After yet another extensive meta-analysis, researchers in the U.S. and U.K. have concluded that governments on both sides of the Atlantic issued dietary fat guidelines without much supporting evidence. The summary findings call into question the low-fat advice given to millions of people for decades.
The study, published in the BMJ journal Open Heart, was conducted by researchers at Saint Luke’s Mid America Heart Institute in Kansas City, MO, in conjunction with researchers from the University of the West of Scotland, Cardiff Metropolitan University and University of South Wales.
Did good research lead to dietary fat guidelines?
Researchers noted that national dietary guidelines were introduced by the U.S. in 1977, and by the U.K. in 1983. Nearly 300 million people were advised to reduce their overall fat consumption to 30 percent of their total calories. They were also advised to limit their saturated fat consumption to 10 percent of their total calories. Low-fat/non-fat foods became dietary staples.
In this review, researchers looked at randomized controlled trials (RCTs) conducted prior to 1983, that showed evidence of the benefits of low-fat diets. They found that 2,467 men participated in six dietary trials, five secondary prevention studies and one study that also included healthy participants.
The results of those studies found that:
- There were no differences in death rates from any cause resulting from dietary interventions
- There were no differences in coronary heart disease rates resulting from dietary interventions
- Reductions in mean serum cholesterol levels did not result in significant differences in coronary heart disease or deaths from any cause
The researchers concluded that, “Dietary recommendations were introduced for 220 million U.S. and 56 million U.K. citizens by 1983, in the absence of supporting evidence from RCTs.”
What this means for us today
The researchers stated that healthcare practitioners, “may be more questioning of dietary guidelines, less accepting of low-fat advice (concomitantly high carbohydrate), and more engaged in nutritional discussions about the role of food in health.