Britain ranks among the poorest countries for “human flourishing”, according to a major study that raises questions about the nation’s wellbeing and younger people in particular.

The survey, which spanned 22 countries on six continents, rated the UK 20th based on a combined score that considered a range of factors from happiness, health and financial security to relationships and meaning in life.

The Global Flourishing Study drew on nationally representative samples to reflect the experiences of nearly half the world’s population. The five-year project launched in 2022 with the aim of quizzing more than 200,000 participants annually and building a detailed picture of what helps and hinders human flourishing.

In a flurry of papers released on Wednesday, researchers outlined key findings from the survey, which posed a dozen questions on flourishing, and many more about people’s past and present lives. The latter included questions on childhood and family relationships, education, religious practice and marital status.

Armed with the data, the researchers identified tentative predictors for human flourishing and produced a score that aims to give an overall sense of how well individual nations are doing, on a scale from one to 10.

“One of the big surprises from the data … is the ordering of the countries,” said Prof Tyler VanderWeele, an epidemiologist at Harvard University. The analysis in Nature Mental Health ranks Indonesia first, followed by Israel, the Philippines and Mexico. The UK, Turkey and Japan take the bottom three spots.

The findings contrast sharply with the World Happiness Report, which is regularly topped by Nordic countries and ranks the UK in the top quarter of 100 countries surveyed.

According to VanderWeele, the disparity might be driven by richer, more developed countries scoring well on financial security and measures such as “life evaluation”, but worse on relationships and a sense of meaning in life. The survey found, for example, that scores for finding meaning in life tended to be lower in countries with a higher GDP.

Part of the survey focused on religion and found that attending religious services in childhood predicted greater flourishing as an adult, though the study cannot prove a causal link. The survey was co-funded by the John Templeton Foundation, which has long been interested in the intersection of science and religion.

One of the more troubling findings, the researchers said, was that young people in countries such as the UK, the US and Australia seemed to be flourishing the least. Again, this counters previous work that shows a U-shaped relationship between wellbeing and age, with the young and old faring better than those in middle age.

In the UK, 18- to 24-year-olds scored “markedly lower” on life satisfaction than 25- to 29-year-olds, who in turn scored lower than the over-80s, said Dr Tim Lomas, a psychologist on the study. “The very youngest in the UK do seem to be particularly struggling,” he said.

As more data is gathered, researchers hope to see how flourishing varies as world events unfold. But VanderWeele said people could use the 12-question flourishing survey to assess the state of their own lives. “I try to do this at least quarterly,” he said. “Over time, you can see what’s improving, what’s staying the same, and what may be getting worse.”

Prof Kate Pickett, an epidemiologist at the University of York, was cautious about some of the findings. One reason was that self-reported measures of wellbeing did not always reflect objective measures of a nation’s health. Japan, which ranked lowest of the 22 countries, had a longer life expectancy and lower infant mortality than any of the others, she said.

Pickett also suspects a pandemic effect. “I’m very surprised there’s not a single mention of the Covid pandemic,” she said. “We know that in the two years prior to the survey, young people would have experienced all the negative impacts of that – lockdowns, anxiety, disruptions to education, training, social relationships and so on – at perhaps a more critical juncture than older adults, with lasting impact for all aspects of their flourishing.”

“We already know from a very large and robust body of evidence that we need to give children a good start in life, give people secure livelihoods, focus on prevention, and reduce economic inequality,” she added.