the carrageenan can be thick enough to “set” in the same way as gelatin or agar does (the latter also extracted from seaweeds).
This gelatinous property is why Irish moss has been used as a food thickener for centuries and why carrageenan continues to have widespread industrial food and cosmetic applications today. Due to the difficulty in mass cultivation of Irish moss, the carrageenans generally found in food products are synthesized from other species within the Gigartinaceae family.
A Functional Food
Irish moss has always been a food plant, and is perhaps most known in this context for being used as a life-saving food during the Irish potato famine of 1846-48.1 Outside of famine times, seaweed has been a supplemental food for humans and livestock alike in coastal communities of Ireland and the UK.
Seaweeds are excellent at taking in the dissolved vitamins and minerals in ocean water and storing them in their fronds; and Irish moss contains notable high levels of calcium, iron, potassium, magnesium, manganese, and copper.2 The calcium in seaweed is actually more bioavailable than that in milk — but you need to eat a lot more seaweed than milk to get the same amount!3 There is also a good amount of vitamin B12 but not in a form that is bioavailable to humans, so it is not an adequate supplement for vegan diets.4 Additionally, Irish moss is an excellent source of polyunsaturated fatty acids (PUFAs).5 Seaweeds are known to be rich in iodine, and while much lower than in the kelps and bladderwrack, Irish moss does have a higher iodine content than most other red seaweeds. Irish moss (as well as seaweeds in the Rhodophyta phylum generally) is also high in protein6 and contains appreciable levels of the amino acids arginine, glutamic acid, citrulline, and taurine.7
Irish moss definitely has a strong briny flavor, so I recommend cooking it in dishes with other strong flavors, or in meals with multiple seaweeds where you are going for that particular flavor palate. However, you might want to use this seaweed in the kitchen for reasons other than the vitamin and mineral content! The carrageenan gel can be used to thicken soups and stews (without adding intense low-tide flavor) and has been used for centuries to make a delicious pudding called blancmange (see recipe below). If you’re wondering why you would use this seaweed gel rather than just adding some cornstarch or gelatin to a recipe, keep reading!
Topical Emollient
Carrageenan gel is fabulous when applied to the skin! I love making a cream that includes a carrageenan-rich seaweed infusion that is great on burns (including sunburns), rashes, and scrapes. The mucilage helps keep moisture on skin longer and feels so silky. I also find that there is something distinctively cooling about it. (And as a bonus, it really helps to emulsify a homemade cream which can be notoriously difficult to accomplish!) See the basic recipe below in the Preparations section.
GI Support
Internally, carrageenan gel is wonderfully soothing to an irritated GI tract, whether that be ulcers, heartburn, sore throat, or IBS presentations.8 It also functions as a prebiotic, feeding the favorable gut bacteria.9 So during convalescence or post-antibiotic use, this could be a helpful one to add to broth and soups! When taken with plenty of water, the soluble fiber of carrageenan also becomes a gentle bulking laxative that can help support bowel motility in periods of constipation.
Respiratory Support
In general, herbs and plants that are demulcent are considered soothing for the respiratory tract because of shared nerve channels between the nerves in the GI tract and those in the lungs. The result is that even though the plant constituents are not actually touching lung tissue, they have a “reflexive” soothing and tonifying effect on lung mucus, cilia, and smooth muscle. In the context of Irish moss, there are a lot of historical records stating its use as a therapeutic for coughs, bronchitis, and other lower respiratory conditions, especially on the cold, damp coasts of northern Europe.10 When Irish moss is cooked, that carrageenan gel that is so lovely on the skin and GI tract also becomes a remedy for respiratory issues. When the cilia in lungs function properly, they are able to clear excess mucus up and out of the lungs, hence the use of Irish moss as an expectorant. Soothing the respiratory muscles helps reduce inflammation of the airways, making this a helpful tonic for asthma, COPD, and even long-term smoking or smoke exposure.11
Cholesterol + Blood Glucose:
When we consider the applications of a focused carrageenan dietary supplement, there is some interesting research. In a small clinical trial in 2014, participants who received a carrageenan supplement for 20 days had markedly lower triglycerides and lower low-density lipoproteins (LDLs) at the end of the study.12 Another clinical trial in 2020 had participants taking a carrageenan jelly or placebo for 60 days, after which those taking the jelly had significantly lower total cholesterol and lower LDL levels.13 Neither of these studies were using whole plant preparations, but given the ease of extracting carrageenan from Irish moss, this seems like a place for so much more research and experimentation.
Adjunct Antiviral Therapeutic
This realm is where we start to see current research building on traditional and folk uses, and some really interesting extrapolatory therapeutics emerging.
HPV
In 2011, a clinical trial was conducted to primarily test the effectiveness of a carrageenan-based cream Carraguard against HIV infections, and secondarily high-risk human papilloma virus (HR-HPV) infections. While the cream was not effective against HIV, it significantly reduced the prevalence of HR-HPV in trial participants.14 Following this, a 2019 clinical trial administered a carrageenan-based vaginal microbicide cream to cis women with gential HPV infections of various strains, and resulted in 60% of patients testing HPV-negative at the conclusion of the study.15 Herbalist Lauren Giambrone has been working with HPV for over a decade, and uses Irish moss tincture in her protocols alongside other antiviral and tissue tonic herbs. She also recommends mixing the infusion of irish moss with chaparral in a sitz bath for active HPV infections and is experimenting with making personal lubricants using carrageenan gel!16
COVID-19
As we now know, the SARS-COV2 virus infects a body via the ACE-2 receptors that are present on cell walls of various tissues throughout the human body. Thus, a substance that inhibits ACE-2 binding effectively inhibits COVID-19 infection.17 Several in vitro studies have shown that sulfated polysaccharides from red seaweeds (carrageenan) competitively bind with the ACE-2 receptors, effectively blocking the spike proteins on the viral envelope of various coronaviruses from attaching and infecting the host cell.18
Two in vitro studies in 2021 focused on the application of carrageenan in nasal/mouth sprays to treat SARS-COV2. Human endothelial cell cultures were grown and administered carrageenan sprays, which showed effective inhibition of viral replication, without damaging the cells.19,20
After these studies, several clinical trials were conducted with human subjects, including one where 394 health care personnel were administered a carrageenan-derived nasal spray or placebo, and the carrageenan group had significantly lower infection rates!21 Nasal sprays such as these are still undergoing clinical trials before being available to the general public.
Constituents
- Polysaccharide: carrageenan (sulfated galactans), specifically lambda-carrageenan22
There are numerous naturally occurring and lab-synthesized carrageenans. Red seaweeds most commonly have iota-, lambda-, and kappa- carrageenans.
- Carotenoids: Beta-carotenes (these are largely responsible for the antioxidant effects)23
- Polyunsaturated fatty acids (PUFAs)
- Tannins (small amounts)
Botanically Speaking
Seaweeds are divided into three groupings based on their signature pigments — Reds (Rhodophyta), Greens (Chlorophyta), and Browns (Phaeophyta). Irish moss belongs to Rhodophyta. Seaweeds are different from vascular land plants in that they do not have true roots or vascular tissues (xylem and phloem). Those species (such as Irish moss) which are not free floating stay anchored with a structure called a holdfast, which looks remarkably similar to roots but does not take up water or nutrients. Seaweeds take in water and nutrients via diffusion through all of their cells. While land plants have stems, seaweeds have a stipe. And rather than leaves, we call them fronds or blades, depending on the species. The whole seaweed body is called the thallus.
Irish moss can be found in Northern intertidal waters on both sides of the Atlantic, as well as into the Mediterranean, Baltic, and Black Seas. They grow on rocky shores just above the low tide mark, as they don’t love being exposed to air and direct sunlight for too many hours in a row. The thalli are short and branch quickly into tufts of fan-shaped fronds which are dark reddish-brown with violet iridescence at the tips. Total length rarely exceeds 6 inches. Irish moss is commonly found growing alongside a morphologically similar red algae, Mastocarpus stellatus, which is also edible, and can be used for similar medicinal applications. The life cycle of Irish moss is rather complex, alternating generations of gametophytes (male and female, produdicng half sets of chromosomes for reproduction) and sporophytes (asexual, contain a full set of chromosomes).24 Gametophytes and sporophytes can all be found growing in the same zone and are indistinguishable except for when the spores form. They can also reproduce vegetatively by growing new fronds from existing holdfasts, or from any part of the thallus.
Irish moss is a frequent find in seaweed that washes ashore after storms, often bleached of color or looking slightly pink. These are fine for using as compost in your garden, but for medicinal use, the seaweed should be harvested fresh!
Harvesting Notes:
Seaweeds are generally fast growing, but harvesting requires care to ensure their continued survival. Use a sharp knife or scissors to cleanly cut off a portion of the thallus, leaving the holdfast and several of the fronts/blades attached. As long as these structures are intact, new growth will originate from the cut place. Also note that seaweeds will accumulate whatever is dissolved in the water into their tissues, so do not harvest in polluted areas or near waste water outlets.
While seaweed harvesting is an exciting and immersive activity that I encourage you to experience if you have access to some ocean coastline, it is not possible for most people. To fill the need there are many seaweed farmers and wild-harvesters. Atlantic Holdfast Seaweeds and Maine Coast Sea Vegetables are direct sources for dried Irish moss, and you can also find it from Mountain Rose Herbs and other larger herb sourcing companies.
Plant Preparations and Dosage Suggestions
Culinary:
Whenever you prepare seaweed for eating, take a moment to check for tiny snails or other organisms that might still be attached to the seaweed!
- Mix the powdered seaweed with sea salt and other powdered herbs for an ocean-mineral infused cooking or finishing salt. I especially love this on eggs!
- Use the powder form as a cornstarch substitute in sauces.
- Add 1–2 tsp powder to smoothies – it will essentially dissolve and blend right in. It won’t make the smoothie thicker though, as heat is needed to extract the carrageenan.
- Making pudding
There are so many recipes for blancmange and other seaweed thickened desserts on the internet, but here is one I have used that is adapted from the Maine Coast Sea Vegetables Blog:
Ingredients
- 1/4 cup Irish Moss Flakes
- 2 cups milk of your choice (I like ½ coconut + ½ almond)
- 2 TBS sugar or honey
- For flavor — 1 tsp vanilla extract, or 1 TBS cocoa powder, 1-2 TBS lemon zest or grated ginger, or really any flavoring that you like! Infuse the milk beforehand with some other botanicals for an extra exciting treat!
Instructions:
- Rinse seaweed flakes several times with cold water in a sieve to remove any rocks or shells.
- Soak flakes in cold water for 1/2 an hour.
- While the flakes are soaking, pour the milk into the top part of a double boiler and begin to warm it slowly.
- Put flakes in a muslin bag, or tied in cheesecloth and add to milk.
- Bring the milk to a gentle boil, then simmer the mixture for a 1/2 to 1 hour, stirring occasionally and pushing the bundle of flakes against the edge of the pot to squeeze out the carrageenan.
- Stir in your flavoring of choice while the milk is hot and starting to get thick but before the mixture fully gels.
- Continue stirring and squeezing the Irish Moss bundle until the mixture reaches a noticeably thick consistency. Turn off heat, remove the seaweed bag, and pour into ramekins or small cups and allow to cool for at least an hour in the refrigerator before enjoying!
Yield: approx 2 cups pudding
Topical Preps:
To make a cream:
I love making seaweed infused creams! I use Rosemary Gladstar’s basic cream recipe and make a seaweed extraction for part of the water phase.
- Put the ¼ cup of Irish moss flakes in a muslin bag, and place in a saucepan with 2 cups of water. The amount of seaweed you use is pretty flexible though, and generally you end up with more gel than you need! Heat just to a boil, then reduce heat and simmer for 20–30 mins. The seaweed should start releasing carrageenan and becoming gelatinous.
- Turn off heat, and let cool just until you can handle it and squeeze as much goo as possible through the cheesecloth and into your water.
- Use this gelatinous carrageenan-filled solution as the water phase for making any cream! You can also just apply this gel (once cooled to room temp) straight to any areas of skin irritation or dryness. It’s cooling and moisturizing, and is also safe for scratches and abrasions that aren’t fully closed yet.
** I recommend combining with a hydrosol or adding essential oils to your cream to help mask the slightly briney scent of freshly made seaweed extract.
Internal Preparations:
Tincture: dried 1:5, 40% (low alcohol percentage is best to keep polysaccharides intact, and tincture should be gently heated to help carrageenan extraction. Lambda-carrageenan is soluble at the lowest temperatures, so of the red seaweeds, Irish moss is your best bet for this to be successful!)
Infused vinegar: add whole dried seaweed to a jar, cover with vinegar and let sit for at least two weeks, shaking daily. Add honey if desired. If using a metal lid, make sure to put a layer of parchment paper between the jar and the lid to prevent any metallic corrosion from entering your infusion. Use on cooked veggies or in salad dressings!
Energetic Medicine
Just as we use flower essences as a gentle but powerful remedy, seaweed essences are also wonderful. Generally, seaweeds hold an energy of staying anchored to self amidst big change and upheaval (think of those holdfasts, gripping tightly to rocks amidst daily tides and crashing waves). More specifically, I think of Irish moss as an essence for finding playfulness, and even pleasure, within the struggle.
Special Considerations
There is no clinical research on the safety of Irish moss in pregnancy or lactation, but given that this plant has been used as a substantive food for hundreds of years, it is most likely safe.
Herb/Drug Interactions: for orally consumed medications, the polysaccharide gels of demulcents (such as Irish moss) can interfere with drug absorption (generally slowing it), decreasing efficacy of the drug. Take oral medications several hours apart from consuming Irish moss gel.
A note on thyroid conditions: there is sometimes concern that the high iodine levels in seaweeds can be detrimental to hyperthyroid conditions. While all seaweeds are high in iodine, Irish moss contains far less than the kelps and other brown seaweeds. Additionally, up to 90% of iodine in seaweed is lost during cooking; so if excess iodine is of concern, use this seaweed in a cooked preparation.
Footnotes
The Herbal Remedy Vault has all of our printable recipe cards...
