Most people associate seaweed with the crispy, salty appetisers served up at Chinese restaurants but seaweed was also once an important part of the British diet and was certainly used by herbalists to cure a variety of ailments from ulcers to cuts and grazes. Now thanks to the interest in artisan foods the wider health benefits of the humble seaweed are beginning to register.
Anecdotes abound about the healing properties of seaweed. Breton legend has it that the earliest seaweed farmers never worried about the cuts and abrasions they sustained during handling the knotted tangles of seaweed and kelp they were harvesting. They knew that the wounds healed up with little or no treatment. Today nurses still use certain dressings which are impregnated with seaweed because it is known to promote rapid healing.
In North Ronaldsay the northernmost part of the Orkney Islands a particular breed of sheep have been found to suffer exceptionally low levels of disease. Their hardiness and resistance to disease has been attributed to their almost exclusive diet of seaweed. For years farmers have understood the nutritional benefits of seaweed in animal fodder. It is added to poultry feed to produce thicker eggshells and yellower yolks and is fed to some farmed mink as a fur conditioner.
The fact that animals are quite prepared to graze on seaweed has led researchers to investigate its nutritional qualities. Seaweeds are a rich source of vitamins such as carotene, fucoxanthin (a precursor to vitamin A) thiamine, riboflavin and vitamin B12. They also contain trace elements such as chromium, zinc, iron, potassium, manganese, boron and magnesium.
Because of their gelatinous quality they are frequently used as gelling agents in a variety of foodstuffs such as hamburgers, ice creams and yogurts. Carageenans which come from certain types of kelp are even used to maintain a frothy head on a pint of beer. Dulse is still popular in Ireland where it is often mixed with potatoes and butter adding a salty, savoury flavour to fried potato. In Brittany it’s boiled with kelp to make pain d’algues-seaweed bread which you can now find in many an artisan bakery.
There have been umpteen clinical studies on the possible uses of seaweed in obesity, cholesterol and blood pressure lowering and even cancer. A US study showed that a diet containing kelp lowers levels of the potent sex hormone oestradiol in rats and raised hopes that it might also decrease the risk of oestrogen-dependent diseases such as breast cancer in humans.
The results, published in the American Journal of Nutrition shed new light on the Japanese diet-10% of which is comprised of seaweed. It may also explain why Japanese women have such a low incidence of oestrogen dependent cancers such as breast, ovarian and endometrial cancer. Prior studies have shown that Japanese women have longer menstrual cycles and lower oestradiol levels than their Western counterparts and it has long been accepted that longer menstrual cycles are linked to lower risks of breast, ovarian and endometrial cancers.
The type of seaweed used in the US study was Fucus Vesiculosis or bladderwrack-the sort of brown seaweed so common on the beaches of Wales and the South West coast of England. It is closely related to its Japanese cousins wakame and kombu. ‘The most profound discovery was that women with endometriosis and severe menstrual irregularities experienced significant improvement in their symptoms after just three months of taking 700 mg of seaweed capsules a day’ says Dr Chris Skibola of the School of Public Health University of California, Berkeley. ‘In the past soya has been cited as the key player in why Japanese women have such low rates of breast cancer. However this new study suggests it could be the seaweed which plays a protective role’ she adds.
For more than twenty years Japanese scientists have run more than 500 clinical trials to discover whether there are elements in seaweed which could suppress the growth of tumour cells. As long ago as 1996 researchers at the Japanese biomedical group Takara Shuzo discovered the polysaccharide known as U-fucoidan which appeared to cause cancer cells to self destruct. Their research showed that when a small amount of fucoidan was added to a culture of colon cancer cells half of them died within 24 hours and the rest were completely eliminated after 72 hours.
Fucoidan studies have been reported in a range of highly respected journals such as the Journal of Molecular Immunology and the British Journal of Pharmacology and Infectious Immunology. Fucoidan has been shown to have a chemical composition closely resembling human breast milk and may also work on other levels to enhance immunity, fight allergies, inhibit blood clotting, decrease cholesterol, lower blood pressure and improve liver function.
In June 1998 the same Japanese researchers discovered that another oligosaccharide found in red seaweed could not only cause human cancer cells to self destruct but could suppress cancer when administered orally in mice. Recent Canadian research shows that certain types of seaweed may inhibit the absorption of lead, cadmium and strontium which could have applications for patients undergoing chemotherapy.
Author Mary Beith who wrote Healing Threads-a book describing the traditional medicines of the highlands and islands of Scotland says that Dulse which is one of the most common seaweeds in this area has long been used in childbirth, to cure goitres and for ulcers. She also tells a marvellous anecdote about an army officer who developed terrible stomach ulcers. ‘They became so painful the army doctors could do nothing for him. In fact eventually he was sent home to Scotland to live out his last few months. A local herbalist fed him on a diet of dulse and he went on to live for many decades afterwards and became a local legend!’ she says.
There may even be an application for seaweed in the ongoing fight against obesity. Native Hawaiians who tend to be stocky and overweight experience very little heart disease or other health problems and attribute their good health to a diet containing plenty of their native kelp known as Limu.
It is worth noting however that kelp contains high levels of iodine which can be toxic at high levels. So don’t rush down to the shoreline to harvest your own supply of seaweed- better to rely on the stuff you buy in your local health food store!