In recent years, seaweed may have gained a reputation for being a superfood, but new research suggests our European ancestors ate the nutrient-rich plant for thousands of years.

Archaeological evidence indicates that seaweeds and other local freshwater plants were eaten in the Mesolithic, through the Neolithic transition to farming and into the Early Middle Ages.

The findings suggest these plants, now rarely eaten in Europe, only became marginal much more recently, researchers say.

The researchers hope their study will highlight the potential for including more seaweeds and other local freshwater plants in our diets today – helping Europeans to become healthier and more sustainable.

It is very exciting to be able to show definitively that seaweeds and other local freshwater plants were eaten across a long period in our European past

Karen Hardy, professor of prehistoric archaeology at the University of Glasgow is principal investigator of the Powerful Plants project.

She said: “Today, seaweed and freshwater aquatic plants are virtually absent from traditional, western diets and their marginalisation as they gradually changed from food to famine resources and animal fodder, probably occurred over a long period of time, as has also been detected elsewhere with some plants.

“Our study also highlights the potential for rediscovery of alternative, local, sustainable food resources that may contribute to addressing the negative health and environmental effects of over-dependence on a small number of mass-produced agricultural products that is a dominant feature of much of today’s western diet, and indeed the global long-distance food supply more generally.”

“It is very exciting to be able to show definitively that seaweeds and other local freshwater plants were eaten across a long period in our European past.”

The research, published in Nature Communications, found that archaeological evidence for seaweed is only rarely recorded and is usually considered in terms of non-edible uses like fuel, food wrappings or fertilisers.

There are historical accounts related to the collection of seaweed in Iceland, Brittany and Ireland dating to the 10th Century, while sea kale is mentioned by Pliny as a sailor’s anti-scurvy remedy.

By the 18th century, seaweed was considered famine food.

Today the plants continue to be popular in parts of Asia but are not common in European diets.

Led by archaeologists from the universities of Glasgow and York, researchers examined molecules extracted from the calcified dental plaque of 74 people from 28 archaeological sites across Europe, from north Scotland to southern Spain.

The findings revealed “direct evidence for widespread consumption of seaweed and submerged aquatic and freshwater plants”.

Some of the samples revealed consumption of red, green or brown seaweeds, or freshwater aquatic plants, with one sample from Orkney also containing evidence for a Brassica, most likely sea kale.

There are some 10,000 different species of seaweeds in the world, yet only 145 species are eaten today, principally in Asia.

The nutritional benefits of seaweed were sufficiently well understood by these ancient populations that they maintained their dietary link with the sea

Co-author of the paper, Dr Stephen Buckley, from the Department of Archaeology at the University of York, said “The biomolecular evidence in this study is over three thousand years earlier than historical evidence in the Far East.

“Not only does this new evidence show that seaweed was being consumed in Europe during the Mesolithic Period around 8,000 years ago when marine resources were known to have been exploited, but that it continued into the Neolithic when it is usually assumed that the introduction of farming led to the abandonment of marine dietary resources.

“This strongly suggests that the nutritional benefits of seaweed were sufficiently well understood by these ancient populations that they maintained their dietary link with the sea.”