Clearing up the confusion on dietary fats

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Sources of polyunsaturated and monounsaturated fats.

Conflicting information about healthy and unhealthy sources of fat continues to baffle Americans. Fortunately, the American Heart Association (AHA) released a Presidential Advisory statement last week to clear it up.

This statement reviewed the most recent findings on the effects of dietary saturated fat and its replacement by other types of fats and carbohydrates on cardiovascular disease. CVD is the leading global cause of death, accounting for 17.3 million deaths a year.

Studies showed that replacing saturated fats (i.e. butter) with polyunsaturated fats (olive oil, avocado, nuts) lowered CVD by about 30 percent ‑ the same reduction achieved by taking statins, a cholesterol-lowering medication. Switching to healthier fats was also linked to lower rates of death from all causes.

Need a refresher on fats? Click here for Fats 101.

The recommendation.
Since 1961, the AHA has recommended a reduction in dietary saturated fat to reduce the risk of CVD. Why? Saturated fat increases LDL (bad cholesterol) levels which can cause atherosclerosisa, a hardening and narrowing of arteries. This increases the risk of such serious health problems as heart attack, stroke and death. The 2015-2020 Dietary Guidelines for Americans recommends limiting saturated fat to less than 10 percent of your total calories, and the AHA/American College of Cardiology recommends limiting it to 5 percent to 6 percent if you have high LDL levels.

Are we doing it?
Not quite. The average Americans gets about 11 percent of their total calories from saturated fat. Only 30 percent to 40 percent of Americans keep their intake below the recommended limit. Since CVD is the leading global cause of death, a universal reduction in saturated fat intake could cut serious health care costs and save a lot of lives.

The confusion.
In the last few years, studies have produced disagreeing conclusions about “the relationship between dietary saturated fat and risk of CVD.” The kink in the chain has been failure to consider what people are replacing saturated fat with – often refined carbohydrates or unsaturated fat. The two most publicized studies (published in 2010 and 2014) did not evaluate the foods replacing saturated fat and drew faulty conclusions that saturated fat does not affect CVD risk. Basically, replacing bacon with doughnuts for breakfast does not improve your health. Nor does adding butter to your coffee. However, studies (2009, 2014, and 2015) that specifically compared the replacement of saturated fat with polyunsaturated fat found significant benefit.

But coconut oil is healthy, right?
A 2016 survey revealed that 72 percent of the American public believe coconut oil to be a “healthy food.” Yet, only 37 percent of nutritionists agree. A 2016 systematic review found that coconut oil raises LDL cholesterol in the same way as other saturated fats found in butter, beef fat and palm oil. The AHA recommends against the use of coconut oil because it “increases LDL cholesterol, a cause of CVD, and has no known offsetting favorable effects.” Use in moderation.

Fat and sugar in dairy.
About half of the fat found in dairy is saturated fat, and it raises LDL cholesterol just like saturated fat found in other foods. Risk of CVD is reduced when dairy fat is replaced with polyunsaturated fat or carbohydrates from whole grains, but no change was found when replacing it with refined carbohydrates.

There’s been a recent attack on low-fat and fat-free dairy claiming that when fat is removed, sugar is added in its place. Not true. If you check the USDA nutrition database, you’ll find that fat-free milk and whole milk both have about eight grams of sugar in eight ounces. The sugar found in unflavored milk (whole, fat-free, or anything in between) is lactose, a naturally occurring sugar.

Keep it simple.
The AHA came up with a simple infographic regarding the Facts on Fat and their recommendations for eating heart-healthy. Here’s a summary:

  • Love it: polyunsaturated and monounsaturated fat lower rates of CVD by lowering LDL and triglyceride levels. They also produces essential fats your body needs but can’t make itself.
    • Olive oil, fish, avocado, nuts
  • Limit it: saturated fats increase the risk of CVD and raise LDL
    • Butter, cheese, bacon, cream
  • Lose it : trans fat, hydrogenated oils and tropical oils increase risk of CVD and raise LDL.
    • Processed goods
    • Coconut oil

Kerri Link Heckert, a registered dietitian at the Children’s Hospital of Philadelphia, earned her master’s degree at Drexel University. She lives in the Philadelphia suburbs. She is also a yoga instructor (RYT-200), ACSM certified health fitness specialist and certified personal trainer.