know your fats
american heart association article
Knowing which fats raise LDL cholesterol and which ones don't is the first step in lowering your risk of heart disease. Saturated fat, trans-fatty acids and dietary cholesterol raise blood cholesterol. Monounsaturated fats and polyunsaturated fats don't. Some studies suggest they might even help lower LDL cholesterol slightly when eaten as part of a low-saturated-fat diet.
Saturated fat is found mostly in foods from animals and some plants.
Foods from animals — These include beef, beef fat, veal, lamb, pork, lard, poultry fat, butter, cream, milk, cheeses and other dairy products made from whole milk. These foods also contain dietary cholesterol.
Foods from plants — These include coconut oil, palm oil and palm kernel oil (often called tropical oils), and cocoa butter.
Polyunsaturated and monounsaturated fats — Polyunsaturated and monounsaturated fats are the two unsaturated fats. They're found primarily in oils from plants.
Polyunsaturated fats — These include safflower, sesame and sunflower seeds, corn and soybeans, many nuts and seeds, and their oils.
Monounsaturated fats — These include canola, olive and peanut oils, and avocados.
Both polyunsaturated and monounsaturated fats may help lower your blood cholesterol level when you use them in place of saturated fats in your diet. But a moderate intake of all types of fat is best. Use polyunsaturated or monounsaturated oils — and margarines and spreads made from them — in limited amounts. This is recommended in place of using fats with a high saturated fat content, such as butter, lard or hydrogenated shortenings.
To make foods that will stay fresh on the shelf or to get a solid fat product, such as margarine, food manufacturers hydrogenate polyunsaturated oils. "Hydrogenate" means to add hydrogen. When unsaturated fatty acids are hydrogenated, some of the hydrogen atoms are added on opposite sides of the molecule to the already attached hydrogen. Cis double bonds convert to trans double bonds, and the fatty acids become saturated.
are trans-fatty acids harmful?
Because there are no standard methods, it's difficult to estimate the TFA content of food items. It's also difficult to estimate intake, especially long-term intake. The four most important sources of TFA in one large group of women studied included margarine; beef, pork or lamb as the main dish; cookies (biscuits); and white bread.
Recently the FDA passed a regulation requiring trans fat to be listed on the nutrition label by January 2006. Although changes in labeling are important, they aren't enough. Many fast foods contain high levels of TFA. There are no labeling regulations for fast food, and it can even be advertised as cholesterol-free and cooked in vegetable oil. Eating one doughnut at breakfast (3.2 g of TFA) and a large order of french fries at lunch (6.8 g of TFA) add 10 g of TFA to one's diet, so the lack of regulations for labeling restaurant foods can be harmful to your health.
butter better than margarine?
Because butter is rich in both saturated fat and cholesterol, it's potentially a highly atherogenic food (a food that causes the arteries to be blocked). Most margarine is made from vegetable fat and provides no dietary cholesterol. The more liquid the margarine, i.e., tub or liquid forms, the less hydrogenated it is and the less TFA it contains.
can I do to regulate my intake of trans-fatty acids?
On the basis of current data, the American Heart Association recommends that consumers follow these tips: