It would be " enormously damaging " if patients decided to opt out of the new NHS data mining scheme, leading medical charities have warned.
The new data pool, which will be collected from GP records from surgeries across England, is "like a jigsaw" and would be incomplete if people choose to opt out, they said.
The central database will enable experts to assess diseases, examine new drugs on the market and identify infection outbreaks, they added.
Throughout January every home in England will be sent a leaflet about the major changes to the way personal information is stored by the NHS.
The care.data programme will see patient records held centrally, with non-identifiable data being extracted and used to asses services and for research.
Concerns have been raised about the prospect keeping all of the information in one place, with campaigners saying that it could lead to privacy problems and data breaches.
Patients who do not want their information to be shared need to contact their GP practice within a month. Data gathering will begin in spring.
But leading medical research charities said that while they "cannot guarantee that the data will be 100% safe" they stressed that it was of "fundamental importance" for people to allow their records to be included in the scheme.
Dr Peter Weissberg , medical director at the British Heart Foundation (BHF), said: "We're worried that some people might think, 'this is a bit dodgy, I'm going to default out of this'. And if they do that, that will have enormously damaging effects on our ability to run the health service and to do good research in the future."
He said it took decades to associate lung cancer and smoking because researchers had to get permission to follow up patients who had lung cancer and to search through their medical records before they realised that the vast majority were smokers.
"In today's health service, if patient data were available and you could just search for 'smoking' and 'cancer', you would suddenly get a huge correlation that would show the link," he said.
He said the NHS was an "ideal" research environment.
"What this proposal is trying to do is make the data that the researchers need - and only the data they need, not personal details - to be able to make advances at the speed with which we need to make them.
"We can carry on making them without but they will be made extraordinarily slowly and people will die in the interim."
He said the new data pool may even stop patients dying from drugs that have unforeseen side effects.
"Real" clinical trials only truly begin once drugs are on the market, he added.
"It's not just about making new discoveries, it's actually about patient safety," he said.
Professor Liam Smeeth, head of the department of non-communicable disease epidemiology at the London School of Hygiene and Tropical Medicine, said: "This sort of information is not just important for running an effective health service it is absolutely necessary.
"When there was a scare that the measles, mumps and rubella (MMR) vaccine might cause autism, we used electronic health record data to show that it was safe in terms of autism and it has led to restored faith in the vaccine.
"We need these sort of data to develop new drugs, new vaccines, new antibiotics that everyone wants and the only way we are going to get new and better drugs is by using these sorts of data."
He said the privacy concerns are "understandable", adding: " There are people worried about confidentiality, but I'm hoping there aren't people who are sitting around saying 'you shouldn't do this because no-one needs this data'. We do need this data, otherwise we are not going to move forward on health care."
Dr John Parkinson, director of the Clinical Practice Research Datalink, said: " I see this almost as the giant jigsaw. Health research is almost the world's largest jigsaw.
"Imagine if we don't have one of the pieces. If we miss those off pieces we might not find the answer."
The BHF, Arthritis Research UK, Cancer Research UK, Diabetes UK, the Academy of Medical Sciences, the Medical Research Council and the Wellcome Trust have launched an advertising campaign encouraging people not to opt out of the initiative.