Fat & Cholesterol
How much fat can I eat?
Although the total amount of fat in your diet doesn't increase your LDL (bad) cholesterol level, it is best not to go higher than 35% of calories from fat–even if this is mostly good fats.2 Fat has more calories per gram than protein or carbohydrates (9 compared with about 4) making it likely that you will eat too many calories (and gain weight) if you eat a lot of fat. It is also difficult to stay within the limits for saturated fat and dietary cholesterol when you eat a high-fat diet.
How much fat do Americans eat?
The average American diet contains 33% of calories from fat.19 About 25% of Americans eat too much fat (more than 35% of calories) and fewer than 5% eat a low-fat diet (less than 20% of calories from fat). As a percentage of daily calories, fat intake decreased from an average of 36% in the early 1970s to 33% in 1999-2000. However, the actual amount of fat eaten per day increased from 73 grams (1989-1991) to 76 grams in the 1990s.20 This is because we are eating more calories now. The latest figures available show that Americans on average eat 81 grams of fat per day (67 g for women and 97 g for men).
What is saturated fat?
Saturated fat is found mostly in meats and dairy products (unless they're nonfat) and tropical oils (coconut and palm oil). Diets with higher amounts of saturated fat increase your risk of heart disease.21, 22 Among more than 80,000 women in the Nurses' Health Study aged 34 to 59 years, those with the highest amounts of saturated fats in their diet had a 16% higher risk of heart disease than women with the lowest intakes.10 This is largely because saturated fats increase LDL (bad) cholesterol levels.23
The various saturated fats differ in their cholesterol-raising effects; for example, stearic acid does not increase LDL cholesterol levels.24, 25 However, most foods that contain saturated fats have a mix, so it's difficult to eat one type without consuming the others.
How much saturated fat can I eat?
The 2006 dietary guidelines from the American Heart Association tightened the limit for saturated fat to less than 7% of daily calories.3 This is stricter than the target listed in the Dietary Guidelines for Americans (less than 10% of your daily calories) and was previously reserved for people who already had heart disease or high cholesterol.2, 23 Most Americans get more than 10% of calories from saturated fat.26 On average, Americans eat 28 grams of saturated fat per day (23 g for women and 33 g for men) making up about 11% of calories.19 Rather than counting calories, the AHA advises that you limit saturated fat by making healthier choices.
What are trans fats?
Trans fats are a type of unsaturated fat. Most unsaturated fats lower your risk of heart disease, but trans fats are the exception. They are made through the hydrogenation of unsaturated fats, a process used to improve the shelf life and flavor of fats and oils that essentially turns healthy fats into unhealthy ones. Trans fats are found in foods containing hydrogenated/partially hydrogenated vegetable oils such as cookies, crackers, other baked goods, commercially prepared fried foods, and some margarines.
Trans fats are worse than saturated fats because in addition to raising LDL (bad) cholesterol, they also lower HDL (good) cholesterol and increase lipoprotein (a)—another type of LDL that raises your risk of heart disease.27 Studies show that the more trans fats in your diet, the higher your risk of heart disease.28 The Nurses' Health Study included more than 80,000 women and found that those with the highest amounts of trans fats in their diet had a 27% higher risk of heart disease than women with the lowest amounts.10
How much trans fats can I eat?It's best to try and avoid commercial trans fats altogether; small amounts of trans fats are found naturally in some meat and dairy. About 80% of the trans fat in American diets comes from commercial sources.29 The average intake is 2.6% of total calories compared with a recommended limit of less than 1%.3 Since January 2006, trans fats have been listed on food nutrition labels and some city health agencies are urging restaurants to stop using them. Foods can claim to have 0 grams of trans fat if they have less than 0.5 grams per serving, so watch your portions. To see if a food is truly trans-fat-free, check ingredients labels for hydrogenated/partially hydrogentated fats and oils.
Is the amount of cholesterol in my diet important?
Yes. The more cholesterol you eat, the higher your blood levels of cholesterol. Increasing the amount of cholesterol you eat by 100 milligrams per day raises blood cholesterol, particularly your LDL (bad) cholesterol, by about 2 to 3 milligrams per deciliter of blood (mg/dL).30 However, people vary widely in how they respond to dietary cholesterol, and it doesn't raise blood cholesterol as much as saturated fat and trans fat. This is why some studies fail to show a connection between higher amounts of dietary cholesterol and heart disease risk.10, 28
Is it OK to eat eggs or other foods that contain cholesterol?
Eggs account for about one third of the cholesterol in the US diet—one large egg has about 213 milligrams of cholesterol.31 Other sources are animal and dairy products, meat, poultry, shellfish (particularly shrimp). Eggs do not increase your risk of heart disease because unlike most other sources of cholesterol, eggs (and shellfish) are low in saturated fat. The Nurses' Health Study followed more than 80,000 women for 14 years and found no difference in heart disease rates for women who ate less than 1 egg per week compared with those who ate 1 or more per day.32 A large study in men also found no risk from eating eggs. That said, some people are more sensitive to dietary cholesterol than others. The Nurses' study and others hinted at an increased risk of heart disease in women with diabetes who ate a lot of eggs.33 For most people, moderate amounts of eggs (2 per week) and shellfish can be incorporated into a heart healthy diet.23
How much cholesterol can I eat?
Healthy eating guidelines set a limit of 300 milligrams of dietary cholesterol per day for most people and 200 milligrams if you have heart disease or high cholesterol.2, 3, 23 The amount of cholesterol in the US diet fell in the past 40 years, but is steadily rising. On average, American women eat 242 milligrams and men eat 341 milligrams of cholesterol per day.26
What are unsaturated fats?
Unsaturated fats are healthy alternatives to saturated and trans fats. People who eat diets high in unsaturated fats have lower rates of heart disease. There are 2 types of unsaturated fats: polyunsaturated fats and monounsaturated fats.
What are polyunsaturated fats?
There are 2 types of polyunsaturated fats: omega-6 and omega-3 fatty acids. The omega-6 fatty acids (e.g., linoleic acid) are found mostly in vegetable oils such as soybean oil, corn oil, and safflower oil. The omega-3 fatty acids include alpha-linoleic acid (ALA) found in flaxseeds, walnuts, canola (rapeseed) oil, soybeans and soybean oil, and the fish oils eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Oily fish such as mackerel, salmon, tuna, and trout have much higher levels of EPA and DHA than lean fish such as cod, haddock, or flounder.
Overall, polyunsaturated fats lower your risk of heart disease. Of the nearly 80,000 women enrolled in the Nurses' Health Study, those who ate the highest amounts of polyunsaturated fatty acids cut their risk of heart disease by 25% compared with women with the lowest intakes after 20 years.34 Women under 65 years seemed to benefit most.
Do fish oils lower my risk of heart disease?
Studies show that eating a diet rich in fish oils can reduce the risk of a heart attack or dying from heart disease in people who have already had a heart attack.9, 35, 36 In September 2004, the Food and Drug Administration (FDA) allowed health claims on foods containing the omega-3 fatty acids found in fish (EPA and DHA) noting that they may reduce the risk of heart disease.37 The other omega-3 fatty acid, ALA, may also lower the risk of heart problems particularly in people who do not eat much fish.38
What about mercury in fish?
All fish contain traces of mercury; some types of fish contain more mercury than others. For most people, the risk of ingesting mercury by eating fish is not a health concern. Mercury in fish poses a slight risk to women who may become pregnant, pregnant women, nursing mothers, and young children. For these groups, the FDA advises avoiding fish that are high in mercury, such as shark, swordfish, king mackerel, or tilefish. Other more common fish—including salmon, cod, canned light tuna, and flounder—are safe to eat twice a week (12 ounces total). Albacore “white” tuna should only be eaten once a week (6 ounces) at most because its mercury content is slightly higher. The FDA has prepared a fact sheet with more information on mercury in fish.
Do omega-6 fatty acids lower my risk of heart disease?
It is not clear whether omega-6 fatty acids lower your risk for heart disease or if they have a neutral effect on health.39-44 It was thought that these fatty acids may counter the heart health benefits of omega-3 fatty acids, and it was advised that you eat twice as much omega-3 fatty acids as omega-6 fatty acids (a dietary ratio of omega-3 to omega-6 of 2 to 1).45 Research has shown, though, that omega-6 fatty acids probably have no effect on the benefits of omega-3 fatty acids.38 While there is no evidence that omega-6 fatty acids are harmful, researchers caution that there is little information about very high intakes (more than 10% of calories).23
How much polyunsaturated fats and fish should I eat?
All polyunsaturated fats are a healthy alternative to saturated fat.23 When they are substituted for saturated fats, blood cholesterol levels improve.46 You can get up to 10% of your calories from polyunsaturates;23 currently, they account for about 7% of total calories in the average American diet.47
You should eat at least 2 servings (about 8 ounces) of fish, preferably oily fish, a week.3 For most people, oily fish is preferred to fish oil supplements because most of the research supporting EPA and DHA was for fish consumption, not pills. In addition, fish is low in calories and saturated fat making it a healthy alternative source of protein and nutrients. Make sure you don't undo the good when preparing the fish--grill, bake, or poach, and avoid cream sauces. Women who have been diagnosed with heart disease or those at high risk should aim for 1 g of EPA and DHA per day; ask your physician if you need supplements. For people with high levels of triglycerides—a type of blood fat that raises your risk of heart disease—a 2-4 gram daily dose of EPA and DHA as capsules is recommended.48
Americans consume 2.92 ounces of fish per week, on average. Tuna is our favorite fish (22%), followed by shrimp (16%) and salmon (9%).
What are monounsaturated fats?
Monounsaturated fats are found in fats and oils (e.g., canola, olive, sunflower), nuts and nut butters, peanuts, avocado, olives, sesame seeds, and tahini. A diet that is high in monounsaturated fats and rich in fruits and vegetables (such as the Mediterranean diet) lowers your risk of heart disease.5, 10 A diet high in monounsaturated fat and low in saturated fat improves cholesterol levels more than a low-fat, high-carbohydrate diet. This is because the monounsaturated fat diet lowers LDL (bad) cholesterol without lowering HDL (good) cholesterol, and it also lowers triglycerides—another type of blood fat that raises your risk of heart disease.15, 48, 49 You don't have to cut the carbs to benefit: if you replace the saturated fat in your diet with monounsaturated fat, blood levels of cholesterol and triglycerides improve and so does insulin sensitivity—an important risk factor for diabetes—even when you eat the same amount of carbs.50
Do diets high in monounsaturated fats help people with diabetes?
There is some evidence that diets high in monounsaturated fats may help people with diabetes control blood sugar levels.51 However, the American Diabetes Association notes that these diets have not been shown to improve fasting glucose or hemoglobin A1c (Hb A1c ) levels.
How much monounsaturated fats should I get?
Your diet can include up to 20% of calories from monounsaturated fats.23 Currently, about 12% to 14% of calories in the average US diet come from monounsaturated fats.48 Most women get 18-24 grams per day compared with 25-39 grams per day for men. Most of the monounsaturated fat in your diet should come from plant rather than animal sources because plants have no cholesterol and are low in saturated fat.
What are essential fatty acids?
Your body needs some fats and cholesterol to function properly. You don't have to eat any saturated fat or cholesterol because your body makes all that you need. Likewise, you don't need trans fats at all. However, some of the fatty acids you need must come from your diet because your body can't make them. These are the essential fatty acids and they include the polyunsaturated fatty acids ALA and linoleic acid.
Signs that your diet doesn't include enough linoleic acid are dermatitis, or rough scaly skin. Deficiencies in ALA result in poor wound healing and more severe dermatitis (with bleeding) that may affect the scalp.
What are plant sterols and stanols?
Plant sterols and plant stanols are vegetable fats. They are not found in all plants, but both are found naturally in small quantities in the following foods:
- pine-tree oils
- sesame, corn, sunflower, and canola oils
- sesame seeds and sunflower seeds
- rice bran
- green peas
They have been shown to lower cholesterol levels, and some food products are enhanced with plant sterols and stanols—primarily commercial margarines. Research shows that eating margarines enriched with plants sterols or stanols (2 g to 3 g per day) can lower LDL cholesterol levels by 7% to 20% (but 2 g appears to give the most benefit).52-55 This benefit has been seen in women with heart disease, and in men and women with normal or high cholesterol levels. Plant sterols and stanols are not available as nutritional supplements.