The United Nations has launched a food safety campaign for an era in which millions are dying of hunger or tainted produce even as more and more people fall ill from eating too much.

"Food safety, quality and quantity must go together," Margaret Chan, director general of the UN World Health Organisation (WHO), said in Paris as she launched World Health Day 2015 on Tuesday under the theme: "From farm to plate, make food safe."

The WHO says about two million die every year of food-borne and water-borne diseases.

Food can be contaminated by viruses, bacteria, parasites or chemicals, sometimes from polluted water. Tainted food causes more than 200 diseases ranging in severity from diarrhoea to cancers.

According to initial figures from a WHO report set to be released later this year, some 582 million people suffered from 22 different food-borne diseases in 2010, and 351,000 people died.

More than 40 per cent of people who fell ill were children under five, and poor countries, particularly in Africa, were hardest hit.

Unsafe food also posed major economic risks, said a WHO statement.

A 2011 E. coli outbreak in Germany reportedly caused $US1.3 billion ($A1.7 billion) in losses for farmers and industry, and $US236 million in emergency aid payments to 22 European Union member states.

"Countries must come up with the right policies and the right systems for prevention and control at source," Chan said.

Another major problem is hunger placing people at risk of killer pathogens, like the Ebola virus, carried by animals they eat or come in contact with in the pursuit of food.

"When there is no food security, meaning people are not sure whether they are going to get food ... they go into the forest to hunt for bush meat," Chan said in reference to the west African Ebola outbreak.

The epidemic, which has claimed more than 10,000 lives since December 2013, has been blamed partly on people venturing ever deeper into the forest in search of resources.

On the other end of the nutrition scale, overeating is becoming an ever bigger challenge for health authorities.

"Eating the wrong type of nutrition, high energy, high fat, can give you heart disease, diabetes and of course obesity," Chan said.