KARMAIYA, Nepal -- The talisman tied above the entrance to Harsha Bahadur Bot's house is a bundle of rice, the flawed foundation of life in the plains of Nepal.
Rice sculpts the landscape into diked squares of green or gold. The diesel pop-pop-pop of the rice mill is the sound of a village from afar, its beating heart. Rice is the basis of every meal, and a family's supply is bank account and insurance policy rolled into one.
That the grain has the power to conjure good or ill seems obvious to Bot, 45, a farmer and fisherman.
"If you have bad luck, and you run out of food," he says, "you cook this rice and eat it, and your luck will change."
Bot knows plenty about bad luck. Of 36 children born to him and his two wives, Sumni and Chandra, 19 died in infancy or early childhood.
"Sometimes it was diarrhea, sometimes fever," he says quietly. He does not connect his children's deaths with their diet. But when malnutrition comes to kill, it often comes in disguise.
In the Third World, 30,000 children younger than 5 die every day, nearly all of diarrhea, pneumonia, malaria or some other infection. But scientists say malnutrition is the underlying cause of more than half of those deaths, turning a passing illness into a mortal downward spiral.
A cunning enemy, malnutrition is not marked by the swollen bellies and stick-thin limbs of starvation. In its most insidious form, called micronutrient malnutrition, a child who eats enough to satisfy his hunger may die because he lacks a pinch of certain vitamins or minerals.
And that is the fatal shortcoming of rice, staple food of half the world: It does not contain certain crucial nutrients, notably vitamin A. Lentils can be added for protein, as is routine in Nepalese cooking. But if a family cannot also afford such vitamin-rich foods as greens, milk or eggs, a diet dominated by rice can destroy the very life it has sustained.
This hidden hunger -- the name often used for micronutrient malnutrition -- first brought researchers from the Johns Hopkins School of Public Health to Nepal more than a decade ago. Now they are trying to find a prenatal vitamin pill that can reduce infant mortality, which casts a fearful shadow over every Third World village.
They are heirs to a century of experiments that replaced food superstition with science and wiped out crippling nutritional disorders in the West. Those experiments began with the discovery of the first vitamin, named for the first letter in the alphabet.
The debut of vitamin A in 1913 opened up a scientific frontier comparable in its potential to genetic engineering today. By 1930, amid an explosion of nutrition research, scientists had established vitamin A's critical role in the body's defenses against disease.
But for a half-century, the lessons of that early work were forgotten. Only after a Hopkins physician, Alfred Sommer, stumbled upon the life-preserving power of vitamin A in Indonesia would the benefits begin to reach children in the developing world.
The convoluted history of the first vitamin is a remarkable drama of science lost and found, of the tunnel vision of researchers and the exacting rules by which truth is separated from myth. It begins nearly a century ago with another Hopkins professor, one whose experiments illustrated perfectly the dangers of an all-rice diet.
Elmer V. McCollum contributed mightily to the quiet revolution that sent the death rate of American children plummeting. And he reaped the usual reward history accords the heroes of public health: Beyond a small circle of scientists, few remember his name.
In 1913, McCollum was an agricultural researcher at the University of Wisconsin, looking for a diet that would make cows thrive.
Researchers had long suspected that in addition to protein, carbohydrates and fat -- the "macronutrients" -- all animals needed minute amounts of certain mysterious substances. One enthusiast even coined a word for these substances: "vitamines," from "vita," for life, and "amines," the class of chemicals he believed, incorrectly, they would come from. Nobody had ever seen a "vitamine," but there was plenty of evidence they existed.
McCollum's childhood offered an illustration. Born to a Kansas farm family in 1879, he developed scurvy at 10 months; by feeding him bits of apple, his mother cured him. He later described the episode as "my first experiment in nutrition."
McCollum's mother had no way of knowing it was the vitamin C in the apple that cured her son. Americans' notions of health then were at least as primitive as those of Nepalese villagers today. McCollum would later write that his schoolmates' parents, fearful of contagious diseases, forced them to wear "stink bags" of foul-smelling concoctions around their necks "to ward off the Devil."