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Sari Rumpai Laut
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Medicinal Uses of Seaweeds


Updated from Gaia 2008 Conference Notes

Seaweeds offer a wide range of therapeutic possibilities both internally and externally. The term Seaweeds in this case refers only to macrophytic marine algae, both wild and cultivated, growing in saltwater.

Botanically, seaweeds are classified as Green, Brown, or Red. A particular seaweed’s placement in one of these groups is determined first by its photosynthetic pigments, then its reproductive mode, then its micro and macro morphologies, and finally by its phycopolymers. The obvious visual color of a particular seaweed species may not match its taxonomic color, which can be confusing to the beginner. Persevere.

Here I will discuss seaweed’s primary and secondary metabolites and some of their respective peculiarities and therapeutic uses. References are provided for further information .

Simply eating unprocessed dried seaweeds can yield many healing benefits. Many physical ailments in both humans and their companion animals can be regularly resolved with the simple addition of seaweeds to their respective diets. Although therapeutic seaweed constituents can be extracted singly or in clusters, in cases of chronic conditions, I usually recommend patients eat seaweeds, not extracts. I prefer the seaweeds to be eaten uncooked in most cases. The digestive flora in a particular person may take up to 4 months to agree to produce dedicated enzymes to thoroughly digest dietary seaweeds. Oftimes the individual’s enteroflora must commit resources to recognizing the molecular structures on and in seaweeds and subsequently use them as food. This is the basis for the recommendation that it is far more productive to eat a small amount of seaweed daily rather than larger amounts occasionally. The key to bacterial dietary adaptation is continual exposure to the new food material. Consequently, positive therapeutic changes caused by eating seaweeds regularly may take several weeks to several months to become obvious.

When patients are oral adverse to the tastes, smells, and/or textures of seaweeds, I urge them to add seaweeds as small pieces or powder(s) to foods strongly flavoured with spices such as: cayenne, fried onions, raw garlic, chili powder, curry, or vinegar.


Seaweeds as the Best Dietary Sources of Essential Minerals

All essential minerals are provided by dietary seaweeds. No land plant even remotely approaches seaweeds as sources of metabolically-required minerals(See Bergner1997). Seaweeds can provide minerals often absent from freshwater and food crops grown on mineral-depleted soils. In addition to eating seaweeds regularly, those gardening for food can use copious amounts of seaweeds for mulch and fertilizer(Traditional Irish fertilizer, see: Man of Aran, and The Field), add seaweeds abundantly to compost, and even make seaweed tea sprayed directly onto leaves for foliar feeding through the stomates , as ways to therapeutically get trace elements into patients a trifle covertly.

Leon Uris in his novel, Trinity, delightfully describes the social scene accompanying “kelping” by the Irish.

Seaweeds are 20-50% dry weight mineral(Kazutosi, 2002). This figure is obtained by burning off seaweed’s organic material and weighing the remaining ash. The elements abundant in seaweeds include: potassium, sodium, calcium, magnesium, zinc, copper, chloride, sulfur, phosphorous, vanadium, cobalt, manganese, selenium, bromine, iodine, arsenic, iron, and fluorine. 

The large Brown seaweeds (Laminaria species ( known collectively as Kombu), various kelps(Icelandic kelp, Norwegian kelp, Bullwhip kelp,Sugar kelp,Giant Pacific kelp, and Hijiki), Bladderwrack, Rockweed, Sargassum, Wakame, and Sea Palm, tend to contain more minerals per unit weight than the Red seaweeds (Nori, Irish Moss, Dulse, Grapestone, and Euchemia). 

Many human body substances require particular mineral elements as part(s) of their respective structure. Examples are iron for hemoglobin and iodine for thyroxine.

For our bodies to function, we use proteins called enzymes. Most enzymes require one or more coenzymatic factors; these coenzymatic factors are usually one or more metals. cations. Chronic dietary shortages or disease-related mineral depletions can produce both specific and general disease conditions: Iodine shortage results in varying degrees of thyroid dysfunction; poor absorption of dietary calcium can result in osteoporosis. Adequate residential body mineral supplies are critical for optimal body system functioning. My personal observations support the notion that non-specific disease categories such as Chronic Fatigue, lack of energy, subclinical depression and depressed immunity are probably due to inadequate minerals either in the diet and /or in the body. Many times I have seen chronically exhausted patients exhibit complete symptom resolution after several weeks of adding 5-10 grams of seaweeds to their daily diets. 

In the hydrated seaweeds, raw or cooked, minerals are mostly in aqueous solution and readily available for intestinal absorption in humans. These accumulated minerals can be loosely considered primary metabolites. Even though they are not manufactured by the seaweeds, they are concentrated against the osmotic gradient to cause a much higher concentration of each mineral inside seaweed cells and intercellular spaces than in the surrounding seawater. This enables seaweeds to use water equilibrium mechanics to move materials in and out of their cells. It is no accident that seaweeds concentrate metal cations and other elements many times their respective concentrations in seawater. They have almost unlimited access to mineral resources unavailable to most land plants and animals.

CAUTION: Celtic Sea Salt and other designer so-called natural or raw, evaporated seawater sea salt products are not good sources of some trace elements, particularly iodine, iron, copper, and selenium. This is unfortunate since just plain sea salt is basically healthier than the modified commercial table salts.

The single most important element provided by seaweeds, is Iodine. It is more abundant in seaweeds, any seaweed, than any plants or animals. Land plants, vascular plants in particular, seem to have no detectable iodine requirement.

ALL vertebrate animals REQUIRE IODINE. This iodine is used in thyroid hormones, T4, thyroxine, and T3, tri-iodothyronine to control all fetal development, postnatal growth, and ongoing daily body metabolism. No iodine, no vertebrate life. The choice of iodine seems to have been its isoptopic stability: there is only one known natural iodine isotope, iodine 127. It is reliable, not subject to radioactive decay.

When vertebrates lived in the sea, even at about 60ppb, there was a constant reliable source of iodine. Since some vertebrates left the sea, obtaining enough iodine has been a challenge to their descendants, including ourselves.

Since no land plants have a need for iodine, their taking it in from roots or leaves may be just incidental. That has meant that few land plants are reliable or even adequate iodine sources unless consumed in large quantities as by large herbivores. Plants grown proximal to the marine environment and those deliberately fertilized with seaweeds can accumulate enough iodine to provide adequate dietary supplies for herbivores and humans. Potatoes, garlic and other root crops are the best accumulators and dietary sources of plant-based iodine supplies.

Eating 3-5 grams of most dried, unrinsed seaweeds will provide the RDA of 100-150 micrograms. 

Lack of iodine can cause developmental structural and neural fetal abnormalities collectively called cretinism. This condition, directly as a result of low maternal iodine supplies, is difficult to correct postpartum, if at all. The treatment is adequate maternal iodine consumption from the mother’s initial beginning as an egg in her maternal grandmother.

That means treating the problem 2 generations before a particular pregnancy. In the moment, maternal iodine supplies can be monitored by maternal urine testing and any deficiencies immediately corrected by adding dietary iodine. Mammalian fetal iodine need is about three times per unit body weight of the mother.

In adult humans, chronic low iodine consumption often results from iodine deficient soils and water, and consequently low iodine food. The human consequence is: first, goiter, an enlargement of the thyroid gland, deliberately generated by TSH (thyroid-stimulating Hormone) to increase thyroid gland cell surface area and more “iodine traps”,and secondly, various manifestations of hypothyroidism.

The treatment is often simply more dietary iodine for both conditions And this can be easily accomplished with dietary seaweeds.

Chronic pernicious human iodine deficiency developed during 7000 of continuous extractive agriculture in the interior of China resulting in tens of millions of near-cretinous citizens by the mid-1900’s. For treatment,the Chinese developed warm-water Laminaria kelp varieties which they now cultivate in great quantity with entire villages growing and processing up to 650,000 metric tons each year to provide more than enough dietary iodine for 1.5 billion Chinese(Druehl,2000). This is a most curious successful marvel; nearly 5000 years ago, in an herbal attributed to the Emperor Shen Nung, goiter was described, and the treatment was seaweed, apparently Fucus. Nori seaweed was also touted as the most wonderful elixer (Katzutosi).

CAUTION: Some individuals are extremely sensitive to iodine. A little bit too much intheir diets and they begin to exhibit hyperthyroid signs and symptoms: nervousness, heart palpitations, sleeplessness, irritability and even iodine-induced goiter. If these symptoms appear, first inquire about seaweed/iodine consumption(from any source, including dairy and baked goods). Individuals with “seafood allergy” seem especially sensitive to iodine. Contrary to some practitioners and their believing patients, nobody has “iodine allergy”. No iodine, no life.

Icelandic kelp, 8000ppm, Norwegian kelp 4000ppm, Atlantic kelp 1500-2000ppm, Pacific kelps 500-1200ppm, Fucus spp. 200-500ppm, Wakame 50-150ppm, Sargassum 35ppm, and Nori 15 ppm. These are all approximate and will vary considerably by season, location, age, and harvest practices.

The Japanese and other Asians apparently usually soak their Kombu and other seaweeds in freshwater for 10-30 minutes prior to using in miso broth and other cooking , which removes about 60% of the iodine (Hazutosi). Curiously, I was told by Japanese nationals that the kombu was left in the miso broth for 10-20 minutes and then discarded.

The soaking or prolonged rinsing of high-iodine content seaweeds may reduce the risks for excess iodine-induced disease. 

For some interesting views on iodine and health, please see Guy Abraham MD’s website,

The iodine story as related to human health took an interesting turn when Uranium was used to cause nuclear fission: one of the decay products of nuclear explosions is Iodine 131. That means not only nuclear weapons, bombs, but also, all of the controlled nuclear events in Nuclear reactor fuel rods. ALL NUCLEAR FACILITIES release radioactive Iodine 131 into the atmosphere. Hundreds of them are licensed to do so. This means that we are all continually and erratically dusted with Iodine 131 every day of every year. As shown by reliable research for over 50 years, nuclear power plant stack gases circle the earth in 3-5 days, continuously dusting us all until all settled. Additionally, there are nuclear disasters, such as Three-mile Island in USA and Chernobyl in Ukraine. The Chernobyl disaster on 26.April 1986 released enormous quantities of Iodine 131 into the atmosphere. Since then, millions of iodine131-induced thyroid disease patients have been reported worldwide starting shortly after the event and continuing today. Relatively rare 20 years ago and unknown prior to 1945, thyroid cancer is now the number one cancer in children in USA. Thyroid cancer is one of the fastest increasing cancers in both adult men and women.

Iodine 131 is hazardous because our bodies will happily take it in if we need iodine. Since prior to the human atomic age there was no iodine 131, we have no defense against it if we need iodine, and no way to selectively excrete it. IF we have sufficient iodine in our bodies, Iodine 127, the only natural iodine isotope, our bodies will not take in the heavier iodine 131. How the weighing is done is an interesting question to be considered elsewhere. The critical information is: if we continually take in 150 micrograms of iodine 127 daily, we will most likely be protected from iodine-deficiency “iodine aggressive uptake”. We can do this by eating 5-10 grams of seaweeds daily. If we are worried about iodine 131 which reasonably might be expected in the seaweed, we can let the seaweed iodine 131 if any, decay for 8 weeks. How do we know and expect this seaweed iodine to be protective against iodine 131 fallout and decay? The Polish example. Within hours after the onset of the Chernobyl disaster, Polish authorities acted to get iodine solutions, potassium and sodium iodide tablets, even seaweed tablets and capsules into as many of their citizens as possible to protect them from the nearby huge amounts of iodine 131 coming their way. Over the intervening 20 years, the Polish people treated with iodine 127 have almost 1000 time less thyroid disease than neighboring countries even further than Poland from the Chernobyl disaster site.

Unfortunately, ALL Nuclear Power Plants are nuclear disasters waiting to happen. Not because of evil intent (we hope) but because of mechanical and materials deterioration and human error. Hundreds more nuclear power plants are planned, especially by developing countries anxious to reduce their energy dependencies on fossil fuels. Of course, that will mean increasingly huge amounts of radioactive iodine 131 into the atmosphere and huge quantities of nuclear waste begging for safe disposal. Simpler of course, would be to boil water with solar mirrors. All nuclear power plants so far are just fancy water boilers. Strange.

Eat your seaweeds.
Iodine passes readily through the epidermis, and alveolar cell walls into the body in addition to intestinal absorption. This means that any iodine 13l we breath or get on our skins is likely to be absorbed if we are the least bit iodine 127 deficient.

How is iodine 131 hazardous? It radioactively decays with a half life of about 8 days. This means in 8 weeks, there is probably not much left in a particular sample, and not enough to cause radiation damage. Iodine 131 decays with the release of a high energy Beta particle, which crashes ionizingly through adjacent tissues, and ionizing high energy gamma radiation. There is no safe exposure to radioactive-decay sourced ionizing radiation (Shannon, 1995) 

All living cells, and that means all of our cells, need potassium all of the time to function and stay alive. There are no exceptions. Our bodies have no innate potassium conservation mechanisms. The human evolutionary assumption seems to be that we will always have plenty of potassium available in our wild and live food diets, since all living cells require potassium. This is in contrast to sodium, also an essential element, for which we have a very rigorous sodium conservation mechanism.

The human tongue, just as the average beginning analytical chemistry student, seems to have difficulty distinguishing potassium from sodium: both taste salty. In equal amounts, potassium is up to 8 times saltier than sodium.

Often, overwrought patients will complain of constant “salt cravings” even though they eat a lot of salty foods.”I just can’t seem to get enough salt” is a common statement. These people are often overweight, puffy (edemic), and complain of exhaustion. I suggest high-potassium powdered seaweed (almost any seaweed, although the kelps tend to have more potassium than other seaweeds) up to 10 grams daily until symptoms resolve. So far, I have not encountered any indications of potassium toxicity which might have been caused by excessive consumption of hi-potassium seaweeds, although such poisoning may be possible. If practitioners are concerned, prescribe less seaweed consumption at any one time.

I believe that almost any craving for salt in our dietary times of heavily salted, with sodium chloride, home-cooking, restaurant meals, and preserved foods is a strong indication of potassium deficiency, especially in pregnancy. 

Potassium is essential for even minimal nerve and muscle functioning, and as a cross-membrane transporter ion for neurotransmittors and hormones. I have observed that adding high-potassium foods, especially seaweeds, to the diets of ADD children (instead of Ritalin) and adults can significantly improve behavior and mental functioning.

Similarly, fibromyalgia patients, the exhausted, the forgetful, the moody, the agitated, anxiety disorders, and depression are all favorably improved with high-potassium diets and seaweeds. 

YES! Before grabbing the herbal nerviness and muscle analgesics, try feeding the nerves and muscles their essential mineral foods: potassium, sodium, calcium and magnesium The last three, are all abundant in all seaweeds: sodium,2-4%, calcium 0.5-1.0%, magnesium 0.2-1.0%.. In addition to optimal nerve and muscle functioning, these four elements are important in transporting many substances along the intercellular integrin network.

Many women patients eating seaweeds to reduce PMS symptom severity report a distinct cyclical waxing and waning of seaweed cravings.

Selenium is present in all seaweeds in physiologically significant amounts.

Selenium is, like its partner in thyroid hormone metabolism, apparently not required by any land plants although some do concentrate it (Brazil nuts are the usual culprit). No selenium, no thyroid hormone production and conversion of T4 to T3.

Selenium is present in all edible animals, and is easily absorbed from eggs in the diet. Selenium is required for many critical metabolic actions besides the selenodeiodinases. 

Men usually have a much higher selenium demand than women because, like zinc, it is secreted in the male reproductive ejaculate, and must be replaced to maintain ejaculate production and sperm fertility. Check for selenium deficiency in males with fertility issues.

All seaweeds contain a large proportion (25-40%) of mucopolysaccharides , collectively referred to as Phycopolymers. 

The brown algal phycopolymers are algin and fucoidan, both sulfated galactans.

Algin has great therapeutic value as a heavy metal detoxifying agent.. When added to the diet as a component of edible brown seaweed, algin powder, or sodium alginate, it can bind heavy metals present in the food stream and carry them out with the stool, since algin is generally not digestible(Schecter.1997).

Excretory algin tends to bind metal ions presented in the small intestine from distal body locations. A complex diffusion gradient transport system will move poisonous metal atoms a few at a time to the intestine for probable binding to insoluble dietary fiber. Apparently this is a way of removing hazardous metals in a way which avoids damaging the kidneys. Regular eating of even small amounts of brown algae can be an ongoing metal detoxification practice which can reduce the quenching of enzymes by heavy metals.

Hair analysis can be a better predictor of excess metal poisoning than blood or urine analysis because the body seems to use the sulfhydral groups in hair proteins as an excretory mechanism which also protects the kidneys. If a patient presents with relatively high levels of toxic metals in hair, blood, or urine, the addition of 3-5 grams brown seaweed to the daily diet will help remove those metals from the body, but not the hair, of course.

Using brown algae as part of an aggressive metal removal treatment plan is recommended for both acute and chronic exposures and actual poisoning. Reducing further exposure to heavy metals is of course essential for a metal removal plan to succeed. I usually recommend a lot of rolled oats in the diet ( every morning) to aid the seaweeds in metal removal. For some persons, adding the seaweed to the oatmeal seems to hasten metal removal. This combination will tend to bulk the stool and reduce transit time. I also encourage at least 2L of water (just water, not drinks) intake daily; as well as frequent hot baths and saunas with vigorous dry skin brushing before and after each bath or sauna.

Chronic Passive Metal Poisoning
Industrial activities, mining, and nuclear power activities release relatively large amounts of usually unseen toxic metals into our air, water, and unfortunately onto our food crops. We are all being continually poisoned.

From nuclear facilities (radioactive medical wastes are increasingly a source of radioactive metal poisoning) we are exposed to radioactive isotopes released into the air by way of gaseous emissions and radioactive substances released into cooling water.

Since most of these exposures are probably going to continue for the foreseeable future, we are advised to do what we can to reduce their negative health effects. The best action may be to eat a diet that is continually detoxifying our bodies. Regular seaweed consumption should be a part of that diet. 

I predict that age-related dementia and perhaps Alzheimer’s can be prevented or suppressed by regular consumption of algin-rich brown seaweeds, to slow the bioaccumulation of neurotoxic metals. The kelps and popular dietary brown seaweeds can do this.

Some of the salts of alginic acid present in aqueous solutions in ingested brown algae, such as potassium and sodium alginates, are digestible by intestinal flora. The metals they contain are released into the food stream and tend to be bound up by the undigested algal fibers.

Fucoidan can be easily cooked out of most edible brown algae by simmering 20-40 minutes in water (alone or in food). When consumed, it seems to reduce the intensity of the inflammatory response and promote more rapid tissue healing after wound trauma and surgical trauma. This means that brown seaweed broth is recommended after auto collision , sports injuries, bruising falls, muscle and joint damage, and deep tissue cuts, including voluntary surgery. 

I recommend patients anticipating surgery eat 3-5 grams brown seaweed cooked as a vegetable broth daily for a week or two prior to surgery. Fucoidan in the pre-surgical patient diet seems to reduce the intensity of blood loss and vascular bed collapse shock during and after surgery. The mechanism for this positive effect is unclear. 

We can all statistically expect major surgery sometime in our individual lives. We are the only animal that voluntarily submits to surgery. I believe this may cause some body integrity sanctity problems internally which may negatively effect the wound response and subsequent healing. Fucoidan may help the body decide to heal after voluntary surgery and other wounding such as radiation and chemotherapy.

Patients undergoing radiation or chemotherapy seem to benefit from regular fucoidan consumption via brown seaweed broth before, during, and after treatments. They report fewer and less intense adverse reactions, better recovery and sense of well-being.

Antiviral Action 
Fucoidan interferes with every stage of viral attack, cell attachment, cell penetration, and intracellular virion production by stimulating the production of antiviral cytokines. There may be some viral suppression in virus-infested patients but results are difficult to verify or measure. Research continues into using fucoidan or its derivatives to combat common viral infestations: HIV, HPV, and Herpes.

A fucoidan curiosity is that its teminal sugar is Fucose. All human cells studied have very precise Fucose recepter sites on their surfaces. Perhaps this results in stronger therapeutic responses.

The main red algal polymers are agar and carrageenan, and mainly porphyran in nori. All of these polymers are sulfated galactans. They are modestly water-soluble, partially digestible and easily extracted from red seaweeds by boiling . 

Carrageenan was originally isolated by simply boiling red seaweeds for an hour or more , discarding the seaweed mass, and saving the usually thick mucilaginous liquid. It was used for soups, hot gruels when mixed with grains, seafood, and peas. It was drunk as a soothing treatment for sore mouths and throats and for constipation relief.

It was used by the poor starving Irish during the oppressive British occupation of Ireland for 800 years as an emergency food, filling if not totally nutritious.

Today, carrageenan is used in over ten thousand proprietary industrial, food, and health and beauty products as a thickener, gelling agent, meat and sugar extender, medicines, and paints. R

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White Seaweed Cottonii - for making Carrageenan

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Green seaweed - Multipurpose used

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Green seaweed - Dried

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Golden cottonii - packaging

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Dried Ulva Lectuca - For animal feed

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Dried Gracilaria Purple

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Dried Seaweed - Processing 

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Green Seaweed - Loading Beach
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