THERE'S gold in our hills and glens. Liquid gold, that is. As we reported last weekend, Scotland's forests are brimming with birch sap – a trendy new "superfood" being marketed as a refreshing health drink. If you believe the hype, it can cleanse livers, ease arthritis and even strengthen teeth, and celebrities are extolling this nutrient-rich fluid as a "hero ingredient".

Yet the Perthshire-based company that is harvesting birch water says it is merely reviving a tradition stretching back to Neolithic times. "In the Highlands, there are records of people using it as a tonic after a long winter; giving it to babies, themselves and even cattle," says Rob Clamp of Birken Tree, adding that the fluid, which is only available for a few weeks in early spring, would have been relished at a time of year when vitamins and minerals were in short supply.

Our ancestors seem to have instinctively understood the nutritional and healing power of native plants. Scottish thistles, for example, were once eaten like globe artichokes and made into tea to treat urinary problems, bad breath and depression. And as everybody knew, yarrow was good for varicose veins, coltsfoot eased coughs and chickweed soothed itchy skin.

According to West Lothian-based herbalist Monica Wilde, our forebears' affinity with local flora was not surprising, since – like all animals – their gut bacteria guided them to gather certain foods during particular seasons, just as deer know instinctively to graze the meadowsweet that helps control intestinal parasites.

In this era of supermarket foods and packaged drugs, we have lost touch with those instincts and she's one of a growing number of foragers dedicated to helping us rediscover them. Mark Williams of Galloway Wild Foods is another, though in some cases, he says, traces of that ancient plant wisdom can still be found lurking in our memories. During springtime foraging trails, he encourages participants to nibble on vitamin C-rich young hawthorn leaves. On tasting them, older people often remember grazing on the leaves – which were popularly known as "bread and cheese – on the way to school.

"Many wild foods are the original super-foods," adds Williams. "Because wild food is growing where it wants to and hasn't been forced into polytunnels, it's getting exactly what it needs to thrive, so is more nutritious."

Dorset-based John Wright, author of The Forager's Calendar, describes Scotland as "a superb place" to go foraging. "You have so much wild land," he says. "You also have the right to roam and that comes with the right to forage, so you are much better placed than we are south of the Border".

How, then, can we make the most of our natural bounty? Inspired by the birch sap revival, we asked these three foraging experts to name their own "hero ingredients".

Wild stings

Stinging nettles are, says Mark Williams, "incredibly high in protein with more vitamin C than oranges" and plenty of trace minerals. A natural antihistamine, it's reputedly good for hay fever and, when served as a tea, is said to aid iron absorption thus helping with anaemia and heavy periods. The Romans supposedly stung themselves with nettles to ease arthritis and rheumatism.

More nutritious than spinach, nettles can be cooked in a similar way and Samuel Pepys wrote that he enjoyed "nettle porridge" during his Scottish travels. The plant can also can be used to make pesto and, according to John Wright, it's delicious as a soup though it "can taste like boiled army blankets" unless combined with good stock and a thickener such as potato or celeriac.

Coastal harvest

Scotland's rocky shores produce an abundance of seaweed and its use dates back thousands of years. St Columba is said to have enjoyed "cropping dulse from the rock" on Iona, where monks gathered it, dined on it and distributed it to the poor.

Long used by crofters as a fertiliser, it was resorted to as a foodstuff during the Clearances and when famine ravaged the Highlands and Islands. Since then, despite its popularity in China and Japan, it has been neglected in Scotland though today it's enjoying a resurgence as a tasty and nutritious culinary ingredient, valued in famous restaurants such as The Three Chimneys on Skye and marketed by the hugely successful Edinburgh-based Mara Seaweeds company.

Packed with minerals, vitamins and amino acids, seaweed's high iodine content is considered beneficial for pregnant mothers and people with thyroid complaints, while its calcium and magnesium help prevent osteoporosis.

"Foraging for seaweed is easy and anxiety-free, since there are none that are poisonous," says John Wright, who gathers dulse by the truck load on visits to Scotland and cooks in a similar way to kale.

He stresses, however, that "good foraging manners" are vital to protect delicate species and that you should "leave more of any specimen than you take".

Hips and pips

Many polytunnel-grown supermarket fruits derive their nutrients from chemicals rather than the soil, says Monica Wilde, who recommends wild strawberries, raspberries, blaeberries and brambles as deserving the accolade of "super-foods". Wild strawberries are particularly nutritious: even the leaf, says Wilde, contains 300 times as much vitamin C per 100g as an orange.

Blaeberries, which have as much zinc as pumpkin seeds as well as powerful antioxidants, can be used to treat diabetes, rheumatism and digestive disorders. They grow abundantly among Scotland's woods and moors and it's been speculated that if harvested commercially, they could yield better agricultural returns than sheep farming.

Wilde is also enthusiastic about rosehips. Known to mischievous children as "itchy-coos" thanks to their seeds' ability to cause irritation when slipped down somebody's back, these shiny fruits are so high in vitamin C that during the Second World War they were harvested on a grand scale and made into rosehip syrup.

It's also said that at one time, people carried them in their pockets to protect against haemorrhoids, though how that's supposed to have worked is unclear.

Coastal concoction

Sea buckthorn grows profusely around Scotland's coasts, particularly in East Lothian. "The juice and seeds are packed with an entire shopping list of things you would buy in the health-food shop," says John Wright, listing vitamins A, C, E and K along with several B vitamins, carotenoids, flavonoids and free amino acids among its nutritional riches.

He makes his own juice from the bright orangey-yellow berries but admits it's an "acquired taste" with a flavour that's "half-way between orange juice and sulphuric acid". Undeterred, he drinks a small glassful each morning as a tonic and feels "hale and hearty" at 67.

Although the juice is widely sold in Scandinavia the challenge, clearly, is to find a palatable way of serving sea buckthorn. Scientists from Edinburgh's Queen Margaret University are on the case, having already collaborated with Borders-based company Cuddybridge to produce an apple and sea buckthorn juice.

Meanwhile, Michelin-starred chef Tom Kitchin is ahead of the game. He harvests the berries each autumn and has written that their "wonderfully unique, honey taste ... works in both sweet and savoury dishes", which he serves in his Edinburgh restaurant.

Common sense

Isn't that an invasive, poisonous plant, I ask Mark Williams when he suggests common hogweed as a potential superfood. "You're thinking of giant hogweed," he says, adding that although the "common" variety needs careful handling because the sap can be harmful, this native plant produces shoots that are extremely high in vitamin C, potassium and phosphorus and, when fried in butter, "tastier than asparagus".

"I've fed them to Michelin-starred chefs, who go crazy for them." Overall, he says interest in wild food is growing "exponentially" – ironically, partly because expensive restaurant menus now feature many ingredients that are free if you find and cook them yourself.

Creepy crawlies

It's been speculated that insects could help solve the looming world food crisis. So could Scotland's teeming beastie population be the "hero food" of the future? John Wright doesn't rule it out but says that while insects are high in protein and low in fat, they are notoriously difficult to catch.

Flying ants, for example, emerge on only one day each year and even then, "the difficulty is getting them into the frying pan without them flying away". If you prefer raw food, he suggests putting your hand on an ant hill, letting the creatures crawl all over it and then licking them off. "They have an intensely citrus flavour," he says, adding that different species offer subtle taste variations, such as hints of tangerine.

Wright isn't squeamish. Fungi, he says, often harbour maggots but he's only put off if the mushroom-to-maggot ratio exceeds 10%. "Don't overcook them, though," he warns, adding that the larvae are best served "lightly done".

Scotland's most notorious beastie is, of course, the midge. Could our luxuriant supply fuel a superfood industry of the future? Wright suggests – not entirely seriously – that would-be small game hunters should arm themselves with "a good quality butterfly net" or, for the more determined, "a mosquito net attached securely to the top of your car with a frame to form a 'sock-net'."

He recommends cooking the spoils into a bacon-infused paté and adds: "Some 200,000 midges are needed to make four ounces (100g) of paste, so you will have a massacre on your hands."

Even so, he admits the impact on midge numbers would be minimal and points out that the goal wouldn't be culinary excellence but retribution.

After all, he says, the creatures locally known as "small wee b******s" have it coming to them.

For information on courses run by the foragers interviewed above visit, (for Mark Williams) and (for John Wright)

John Wright's new book, The Forager's Calendar, is published by Profile, £16.99