For decades now, we've been told that saturated fat is to be avoided at all costs. Indeed, by government decree, all food labels must clearly spell out saturated fat content, and it has become widely understood that cheeseburgers, steaks, and ice cream are the food equivalents of ticks in a heart disease time bomb because they are loaded with saturated fat. But now, a highly cited study has seemingly called into question the dangers of saturated fat and has left many wondering if they’ve been duped.
Big study, big implications?
The recent study was a comprehensive review that compiled 32 observational studies in which more than 500,000 participants self-reported their dietary patterns and another 17 studies in which more than 25,000 participants had blood levels of fatty acids measured. While the authors did confirm that trans fats – which the FDA has recently limited – were, in fact, linked to heart disease, they found no association between the reported saturated fat intake or blood level measurements and the risk of heart disease.
Saturated fat is not so innocent
Before we hold a cheeseburger party to celebrate the good news,we should pause to consider these results and appreciate the fact that, as in all scientific studies, the devil is in the details. First, self-reporting of saturated fat intake may not be an accurate measure of true consumption (because who wants to admit to an unhealthy diet?). Also, despite the large number of participants, mixing different studies in this fashion (called performing a meta-analysis) can be a bit like comparing apples and oranges, and the authors did acknowledge variability between the studies. Most importantly, though, we cannot ignore the numerous other studies that have shown a direct correlation between saturated fat intake and higher cholesterol levels.
Without question, reducing saturated fat in the diet can also lower cholesterol levels meaningfully in those with high cholesterol. In the United States, cholesterol levels reached their peak in the 1960s and 1970s, spurring the formation of the National Cholesterol Education Program and eventually leading to a societal shift away from saturated fat. With a steady decline in saturated fat intake, LDL (or "bad") cholesterol levels are currently at their lowest level in decades, as are deaths from heart disease.
Modern dietary advice – patterns not pieces
So now that we are left with conflicting information, what are we to do? The study in question today actually adds to the general shift in thought among those in the nutrition field away from a focus on single dietary components (macronutrients) like saturated fats or carbohydrates to a focus instead on dietary patterns.
When we decrease intake of a single macronutrient, we often compensate by increasing another. For example, some low-carbohydrate dieters replace carbs with high quantities of saturated fat and subsequently have increased cholesterol levels. Similarly, some individuals who lower their saturated fat intake substitute with large quantities of simple carbohydrates, which can raise triglycerides, lower HDL ("good") cholesterol levels, increase weight, and result in insulin resistance.
Focusing on overall dietary patterns is a healthier approach. Recently, a large, randomized trial of more than 7,000 people found that the group who followed more of a Mediterranean dietary pattern had a 30% reduction in developing heart disease and a significantly reduced risk of stroke and diabetes. In a nutshell, the Mediterranean diet consists of eating more fruits and vegetables, whole grains, and fish and eating less red meat and sweets. It also includes healthy servings of monounsaturated fats in the form of olive oil (a liter a week!) and nuts.
Some in the medical community have questioned which component of the Mediterranean diet is responsible for its beneficial effects. I think they are missing the point, which is that when it comes to dietary recommendations, it's patterns, not pieces, that matter.
In my opinion, that's a message that’s easy to swallow.