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.

Kombu

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

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.

Wakame

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.