The coronavirus pandemic and related restrictions have jacked up food prices around the world and spurred a surge in unhealthy eating, according to a set of papers published on Monday by the American Society for Nutrition (ASN).

According to author Caroline Um of the American Cancer Society, the researchers found a "decrease in the consumption of many food groups, particularly healthy foods such as vegetables and whole grains, compared to before the pandemic."

"We saw panic buying, problems in the food supply chain, increases in food prices and rising unemployment rates," Um said.

Researchers at Tufts University said food prices went up across 133 countries as pandemic-related curbs were introduced.

"More stringent restrictions were linked with a higher price of food and a higher ratio of food prices to prices across all consumer goods," they said.

In the U.S., a survey of almost 4,000 people by the government's Centers for Disease Control and Prevention (CDC) found that "a sizeable portion of Americans increased their consumption of unhealthy snacks, desserts and sugary drinks during the CODID-19 pandemic."

Another survey, of around 60,000 Americans and covering the period either side of the 2007-2009 recession, suggests "dietary quality plummeted along with the economy."

The findings suggest that economic factors weigh heavily on diets, with Um warning that "the shift in consumption of fewer healthy foods could continue" leading to higher incidences of conditions such as diabetes and heart disease that in turn heighten vulnerability to COVID-19.

Older people already afflicted by such co-morbidities have made up most of the world's coronavirus-related deaths.