Do Saturated Fats Really Increase the Risk of Heart Attack and Stroke?

For the last 35+ years, the Canadian and American Dietary Recommendations have been telling us to eat less fat overall (not more than 20-35% of daily calories) and in particular, to eat much less saturated fat. Saturated fat is naturally found  in red meat, dairy products and certain oils, such as coconut oil and palm oil. For years, a debate has raged over whether saturated fat contributes to poor heart health.

Neither the American and Canadian Dietary Recommendations have set a Daily Recommended Intake (DRI) for saturated fat, but both recommend that saturated fat intake remain as low as possibledue to its positive relationship with coronary heart disease risk“.

The American Heart Association warned that saturated fat can raise the risk of cardiovascular disease and urged people to limit consumption of dairy, red meat and fried, processed food and until recently, the Heart and Stroke Foundation of Canada was recommending the same as Health Canada (limit overall fat to 20-35% of daily calories, keeping saturated fat to <5% of daily calories).

In September 2015, the Heart and Stroke Foundation released on new position statement titled “Saturated Fat, Heart Disease and Stroke“, which takes a closer look at how dietary choices affect heart disease risk, encouraging Canadians to stop focusing on one particular aspect of food such as fat, sodium, calories, sugar – and instead focus on eating unprocessed, whole foods. 

With respect to “low fat foods”, the Heart and Stroke Foundation clarified that

confusion around fats and their impact on our health has led to a proliferation of processed foods labelled “low fat”. While these products may indeed be lower in fat than some others, that doesn’t necessarily make them healthy. In fact, these foods are often highly processed and loaded with calories, sodium and refined carbohydrates, including sugar. The focus on “low fat” has not benefitted Canadians’ diets.”

A recent research paper published in August 2015 in the British Medical Journal and whose lead research is Dr. Russell de Souza, a nutrition epidemiologist at McMaster University in Hamilton, Ontario found that saturated fat is not linked to stroke, type 2 diabetes, heart disease or death but did find a clear relationship between trans fats (often found in processed or fried foods) and poor heart health.

The Heart and Stroke Foundation has concluded that

“Research provides a mixed picture of the association between saturated fat, heart disease and stroke. Early studies found an association existed, while more recent studies have found no such association. These mixed findings have been the focus of recent scientific debate, and show us that saturated fats are complex.”

Saturated fats are found in meat, butter, cheese, tropical oils (such as coconut) and many processed foods. Most of the saturated fat in the average North American diet doesn’t come from whole foods like beef or coconuts; instead it comes from processed foods such as pizza, cakes, cookies, donuts and ice cream.

The Heart and Stroke Foundation repeated the same findings as Dr. deSouza’s August 2015 study and that is;

The one constant that is not in dispute is the harm of artificially produced trans fat on heart health. This fat raises LDL (bad) cholesterol, lowers HDL (good) cholesterol, and should be avoided. Trans fats have been linked with up to a 10-fold higher risk of heart disease.

Something many people don’t realize is that;

Trans fats are still widespread in our food supply, despite a voluntary reduction by food companies directed by Health Canada.

Their finally recommendations are;

“Reduce your intake [of trans fats] by avoiding foods that contain partially hydrogenated oil, hard margarine or shortening, and cutting back on commercial baked goods, which have the most trans fat.

Heart disease prevention comes from whole food-based diets, filled with vegetables, fruit, whole grains, lean protein (including lower fat dairy and alternatives), fish, legumes, nuts and seedsand fat is naturally found in this diet! Eating this way means not having to worry about any one nutrient in isolation. It’s the big picture that matters most.”

A few thoughts on the Heart and Stroke Foundation’s new position statement;

There are many recent studies that seem to indicate that saturated fat consumption is not the issue when it comes to heart risk — and that saturated fat may actually be protective against heart risk and there are many studies showing the benefits of consuming MCT oil and that it reduces “abdominal fat”, which in turn is associated with lower cardiovascular risks.  I think it is erroneous to say that high fat consumption in general is a risk to heart health — when one can consume very high amounts of monounsaturated fats such as olive oil or avocado oil and omega 3 polyunsaturated fats in fatty fish such as salmon, mackerel and tuna and have no increased risk of cardiovascular disease related to fat consumption. I also think saying that “saturated fat” is  “bad” or “dangerous”, when an oil such as coconut oil, which is 50 % saturate fat which is an MCT oil, is misleading.

Looking at the epidemiological data from the last 35 years, we can see what has happened to obesity rates and diabetes rates since both the American and Canadian governments have been encouraging us to eat “low fat” everything. Lower fat has not translated to improved health outcomes.

If we cannot say that naturally occurring fats such as olive, avocado and coconut oil result in an increased rate of heart attack and stroke then why vilify fat.

If the real issue is synthetic “trans fats” and processed omega-6 polyunsaturates (associated with increased inflammation) then I believe as health-care professions, we should be focusing on those.

Certainly, as a Dietitian, I cannot in good conscience encourage people to eat a low fat diet, when doing so leads to them eating “low fat” manufactured products that have increased sugar.

 

 

References

  1. de Souza Russell J, Mente Andrew, Maroleanu Adriana, Cozma Adrian I, Ha Vanessa, Kishibe Teruko et al. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies BMJ 2015; 351
  2. Health Canada, Do Canadian Adults Meet their Nutrient Requirements Though Food Intake Alone? Cat. No.: H164-112/3-2012E-PDF, 2012
  3. Heart and Stroke Foundation of Canada, Position Statement “Saturated Fat, Heart Disease and Stroke, September 24, 2015
  4. Institute of Medicine. Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Washington: The National Academies Press; 2006