What are Fats?
Dietary fats are the fats found in foods. Fat, like carbohydrate and protein, are a source of nutrients and energy for the body, and some are essential for proper health. Composed of the elements carbon, hydrogen, and oxygen, fat is a mixture of triglycerides, with some other minor components. Compared to the four calories that protein and carbohydrates provide per gram, fat provides nine calories.
Dietary fats should be referred to in plural form because there is no one type of fat. Rather, fats in foods are combinations of various fatty acids that have different characteristics and effects in the body.
Why are fats necessary for health?
Fats provide energy and play an important part in an overall healthful lifestyle. They supply essential fatty acids – linoleic and linolenic acids – which are not produced in the body.
Fat also helps to maintain healthy skin, regulate use of cholesterol in the body. Fat also promotes absorption of the fat soluble vitamins A, D, E, and K and carotenoids. On the flip side, dietary fats, such as butter, margarine and oils may contain fat-soluble vitamins, as is the case with soybean oil, a major source of vitamin E.
Additionally, consuming certain types of fats is necessary for making prostaglandins and leukotrienes, hormone-like substances that regulate a number of functions throughout the body.
What are the different types of fatty acids?
The various types of fatty acids can be described on the basis of their chemical structure and physical characteristics. Fatty acids are composed of the elements carbon, hydrogen, and oxygen. The presence or absence of double bonds in the fatty acid’s carbon chain, determines whether or not the fatty acid is unsaturated or saturated respectively.
In general, fats that contain a majority of saturated fatty acids are solid at room temperature; however some solid vegetable shortenings are up to 75 percent unsaturated. Fats that contain mostly unsaturated fatty acids are usually liquid at room temperature and are called oils.
Two types of fatty acids – monounsaturated and polyunsaturated – constitute the healthful, unsaturated, fatty acids, which have a beneficial effect in the body. Currently, the 2005 Dietary Guidelines for Americans recommend that 20-35 percent of your daily calories come from fats that are either monounsaturated or polyunsaturated. Saturated fatty acids should compose 10 percent or less of daily calories.
What are essential fatty acids?
Essential fatty acids, like vitamins, are necessary for proper bodily function, but because the body cannot produce them, they must be obtained from food sources. Two polyunsaturated fatty acids, alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid), are essential fatty acids.
Which foods are good sources of essential fatty acids?
Fish, flaxseed and walnuts, as well as soybean, corn, fish, and canola oils are all good sources of essential fatty acids.
What are trans fats?
Trans fats are a type of unsaturated fatty acid formed during partial hydrogenation, when vegetable oils are made more solid or into a more stable liquid. When a fat is fully hydrogenated it is a saturated fat. Small amounts of trans fats also occur naturally in some foods.
How do the different types of fatty acids affect health and heart disease risk?
In general, fats are an important part of a balanced, healthful eating pattern. The latest research recommends consuming a moderate amount of fat, between 20-35 percent of calories, for good health, including heart health.
Monounsaturated and polyunsaturated fats help reduce blood cholesterol levels and thus lower heart disease risk, particularly when they replace saturated and trans fats in the diet.
Conversely, excess dietary saturated and trans fats can raise LDL (“bad”) cholesterol, a risk factor for development of coronary heart disease. An exception among saturated fatty acids is stearic acid, found primarily in cocoa butter and animal fat, which appears to have a neutral effect on blood cholesterol. In addition, some evidence suggests intake of trans fats lowers HDL (“good”) cholesterol.
Why do foods contain fats?
Fats are important parts of many foods because they enhance taste, aroma, and provide appropriate texture.
Because of their structure, saturated fatty acids in particular are more stable than unsaturated fatty acids. This stability helps to prevent rancidity and off flavors or odors. Solid fats are vital in the production of certain products, such as baked goods, for example.
Which foods contain unsaturated fats?
Good sources of polyunsaturated and monounsaturated fatty acids include fish, nuts, vegetable oils, and avocados.
Which foods contain saturated fats?
Meats, baked goods, and full-fat dairy products contain a significant amount of saturated fats in most diets. Coconut, palm, and palm kernel oils also contain saturated fats.
Which types of foods typically contain trans fats?
Trans fats are present in variable amounts in a wide range of foods, including most foods made with partially hydrogenated oils, such as baked goods and fried foods, and some high-fat margarine products (margarines that are lower in fat contain more unsaturated fats and only a marginal amount of trans fat). Trans fats also occur naturally in low amounts in certain meats and dairy products.
The food supply is currently evolving and trans alternatives are being used whenever possible to reduce the amount of trans fats in the American diet.
How much fat should I consume?
Low is out, moderate is in. The 2005 Dietary Guidelines for Americans recommend a moderate total fat intake between 20 and 35 percent of calories for adults to meet daily energy and nutritional needs while minimizing risk of chronic disease. Most fats in the diet should come from sources of polyunsaturated and monounsaturated fats such as fish, nuts, and vegetable oils.
Consuming less than 20 percent of calories from fats may decrease HDL (“good”) cholesterol. Low intake levels of dietary fats can also lead to inadequate intakes of vitamin E and essential fatty acids. Consuming more than 35 percent of calories from fats generally increases saturated fat intake and may make it more difficult to avoid consuming excess calories.
The 2005 Dietary Guidelines recommend a diet low in saturated fat, with less than 10 percent of calories coming from saturated fat – that is, less than 22 grams of saturated fat in a 2,000-calorie-a-day diet.
The 2005 Dietary Guidelines and other health authorities recommend keeping trans fat intake as low as possible while consuming adequate amounts of other nutrients.
How does fat affect weight?
Maintaining a constant body weight depends on balancing daily activity (i.e., energy use) with the amount of calories (a measure of energy) consumed, regardless of the source of calories. This means extra calories leading to weight gain can come from fats, carbohydrates, or proteins.
Fats are the most calorically dense of the three macronutrients, as they supply nine calories per gram compared to the four calories per gram of carbohydrate or protein. While fat does have a role in supporting health, it is important to monitor fat intake because gram for gram it contains twice as much energy as carbohydrates and protein. Consuming fats in moderation with a balanced diet, however, is an important part of a healthful lifestyle.
Is a high total fat intake related to cancer risk?
There may be a link between total fat intake and certain cancers, but evidence is not conclusive. Diets low in folate and calcium and high in total fat, calories, meat, and alcohol are associated with an increased risk of colorectal cancer. In addition, fat from animal sources may be linked to a higher risk of prostate cancer. According to current research, fat intake in general does not seem to be associated with risk of breast cancer.
It is not yet known whether these associations are related to the amount of fat, type of fatty acid, or another factor in food.
What do I need to know about fats information on the food label?
Total fat and saturated fat amounts have been listed on the Nutrition Facts panel for some time, while trans fat content has been listed have been required since January 2006. Food manufacturers may also choose to list amounts of polyunsaturated and monounsaturated fats.
Fats are included in health claims statements on food packaging that describe scientific evidence linking particular foods or food components with beneficial health effects. These health claims, along with fat amounts on the nutrition facts panel, can be useful educational tools for consumers trying to purchase healthful foods and consume a balanced diet.
What are some of the most common misconceptions about dietary fats?
- All trans fats are “bad.”
Small amounts of some trans fats, such as conjugated linoleic acid and vaccenic acid, occur naturally in meat and dairy products. Emerging evidence suggests these naturally-occurring trans fats may have some health benefits.
- The food label is “wrong” if it lists zero grams of trans fats, but contains partially hydrogenated oil in the ingredient statement.
The amount of trans fat, or any fatty acid, per serving may be listed as zero when a serving contains less than half a gram. The words “partially hydrogenated vegetable oil” in an ingredients list means the product most likely contains trans fat, but the amount may be nutritionally insignificant.
- Monounsaturated and polyunsaturated fats should be avoided.
Monounsaturated and polyunsaturated fats are healthful oils and should be included in a balanced diet. Sources of these fats include fish, nuts, vegetable oils, and flax.
- A healthful diet contains very low amounts of fats.
Moderate amounts of fat are needed for health, including heart health. Fats perform a number of functions in the body and help the body absorb vitamins.
- Fat causes weight gain more than other types of nutrients.
Weight gain stems from consuming more calories than you use, regardless of the source of calories. Excess calories could come from fat, proteins, or carbohydrates. Eating a balanced diet that contains an adequate amount of calories and being physically active helps to prevent weight gain.
