By Pallab Ghosh
BBC science correspondent
British researchers are set to begin the largest ever study into the genetic and environmental causes of disease.
Project will focus on genes
The UK Biobank aims to obtain DNA samples from 500,000 people aged 40-69 and track their health.
This database will be made available to researchers wanting to discover the causes of diseases.
Lead investigator Professor Rory Collins said the project could have a profound impact on scientific understanding of disease.
He said: "In 10, 20, or 30 years time we'll be able to confirm or refute various theories about how some diseases are caused.
"We'll be able to identify new ways of identifying diseases and preventing them."
Professor Collins believes that the biobank could be used to find cures for some of the biggest killers including heart disease, diabetes and various cancers.
Biobank was conceived five years ago, but it is only now that the project is recruiting volunteers for the study.
The first wave will be from south Manchester: 3,000 people are being sent letters for the start-up phase.
It is hoped that Biobank will begin recruiting nationally by September.
If accepted for the study volunteers will give a sample of their DNA and answer questions about their current health and lifestyle.
Researchers will then track their health for several decades. Their names and addresses will be kept confidential.
This information will be made available to anyone wanting to discover links between lifestyle, genes and disease.
A committee will consider applications from academic scientists and private companies.
It will only approve research that it deems to be ethical.
Alan Langlands, chair of the UK Biobank board, said: "The privacy of participants will be protected throughout the lifetime of the project.
"The security of patient data has to be guaranteed to have the confidence of the public.
"In addition UK Biobank's action will be independently monitored both ethically and scientifically."
But Biobank does not have universal support. Many leading medical researchers are concerned that it will be difficult to accurately track lifestyle factors, such as diet and exercise of 500,000 people.
As a result, they say, the study will be superficial - and find false links between genes and disease.
Professor Collins said that those criticisms were out of date.
Biobank was now putting more emphasis on getting information about lifestyle factors, he said.
"I'm aware of uninformed criticism but I'm not aware of informed criticism.
"The science behind the project has been reviewed by our experts and they are telling us it's a very good project."
Privately though some still think there's not been enough investment in gathering lifestyle data.
The researchers I spoke to were reluctant to be named for fear of offending the Medical Research Council and the Wellcome Trust - who are behind Biobank, and are the country's largest funder of medical research.
One senior researcher, who did not want to be named, said: "Our very real concern is that there's been no real consultation with scientists who know how to collect information about behaviour.
"The quality of information that you get is directly proportional to what you spend on it and the care with which you collect it.
"Although there's been a huge investment into the genetic aspect of this kind of research - that's not been matched in the area of data collection."
In other words the old computer information maxim applies - if you put rubbish in you get rubbish out.
The researcher's feelings are shared by Dr Helen Wallace, of the pressure group Gene Watch.
She said: "Biobank is based on a false assumption that genes are responsible for big killer diseases.
"The project will divert energy and resources from other studies and throw up spurious results.
"The questions will be focused on genetic factors rather than environmental factors which will be looked at superficially over emphasises genetic factors."