It’s important to understand the role of fat in the diet and the different kinds of fats in foods in order to make healthy choices.

Fat is an energy source for the body. It also aids in the absorption of fat-soluble vitamins. When eaten in moderation, fat contributes to proper growth, development and good health. Unfortunately the amount of fat we eat is often more than the amount needed for good health, and the typical American diet is often too high in the kinds of fat which cause health problems.

There are four kinds of fats found in foods, and they vary in their food sources and their effects on health. Saturated and trans fats have both been found to raise levels of LDL-cholesterol, the “bad” cholesterol, in the blood and to increase the risk of heart disease. Monounsaturated and polyunsaturated fats do not raise LDL cholesterol and are beneficial when eaten in moderation.

Trans fats have been in the news since they were added to the Nutrition Facts label in 2006. A small amount of trans fat is found naturally in foods, but it is most often found in processed foods made with partially hydrogenated vegetable oils such as vegetable shortenings, some margarines, crackers, candies, cookies, snack foods, fried foods and baked goods.

When it comes to trans fat, sometimes zero doesn’t really mean zero. Manufacturers are allowed to list amounts of trans fat with less than 0.5 gram as zero on the Nutrition Facts panel. You may see products that list 0 gram trans fat on the label, while the ingredient list on the label includes partially hydrogenated vegetable oil. This means the food contains very small amounts (less than 0.5 gram) of trans fat per serving.

The American Heart Association recommends that less than 1% of daily calories come from trans fats. That means a limit of about 2 grams per day for an average 2,000 calorie diet. It doesn’t take too many fractions of grams which might actually be labeled as zero grams to add up to 2 g or more. Reading the ingredient statement as well as the nutrition label can help you make healthier choices and avoid trans fats as much as possible.

Saturated fats are found mainly in animal products like the fat in meats, the skin of poultry, and dairy foods. They are also found in tropical oils like palm, palm kernel and coconut oils. Some manufacturers use tropical oils in place of partially hydrogenated vegetable oils to cut out trans fats, but that increases the amount of saturated fat. Both saturated and trans fats should be limited in the diet because of their harmful effects on heart health.

Monounsaturated and polyunsaturated fats are found in vegetable oils, fatty fish and nuts and seeds. They are healthier choices, and some forms of polyunsaturated fats, such as omega-3 fatty acids, may increase good cholesterol and lower risks of heart disease.

All fats are high in calories compared to carbohydrates and protein. No matter where calories come from, if you eat more than you use, you will gain weight. You can replace saturated and trans fats with the healthier forms, monounsaturated and polyunsaturated, for heart health. To avoid weight gain, you also need to limit total fat and calories.