We are in the midst of a dramatic evolution in our understanding of dietary fats and their impact on health and disease.
In the past 30 years, there has been a complete shift of dietary recommendations. When I was finishing pharmacy school in the 80s, I recall how saturated fats were vilified as the culprit in heart disease and obesity. Recommendations were made to reduce intake of saturated fats such as butter, meat, etc. and eat more vegetable oils (margarine spreads) and carbohydrates. People were tossing out their butter and buying margarine spreads. We thought we were making a better health choice.
Then came the research showing that trans fats – created during the hydrogenation process that turns a liquid vegetable oil into a solid – were actually worse for us than the saturated fat that we were trying to avoid. In response to this, people started cutting out animal fats and buying low-fat, fat-free products, non-hydrogenated vegetable oils and increasing carbohydrate consumption.
This was all met with great consequence. Numerous studies revealed that our over-consumption of refined and highly processed carbohydrates was actually worse for our hearts than saturated fat. The glycemic impact of these carbohydrates was fueling insulin resistance, inflammation and altered hormone levels that contributed to obesity, heart disease and diabetes.
Today, there is mounting evidence challenging the current heart health guidelines that advocate consuming foods rich in omega-3 and omega-6 polyunsaturated fatty acids and avoiding those laden with saturated fats.
In a meta-analysis entitled, Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk, published in the March 18, 2014 issue of the Annals of Internal Medicine, researchers concluded that current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids (PUFAs) and low consumption of total saturated fats. Essentially this review, which involved more than 70 studies looking at dietary fat intake and circulating fatty acid levels, did not find an association between total saturated fatty acids and coronary risk. Nor did the researchers find any significant associations between cardiovascular disease risk and dietary intake of long-chain omega-3 and omega-6 PUFAs.
Not surprisingly, this report has generated criticism. While this is not the first study to question the impact of saturated fats on heart health, it is the largest. As with any major shift in thinking, mainstream acceptance will take time. In the meantime, the debate continues and undoubtedly this issue will be looked at again in future research.