ROME - India could save water and reduce planet-warming emissions if people added more vegetables and fruits like melon, oranges and papaya to their diet while reducing wheat and poultry, researchers said on Wednesday.

India's population is forecast to rise to 1.6 billion by 2050, and to ensure there is enough available freshwater, water use will have to be cut by a third, according to a study published by The Lancet Planetary Health journal.

But population growth will also lead to an increase in demand for food, putting more pressure on water through farming.

By 2050, irrigation will account for 70 percent of total water use in India, up from the current 50 percent, unless farming methods change and diets shift toward food that needs less water to grow, the study said.

"In India, the proportion of freshwater available for agricultural production may already be unsustainably high," said James Milner, the study's lead author from the London School of Hygiene & Tropical Medicine.

"Modest dietary changes could help meet the challenge of developing a resilient food system in the country," he said in a statement.

The study, which Milner said was the first to look at changing food habits to save water, found that freshwater use could be reduced by up to 30 percent by lowering consumption of wheat, dairy and poultry in favor of fruits and vegetables.

The best kind of diet would also include legumes, and swap fruits requiring more irrigation, like grapes, guava and mango with more water-efficient crops such as melon, orange and papaya, the study said.

The dietary changes would also lower the risk of cardiovascular diseases and cancer in humans, while protecting the planet by cutting greenhouse gas emissions by up to 13 percent.

In 2011, India was the world's fourth largest emitter of greenhouse gases from farming behind China, Brazil and the United States, according to the World Resources Institute.

Livestock accounts for almost two thirds of total agricultural emissions, mainly from manure and feed production, according to government statistics.