The Women's Health Initiative was a massive study of the benefits of reducing the percentage of dietary calories from fat. It involved 48,835 women, so not a small study. Remember that small effects require large studies to detect them. Big effects will show in small groups, so I don't like this study. However it involved a massive input of money to produce a snippet of interest. It also kept 47 authors in gainful employment for over eight years. The women in the intervention group achieved intakes of saturated fat and cholesterol that were less than 10% of energy intake and less than 300 mg/d, respectively. The question is, does reducing your fat intake by 8.2% provide any benefit on cardiovascular disease risk?
The answer is "No", not if you were free of heart disease to begin with. Summary:
There is no benefit. I mean
*******THERE IS NO BENEFIT********
What if you are already suffering from heart disease? There was a small subgroup (1,656 women) who had cardiovascular disease at the start of the study. This is what happened to them, and I quote
"The intervention was associated with increased risk in the 3.4% of women with baseline CVD; this may be a chance observation, or rates in this small subset may be confounded by concurrent therapy or comorbid conditions"
The hazard ratio was 1.26 for this group. That is, there was a 26% increase in risk of a cardiovascular incident. You notice from the quote that this "may be a chance observation". I'll translate this for you. What the authors mean is:
They found that reducing the amount of fat in your diet INCREASES your risk of cardiovascular disease. They've tried every possible way of explaining this away and have COMPLETELY failed. If you have already got heart disease you must not reduce your fat intake, unless you really want increase your risk of another heart attack.
You could call this a paradox. I mean yet another paradox.
Or just accept that fat is not the cause of heart disease.
By the way, none of this made it in to the abstract, you must access the full text of the JAMA paper, where you have to trawl through the results to get the Hazard Ratio number.