Just Read: Evidence from randomised controlled trials does not support current dietary fat guidelines: a systematic review and meta-analysis.

This is a follow up to my last post on the subject (Just Read: Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis), and is a follow up paper by Zoë Harcombe, Phd (@ZoeHarcombe) et al.

Note the word change in the title of this paper – from “did” to “does,” because the next question to be asked if dietary fat guidelines were created without an evidence base in 1977 (US) and 1983 (UK), is: is there evidence now, 40 years later?

And the answer is still no

10 studies meeting review criteria (“RCTs that examined the relationship between modified or reduced dietary fat intake, serum cholesterol and mortality from CHD and all causes) were analyzed

This meta-analysis of 10 RCTs, in comparison with Harcombe et al’s review of 6 RCTs, increased the number of people studied from 2467 to 62447. It increased the number of women studied from 0 to 53 499, the majority. It increased the number of primary prevention subjects from 676 to 56291.

The big increase in subjects studied is due to the Women’s Health Initiative, which, despite demonstrating the successful reduction of calorie intake from fat and saturated fat, was a negative study.

The various methodological problems as well as the data failing to show reductions in CHD deaths from the other studies is laid out in detail.

There’s an additional summary paper that I’ll post on next. As Harcombe points out, the 2015 United States dietary guidelines no longer limit dietary cholesterol, and the UK guidelines never had a limit. The guidelines about fat intake are also changed, without a limit on total fat intake, but still with a recommended limit on saturated fat intake.

There are no responses to this paper listed on its web site. I’ll post on the fourth paper next.

Ted Eytan, MD