Ethnobotanists are re-examining years of data and revisiting distant indigenous peoples as they discover that information they have collected about medicines has a gaping hole.
Ethnobotanists and ethnopharmacologists, who study different cultures' traditional uses of plants and medicines, met last week in London to discuss the fact that for years their subject has ignored one of the most important medicines of indigenous peoples - food.
Paul Cox, professor of botany at Brigham Young University in the United States, said that academics are now recognising that many cultures combat and prevent disease through stews, porridges and drinks.
"We have been finding that our discrete categories between food and medicine are becoming very blurred because indigenous peoples don't distinguish between the two," he said. "I am going back through all my field notes".
Timothy Johns, of the centre for nutrition and the environment of indigenous peoples at McGill University in Canada, said: "Until recently biomedicine has regarded foods as chemically mundane."
But food could provide remedies for chronic diseases such as diabetes and heart disease. Studies of how local people treat diarrhoea, for example, have missed two of the most effective ways of treating it. Diarrhoea kills five million people a year.
Michael Heinrich, of the Institute of Pharmaceutical Biology in Freiburg in Germany, told the conference, "Plants for Food and Medicine", of new studies in Mexico revealing that rice gruel and corn gruel have all the advantages of modern oral rehydration therapies.
Professor Johns described additions to his research published last year which solved the mystery of the absence of heart disease among the Masai.
They eat a soup of cattle blood and milk - "they go out of their way to eat as much fat as they can," said Professor Johns.
Such saturated fat should lead to heart disease. But it is also full of spices from bark and roots, which counteract the fats. He has now found that the Masai also chew tree gums, particularly a variety of myrrh, which may also lower blood fat levels.
He told the conference, held jointly by the Society for Economic Botany and the International Society for Ethnopharmacology, that the change in thinking lies in a culture change in medicine.
The "magic bullet" approach to disease has depended on a concept of discrete diseases with specific aetiologies. But diseases such as heart disease, cancer and pulmonary disease are proving to have more complex causes. An acceptance of complexity makes it reasonable to believe that whole foods, rather than single chemicals, may be helpful.
"We recognise increasingly the complexity of active chemicals that exists in food plants," said Professor Johns. There is also a new respect for indigenous people which makes it harder to dismiss their assertions about their foods, he said.
For example, when Professor Cox investigated Samoan medicines he ignored a drink they take because they described it as a general tonic. He has now tested the brew and found a chemical which doubles the life span of T lymphocytes - it may therefore stimulate the immune system.
Professor Cox predicted that indigenous foods will soon be a source of medicines.