Arctic kidney lichen

What is Arctic kidney lichen?

Arctic kidney lichen is a leafy lichen of cold northern forests and tundra. In Norway it is called storvrenge. In Sweden it is called norrlandslav.

It is not a plant. A lichen is a fungus and an alga living as one body. The top is smooth and pale green, with brown kidney-shaped discs near the edges.

Scandinavian and Sámi households gathered it as famine food and winter feed for livestock. It was always boiled first, to soften it and cut the bitter taste.

Here is the plain evidence verdict. No human trial supports any health use of this lichen. Traditional use is not proof of effect, and it is not proof of safety.

How does Arctic kidney lichen work?

No one has shown that arctic kidney lichen does anything useful inside the human body.

Lichens make bitter acids that protect them from grazing and microbes. In test tubes, extracts of several lichens slow the growth of some bacteria and fungi. Whether that happens in a person who eats or drinks the lichen is unknown.

Lichens also hold long sugar chains called polysaccharides. In cell and animal studies, sugars of this kind can nudge immune cells. That work was not done with arctic kidney lichen, and it has not been repeated in people.

Nothing is known about how much of any lichen compound reaches your blood after a meal or a brew. Without that, a mechanism cannot be turned into a health claim.

The old cooking steps had a simple purpose. Boiling, and soaking in water or wood-ash lye, pulled out bitterness and made the lichen easier to eat. That was food preparation, not medicine.

What forms does Arctic kidney lichen come in?

There is no standard commercial product. You are most likely to meet this lichen in the wild, not on a shelf.

Forms seen in past or present use:

- Fresh lichen, picked from the forest floor or tundra

- Dried lichen, stored for winter

- Boiled lichen, eaten soft or mashed

- A thick brew made by simmering it in water or milk

- Ground lichen mixed into flour to stretch bread

- Boiled feed for pigs and other livestock

Tinctures, capsules and standardised extracts are not normal products for this species. If you see one, nothing tells you what is in it. There is no agreed marker compound and no quality standard.

Some foraging suppliers sell dried Nordic lichens as novelty food. Labels rarely name the exact species, and lookalikes are common.

Where it comes from:

Arctic kidney lichen has a modest place in northern Scandinavian folk life. It was known mainly as a food of last resort, not as a medicine.

Sámi and settler households in Norway, Sweden and Finland boiled it in water or milk. Some mixed the mash into flour to stretch bread in hard years. Pigs and cattle were fed boiled lichen too.

Folk health use was thin and local. Collectors recorded boiled lichen drinks given for coughs, weak stomachs and slow recovery after illness. The records are patchy and never say whether anyone got better.

Interest faded in the twentieth century as food supply improved. Today the lichen turns up mostly in foraging books, museum notes and plant-lore collections.

What does Arctic kidney lichen help with?

• Famine and survival food: This is the use with the strongest record. Boiled lichen gave bulk, some sugars and a little protein in hungry years. It was never a good food. It is low in calories and hard to digest raw. Modern survival books still list it, but as a stopgap only.
• Cough and sore throat (folk use): Tradition used warm, slippery lichen brews to coat a sore throat. The same idea drove the much better known use of Iceland moss. No trial has tested arctic kidney lichen for cough or throat pain. Any soothing feeling likely comes from warm, thick liquid, which you get from many drinks.
• Upset stomach and poor appetite (folk use): Bitter plants and lichens were given to wake up appetite in northern folk practice. Arctic kidney lichen was sometimes used this way. There is no human study on it. Poorly cooked lichen can irritate the gut rather than settle it.
• Weakness during recovery from illness (folk use): Thin milk-and-lichen gruel was fed to people getting over illness. The value was food, not medicine. No research supports a tonic or strengthening effect. Ordinary nourishing food does the same job with less risk.
• Animal feed: Boiled lichen was fed to pigs and other stock when fodder ran short. This is a documented farm practice, not a health claim. It says nothing about safety or benefit for people.

Which foods are rich in Arctic kidney lichen?

This lichen is itself a wild food, so it is not a nutrient found in other foods. No ordinary grocery item contains it.

What are the side effects of Arctic kidney lichen?

• Stomach cramps, nausea or loose stools, especially if it is undercooked
• Bitter taste that puts people off food
• Bloating or constipation from the gel-forming sugars
• Skin rash or itching in people who handle lichens often
• Build-up of heavy metals or radioactive caesium with long, heavy use
• Serious illness from eating a misidentified lichen or plant

Good to know:

Nobody has tracked side effects in a proper study, so these come from general lichen use and folk reports.

Short, well-cooked, food-sized amounts seem to be mostly tolerated. Gut upset is the common complaint.

The larger risks are not the lichen itself. They are wrong identification and contamination from the place it grew.

How much Arctic kidney lichen should you take?

• Recommended daily: No dose can be given, because no safe or useful dose has been worked out. There is no licensed product and no label amount to quote. Historically it was handled as a food, boiled and eaten in small amounts alongside other foods. That is a record of past practice, not a serving size for you. If you are thinking of eating wild lichen, speak to a doctor or a dietitian first, especially if you take regular medicines.
• Best time of day: Time of day does not matter in any way that has been shown. It was treated as food and eaten at meals.
• With or without food: It was eaten as part of a meal, always cooked. Raw lichen is bitter and hard on the stomach. If you take medicines by mouth, thick lichen brews may slow how they are absorbed. Leaving a gap of a couple of hours is the usual cautious approach.
• Time to effect: There is no proven effect, so there is no honest time to give. A warm brew may feel soothing while you drink it. It may also do nothing at all. If you are using it instead of care for a real symptom, the delay is the risk.
• How long to take it: No safe length of use is known. Nothing has been measured over days, weeks or months in people. In the past it was eaten seasonally, in lean months, then dropped when better food returned. Long daily use raises a real concern, because lichens can build up heavy metals and radioactive caesium.