Cardiovascular disease continues to be the top killer in the United States. A new review from the American Heart Association reiterates the importance of replacing saturated fats with unsaturated ones to reduce cholesterol and heart disease risk.
Saturated fats are known to raise cholesterol levels and increase cardiovascular risk. Meat, full-fat and reduced fat dairy products, and fried foods, as well as bakery products, all have a high content of saturated fats.
Cardiovascular disease (CVD) continues to be the leading cause of mortality across the U.S., accounting for approximately 1 in 4 yearly deaths.
One of the main prevention guidelines for CVD is to reduce the dietary intake of saturated fats and reduce cholesterol. Studies have shown that replacing saturated fats with unsaturated ones can lower the risk of CVD, and that following a diet rich in vegetables, fish, and whole grains is key for keeping the heart healthy.
However, other studies have questioned the strategy of replacing saturated fats with unsaturated ones. The argument goes that limiting saturated fats may increase a person’s intake of carbohydrates, sugar, and calories.
Inconsistencies persist, even in the official guidelines regarding saturated fat intake. The 2015-2020 Dietary Guidelines for Americans recommend that saturated fats should make up no more than 10 percent of a person’s overall calorie intake, whereas the American Heart Association (AHA)/American College of Cardiology Dietary Guidelines propose reducing this to 5 or 6 percent.
A New Look at Existing Data
Now, the AHA have conducted a new review of the existing evidence on the effect of saturated fats in our diets. The new advisory, published in the journal Circulation, reaffirms the benefit of unsaturated fats in one’s diet.
Dr. Frank Sacks, the lead author of the advisory and a professor of cardiovascular disease prevention at the Harvard T.H. Chan School of Public Health in Boston, MA, further explains the motivation for this analysis:
“We want to set the record straight on why well-conducted scientific research overwhelmingly supports limiting saturated fat in the diet to prevent diseases of the heart and blood vessels,” he says. “Saturated fat increases LDL [low-density lipoprotein] – bad cholesterol – which is a major cause of artery-clogging plaque and cardiovascular disease.”
Limiting saturated fat intake has same effect as taking statins
The AHA recommend replacing saturated fats with mono- and polyunsaturated fats, such as those found in the Mediterranean diet and the Dietary Approaches To Stop Hypertension (DASH) diet.
Both of these diets consist mainly of fruits and vegetables, unsaturated vegetable oils, nuts, low-fat dairy, and whole grains, as well as fish and poultry. The Mediterranean and DASH diets also limit red meat, sugar, and salt intake.
The AHA meta-review of existing randomized controlled trials found that restricting dietary saturated fat and replacing it with polyunsaturated vegetable oil lowered CVD risk by approximately a third.
Making this dietary change accounted for a 30 percent decrease in CVD risk, which is roughly the equivalent of what statins – a class of drug generally prescribed to lower cholesterol – can achieve.
Polyunsaturated fats are commonly found in oils made from corn, soybean, and peanut, among others.
Coconut oil, on the other hand, has been shown by several studies to increase “bad” cholesterol levels just as much as products such as beef or butter do.
Additionally, the review found that observational studies indicated that reduced intake of saturated fat, together with a higher consumption of mono- and polyunsaturated fat, correlates with lower odds of developing CVD.
The AHA also caution that replacing saturated fats with refined carbohydrates and sugars does not lower the risk of CVD:
“A healthy diet doesn’t just limit certain unfavorable nutrients, such as saturated fats, that can increase the risk of heart attacks, strokes, and other blood vessel diseases,” Sacks continues. “It should also focus on healthy foods rich in nutrients that can help reduce disease risk, like poly- and mono-unsaturated vegetable oils, nuts, fruits, vegetables, whole grains, fish, and others.”