It wasn’t so long ago that the only seaweed that passed most British lips was deep fried, heavily sugared … and made from that distinctly less exotic landlubber, the spring cabbage. Although as an island nation we’re well stocked with the stuff, we’ve never embraced this particular maritime bounty with the same wholehearted enthusiasm as the far east, and Japan in particular, where seaweed is an important part of the daily diet.
Indeed, although a sixth-century poem in the Celtic Psaltery describes the monks of Iona gathering dulse from “the rocky shore”, with a few notable regional exceptions it seems to have been historically largely used as a fertiliser or a medicine rather than a foodstuff. In her excellent 2015 book Seaweed in the Kitchen, Fiona Bird describes seaweed as being taken for a variety of ailments, from constipation to loss of appetite, sold as street food (its salty flavour made it a canny choice of bar snack for the thrifty publican) and, of course, cooked into the thick green paste we still know as laverbread.
But it is amazing what a bit of good press can do for an unpromising green thing – and, as with kale, the superfood label has transformed seaweed from frump to feted fashion plate. Jamie Oliver namechecked it as “the most nutritious vegetable in the world”, after incorporating it into a new, healthier diet that helped him to lose two stone in the runup to his 40th birthday, Heston Blumenthal reckons the NHS should be seasoning patient meals with seaweed instead of salt, while detox magnate Geeta Sidhu-Robb goes as far as to suggest that kelp’s “complete nutrient profile” means “it can heal the world”.
Powerful claims for what is, essentially, slimy flotsam. But what is the truth?
Edinburgh-based Mara Seaweed doesn’t hold back, declaring their raw material “the most mineralised vegetable on earth” – and Dr Stephen Glover Bird, who contributed a chapter on seaweed and health to Seaweed in the Kitchen, agrees that “edible seaweeds do indeed provide a rich and balanced source of key macro- and micronutrients, antioxidants, polyunsaturated fatty acids, vitamins and minerals”. The problem is, as he observes, one of bioavailability – put simply, how easy it is for the human body to access this nutrient content.
Nutritionist Kerry Torrens agrees with Mara that “seaweeds such as nori [laver] are good sources of protein” – although she points out that one tends not to eat that much of them at a time – and calls their mineral content “especially interesting” in terms of the “valuable contribution” it can make to the typical western diet. But, as Dr Bird reminds me, there are at least 10,000 different species of seaweed, and although we only harvest about 20 in the UK, even this handful display very different nutritional profiles. As fresh seaweed is about 95% water, drying or cooking it provides yet more opportunities for variation, and the same species, prepared in the same way, show marked differences at different times of the year.
One thing that is certain, however, is that most seaweed is a rich source of easily accessible iodine, an element found in seafood and dairy products, which is important for proper thyroid function, and in which the British diet is often mildly deficient. However, in this case you can have too much of a good thing; the British Dietetic Association warns that “it can provide excessive amounts (particularly so in the case of brown seaweed such as kelp), and therefore eating seaweed more than once a week is not recommended”, especially for children and pregnant women.
Dr Bird, meanwhile, cautions that “seaweeds have a real ability to uptake and store heavy metals”, which means it is vital to ensure they come from clean water. So although “common sense” suggests freshly harvested greens from an uncontaminated source must be good for us, the specifics, it seems, are still unclear.
There is no disputing seaweed’s usefulness as a salt replacement, though: as Xa Milne explains in her Seaweed Cookbook, seaweed in the dried form – in which most of us are most likely to encounter it – contains on average 10% sodium chloride, as opposed to 98% in table salt. And, thanks to its high umami readings – kelp boasts more naturally occurring MSG than any other raw, organic substance – seaweed is an easy way to give food a bit of savoury oomph; the distinctive flavour of miso soup, for example, is largely down to a kombu-based stock known as dashi.
More speculatively, promising findings have resulted from experiments on certain alginates in kelp that seem to slow down the enzymes that help us digest fat – potentially blocking its absorption, in simple terms – but only, as yet, under lab conditions. The same goes for its potential as a protective tool against cancer, a use suggested by the relatively low rates of certain cancers in the Japanese population, which records the highest seaweed consumption in the world. Although a number of avenues are being explored, as yet there is no conclusive evidence in human studies.
As a recent paper published in the Journal of Applied Phycology concludes: “It is clear that there is substantial evidence for algae as nutritional and functional foods, yet there remain considerable challenges in quantifying these benefits.” In short, it seems probable that seaweed is a pretty useful thing to include in a varied and balanced diet – but more work needs to be done before the reasons for this can be conclusively proved.
How to eat it
Helpfully there are no poisonous seaweeds – “though some are tastier than others,” as Fiona Houston of Mara Seaweed puts it. But none, eaten in moderation and harvested from clean waters, will do you any harm. So if you happen to find yourself on such a beach, there are plenty of clear guides online as to which varieties are good to eat, and how to prepare them.
If not, fresh seaweed is intermittently spotted in supermarkets, but also sold online by the Cornish Seaweed Company, Just Seaweed from the Isle of Bute, or Belfast-based Irish Seaweeds. Cooked Penclawdd laverbread can be ordered from Celtic Crab Products. A casual Twitter inquiry about products containing seaweed elicits a long list of recommendations, from “ace” seaweed and cider salami from the Cornish Charcuterie Company to Nigella Lawson’s beloved Abernethy butter with dulse and Itsu’s widely available crispy laver snacks.
The simplest way to incorporate seaweed into your daily diet in the long term, however, is probably to get hold of some dried flakes to use as a seasoning. Houston is keen to stress that, because dried seaweed is so concentrated, you don’t have to be a “hardcore” health nut to get your fix – “it’s really, really easy”. She recommends stirring a teaspoon of Mara’s Shony blend into scrambled eggs, sprinkling it on salads, or tossing it through buttered green beans or kale.
After a bit of experimentation, I can confirm the seaweed flakes she sends me to try are pretty useful things to have around. The intensely savoury, rounded, salty depth they give to a bloody mary, a plate of noodles or a salad will earn them a place in my kitchen whatever their nutritional credentials. As a delicious, sustainable, local resource, seaweed should be celebrated. If it also turns out to help you live for ever, well, that’s surely not a bad bonus.
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