National U.S. and British advice for citizens to cut fat consumption to reduce heart disease lacked any solid trial evidence to back it up, and “should not have been introduced,” concludes research in a journal published in conjunction with the British Medical Journal and the U.K. National Cardiovascular Society.
Dietary guidelines issued in 1977 and 1983 recommended reducing overall dietary fat consumption to 30 per cent of total energy intake, and saturated fat to 10 per cent of total energy intake.
Writing in the online journal Open Heart, researchers said they carried out a systematic review and meta-analysis of the randomized control trial data that would have been available to the U.S. and U.K. regulatory committees at the time.
They found six relevant trials, covering seven different dietary interventions, spanning an average of five years, and involving 2,467 men. All the trials had been published before 1983 and had looked at the relationship between dietary fat, serum cholesterol, and the development of coronary heart disease.
A British Medical Journal release said the pooled data revealed a total of 740 deaths from all causes, and 423 from coronary heart disease.
“There was no difference in deaths from all causes between the ‘treatment’ and comparison groups, with 370 deaths in both. And there was no significant difference in deaths from coronary heart disease, with 207 in the ‘treatment’ groups and 216 in the comparison groups.”
The researchers highlighted several caveats in the evidence available at the time: no women were included, no trial tested the dietary recommendations and no trial concluded that dietary guidelines should be drawn up.
“It seems incomprehensible that dietary advice was introduced for 220 million Americans and 56 million U.K. citizens, given the contrary results from a small number of unhealthy men,” the researchers wrote.
They concluded: “Dietary advice not merely needs review; it should not have been introduced.”
But in a linked editorial, Rahul Bahl of the Royal Berkshire NHS Foundation Trust, sounded a note of caution and said that while the data was limited, there is some evidence suggesting a link between dietary fat and heart disease.
“There is certainly a strong argument that an overreliance in public health on saturated fat as the main dietary villain for cardiovascular disease has distracted from the risks posed by other nutrients, such as carbohydrates,” Bahl wrote.