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Kelp, Iodine and Fucoidan

Kelp is a nutritional superstar containing large quantities of vitamins and minerals for its weight, notably iodine.  It also contains fucoidan, a water-soluble polysaccharide, which has been proven to aid many disorders including cancer, cardio vascular disease (CVD) and cognitive decline.  Vanadium, a naturally occurring metal in kelp, has shown to reduce blood pressure, triglycerides and glucose, and increase bone density.  Kelp is commonly prescribed by Naturopaths to treat iodine deficiency and hypothyroidism.  It has been used in Japanese and Chinese cooking for centuries.  It is easily accessible in the forms of dried powder, capsules containing dried powder, liquid, and in salts.  Caution should be practised when consuming kelp with hyperthyroidism.  Kelp consumption is not recommended when a patient is taking psychiatric medications containing lithium.

Kelp’s nutrient profile:

Kelp (Ecklonia radiata) is a type of seaweed, boasting a superb nutrient density for its weight.  Per 100 grams (g), it contributes the following micronutrients: 66 micrograms (mcg) of vitamin K, which is 82% of the daily value (DV) estimated by Food and Drug Administration (FDA) to be adequate for the average person eating approximately 8,700 kilojoules per day.  It also contributes 180mcg of folate (45% DV), as well as traces of carotenoids, vitamins C and E, and B vitamins.  Notable minerals include 121milligrams (mg) of magnesium (30% DV), 168mg of calcium (17% DV), 2.8mg of iron (16% DV), 233mg of sodium (10% DV), 0.2mg manganese (10% DV), 1.2mg of zinc (8% DV), 0.1mg of copper (6% DV), 42mg of phosphorus (4% DV), 89mg of potassium (3% DV), 0.7mcg of selenium (1% DV), and 35400mcg of iodine (23600% DV).  All of these essential nutrients are provided at a mere 43 calories per 100g, which contains 10g of carbohydrates, 2g of protein, 1g of fat and 1g of dietary fibre (“Nutrition Facts and Analysis for Seaweed, kelp, raw”, 2012). 

Balch (2010) states that kelp is a rich source of B vitamins and minerals.  She states that it is reported to be beneficial to membranes surrounding the brain, sensory nerves, spinal cord, nails and blood vessels.  She says that it is used to treat thyroid problems due to its iodine content.  It is also useful for hair loss, obesity and ulcers.  Balch (2010) has also written that it protects against the effects of radiation, and it softens stools.  These symptoms may be due to the fact that hair loss, weight gain and constipation are all symptoms of hypothyroidism.

Balch (2010) believes that iodine helps to metabolise fats, therefore, it is helpful for weight loss.  Iodine is significantly deficient in New Zealand soils and therefore, kelp is especially important for New Zealanders.  Balch (2010) states that iodine deficiency in children may result in mental retardation.  It has also been linked to breast cancer, fatigue, hypothyroidism and weight gain (Balch, 2010).  Kelp is commonly found alongside lecithin, cider vinegar and vitamin B6 in weight loss supplements.

Sircus (2011) states that “iodine is the most obvious and important element in protecting against radiation damages.”  He believes that radioactive iodine (the undesirable type) competes for absorption with dietary iodine, and because over 90% of Americans are iodine deficient (Sircus 2011), they are “incredibly vulnerable to radioactive iodine”.  Jaffe (2011) believes that kelp should be included in an anti-radiation diet due to its high iodine content, so natural iodine can be absorbed preferably to radioactive iodine.  However, radioactive iodine is commonly used as a treatment for hyperthyroidism to block absorption of natural dietary iodine.

Therapeutic actions and health benefits of kelp:

Fucoidan is a water-soluble, sulphated polysaccharide found in kelp.  It has been shown by Hsu et al. (2012) to reduce tumour cell proliferation in women with breast cancer.  Therefore, kelp would be a useful dietary addition for women suffering from breast cancer.  Kelp should also be used as a preventative by women, as breast cancer affects 1 in 9 woman as of October 2009 (The New Zealand Breast Cancer Foundation, 2009).

Vishchuk et al. (2011) noted that certain polysaccharides (laminarans, fucoidans and alginic acids) found within kelp inhibit carcinogenic tumours causing breast cancer and melanoma.  Yet another study by Ermakova et al. (2011) concludes that these powerful polysaccharides have an inhibitory effect on the formation of melanoma and colon cancerPatel (2012) summarises many investigations regarding the use of polysaccharides (predominantly in-vivo), to conclude that these compounds promote apoptosis of carcinogenic tumour cells throughout the body.  Charles et al. (2007) believes that brown alga has the ability to function as chemotherapy prevention.

Brown alga have properties of being anti-inflammatory, anti-coagulant, and anti-adhesive (Cumashi et al., 2006).  Kelp may be beneficial to individuals suffering from inflammatory diseases e.g. inflammatory bowel disease (IBD), Coeliac disease and rheumatoid arthritis (and multiple other autoimmune conditions), atherosclerosis, asthma and hay fever.  The anti-coagulant and anti-adhesive properties of kelp aid blood thinning and prevent plaque sticking to arteries.  Potentially preventing atherosclerosis, which contributes to hypertension and CVD.

Fucoidan found in brown alga acts as an antioxidant Ananthi et al. (2010).  This prevents oxidative damage, causing aging.  Oxidative cholesterol deposited in arteries may cause atherosclerosis, hypertension, CVD and hypercholesterolaemia.

Huang et al. (2010) treated hyperlipidaemic with fucoidan in-vivo.  This reduced serum cholesterol, triglycerides and low density lipoprotein (LDL) cholesterol, while high density lipoprotein (HDL) cholesterol increased desirably.  It appears that kelp is be helpful for people with hyperlipidaemia.

Gao et al. (2012) investigated the effects of fucoidan on learning and memory in-vivo.  They concluded that the complex polysaccharide inhibits apoptosis, reduces oxidative stress, and aids nervous system regulatory.  This would help patients suffering from cognitive degeneration e.g. Alzheimer’s disease or dementia.

Tsiani et al. (1997) states that tyrosine phosphatases, a protein found in vanadium/ vandyl sulphate, mimics insulin in the body, while also reducing serum triglycerides and blood pressure.  They suggest vanadium as a treatment for diabetes, however, caution should be taken to prevent metal toxicity.  Acu-Cell Nutrition state that the recommended daily intake (RDI) for vanadium is 50-100mcg as there is a risk of toxicity.  Symptoms include wheezing, coughing, conjunctivitis and rhinitis.

Vanadium reduces hyperglycaemia and insulin resistance Cusi et al. (2001).  This would help patients suffering from diabetes mellitus to manage their condition.  It may reverse non-insulin dependent diabetes and pre-diabetes.


Srivastava et al. (2005) states that vanadium stimulates the uptake of glucose and lipids into skeletal muscle glycogen.  It inhibits gluconeogenesis, enzymes, phosphoenol pyruvate carboxykinase and glucose-6-phosphatase, thereby, preventing breakdown of muscle tissue for energy.  This aids storage of energy into glycogen as opposed to adipocytes, aiding weight management.

Vanadium may enhance insulin-like growth factor and mimic its enzyme.  It may be assumed that this aids the building of lean body mass and fat loss.  Vanadium supplements are common in body builders.  Barrio et al. (2010) state that vanadium activates osteoblasts which promote minerals deposition into bones, increasing bone density.  Kelp may help people suffering from osteoporosis.

Evangelou (2002) shows through animal studies that vanadium prevents against chemical carcinogens.  This is due to its ability to modify xenobiotic enzymes, which inhibit carcinogen derived active metabolites.  He even calls it an “anti-tumour agent”.  This proves kelp to be useful in the prevention of cancer, which is estimated by The Cancer Society of New Zealand, 2011, to cause 29.4% of all deaths in New Zealand.

Mukherjee et al. 2004 suggest that physiological malfunctioning of the thyroid gland, and glucose and lipid metabolism occur in response to a vanadium deficiency.

Applications of Kelp in two common health conditions:

Due to kelp’s incredible iodine content, it is most often prescribed to clients by Naturopaths for iodine deficiency and/or hypothyroidism.  Although it is uncommon, kelp may also be prescribed for diabetes and/or obesity.  Veracity (2005) states that the following symptoms are common for those individuals suffering from hypothyroidism: weight gain, fatigue, forgetfulness, brain fog, irritability, and unhealthy skin, hair and nails.  However, symptoms are often not expressed during early stages of the disorder.

Failure of the thyroid gland to produce adequate hormones may be caused by one of the following:

  • An autoimmune disease e.g. Hashimoto’s Thyroiditis
  • Thyroid surgery (if part or all of the thyroid gland has been removed – in this instance thyroid hormone must be taken for life)
  • Radiation therapy e.g. cancer
  • Medications (psychiatric patients may be treated with lithium which often causes hypothyroidism)
  • Treatment for hyperthyroidism (people who produce excess thyroid hormone are often treated with radio-active iodine or anti-thyroid medications, which can swing the opposite way and cause hypothyroidism)
  • A congenital disease (babies may be born with a defect of their thyroid gland or no thyroid gland)
  • Pregnancy (postpartum hypothyroidism may be developed during/post pregnancy.  This may negatively affect the developing foetus if occurrence is during pregnancy, as it may cause a miscarriage or premature birth)
  • Iodine deficiency (common in New Zealand as soils are low in iodine.  Foods containing iodine include seaweed (including kelp) and seafood.  Small amounts are found in asparagus, garlic, lima beans, mushrooms, sesame seeds, soy beans, spinach, pumpkin and turnip greens.  Crops grown closer to the coast contain more iodine (Balch, 2010).  Iodised table salt is a source of iodine, however is not recommended due to aluminium anti-caking agent being used to create the ‘free-flowing’ characteristic, additionally it is bleached to achieve its glossy, white appearance.  Table salt acts as an antibiotic by killing healthful probiotics in the large intestine.  This in turn leads to further health problems, including digestive issues.  Due to table salt being composed of solely sodium chloride, it lacks trace minerals.  Whereas natural salt e.g. Celtic Sea Salt is approximately 94% sodium chloride, and contains 6% essential trace minerals, including 3% magnesiumHowever, Celtic Sea Salt only contains trace amounts of iodine, therefore, it should be consumed simultaneously with seaweed (including kelp).
  • Disorder within the pituitary gland (e.g. failure to produce Thyroid Stimulating Hormone – TSH)

Untreated hypothyroidism may contribute to the following health problems:

  • Goitre (Hashimoto’s thyroiditis is the most common cause)
  • Heart complications (elevated levels of LDL cholesterol are more common in people suffering from hypothyroidismHypothyroidism may increase the size of the heart muscle, occurring with overwork, and ultimately leads to heart failure)
  • Mental issues (may feel depressed living with prolonged symptoms of hypothyroidism including fatigue, brain fog and irritability)
  • Peripheral neuropathy (long-term hypothyroidism may damage peripheral nerves that connect information from the brain and spinal cord, to the rest of the body.  Symptoms of damage include paraesthesia and restless leg syndrome)
  • Myxoedema (life threatening disease where one experiences the following symptoms: cold intolerance, lethargy, fatigue and even unconsciousness)
  • Infertility (hypothyroidism interferes with ovulation)
  • Birth defects (may affect babies of women experiencing hypothyroidism)

Marieb (2010), states that iodine is required to produce thyroxine (T4) which is secreted by the thyroid.  It is then converted into triiodothyronine (T3) in organs.  Thyroid hormones (TH) are composed of two linked tyrosine molecules (tyrosine is an amino acid).  T3 contains three bound iodine atoms, while T4 contains four iodine atoms.  Marieb (2010) states that TH increases the body’s basal metabolic rate (BMR), which is the amount of energy consumed at rest.   Therefore, this increases heat production, as with an increase in energy (kilojoules) consumed, heat is released as a by-product of metabolic activities.  This describes the calorigenic (‘heat producing’) effect.  Marieb (2010) also mentions the importance of TH on the regulation of tissue growth and development, as well as development of the reproductive and nervous systems.

Traditional use of Kelp:

According to Shimamura (2009), the history of kelp dates back hundreds of years, especially in Japanese and Chinese cooking.  He states, the word kombu (another name for kelp) appears in Chinese documents in the third century AD.  It is present in Japanese cooking because of its umami flavour, due to it being high in glutamine.  Glutamine is an amino acid (building block of protein) that is also present in the synthetic flavouring Monosodium Glutamate (MSG).  However, the glutamates found within certain foods e.g. mushrooms, traditionally fermented soy sauce and yeast; are naturally present.  Kombu is a key ingredient in making dashi stock (a flavourful base for miso soup).  Japanese enjoyed kombu as a salt alternative by cooking it for a long period of time until the seaweed unshaped itself.

Methods of delivering Kelp:

Kelp may be purchased in dried powder form.  0.25g contains approximately 590% of the RDI for the average New Zealander consuming 8700 kilojoules per day.  Kelp can be purchased in capsules in its dried form, or alternatively in a bottle in liquid form.  Dosage of kelp capsules depends on how large the capsules are and how much powder is inside the capsule.  Dosage of liquid kelp depends on how concentrated the tonic is.  Kelp noodles may also be purchased, which contain three ingredients: kelp, water and sodium alginate (gum extracted from cell walls of brown alga).  They contain three servings per bag, one serving is 30g.  They are extremely low in kilojoules, supplying a mere 12 kilojoules per serve.  One serve has no fat or protein, 0.8g of carbohydrates (no sugar), 0.3g of dietary fibre and 16.3mg of sodium (only 0.8% of the RDI).  ‘Kelp salt’ (naturally iodised salt) is another product that can be purchased.  It is composed of kelp and sea salt.  These products can be purchased from health food stores or online.  The amount of time required for kelp to improve a deficiency or hypothyroidism depends on the severity of the condition.

Cautions/contraindications of kelp consumption/supplementation:

Caution should be taken with kelp ingestion due to its extremely high iodine content.  Balch (2010), states that excessive iodine intake may inhibit the secretion of TH; producing a metallic taste in the mouth, swollen salivary glands, diarrhea, and vomiting.  Excessive TH may be produced which can cause hyperthyroidism, symptoms include: weight loss, heart beat irregularities (tachycardia, arrhythmia or palpitations), increased appetite, nervousness, anxiety, irritability, tremours, sweating, hot, frequent bowel movements, goitre, fatigue, difficulty sleeping, brittle hair, and skin thinning.  The most common cause of hyperthyroidism is Grave’s disease (PubMed Health, 2012).  This is an autoimmune disorder in which the thyroid gland is overactive.  Caution should be taken, as some symptoms for hyperthyroidism are common to hypothyroidism; consult with a health practitioner for an accurate diagnosis as a blood test is required.

According to Jorgensen et al. (1973), high doses of kelp and/or iodine supplements are contraindicated to psychiatric medications containing lithium and/or lithium salts.  This interaction is yet unknown, but causes symptoms including tiredness, coldness and weight gain, similar to symptoms of hypothyroidism.

Kelp is extremely nutritionally dense, and sprinkling it on food is an easy way to supplement an iodine-deficient diet to ensure adequate iodine intake and maximal health benefits.  Kelp may be used for a broad range of disorders including hypothyroidism, diabetes, cancer and osteoporosis.  It is easily obtainable and requires minimal preparation.



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