Polysaccharides in seaweeds

What type of polysaccharides are found in seaweed?

Seaweeds contain large amounts of polysaccharides, notably cell wall structural polysaccharides that are extruded by the hydrocolloid industry: alginate from brown seaweeds, carrageenans and agar from red seaweeds. 

Other minor polysaccharides are found in the cell wall: fucoidans (from brown seaweeds), xylans (from certain red and green seaweeds), ulvans in green seaweeds.

Seaweeds also contain storage polysaccharides, notably laminarin (b-1, 3-glucan) in brown seaweeds and floridean starch (amylopectin - like glucan) in red seaweeds.

Polysaccharides as dietary fibres

When faced with the human intestinal bacteria, most of these polysaccharides (agars, carrageenans, ulvans and fucoidans), are not digested by humans and therefore can be regarded as dietary fibres.

Water soluble and water insoluble fibres have been associated with different physiological effects. Many viscous soluble polysaccharides (pectins, guar gum etc.) have been correlated with hypocholesterolemic and hypoglycemic effects, whereas water-insoluble polysaccharides (cellulose) are mainly associated with a decrease in digestive tract transit time (Southgate 1990).

Fucoidan and potential applications

Among polysaccharides, fucoidans were particularly studied as they showed interesting biological activities (anti-thrombotic, anti-coagulant, anti-cancer, anti-proliferative, anti-viral, anti-complementary and anti-inflammatory).

These properties open up a wide field of potential therapeutic applications, some of which are already the subject of patents concerning notably the anti-coagulant and anti-thrombotic properties (Charreau et al. 1995, Nasu et al 1997, Angstwurm et al. 1997). As for xylans and laminarans, they are completely and rapidly degraded by intestinal bacteria, alginates are only partly degraded and lead to a substantial production of short chain fatty acids.

  • Timothy Kinghan

Pigments in Seaweed and their benefits

The Pigments in Seaweed

Seaweeds are photosynthetic organisms and they can be split into three different colour categories; red, green and brown.

As photosynthetic organisms, seaweed contains a number of pigments that are responsible for the variety of colours observed in brown, green and red seaweeds. Together, these pigments allow seaweed to absorb the light necessary for photosynthesis at depths that have various degrees of light intensity. These pigments can be divided into three main groups which include chlorophylls, phycobiliproteins and carotenoids and have a number of health benefits when consumed. Research concerning these seaweed-derived bioactive compounds has increased significantly in recent years and there is currently considerable interest in the anti-oxidant, anti-obesity and anti-cancer activity of macroalgal pigments.

Chlorophyll: The Green Pigment

Chlorophyll is a green pigment found in both algae and land plants and is necessary for photosynthesis as it facilitates the absorption of energy from light. Chlorophyll and its derivatives such as pheophytin, pyropheophytin and pheophorbide are associated with a number of health benefits including anti-oxidant and anti-mutagenic activity which may help to prevent cancer (Chernomorsky et al., 1999). It is also likely that chlorophyll-derived compounds can bind certain cancer-causing chemicals, such as heterocyclic amines in the digestive tract, thus reducing their absorption (Breinholt et al., 1995; Dashwood et al., 1996).

Phycobiliproteins: The Red-Brown Pigment

Phycobiliproteins are water-soluble pigments that are found in red seaweeds and include phycoerythrin, phycocyanin and allo-phycocyanin. Previous scientific studies have reported that this group of proteins possess anti-inflammatory, liver protecting, anti-viral, anti-tumour, serum lipid reducing and anti-oxidant activity (Sekar and Chandramohan, 2008). Phycobiliproteins are found in red seaweeds such as Chondrus chrispus and Palmaria palmata and are responsible for the red-brown colour of these species.

Carotenoids: β-carotene, Fucoxanthin and Tocopherol (amongst others!)

Carotenoids are important pigments that are found in seaweed but are also present in land plants, microalgae and photosynthetic bacteria. As animals (and humans) cannot produce carotenoids, these pigments must be obtained from the diet. Over 600 carotenoids have been identified but prominent examples found in seaweed include β-carotene and fucoxanthin.

Examples of other carotenoids which are found in seaweed include astaxanthin, violaxanthin, tocopherol, zeaxanthin and lutein (Holdt and Kraan, 2011).

Carotenoids are potent anti-oxidants which prevent oxidative damage to cellular components caused by reactive oxygen species. As reactive oxygen species are associated with the development of many chronic diseases it is not surprising that carotenoids have been linked with the prevention of many chronic diseases (Cooper et al., 1999).

β-carotene: The well-known carotenoid

β-carotene is a well-known carotenoid that is present in seaweeds including Ascophyllum nodosum, Fucus vesiculosus, Fucus serratus, Laminaria digitata, Ulva sp. and Sargassum sp. at various levels. β-carotene is an antioxidant that has been shown to reduce the risk of cardiovascular disease and possibly certain types of cancer (Holdt and Kraan, 2011).

Fucoxanthin: A carotenoid with promising signs of anti-cancerous properties

Fucoxanthin is another carotenoid present in brown seaweeds such as Ascophyllum nodosum and Laminaria digitata. This pigment has received much interest in recent years due to its reported anti-obesity and anti-cancer activity. There is scientific evidence to suggest that fucoxanthin prevents the cellular proliferation of cancer cells in studies investigating prostate, colon, liver, bladder, gastric and breast cancer and also lymphoma. Fucoxanthin has also been shown to induce apoptosis which plays an important role in the prevention of cancer development (Rengarajan et al., 2013).

The presence of health-promoting compounds such as the above mentioned pigments in seaweed makes it an excellent choice for inclusion in pet food. This should enable pet owners to contribute to pet health using a 100% natural and sustainable resource.

  • Timothy Kinghan

Iodine | More important than you think

Iodine is present in the soil and sea waters of the world. The amount in soil is believed to be steadily depleting and it is much more abundant in the sea waters.

With varying levels in the soil it is very difficult to know how much is present in food if the iodine levels are not tested. The soil is also steadily being depleted of iodine meaning the amounts present in land plants is diminishing. Livestock are routinely supplemented with iodine leading to it being present in varying amounts in animal foodstuffs, but the levels in meat and dairy are not tested.

Natural Source of Iodine

Seaweed is known as the best natural source of iodine but care should be taken when introducing it into the diet. This is because if someone is used to low levels of iodine then a large increase in iodine consumption can cause thyroid issues. Start by consuming low amounts and then increase until the desired intake is achieved.

View the "Natural Sources of Iodine" table here

Due to the varying levels of iodine in different seaweed - depending on where they were sourced from, seasonal variations and differences between species, it is recommended to only eat seaweed with verified iodine levels. This is especially true if only beginning to consume sources of iodine as a sharp increase in the daily iodine consumption can have an adverse effect on some individuals. For this reason each batch of our dried and milled seaweed has verified Iodine levels.

Why do we need iodine?

Iodine is an extremely important trace element that cannot be synthesised by the body and is necessary for some very important bodily functions.

  • Normal Cognitive Function: Iodine deficiency can lead to decreased cognitive ability. Low intake of Iodine is believed to be the world’s leading cause of intellectual deficiency.
  • Normal Energy Yielding Metabolism: Metabolism converts the fuel in the food we eat into the energy needed to power everything we do, from moving to thinking to growing.  
  • Normal Functioning of the Nervous System
  • Maintenance of Normal Skin: The healthy development of skin, teeth, nails and bones are all related to normal iodine levels.
  • The Normal Production of Thyroid Hormones and Normal Thyroid Function: The thyroid gland needs only a trace amount of iodine, to synthesize the requisite amounts of T4 and T3 used to regulate metabolism and ensure normal growth and development.
  • Crucial pre-pregnancy, during pregnancy and when lactating. The female body needs to have sufficient levels of iodine before pregnancy as the foetus is reliant on the mother’s thyroid hormones during the first few months of gestation and her iodine supply after this.

“Iodine deficiency is the world’s most prevalent, yet easily preventable, cause of brain damage.” World Health Organisation (WHO)

Iodine Deficiency

Iodine deficiency is a major public health problem for populations throughout the world, particularly for pregnant women and young children. The most devastating outcomes of iodine deficiency are increased perinatal mortality and mental retardation. Iodine deficiency is the greatest cause of preventable brain damage in childhood and can cause adults to not think clearly or produce thyroid hormones.

Iodine deficiency in the UK and Ireland

A 2009 study in the U.K of 14-15 year old schoolgirls showed that 51% were mildly iodine deficient, rising to 85% in Belfast. Their conclusion was that Britain was suffering from iodine deficiency. Likewise, the Republic of Ireland is believed to have a mild to moderate iodine deficient population. 

Established Thyroid issues

Talk to your doctor or endocrinologist if you are suffering from established thyroid issues, like Hashimoto’s thyroiditis, before taking this product or any others with iodine.

Thyroid issues are incredibly complex, and too much iodine can actually exacerbate existing thyroid disorders just as too little can create them, so concrete recommendations can’t really be established. As with many bodily functions and nutrient requirements, recommendations can differ from person to person.

  • Timothy Kinghan

Natural Sources of Iodine

Iodine is a trace element that cannot be synthesised by the body. Due to this it is necessary to obtain the bodies iodine requirements from dietary sources.

Unfortunately though Iodine is not present in many foods and the ones that it is present in tend not to have the levels verified. Hence it is virtually impossible to know how much iodine you are consuming in your diet. The below table shows you the foods that are considered to have the most iodine present in them, the only glaring omission is seaweed - that is by far the best natural source of Iodine. 

Please note the below amounts are only indicative and can very greatly. This is because the amount of Iodine in soils will vary greatly depending on location and fertilisers being used. Iodine is believed to be getting further depleted from much of the soil and this has a direct effect on the amount of Iodine in the plants being grown.

 Natural Food Sources of Iodine



Average iodine/ portion (mcg)

Cow’s milk



Organic cow’s milk







1 egg (50g)





White fish



Oily fish
















1 slice (36g)


Fruit and veg

1 portion (80g)


**Depending on the season, higher value in winter. These amounts will vary greatly and are meant as indicative.

The above table highlights that it is difficult to get sufficient Iodine into the diet, especially for Vegans! Luckily though seaweed is by far the best natural source of Iodine. Many dietary associations and bodies recommend not consuming seaweed as the levels of Iodine can be so concentrated that it can cause an adverse reaction in people who are not used to consuming high amounts. 

To alleviate this issue we verify the iodine levels in each batch of our dried and milled seaweed. This means the consumer knows exactly how much they are eating and whether they are getting sufficient amounts in their diet. Most seaweed products only show the Typical Nutritional Profile of the seaweed in question and not the quantities in each individual batch. To highlight the differences in Iodine levels of different seaweeds, please view the below table.

As mentioned the levels of iodine present will vary but it is a good indicator of how different the iodine levels are depending on seaweed variety.

Seaweed Name Iodine Levels (ppm)
Dulse  150 - 550
Sea Spaghetti  185
Nori 150 - 550
Laminaria Digitata 800 - 5000
Alaria 165
Irish Moss 200 - 300
Sea Lettuce 240
Sea Grass 780
Bladderwrack 500
Sugar Kelp 5000
Sargassum 30
Ascophyllum 700 - 1200


Amount of Iodine needed daily

How the daily Iodine intake is calculated

In the Western world the RDA of iodine is based on providing enough iodine for the thyroid glands to produce the two thyroid hormones triiodothyronine (T3) and thyroxine (T4). It is necessary to consume it as the body can not produce iodine from other sources.

These two hormones are used in every tissue throughout the body where they control metabolism amongst other functions.

Simple Definition of Metabolism

“Biology: the chemical processes by which a plant or an animal uses food, water, etc., to grow and heal and to make energy"


So the Thyroid hormones help the body use energy, stay warm and keep the brain, heart, muscles, and other organs working as they should.

However, in addition to helping the thyroid produce hormones, iodine is believed to be used in other organs, as some of them have a sodium-iodide symporter pump. This means that they are able to absorb and use iodine. However these functions are not accounted for in the RDA's.

Reason to introduce iodine slowly into the system
Before you view the RDA, a quick note on the the introduction of iodine into the system. This is for people who are deficient in iodine.

If someone has been existing with iodine deficiency then their body is used to operating on low levels of iodine. To avoid any adverse reactions from an increase in iodine consumption it is advisable to introduce the iodine slowly into the body and to be aware of the level available in the food that you are eating (find out natural sources of iodine here).

Also, though the occurrence is rare, in less than 1%, iodine consumption can cause allergies, swelling of the salivary glands and thyroid, and iodism.

Recommended Amounts of daily Iodine by Worldwide bodies

 Age                                   Adequate Intake (µg/day)
7 – 11 months 70
1 – 3 years 90
4 – 6 years 90
7 – 10 years 90
11 – 14 years 120
15 – 17 years 130
≥ 18 years 150
Pregnancy 200
Lactation 200

Source: P33 EFSA Journal 2014; 12(5):3660

Iodine Global Network (IGN), WHO and UNICEF

 Age (Years)                                 Daily Amount (Micrograms/mcg)
0 - 5 90
6 - 12 120
Older than 12 150
Pregnant and Lactating Women 250

(Source: Iodine Global Network, 3. How much iodine should we get?,

Food and Nutrition Board (FNB): Institute of Medicine of the National Academies

 Age Daily Amount (Micrograms/mcg)
Birth to 6 months                          110
7 - 12 months 130
1 - 3 years 90
4 - 8 years 90
9 - 13 years 120
14 - 18 years 150
19+ years 150
Pregnancy 220
Lactation 290

Tolerable Upper Intake Levels

 Age                                              Daily Amount (Micrograms/mcg)
Birth to 6 months Not Possible to Establish
7 - 12 months Not Possible to Establish
1 - 3 years 200
4 - 8 years 300
9 - 13 years 600
14 - 18 years 900
19+ years 1100
Pregnancy 900
Lactation 1100
Source: Updated: February 11, 2016

To help you meet the RDA’s and to prevent excess consumption, it is good to know the dietary sources of iodine and the foods that can prevent the absorption of iodine within the body.


  • Timothy Kinghan