REPORT #455 December 2001

Produced by the Belize Development Trust

Sustainable Tropical Agriculture in Belize!
The University of the Yucatan confirms Velvet Beans succeed where Soya Beans fail

Tom Post in Belize forwarded us a report like none other I have encountered from the book Poisonous Plants of the United States and Canada by J. M. Kingsbury. Using the velvet bean grown in Florida years ago "even boiled for an extended time, the beans were unpalatable and produced, an hour or more after ingestion, symptoms of nausea and discomfort. While cooking, the beans gave off a volatile substance which produced a smarting sensation in the eyes and a pronounced headache among those experimenting with them." This is so unlike recent reports where the tropical velvet bean is being used that there must be considerable differences in toxicity between varieties. ECHO distributes two varieties of velvet beans. One is the kind that has no itch-producing fuzz on the pods and produces seed only during short days. We call it our "tropical velvet bean." That is the one we normally send overseas unless specified differently. Seeds may be white, mottled or colored. The other is the less vigorous kind grown in the southeastern USA which we call the 90-day velvet bean and is possibly the kind mentioned in this report. However, Sarah's experiments with mice described below were with this 90-day type and she found no such problems. ...

A study in the States showed that the likely benefit to the plant of such a high concentration of L-dopa is protection of the seed. "Mature seeds of velvet bean are conspicuously free from attack by small mammals and insects." Small amounts of L-dopa that they added to an insect diet produced toxic effects. Concentrations as high as found in velvet bean seeds inhibited feeding completely.

[However, Rolf Myhrman at Judson C. in Elgin, IL has done quite a lot of research on the velvet bean and has found out how to process it for human consumption, last I talked with him. The ECHO webpage has more (below).]

WHAT PERSPECTIVE CAN WE GIVE? There is not enough evidence to say with certainty that there are no problems from eating cooked velvet beans. We very much need more research, but human need does not wait for science. What should you recommend in the meantime? Considering everything that has been said above, if velvet beans were available and I was hungry or my diet was low in protein, I would definitely eat them after thorough cooking. If I were neither hungry nor malnourished, but was living at a subsistence level, I would occasionally eat velvet beans. (I am none of the above and do not eat velvet beans except as a curiosity if they are offered.) I would definitely eat modest servings at first, and consider changing my cooking methods if nausea occurred. I would warn families of possible symptoms and ask them to report any problems to me. I would not eat the wild velvet beans unless forced to do so and would be doubly cautious. The same would go for any new variety that I might obtain unless I knew that it was eaten elsewhere. I would feed them freely to pigs and chickens only if I had the firewood to cook them first. If at all possible I would "take a lesson from the deer" and browse small quantities of many foods, not eating too much of one thing.

New evidence has led us to offer the following guidelines at present. Has there been a failure of the bean crop in your area, but velvet beans are abundant? If so, it is almost certainly better to make use of velvet bean than to suffer hunger or protein malnutrition. Is the food situation a bit less desperate than that, but people still do not have enough to eat? If so, consider using velvet beans in moderation and not every day. Are there plenty of alternative sources of protein? If so, do not eat the velvet beans. Velvet bean coffee has a lot of dopa in it. It should not be consumed regularly. Return to CONTENTS.

NEW INFORMATION ON THE TOXIC SUBSTANCE IN VELVET BEANS. Velvet beans are being grown more widely, because corn yields can be increased considerably by intercropping with velvet beans. Velvet beans have potential to be a significant food. Bean yields are high, sometimes when common beans fail due to drought. The beans are nutritious, with a high protein content. Many recipes have been developed for their use and people enjoy the taste. Herein lies a major dilemma for farmers and their advisors. About 5% of the weight of the bean is a psychoactive substance called "dopa." Dopa is still a commonly prescribed treatment for Parkinson's disease, though it has side effects such as uncontrolled muscle twitches and, in extreme cases, even psychotic disorders including schizophrenia.

Dr. Rolf Myhrman brought both good and bad news on the subject at ECHO's Conference for Agricultural Missions. In his lab at Judson College in Illinois, he has been studying dopa in velvet beans from different countries and after different methods of preparation for human consumption. One thought has been that one might get rid of the dopa by removing all the seed coats. This can be easily done by hand after cooking. However, Rolf was unable to detect any dopa in the seed coats.

One major use of velvet bean by humans is to make a coffee substitute. (The coffee is called "nutri cafe" in Central America and the bean is sometimes called "Nescafe bean.") Ideally, the dopa would either be destroyed by the heat or remain in the grounds, leaving the coffee free of dopa. Rolf found, on the contrary, that making "coffee" is an ideal way to extract intact dopa! "An 8-ounce cup of velvet bean coffee can be expected to contain between 250 and 300 mg of dopa. For comparison, a physician might start a Parkinson's patient on 500-1,000 mg of dopa per day." [The other side of the question is whether someone with Parkinson's disease, but who cannot afford prescription dopa, could drink velvet bean coffee as a treatment. Do any physicians in our network have ideas on this?]

Rolf is working closely with Dr. Dan Buckles at CIMMYT, the International Center for Improvement of Corn and Wheat. According to Dr. Buckles, many people in Ghana eat velvet beans most days, using them primarily as a soup thickener. People in Benin mix 10-30% velvet bean flour with corn meal. Various preparation techniques are being used and sent to Rolf for analysis.

The good news is that a large fraction of the dopa can be removed from beans by grinding and soaking in water. Simple detoxification techniques might soon be available to remove most of the dopa. "Soaking the powder in room-temperature water, even for only two minutes, removes over half of the dopa. A second two-minute soak removed another 29%. Eighty percent is removed in two short soaking periods." Soaking 5-10 minutes does not remove additional dopa.

Using 50 deg.C water is no more effective than water at room temperature. However, soaking 5 minutes in boiling water removed 89% of the dopa and repeating the soak removed 99%.

Dr. Buckles sent Rolf velvet beans from a community in Ghana where people regularly eat velvet beans. Might these be extra low in dopa? Surprisingly, they had even more dopa than some others. Rolf suspected that they are detoxifying the beans and requested details of food preparation methods.

"We now understand how the Ghanians remove the dopa. They boil the beans 45-60 minutes, discard the water, add cool water and let the beans cool, then discard that water. Although our extraction techniques have all been with flour, it does not surprise me that they are removing a significant amount from whole beans by boiling."

You may contact Dr. Myhrman at fax 708/695-0407 or e-mail [email protected] This work began when Rolf requested an ECHO publication called Hunger-Related Research Opportunities, which lists research projectsthat could be performed with a modest budget that would benefit peasant farmers. Return to CONTENTS.

SPANISH-ENGLISH VELVET BEAN RECIPES. Aware of all these cautions, some of you still may decide it is necessary to use velvet bean as a food source, if people are hungry or suffer from protein deficiencies and there are no other alternatives. When I visited the World Neighbors project in Honduras a few years ago they were in the midst of a drought. The crop of common beans had failed, but the velvet beans produced abundantly. This led to efforts to incorporate velvet bean into local recipes. Additionally, new recipes were developed based on their work with soybean, after changes to improve the taste and consistency.

Milton Flores of CIDICCO shares his own experience. "Although many people are eating the velvet bean in more than one way, we are careful to caution them to use it with care. We have observed symptoms such as drowsiness and headaches. This is especially true when people mix several [velvet bean] dishes at a time. In my own opinion, some people are more sensitive than others. I can stand only one cup of velvet bean coffee and one or two velvet bean tortillas at one time. When we have cooking demonstrations, with several dishes prepared and offered at the same time, it is usual that a couple people report symptoms like those I have mentioned. Most people, however, do not seem to be affected in any way."

A recipe book can make everything look very straightforward and safe. Eating velvet bean has not been proven to be safe, but it is safer than trying to live without protein. (I imagine other beans could be made to fit into these interesting recipes.) World Neighbors/ACORDE has made available the Spanish-English recipe book Nutri-Cocina/Nutri-Kitchen. It gives guidelines for using seeds of this productive green manure crop to prepare 23 foods. The toasted nutri-flour and mashed cooked beans are used to prepare hot, high-protein drinks, tortillas, doughnuts, ravioli, pasta, and several sweet cakes and desserts. Ingredients are simple and common, and the directions are complete and easy to follow. You can order the book for US$7 plus postage: $3 in US/$7 overseas, from World Neighbors, 4127 NW 122 St., Oklahoma City, OK 73120-8869, USA; phone 405/752-9700; fax 405/752-9393; e-mail [email protected] If you are in Central America, contact the regional office of Vecinos Mundiales, Aptdo. Postal 3385, Tegucigalpa, HONDURAS; tel/fax (504) 32-7471. They are an excellent source of information on the uses of velvet bean in Central America.

A third practice, which is now more widespread but which is still under-appreciated, is the use of green manures and cover crops to stabilise swidden agriculture. Since decreased fertility and weed infestation are the two most important reasons why farmers abandon their fields today, and since green manures and cover crops can, to some extent, often solve both these problems they have proved to be an effective way of stabilising shifting cultivation in many countries.

One dramatic example can be drawn from the work of the Centro Maya in Guatemala's northern Peten region. In this humid forest area, farmers could only grow maize for one or two years and then the ground had to be left to regenerate. Now hundreds of farmers are growing velvet bean intercropped with maize on the same fields year after year. Those who initially adopted this system have been growing maize on the same land for eleven consecutive years and productivity has improved over time. Another interesting example is that of Central Ghana, where village farmers are inventing their own ways of stabilising their agriculture, including one system in which 30,000 leucaena trees (Leucaena spp.) are intercropped with maize and burned very lightly each year. This practice has allowed maize to be planted on the same land for 20 years in succession.

A well financed bank loan attempt to use a temperate zone of Soya Beans in Tropical Belize failed. Required to many foreign exchange imported chemicals by the second and third years. Another foreign idea promoted by experts in the wrong climate zone. Will they never learn that the tropics is not a temperate zone and agriculture is different?

A fourth potential benefit that will probably acquire more insignificance as experience increases, is the use of green manures as animal feed. Most green manures and cover crop species, with the major exception of Melilotus albus cannot be grazed well, but many can be used for cutting and carrying even after months of drought, the most notable examples of this type being Lathyrus nigrivalvis and lablab bean (Dolichos lablab). Seeds also provide fodder, one good example being the seeds of the velvet bean which in Campeche, Mexico are cooked for half-hour, mixed with an equivalent amount of maize and then ground into pig feed. The University of Yucatan calculated that this velvet bean feed cost less than commercial feeds per unit of weight gained.

Green manure and cover crops can be used in other ways as well. Two years after Alter-Vida stopped working in El Naranjito, Paraguay, farmers abandoned using velvet beans as a green manure, but continued to used to use them when they wanted to prepare their land for tobacco. In Southern Brazil, hundreds of thousands of farmers regularly use some 25 different species of green manure and cover crops for soil improvement partly because this allows them to increase the amount of organic matter in their soil to the point where tilling is no longer necessary. The financial as well as ecological advantages of zero-till systems are tremendously attractive.


A number of conclusions can be drawn from the examples given above. First, the variety of sustainable green manure and crop cover systems already established in traditional as well as more recently introduced agricultural system is remarkably diverse. Green manures and cover crops have been adopted on a wide scale despite the seemingly prohibitive conditions mentioned earlier in this article. The fact that virtually every system we have refered to has some elements of these conditions confirms their predictive value. Thus, programmes to introduce new green manure and cover crop systems should teach farmers not only how these species can be used to improve their soil but that they have other uses as well.

Tremendous potential still exists for the development of new green manure and cover crop systems. Scores of potential systems for using green manure and cover crops still need to be investigated, most notably the major possibilities of using them for animal feed; the potential latent in new as yet untried species, including trees and non-legumes, and the value to be derived from using combinations of green manures and cover crops rather than individual species. Experience leads us to believe that, with the possible exception of very intensive farming systems such as irrigated vegetable and rice, green manure and cover crops systems can probably be introduced into many, if not most of the world╠s, small-scale farming systems.

Roland Bunch, COSECHA, Apartado 3586, Tegucigalpa, Honduras

References - Wilken, Gene C 1987 Good farmers: traditional agricultural resource management in Mexico and Central America. University of California Press, Berkeley, California

- Young, A 1989 Agroforestry for soil conservation. CA International, Wallingford, UK

- Bunch, R 1995 The use of green manure by village farmers. What we have learned to date. Technical Report No.3, 2nd edition, July. CIDICCO

- Ministerio de Agricultura y Ganaderia (MAG)/GTZ, 1995 Siembra Directa, Primer Encuentro de Productores, Organizaciones y T╗cnicos. MAG/GTZ, AsunciĄn, Paraguay.

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