Are all fats in our diet bad for us? Are some fats terrible and others a cure-all? Since the mid-1950s, dietary guidelines and published research on the subject have taken enough twists and turns to leave many of us confused.

The three main categories of fat are trans fats, unsaturated fats and saturated fats. In the early 1980s, the U.S. Department of Agriculture recommended avoiding all types of fat. Low-fat diets became the craze and numerous "low-fat" items appeared on grocers’ shelves.

The problem was that many of these products replaced the fat with refined sugars and junk food carbs, knocking out the health benefits. And labeling all dietary fats as bad ignored the fact that we need some fats to help us absorb certain nutrients.

A few years later, experts narrowed the warning about fats. They recommended that people strongly limit saturated fats because they tended to raise LDL cholesterol levels and could increase risk of cardiovascular disease (CVD). The main sources of saturated fats are butter, whole-fat dairy, lard, beef tallow, palm oil, palm kernel oil and coconut oil.

Today, we hear a lot about the hazards of trans fats. A large body of research has shown that artificially created trans fats should be avoided because they elevate LDL levels (bad cholesterol) and decrease HDL levels (good cholesterol), putting you at an increased risk of CVD. Another name for trans fats is "partially hydrogenated oils." These fats are typically found in pie, stick margarine, canned frostings, creamers, many frozen pizzas and some packaged snacks.

Research also supports the conclusion that unsaturated fats — both monounsaturated and polyunsaturated varieties — can actually lower the risk of CVD. Monounsaturated fats are found in olive, peanut and canola oils; avocados; almonds, pecans, pumpkin, sesame seeds and other nuts. Polyunsaturated fats are in salmon, trout, walnuts, as well as safflower, corn and soybean oils.

One conclusion that researchers continue to debate is the level of CVD risk related to consuming saturated fats. A study published in the journal Circulation in 2017 attempts to clear up the confusion about dietary fats — especially saturated fats. "Dietary Fats and Cardiovascular Disease, A Presidential Advisory from the American Heart Association" reports on the American Heart Association’s (AHA) analysis of past research and offers its recommendations:

The Advisory authors say, "…we conclude strongly that lowering intake of saturated fat and replacing it with unsaturated fats, especially polyunsaturated fats, will lower the incidence of CVD." They even go on to say that replacing saturated fat with polyunsaturated fat lowers the CVD risk by about 30 percent, similar to the effect of statin drugs.

They caution: "A dietary strategy of reducing total dietary fat, including saturated fat, and replacing the fats mainly with unspecified carbohydrates does not prevent CVD."

And what about the current hype on the "benefits" of coconut oil? The study says the food industry’s marketing efforts could account for the following discrepancy: 72 percent of Americans surveyed rated coconut oil as a "healthy food" compared with 37 percent of nutritionists. The AHA Advisory’s conclusion: "Because coconut oil increases LDL cholesterol, a cause of CVD, and has no known offsetting favorable effects, we advise against (its) use."

The bottom line — if you want to reduce your risk of cardiovascular disease, avoid trans fats and limit your intake of saturated fats, choosing healthier fats instead. Think substitutes. Add walnuts to your salad instead of chunks of cheese. Dribble olive oil on your steamed vegetables instead of butter. Adopt a diet rich in whole grains, low-fat dairy products, lean meats and seafood, nuts and beans. And avoid reaching for the sugary items to replace those high in fat.

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