The high season is not very long, from early March to mid-April most often, during which Christian Mallo and half a dozen seasonal workers work daily to harvest the precious nectar.

"You have to be in the forest every day, the sap has to be taken every morning otherwise it would start to ferment," says Mallo.

As with maple sap harvesting, the Canadian cousin, one or two small holes are drilled in the bark of the birch trees and the sap drops into a bucket.

"In total, we have 1,700 buckets to pick up every day. Then we take the barrels home and vacuum in the afternoon, in hermetic bags of three liters, "says the harvester. "Then we deliver very quickly to customers: we have no stock, the product must remain fresh, production starts immediately."

Christian Mallo was one of the first in France to start producing birch sap in 2012 after returning from a trip to Finland, where he discovered this crop.

Birch sap harvesting in a forest in Geudertheim, on April 4, 2023 in the Bas-Rhin © Frederick FLORIN / AFP

His company, Sève'Up, now supplies 180 stores in eastern France.

Strangely, no official body seems to have looked at birch sap and it is impossible to obtain a figure for production or the number of farmers in France.

"Blood test"

The importance of the harvest depends on many factors, according to Mallo: "Trees flow differently depending on exposure, development, phases of the moon, if it's hot... This year, we will harvest about 17,000 liters, it's average: last summer was very hot and the winter was quite dry."

As for the birches themselves, the samples are painless: "We harvest from trees that are about 40 years old, it does not harm them at all, it's like a small blood test. The sap rises into the tree to feed the buds, which will then make leaves. As soon as the buds are fed enough, the sap stops flowing," says the 51-year-old producer.

An operator installs a drip system to harvest birch sap, in a forest in Geudertheim, on April 4, 2023 in the Bas-Rhin © Frederick FLORIN / AFP

The soil at the foot of the trees is analyzed regularly to ensure that it is not polluted, and obtain the organic label.

Well known in northern countries, birch sap is ideal for a cure at the end of winter, says Mr. Mallo: "It is a super product, natural, organic, full of virtues, which detoxifies the liver, kidneys and intestines".

However, no scientific study has really looked into the subject and medicine recognizes only a diuretic effect.

"I never prescribe birch sap, I stick to what I've learned. I admit that I have never been too interested in this product," says Dr. Marine Bouisset, a doctor in Strasbourg.

"Three-week cure"

"It will never replace conventional drugs, but it is what we can call a + nutraceutical+, which we can add to our daily life and help you feel good," says Céline Touati, nutritherapist and naturopath, author of several books on diet and well-being.

"There are two main beneficial effects: it will drain everything we have accumulated during the winter, and it is a substance that remineralizes, which brings trace elements, magnesium and selenium in particular," she adds.

Birch sap harvesting in a forest in Geudertheim, on April 4, 2023 in the Bas-Rhin © Frederick FLORIN / AFP

The latter recommends a three-week cure (which will cost about thirty euros), with a small glass on an empty stomach every morning. The sap, which keeps for six weeks, has almost no taste at first, but it asserts itself little by little over the course of fermentation.

If fashions come and go regarding the many herbal wellness treatments, the beneficial effects of birch sap have been reported since the Middle Ages, before being forgotten.

"The ancients knew its virtues, and it is no coincidence that today cosmetic manufacturers are starting to reintroduce it into their products," says Myriam Raoux, partner of Mr. Mallo.

© 2023 AFP