Each week a nutritionist from the University of Maryland Medical Center provides a guest post on healthy eating . This week, Debra Schulze writes about benefits of oils.

Oils are fats that are liquid at room temperature and come from many different plants and fish. While not a food group, they provide essential nutrients.

Fats and oils can be categorized as saturated fatty acids (solid at room temperature) and unsaturated fatty acids (liquid at room temperature), which include monounsaturated fatty acids and polyunsaturated fatty acids.

Some common oils include canola, corn, cottonseed, olive, safflower, peanut, soybean and sunflower. Others that are used for flavoring include walnut and sesame oil. Oils from plant sources do not contain cholesterol, but some are high in saturated fat, such as coconut, palm and palm kernel oil. Examples of saturated fats include butter, milk fat, animal fats, stick margarine, shortening and partially hydrogenated oil.

Following all the recent reports of trans fats and their contribution to increased risk of heart disease and certain cancers, consumers are looking for healthier fats and oils to incorporate into their diets. Trans-fatty acids are created by converting unsaturated fatty acids (oils) to saturated fats. It is recommended that you decrease the amounts of saturated and trans-fatty acids in your diet since they may raise your cholesterol and put you at higher risk for heart disease.

On the other hand, consuming foods high in unsaturated fatty acids may offer health benefits, including lowering your total and LDL or “bad” cholesterol. They may also help normalize blood clotting, according to Mayo Clinic, and some research shows they may also benefit insulin levels and improve blood sugar control.

Pick your oil carefully

Oils are a good source of monounsaturated fatty acids and polyunsaturated fatty acids, but you must choose them carefully. Sources of healthy monounsaturates attracting attention include olive, avocado, peanut, pistachio and grapeseed oils, as well as oil from walnuts, almond and hazelnuts. Like olive oil, these oils have unique flavors that add to their attraction.

Omega-3 and omega-6 fatty acids are two main classes of polyunsaturated fatty acids and are considered essential because our bodies cannot make them. Flaxseeds are a rich plant source of omega-3 fatty acids and also contain omega-6 fatty acids, making them a healthy choice. This oil contains alpha-linolenic acid, which is being researched for its potential to reduce conditions such as stroke, certain cancers and skin ailments.

Extra virgin and virgin olive oil contain high levels of polyphenols, an antioxidant that may reduce the effects of aging on the body.

How much do I need?

Since oils contain essential fatty acids, there is an allowance in the food guide. Recommendations are based on a person’s age, sex and level of physical activity, and they can range from 3-6 teaspoons of oils per day or 28 percent to 30 percent of daily calories. Most oils contain about 120 calories per tablespoon.

As you plan your meals, keep in mind that other foods consumed can provide adequate oils, such as nuts, fish, cooking oils and salad dressings. It has been determined that some oil is needed for health, so try to include a variety in your daily diet.