Devil's claw: The medicinal plant from southern Africa against rheumatic complaints

Sustainable cultivation by A.Vogel

Environment and philosophy

Clemens Umbricht
Clemens Umbricht

04 April 2021

In the border region of South Africa, Namibia and Botswana, in a dry climate and sandy soils, the striking medicinal plant thrives. Remarkable: It takes a whole 100 kilograms of fresh roots to obtain 10 kilograms of extract (active ingredient), for example for highly effective Harpagophytum tablets.

A demanding plant

Devil's claw is a medicinal plant with very special characteristics. Each of its bright red to pink-violet, trumpet-shaped flowers appears for only one day during the short rainy season. It owes its mysterious name to the claw-like barbed fruits that emerge from the flowers.

Harpagophytum procumbens is picky when it comes to growth: It thrives exclusively in the steppe regions of Namibia, Botswana, South Africa and Angola, which form the Kalahari Desert. Devil's claw has a main or primary tuber and several secondary storage tubers. The plant can only regenerate from the primary tubers. However, only the tubers of the secondary root are used medicinally. These secondary storage roots, up to six centimetres thick and 20 centimetres long, reach down to a depth of one and a half metres.

So the "harvest" is anything but easy, and digging it out in the African heat is a real challenge. Andreas Ryser, until recently Head of Medicinal Plant Cultivation at A.Vogel AG, needed one and a half hours to dig up the tubers of a single plant during a visit to South Africa! The roots are then cut into thin slices and dried.

Traditional and sought-after remedy

Whether for liver, gall bladder, stomach, kidney or rheumatism: Local medicine men have been prescribing the dried roots for centuries. The use of this analgesic and digestive plant was also popular in the treatment of wounds and in obstetrics.

Like other researchers before him, the Swiss naturopathy pioneer Alfred Vogel (1902 - 1996) was drawn to the Kalahari and Namib deserts in the 1960s to investigate the effects of devil's claw. What struck him right away, despite all the fascination, was the considerable overexploitation of the plant, which is sought after throughout the Western world.

Therefore, there was only one option for the company A.Vogel from the very beginning: the cultivation of Harpagophytum procumbens. An undertaking that proved to be no easy task in the desert regions at the southern tip of the African continent.

Sustainable cultivation project

In a network, to which A.Vogel and another companies belong, a sustainable cultivation project was carried out from 1998 to 2005 on the farm "Avontuur", 150 kilometres north of the South African city of Kuruman, together with Prof. Dieter J. von Willert from the Institute for Plant Ecology at the University of Münster (GER).
This project had three objectives:
1. The prevention of overexploitation.
2. The supply of raw materials with good, consistent quality
3. Involving local people in the demand for their native plants.

The background to this is the virtually skyrocketing demand for devil's claws since the 1990s. Exports from Namibia alone have levelled off at around 650 tonnes per year in recent years. This amount corresponds to eight to eleven million plants! Due to the extremely low renewal rate through seed germination, the size of the wild populations is thus successively decimated.

In view of this threat, urgent measures were (and are) needed to protect this valuable desert plant.

Higher crop yield thanks to sustainable cultivation

The basis for the development of the sustainable cultivation of devil's claw was a proposal by the "Avontuur" farmer Gert Olivier. He developed a process on the basis of which devil's claws from cultivation yield roots several times larger than those from wild collections. For 200 metres, Olivier has treated the pastureland to remove all vegetation from three-metre-wide strips. These vegetation-free strips alternate with five-meter-wide strips whose vegetation has been left in place. Various reaction mechanisms lead to the fact that the soil of the vegetation-free strips contains significantly more water and the water content is subject to much smaller fluctuations in the rainy season than the soil of the vegetation strips.

A comparison of yields shows that the cultivated plants already have more dry matter on the scales at the end of the first growth phase than the wild plants. By the end of the third vegetation phase, the yield of cultivated plants has increased almost eightfold compared to wild plants - and this with the same concentration of ingredients!

This is of decisive importance not least because, as described at the beginning, from 100 kilograms of fresh roots of this unique plant just about 10 kilograms of extract (active ingredient) are obtained for the highly effective Harpagophytum tablets from A.Vogel.

Best possible quality of the raw material

Meanwhile, sustainable cultivation of devil's claw in South Africa meets all specifications, and digging out the plants has been greatly facilitated. The farm workers do not dig their holes up to one and a half metres deep, as is the case with the wild plants, but only about 20 to 30 centimetres. The soil in the cultivation strips is looser than the desert soil and the secondary tubers grow less deep than those of the wild devil's claws thanks to the higher moisture content in the upper soil layers.

The cultivation project has also brought other benefits: It prevents, for example, the confusion with tubers of other plants that often occurs in wild plant collections. Moreover, because the locations are known, harvesting (after four years of growth) can take place at any time of the year. Since the cultivated plants produce about 100 times more fruit, propagation is done by seed. This means that the genetic diversity of the planting material is preserved.

Although locals still collect the plants, the wild stocks are no longer exploited. This is a significant contribution to the protection of devil's claw, the preservation of genetic resources and the assurance of the best possible quality of the raw material - not least for A.Vogel's Harpagophytum tablets.

Since 2018, no raw material can be sourced from the Farm Avontuur. The reason is the lack of a successor for the business. There is a transfer of knowledge to a grower in Namibia. For this purpose, the previous, old grower, a new grower and experts from A.Vogel AG met in Namibia. There, cultivation is currently (as of the end of 2020) being established in a similar manner, with the same sustainable goals.

Alfred Vogel and the devil's claw

"At the time I was looking for devil's claw, this plant was almost unknown in Europe. But then the ... business world ... discovered it and advertising helped to make it widely known. This increased demand so much that collectors supplied similarly bitter-tasting roots instead of the real devil's claw. It was not easy to sort out the mess later on. However, as the government campaigned against exploitation and put restrictions in place, it was possible to give the plant some protection. As a result, it has now almost fallen into oblivion again. I myself, during my stay, was busily engaged in studying the plant's medicinal powers .... I brought a thin slice of the storage root into contact with the saliva in my mouth in order to bravely swallow the bitter substances dissolved by it ... Of course, I have also made use of devil's claw when suffering from health disorders during my stays in the tropics."

Alfred Vogel, 1970, as quoted in: „A.Vogel – Aktiv gegen Rheuma. Strategien für eine ganzheitliche Behandlung. Tipps zur Vorsorge und Selbsthilfe", Heinz Scholz, Verlag A.Vogel AG, CH Teufen AR


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