Fats were once an ingredient to be avoided at all costs, but opinions on fat in the diet have changed, as research has shown some types benefit the heart.
In a Food Product Design article, Marie Spano, M.S., R.D., C.S.C.S., a nutrition communications expert, noted in the 1950s, doctors advised patients to decrease total fat intake, and for 40 years after that, people were told to reduce total fat, saturated fat and cholesterol. Now, the focus has shifted to reducing “bad fats,” like saturated and trans fats; and increasing “good fats,” like the omega 3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Interestingly, she noted despite the general negative view of saturated fats, recent research indicates not all of them are harmful for the heart. She wrote several factors can influence the atherogenic potential of specific saturated fatty acids, including chain length, fats eaten concurrently, overall diet, carbohydrate intake, and the person’s state of health. Studies show stearic acid has a neutral effect on high-density lipoprotein (HDL) and lowers low-density lipoprotein (LDL) in comparison to unsaturated fatty acids, and other studies show replacing carbohydrate with fat (including saturated fat) will decrease triglycerides and increase HDL cholesterol.
When it comes to trans fats, research shows man-made trans fatty acids, in the form or hydrogenated or partially hydrogenated oils, is bad for the heart; however, she said studies indicate the naturally occurring trans fatty acid vaccenic acid has no affect on cardiovascular disease (CVD) and may in fact have some health benefits.
At this point many studies have shown the heart benefits of polyunsaturated and monounsaturated fatty acid, highlighting their abilities to help lower LDL cholesterol while raising HDL. Among polyunsaturated fats, omega-3 fatty acids stand out, especially EPA and DHA, both of which are considered cardioprotective. Studies on the omega-3 alpha-linolenic acid (ALA) have been mixed, but it has been associated with a decreased rate of fatal and nonfatal coronary events, and a reduction in arrhythmia.
She also discusses interesterified fats, which have shown varied results on heart health; and the genetically modified soy bean oil, which has shown to increase levels of EPA, but not DHA in the body.