When Drought Reigns, Diets Can Turn Poisonous

This time of year, most of the Western world is focusing on holiday indulgences: how many presents to buy, how many lights and candles to festoon the home, and how many sweets and feasts to offer family and friends. However, for many people in drought-stricken Africa, food and water will be in perilously short supply this season. So short, in fact, that some people in Ethiopia are already making the grass pea–a cousin of the sweet pea–a dietary staple.

Although that sounds benign, it could be dangerous. Ordinarily, herders plant this legume as forage for their livestock. And in small quantities, the grass peas–the plant’s seeds–are safe ingredients of recipes of cuisines from Afghan to Chinese. As such, the legume serves as a low-cost base for stews, breads, and gruel. However, when eaten to excess–as happens in arid Ethiopia and many other regions of the world when drought persists–grass-pea consumption may lead to permanent paralysis because the seeds contain an unusual neurotoxin.

Although many people in sub-Saharan Africa and elsewhere are aware of the grass pea’s hazard, during drought they confront a Hobson’s choice: starve or eat more of one of the only foods available. The enduring irony is that the protein-rich grass pea is one of the few arid-region crop plants to thrive when drought sets in. Moreover, when food is scarce, robust men usually receive the biggest portions to support their breadwinning activities. So, the individuals most important to a community’s survival are often the first ones felled by the grass pea’s poison.

Food aid–especially deliveries of cereal grains such as wheat and corn–from other countries can make a big difference, an international team of researchers now reports. Writing in the Nov. 29 Lancet, Fernand Lambein of Ghent (Belgium) University and his colleagues show that even when large quantities of grass peas are regularly consumed, mixing them with other cereals can substantially diminish the risk that the grass-pea toxin will paralyze people.

The scientists acknowledge that they don’t know whether the additional starches contain nutrients that reduce an individual’s vulnerability to the legume’s neurotoxin or whether making grass-pea recipes with the added grains typically requires more water, which could dilute or leach out the toxin.

The problem

The grass pea (Lathyrus sativus) produces an unusual amino acid known as beta-N-L-alpha-beta-diaminopropionic acid, or ODAP. While this compound may provide the legume some resistance to pests or climatic extremes, it is a potent neurotoxin. It appears to kill mammalian nerve cells–especially those in the legs–through overstimulation.

One of the first symptoms of ODAP poisoning–or lathyrism–is weakening and spasticity of the legs. If the condition is allowed to progress, the victim will eventually be reduced to crawling. Wheel chairs aren’t an option for most lathyrism sufferers, as they tend to live in dirt-floor huts in rural communities with no paved roads.

An August report by the Famine Early Warning Systems Network (FEWSNET), hosted by the U.S. Agency for International Development, noted that 13.2 million people in sub-Saharan Africa were in need of food aid totaling some 739,000 metric tons (MT)–with the peak supply needed between August and this month.

The emergency alert noted, “Ethiopia, in the midst of a worsening humanitarian emergency due to consecutive droughts, deep poverty, and ensuing livelihood crises, has averted outright famine due to massive food-aid pledges and deliveries.” The report continued, however, that the single country needs an additional 200,000 MT of cereals and 50,015 MT of legumes “to cover unanticipated needs during the early months of next year.”

A little over 2 weeks ago, FEWSNET issued another emergency alert, noting that in nearby Somalia, more than 90,000 people who ordinarily herd livestock now confront “an emergency food-security situation due to lost income from livestock and milk sales.” Roughly 60 percent of herds have died or been sold in distress during this seventh-consecutive drought during the rainy season.

North Africa isn’t the only affected region. Last December, Robert A. Simpson, a physician who spent 7 months in remote Afghanistan, working for the France-based Doctors Without Borders, reported a lathyrism endemic in remote villages. Writing in the Medical Journal of Australia, he noted that routine check-ups in many villages found undiagnosed individuals complaining of stiff muscles. Upon examination, most displayed lathyrism’s characteristic spastic leg movements.

Simpson concluded, “Most of the locals knew of the association between patak [the local name for grass pea] and lathyrism but continued to eat it out of economic necessity.”

Recipes for safer consumption

Many studies have shown that soaking grass peas prior to cooking can leach out ODAP. So, nutritionists have recommended that cooks pretreat the legumes this way and pitch the water.

The problem, of course, is that when people dramatically increase their grass-pea consumption, water supplies are so low that they tend to reserve for drinking what little water is available.

Lambein’s team, headed by Haileyesus Getahun with the South Gonder Health Department in Ethiopia’s Amhara Regional State, surveyed individuals in an area where lathyrism has become epidemic, with some 1.2 percent of the population affected. The researchers asked what the local people had eaten over the 1995 to 1999 period, how much food aid they had received, and how they prepared any grass-pea-based meals.

In their report, the researchers say they found that while families received about 12.5 kilograms of cereal aid per person during the food crisis, delivery was irregular. Delays in the supplemental grain, the researchers note, “coincided with the peak [lathyrism] epidemic in 1997, when 1,454 new cases (9.6 per 1,000) were reported.”

By comparing families that used different recipes or received supplemental grains regularly versus irregularly, Getahun evaluated the lathyrism risk from various grain combinations. He found, not surprisingly, that eating plain grass peas roasted, boiled, or raw was associated with an increased risk for lathyrism. However, there was “no raised risk” from eating grass-pea flour in fermented pancakes, unleavened breads, and gravies.

Cooks often added supplemental grains to the pancakes and breads, the researchers note–perhaps diluting any ODAP these foods contained. Moreover, condiments added to the gravies might have made these sauces more nutritionally balanced than dishes containing plain grass peas. Finally, the additional cooking steps involved in preparing gravy or using supplemental grains may have washed out most of the grass peas’ ODAP.

What this suggests, the researchers conclude, is that even where consumption of grass pea is heavy, adoption of certain food-preparation techniques and the availability of supplemental cereals could limit lathyrism.

Safer legumes on the horizon

A United Nations consortium known as the International Center for Agricultural Research in the Dry Areas (ICARDA), headquartered in Aleppo, Syria, has succeeded in breeding virtually toxinfree cultivars of L. sativus (SN: 7/29/00, p. 74: Detoxifying Desert’s Manna).

In its 2002 annual report, ICARDA reported on field experiments with these plants grown in Ethiopia. The tests showed that the new cultivars’ lowest ODAP production occurred when the legumes had been planted early, during a relatively wet spring. As soil moisture fell, the seeds’ ODAP concentrations climbed.

“This suggests,” the report said, “that combining low-neurotoxin lines with early sowing regimes will reduce [ODAP] content to a level safe for both human and animal consumption.”

Unfortunately, Lambein says, these new low-ODAP lines are still at least 2 years away from commercial distribution. This is particularly troubling, he notes, because roughly a third of the more than 13 million people in sub-Saharan Africa at risk for ODAP poisoning live in the grass-pea-growing region of Ethiopia, “setting the stage for a new epidemic” of lathyrism.

Moreover, he worries, although Ethiopia received more than 100 percent of its requested emergency food this year, “donor fatigue may make this a 1-year postponement only for the emergence of another food crisis.”

Dirk Enneking, a lathyrism expert in Germany who also toured Ethiopia’s drought-affected regions this year, has another concern: “Since ICARDA has announced that the problem of lathyrism would be solved by the low-ODAP lines, there are very few people who still consider lathyrism a problem.” In fact, it currently remains as big a threat as ever, he notes.

He recommends that until low-ODAP grass-pea cultivars get out to people, world-health and aid agencies should develop an early warning system to monitor and report signs that drought might be about to induce poor people to overconsume grass peas. That may require mapping grass-pea growing regions and the legume’s abundance relative to other crops in local markets.

Adds Getahun’s team: “Food aid should . . . not be restricted to the almost starving but should also be urgently sent to people in [lathyrism]-prone areas before they are forced into exclusive grass-pea consumption.”