Dietary Fat, Carbs, and Heart Disease

I recently read an article title, “Sugar Shocked? The Rest of Food Industry Pays for Lots of Research, Too.” According to this article, 50 years ago the sugar industry paid Harvard scientists for research that minimized sugar’s role in heart disease and pointed toward dietary fat as the culprit. This article inspired me to dig a little deeper to learn more about dietary fat's role (if any) in heart disease.

Heart disease and type 2 diabetes:

According the American Heart Association, adults with diabetes are two to four times more likely to have heart disease. Risk factors for heart disease are divided into 2 categories: modifiable and non-modifiable. Modifiable risk factors include:

• Tobacco smoke
• High blood pressure
• High blood cholesterol
• Physical inactivity
• Overweight and obesity
• Diabetes

A lipid panel is done as part of a heart disease risk assessment. This blood test typically includes the following:

• Total Cholesterol
• Low-Density- Lipoprotein (LDL): “Bad” Cholesterol
• High-Density- Lipoprotein (HDL): “Good” Cholesterol
• Triglycerides

Lipid Panel Target Levels:

• Total Cholesterol: <200 mg/dL
• Low-Density- Lipoprotein (LDL): <100 mg/dL (possibly even lower)
• High-Density- Lipoprotein (HDL): >60 mg/dL
• Triglycerides: <150 mg/dL

So what happens if you learn that your lipid profile is abnormal?

Your doctor will likely recommend starting with the following lifestyle changes:

• Weight loss
• Increase physical activity
• Tobacco cessation
• Improving diet

Diet recommendations often focus on reducing total fat intake with an emphasis on consuming less saturated fat. In America the major sources of saturated fat are full fat dairy and red meat.

The American Heart Association recommends the following in regards to saturated fat intake:

• “Aim for a dietary pattern that achieves 5 to 6 percent of total calories from saturated fat.”

Where did this concern for saturated fat stem from?

The Framingham Heart Study (first started in 1948) reported that high blood cholesterol levels were a major risk factor for heart disease. Since that time it has been a widely accepted belief that dietary saturated fats and dietary cholesterol increase blood cholesterol and LDL cholesterol, thus increasing the risk for heart disease.

The first set of Dietary Guidelines for Americans were published in 1980.

A few of the guidelines included:

• “Avoid too much fat, saturated fat and cholesterol”
• “Substitute starches for fats and sugars”

What has resulted: more heart disease, more diabetes, and more obesity

More recently, research has pointed to a lack of evidence in supporting a diet low in saturated fat as treatment/prevention of abnormal blood lipids and heart disease.

The following is a list of key takeaways from the research I have done thus far:

• When dietary fat is reduced, carbohydrate intake is generally increased (typically the increased carbohydrates come from refined grains/processed food).
  • A high carbohydrate, low-fat diet may result in an unfavorable lipid profile:
    • Increase in small, dense LDL particles (this form of LDL cholesterol is considered more atherogenic)
    • Lower HDL cholesterol
    • High triglycerides
• Research indicates that the substitution of saturated fats for carbohydrates results in increased HDL cholesterol and may also lower small, dense LDL particles.
  • For individuals with type 2 diabetes: Metabolic studies have shown that saturated fat may impair insulin sensitivity, while unsaturated fat (such as monounsaturated fat) improves insulin sensitivity.
  • According to researchers Volek and Phinney (see references), insulin sensitivity worsens when total fat intake ranges from 30 to 60 percent of total energy intake. However, once total fat intake is above 60 percent of total energy intake insulin resistance starts to improve.
• The type of saturated fat (along with the protein and calcium) found in milk fat may have positive effects on HDL cholesterol and be helpful in reducing blood pressure, inflammation and type 2 diabetes risk.

• Foods with a high glycemic load (typically refined grains/processed foods) may increase risk of heart disease.

• The type of polyunsaturated fat may make a difference in heart disease risk:
  • Polyunsaturated fats include Omega 3 fatty acids (found in foods such as salmon, tuna, and mackerel) and Omega 6 fatty acids (found in foods such as vegetable oils).
  • A greater percentage of polyunsaturated fats coming from omega-3 fatty acids may offer more health benefits/protection from heart disease.
• A Mediterranean style eating pattern is considered to have a healthier balance between omega-3 fatty acids and omega-6 fatty acids.
  • To learn more about Mediterranean diet: https://type2diabetes.com/nutrition/mediterranean-diet-made-simple/
• Individuals who follow a very low carbohydrate ketogenic diet (typically less than 50 grams of carbohydrate per day), once keto-adapted (about 2 weeks or so after the initiation of the diet), will begin to burn more saturated fat, as saturated fat becomes the preferred fuel for the body.

What should you do with the above information?

• Have you had a lipid panel done recently? If it has been more than 5 years, speak with your doctor about having this panel of blood tests done.
• If your lipid panel comes back abnormal it may be time to reevaluate your current eating habits.
• Before making any major diet changes make sure to first speak with your physician.