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Newsletter 04

One of the seas nutritional superstores

Kelp (Laminaria) is a seaweed or sea vegetable in the brown algae family. Sea vegetables are commonly eaten delicacies in some parts of Asia. In Western societies, until recently, sea vegetables were largely associated with localised use in coastal areas or through historical records. However, they are becoming increasingly widely recognised as delicious and nutritious additions to the Western diet. Kelp is rich in minerals due to the marine environment in which it grows and its ability to absorb a wide range of nutrients.

FibreKelp is higher in soluble fibre than most terrestrial fruit and vegetables. An 8g portion of dried kelp contains 3g of fibre, this is approximately 12% of the guideline daily amount (1). The fibre in kelp absorbs water to form a gel which aids the transit of food through the digestive tract thus having a protective effect against colon cancer (1,2,3). The fibre in kelp also increases feelings of satiety, thus helping to stave off hunger.

Kelp and the Essential FatsKelp contains a good balance of both the omega 3 and 6 essential fats which have to be derived from food as the body can’t make them (1). These fats are vital for brain health, hormonal balance, the correct functioning of the immune system and skin health as well as the health of every cell in the body.

VitaminsCompared to terrestrial plants and animal foods sea vegetables are rich sources of many vitamins including B3, B6, B12 and folic acid, as well as carotenoids – the precursors to vitamin A (3,4).

MineralsKelp is a rich source of many minerals including iodine, potassium, magnesium, calcium and iron (2).

An 8g serving of dried kelp provides:

Over 175mg of calcium - 25% of the reference nutrient intake.

Over 970mg of potassium - 27% of the reference nutrient intake.

Over 195mg magnesium – 65% of the reference nutrient intake.

Over 22mg of iron – more than the double the daily reference nutrient intake.

Over 34mg of iodine – again, more than the daily reference nutrient intake. (1)

Kelp is one of the most efficient accumulators of iodine of all living organisms (5). Iodine is an essential trace element needed for the synthesis of thyroid hormones. Iodine requirements vary throughout life, particularly increasing during pregnancy and breastfeeding.

The Role of IodineIodine is a crucial part of two thyroid hormones known as T4 and T3. These hormones are essential for all parts of human metabolism. It is known that iodine deficiency can be considered as the sole cause of many thyroid abnormalities including mental disorders (6). Iodine deficiency can lead to psychological disorders in adults and problems with brain development in babies (6)

It is estimated that up to two-thirds of the population of Western and Central Europe are iodine deficient. World wide it is estimated that 2 billion people are thought to have an insufficient iodine intake (7). The development of a swelling on the neck, known as goitre, is the most visible sign of iodine deficiency. Other consequences include impaired neuro-development, particularly in early life. In the foetal brain inadequate thyroid hormone impairs myelination and cell maturation. Moderate-to-severe iodine deficiency during pregnancy increases rates of miscarriage, reduces birth weight and increases infant mortality. Offspring of deficient mothers are at high risk of cognitive disability. Moderate-to-severe iodine deficiency during childhood reduces growth rates. The good news is that correction of mild-to-moderate iodine deficiency in primary school aged children improves cognitive and motor function (7))

Iodine and ReproductionAdequate iodine intake is needed to prevent infertility as well as during pregnancy and breast feeding when it is essential for the synthesis of maternal thyroid hormones needed to support healthy foetal and infant development (8). Research from Switzerland suggests that most women in Europe are iodine deficient during pregnancy. Despite this less than 50% receive supplementation with iodine (9). It is not surprising that thyroid disorders are common during and after pregnancy. If left untreated even moderate iodine deficiency during pregnancy can adversely affect the thyroid function of the mother and the new born baby. In addition the mental development of the baby may be impaired since iodine is vital for the growth and maturation of the brain.

One study found that pregnant women given iodine supplements for 3 months experienced reduced weight gain during pregnancy while their babies weighed more than the control group (10).

Kelp and Weight LossResearch into the effects of kelp on weight loss shows mixed results. One piece of research from Japan found that feeding obese rats shaved kelp had an anti-obesity effect. (11). The iodine in kelp is thought to have lipolytic agents that stimulate the break up of fat (2).

Kelp, Cancer and ToxicityIn Japan mice fed diets rich in seaweeds such as kelp who were subsequently exposed to radiation experienced a reduced uptake of radiation by the thyroid. It seems that dietary seaweeds may have a protective effect on the thyroid against radiation (12).

Japanese kelp has been found to have a protective effect against carcinogens. This is attributed to the fibres in sea vegetables that help to remove toxins via the bowel (13).

Epidemiological evidence suggests that populations consuming typical Asian diets have a lower incidence of hormone-dependent cancers than populations consuming Western diets. These differences have been attributed to the higher intake of soya amongst Asians. However, studies show that kelp may also have oestrogen and progesterone modulating properties that may contribute to the lower incidence of hormone related cancers amongst the Japanese (14).

Kelp may also be used to reduce angiogenesis (the growth of new blood vessels) in tumours thus reducing their growth (2).

CautionsIf you are taking thyroid medication consult with your doctor before introducing kelp into your diet. There may be contraindications. Excessive intake of iodine

has the potential to cause both hyperthyroidism and hypothyroidism so kelp should be used in moderation.

How to Use Kelp Powder The abundance of essential vitamins, minerals and phytonutrients in kelp indicates that moderate but regular use of it can enhance the nutritional quality of the diet. Kelp has a strong savoury flavour that is rich in Umami – the fifth taste that imparts a delicious and satisfying mouth feel to foods. Kelp powder can be sprinkled onto soups, salads or grains or stirred into smoothies or juices. Here are a couple of ideas to get you started:

Kelp Condiment5 tbsp sesame seeds, toasted

2 tsp sea salt or rock salt

1 tsp turmeric

1 tsp ground cumin

1 tsp ground coriander

1 tbsp paprika

¼ tsp cayenne pepper

1 tsp freshly ground black pepper

2 tsp kelp powder

Grind the sesame seeds in a seed mill. Add the other ingredients and mix them well.

Store in a spice jar. Sprinkle onto soups, salads, brown rice and casseroles.

Green Dream 2 ripe avocados, peeled and stoned

Juice of 1 lime

1 clove of garlic, finely chopped

3 tomatoes, finely chopped

2 tsp of kelp powder

Salt and freshly ground black pepper

1-2 tbsp olive oil

Mash the avocados with the lime juice.

Stir in the chopped garlic, tomatoes, kelp powder, salt and pepper.

Sprinkle olive oil over the top and serve immediately with crudités, crackers or bread.

ReferencesMacArtain P, Gill Cl, Brooks M, Campbell R, Rowland R. Nutritional value of edible seaweeds. Nutr Rev. 2007 Dec;65(12 Pt 1):535-43.

Kim SK, Bhatnagar I.Physical, chemical, and biological properties of wonder kelp-laminaria. Adv Food Nutr Res. 2011;64:85-96

Rajapakse N, Kim SK. Nutritional and digestive health benefits of seaweed. Adv Food Nutr Res. 2011;64:17-28.

Skrovankova S. Seaweed vitamins as nutraceuticals. Adv Food Nutr Res. 2011;64:357-69

Verhaeghe EF, Fraysse A, Guerquin-Kern JL et al. Microchemical imaging of iodine distribution in the brown alga Laminaria digitata suggests a new mechanism for its accumulation. Biol Inorg Chem. 2008 Feb;13(2):257-69.

Mansourian AR. A review on the metabolic disorders of iodine deficiency.Pak J Biol Sci. 2011 Apr 1;14(7):412-24.

Zimmerman MB. The role of iodine in human growth and development. Semin Cell Dev Biol. 2011 Aug;22(6):645-52.

Leung AM. Pearce EN, Braverman LE. Iodine nutrition in pregnancy and lactation. Endocrinol Metab. Clin North Am. 2011 Dec;40(4):765-77.

Zimmerman M, Delange F. Iodine supplementation of pregnant women in Europe: a review and recommendations. Eur J Clin Nutr. 2004 Jul;58(7):979-84.

Joshi A, Pokhrel T, Bastola SP, Banjara MR, Joshi AB. Iodine supplementation in pregnancy and its effects on perinatal outcome. Nepal Med Coll J. 2011 Jun;13(2):128-30.

Miyata M, Koyama T, Kamitani T, Toda T, Yazawa K. Anti-obesity effect on rodents of the traditional Japanese food, tororokombu, shaved Laminaria. Biosci Biotechnol Biochem. 2009 Oct;73(10):2326-8.

Maruyama H, Yamamoto I. Suppression of 125I-uptake in mouse thyroid by seaweed feeding: possible preventative effect of dietary seaweed on internal radiation injury of the thyroid by radioactive iodine. Kitasato Arch Exp Med. 1992 Dec;65(4):209-16.

Sakakibara H, Nakagawa S, Wakameda H, Nakagiri Y, Kamata K, Das SK, Tsujui T, Kanazawa K. Effects of Japanese kelp (kombu) on life span of benzo[a]pyrene-fed mice. J Nutr Sci Vitaminol (Tokyo). 2005 Oct;51(5):369-73.

Skibola CF, Curry JD, VandeVoort C, Conley A, Smith MT. Brown kelp modulates endocrine hormones in female sprague-dawley rats and in human luteinized granulosa cells. J Nutr 2005 Feb;135(2):296-300.

Writtten by Josie Cowgill

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