The government needs to show vocal support for the National Institute for Health and Clinical Excellence (NICE), a leading medical journal says.
The Lancet wants a debate on how to finance health
A Lancet editorial said the NHS drugs watchdog should be backed for being the best way to ensure fairness across the country's health system.
The call follows Alzheimer's groups accusing NICE of "blatant cost cutting" over a decision on drugs.
The government said the body should operate without political interference.
NICE was set up seven years ago to advise ministers in England and Wales on what treatments should be available on the NHS.
The Health Secretary and the Welsh Assembly can instruct NICE to consider whether certain drugs or treatments should be used on the NHS.
'Not a rationing body'
Last week it rejected five appeals against its guidance to restrict the use of four drugs for Alzheimer's disease, prompting condemnation from support groups.
The government's response at the time was to say that it would be "entirely inappropriate" to overrule NICE's decision.
NICE was set up by the Labour government in 1999
It has looked at drugs for flu, multiple sclerosis, hip replacements, coronary heart disease and breast and ovarian cancer
Decisions only apply in England and Wales
They can only be implemented by the Health Secretary and the health minister for Wales
The Lancet says NICE's recommendations are necessary to make the best use of limited NHS funds and the government's patient choice agenda ignores the need for rational spending.
The Department of Health said: "It [NICE] is not a rationing body.
"The institute was established to give advice to the NHS where there was uncertainty over the clinical and cost effectiveness of specific drugs and other treatments.
"NICE's remit is to produce robust, workable and evidence based guidance, free from political interference and we support the Institute in this role."
But the Lancet said: "If the government really wants to extend choice within the NHS, as it has pledged, it should launch a debate about the health-financing framework necessary to support this philosophy.
"But its first obligation should be to show vocal support for NICE as the best mechanism to ensure equity in the UK's current health system."