Actually, the issue of saturated fat is such a key one for us all to understand, I'm c+p Nina Teicholz's blog post here:
Where does the data now stand on saturated fats?
Since 2014 when my book was published, the data exonerating saturated fats has grown even stronger. There are now more than 17 systematic reviews and meta-analyses of scientific studies looking at the relationship between saturated fats and heart disease. These studies include randomized, controlled clinical trials on more than 50,000 people, which is an enormous amount of the most rigorous kind of data available.
Nearly all of the analyses reviewing this data have concluded that:
- Saturated fats have no effect on cardiovascular mortality and/or
- Saturated fats are not associated with heart disease.
- Don’t these studies conflict with our official nutritional advice?
They do. To understand why, one needs to know the history of why we believe these fats are bad for health.
Beginning in the 1950s, University of Minnesota pathologist Ancel Keys, launched the so-called “diet heart” hypothesis, which states that saturated fats and dietary cholesterol cause heart disease. Largely due to his outsized personality, Keys was able to get this idea implanted in the American Heart Association, which in 1961, became the first group in the world to recommend that the public cut back on saturated fat and cholesterol to prevent cardiovascular disease.
In subsequent decades, Governments and public health groups around the world spent billions of dollars on clinical trials (the “gold standard” of scientific evidence) trying to ‘prove’ this hypothesis, but all of these trials had “null” results—which is to say, they could not show that Keys was correct. In some cases, trials showed that reducing consumption of saturated fat and cholesterol (and replacing them wiht polyunsaturated vegetable oils) actually caused harm, including increased death rates from cancer and suicides.
Rather than respond to this ‘inconvenient’ data, however, scientists instead persevered in their belief that saturated fats must somehow be bad for health. These scientists, together with their funders at the National Institutes of Health, the American Heart Association, and elsewhere, ignored or even buried inconvenient data for decades. My book tells this story.
The story is largely one of politics: the influence of the food industry, the inability of large public health institutions, including our own federal government, to back out of a failed hypothesis, and the reality of nutrition experts who are unable or unwilling to change their minds, despite an overwhelming amount of evidence to the contrary.
Recently, however, there has been change. Beginning in 2010 with the work of Ron Krauss, scientists around the world have begun to unearth and reexamine the long-ignored literature on saturated fats, resulting in the 17 meta-analyses and reviews listed above.
Note that in response to this evidence, the Canadian Heart and Stroke Association in 2015 dropped its previous % limits on saturated fats.