Your guide to seaweed and its health benefits
People in the South Pacific and East Asia have been aware of the health-giving properties of seaweed for thousands of years. There are accounts that the Tongans offered Captain Cook a meal of seaweed on his arrival in Tonga, to increase his strength and energy. The Japanese and Chinese have been eating seaweed for millennia and people have been cultivating seaweed as a food crop in Japan since the 17th century. The four main varieties of seaweed available for use in Australia are kombu, arame, wakame and nori, each with its own unique flavour and specific health benefits.
This is a dark-green variety of kelp and is one of the essential ingredients in dashi, the basic stock used for many Japanese recipes. Kombu comes in dried pieces, which are added to boiling water to give flavour and nutrients to the food being cooked; the seaweed can be removed from the pot before serving or can be eaten. It contains high levels of iodine, iron and potassium and is also very good to add to legumes while they are cooking, to improve digestibility.
Kombu is also rich in alginates, which are responsible for its slimy, slippery feel. These alginates have been found to bind to and remove heavy metals, such as lead and mercury, from the body. This is the reason many cleansing and detoxification programs include foods containing kombu.
As a rich source of iodine, kombu promotes healthy metabolism and thyroid function by providing adequate quantities of iodine to be used in the production of thyroid hormones. If a person does not have adequate amounts of iodine in their diet, they can develop a condition known as goitre, which is typically treated by supplementing with iodine.
Nori is the deep-brown flat sheets of seaweed used to wrap the sushi rolls many people eat for lunch. Nori has a crispy texture when dry and a soft, chewy texture when wet. It’s very high in protein (35 per cent) and contains high amounts of the amino acid taurine, as well as being rich in zinc, copper, manganese and selenium. It can be eaten in the sheets used in sushi preparation or as toasted, dried flakes used instead of salt to season foods.
The most popular type of seaweed in Japan, wakame is often served fresh as a side salad. It is prized there for its fresh, salty taste and chewy, slightly crunchy texture and is available in Australia in both fresh and dried forms. The dried form has to be rehydrated by soaking in room-temperature water for 10 minutes, while the fresh variety can be eaten as it is or used in salads. The bright-green variety of fresh wakame can be bought at most good seafood markets and some Asian Grocery stores.
A rich source of minerals including calcium, potassium and magnesium, wakame also contains high amounts of betacarotene and, when eaten fresh, provides moderate amounts of B vitamins and vitamin C. A unique plant pigment called fucoxanthin is found in wakame in high quantities. Preliminary Japanese research using animal models of obesity have shown some promise that this carotenoid may help reduce the amount of fat tissue in the body by increasing the genes involved in fat burning.
Arame is a dark-brown variety of kelp with thin, feathery fronds. It has a light, delicate flavour and is the sweetest of all the seaweed varieties. It’s often used in soups or soaked and marinated for use in salads and stirfries. Arame is rich in certain polysaccharides, which laboratory research has found to have immune-stimulating properties. Lignans, a type of phyto-oestrogen, are also found in arame in moderate quantities.
Rich in calcium, iron, potassium and iodine, arame, like many of the kelp varieties, contains high amounts of the polysaccharide, fucoidan. Fucoidan is currently the focus of research in Japan and Australia to examine the anti-cancer, immune-boosting and anti-inflammatory properties of this algae extract. In Japan, several functional food products, such as fruit juice and yoghurt, are fortified with fucoidan to offer Health benefits.
There are some concerns about the possibility that some seaweed may contain trace amounts of heavy metals and other environmental pollutants. To avoid the possibility of any contamination of the seaweed you eat, always choose seaweed that is organically certified as this ensures it will have been grown or harvested from a pristine and unpolluted environment.
How much to eat
Adding 20g–50g of rehydrated seaweed to your diet two to three times a week can significantly increase the amount of minerals in your diet and also provide other unique phytonutrients such as polysaccharides, antioxidant pigments and lignans, which have their own health benefits. As all types of seaweed contain high levels of iodine, it’s advisable that people with thyroid conditions should not consume large quantities regularly without discussing this with their healthcare practitioner.
Gerard Elms is a naturopath, nutritionist and herbalist with a practice in Neutral Bay, Sydney. He specialises in digestive disorders and men’s health. T: 02 9904 0734, E: firstname.lastname@example.org.
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