Caerphilly Cohort Study: What did we learn?
It is one of the most important health studies of its time and it was made possible thanks to 2,500 men from south Wales.
Tracking the lifestyle habits of middle aged men living in the Caerphilly area from 1979 to the present day, the Caerphilly Cohort Study is the longest-running of its kind looking at the influence of environmental factors on chronic disease.
It is a fascinating piece of work and has since inspired more than 400 research papers and further study around the world.
But where did the idea come from and what does it tell us?
Started in the late 1970s, it came off the back of an earlier investigation in the 1960s which looked at whether aspirin could reduce the risk of heart disease.
Researchers found it did, and so Prof Peter Elwood and his team at Cardiff University decided to embark on a longer term study investigating how people's lifestyles affected their health.
Caerphilly was chosen because it was home to a diverse mix of people from different socio-economic backgrounds, age groups and those with varying conditions of health, and was felt to be representative of the wider Welsh population.
Communities further up the valleys were dismissed over fears people living in some areas might have certain illnesses because of the region's industrial past, or that the more healthy and wealthy residents may have moved away.
Who took part?
Researchers chose men because they are four to five times more likely than women to develop heart problems.
To be as representative as possible, they recruited 90% of the middle aged men living in the county at the time.
This was crucial because studying only volunteers or existing patients may have distorted the findings.
What did they find out?
Among the study highlights was the discovery that drinking milk could reduce the risk of heart disease and diabetes, and those who ate oily fish regularly are less likely to suffer a heart attack.
But its most marked success was the finding that leading a healthy lifestyle could significantly reduce a person's chances of chronic illness.
The survey found that those who did not smoke, had low alcohol intake and maintained a healthy weight, had a balanced diet and did exercise, had a dramatically lower chance of developing conditions including diabetes, cancer, heart disease and dementia.
While all this is common knowledge now, the science behind the findings was gleaned from the Caerphilly group.
But despite the public health warnings so familiar to us today, the latest information from the Welsh government suggests on many measures we are still living as unhealthily as we were in 1979.
The study perhaps serves as a wake-up call for us all to change the way we live.
Researchers had wanted to build on the earlier aspirin study and see if a test could be developed to predict whether or not someone was at higher risk of heart disease by looking at blood platelets.
But the study revealed such a test was unlikely to work.
The men came from different backgrounds, but the ones I spoke to have one thing in common - all have an immense feeling of pride at being involved in something they consider to be very special.
Many likened the regular meet up for tests to a school reunion and said they felt part of a community - something which cannot always be said of those who take part in scientific studies.
And despite its findings, they all have different theories about the secret to longevity.
One man said it was keeping the mind active, others think it is more to do with genetics, while another put it down to having an understanding wife.
Now in their late 70s to mid-90s the remaining members of the group are currently contributing to research on prostate cancer, dementia and whether a person's mood, attitude and outlook on life can affect their health.
But even when there are no members left, the research may continue to provide a reference point against which future theories can be tested.
And the benefits of the study do not stop there because for many it was a springboard to work on other important research.
Among them is Prof John Gallacher, who has since gone on to lead the UK Biobank, a study of 500,000 people aged between 45 and 69 aimed at finding out why some people develop particular diseases and others do not.