V. Adopting Healthful Lifestyle Habits to Lower LDL Cholesterol andReduce CHD Risk
2002; Lippincott Williams & Wilkins; Volume: 106; Issue: 25 Linguagem: Inglês
10.1161/circ.106.25.3253
ISSN1524-4539
Tópico(s)Cardiovascular Health and Risk Factors
ResumoHomeCirculationVol. 106, No. 25V. Adopting Healthful Lifestyle Habits to Lower LDL Cholesterol and Reduce CHD Risk Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUBV. Adopting Healthful Lifestyle Habits to Lower LDL Cholesterol and Reduce CHD Risk Originally published17 Dec 2002https://doi.org/10.1161/circ.106.25.3253Circulation. 2002;106:3253–32801. Population approach: promoting a base of healthy life habitsNCEP advocates a two-pronged approach for reducing CHD risk: the population approach and the clinical strategy. The two are closely linked. The population approach, which is outlined in the 1990 report of the Population Panel,5,6 is designed to lower risk in the whole population through adoption of healthy life habits including a healthy diet, weight control, and increased physical activity. The clinical strategy is described in the ATP reports. This section summarizes the population approach and connects it to the clinical strategy. The clinical management team must recognize that they are an integral part of the population approach and contribute to it by providing education and guidance to the patient with high serum cholesterol and the patient's family.The health community has provided the American public with consistent messages on cardiovascular risk reduction for the past four decades. These messages have encouraged avoidance or cessation of cigarette smoking, reduction of intakes of saturated fats and cholesterol, achieving and maintaining a healthy body weight, regular physical activity, and routine medical check-ups for blood pressure and cholesterol. Table V.1-1 (derived from the Healthy People 2010 publication)620 reports the current status of the U.S. population on various healthy lifestyle habits and compares it with the goals for 2010.Table V.1-1. Status Report on Healthy Lifestyle Habits: Healthy People 2010Lifestyle HabitStatus in the 1990sGoal for 2010Healthy weight (BMI <25 kg/m2)42%60%Saturated fat intake <10% calories36%75%Vegetable intake of at least 3 servings/day with at least 1/3 dark green or orange3%50%Fruit intake of at least 2 servings/day28%75%Grain intake of at least 6 servings/day with at least 1/3 whole grain7%50%Smoking cessation by adult smokers41%75% Regular physical activity of moderate intensity 15% 30%Although progress has been made, it is clear that much more is needed to bring about the changes required to achieve the goals for 2010. The physician has an important role to play in this effort to help attain these goals.The NHLBI, American Heart Association, and other organizations have mounted a major effort to reduce risk factors for CHD in the United States. Not only is there continuing research on improved methods for risk reduction, but national educational programs have also been put into effect. Table V.1-2 lists some of the Web sites of the programs sponsored by the U.S. Government.Table V.1-2. Government-Sponsored Web Sites for Public Information: An Effective Way to Implement the Public Health ApproachDietwww.nhlbi.nih.gov/chdwww.nhlbi.nih.gov/subsites/index.htm— then click Healthy Weightwww.nhlbi.nih.gov/hbpwww.nutrition.govPhysical activitywww.fitness.govBody weightwww.nhlbi.nih.gov/subsites/index.htm— then click Healthy WeightCholesterolwww.nhlbi.nih.gov/chdBlood pressurewww.nhlbi.nih.gov/hbpSmoking cessationwww.cdc.gov/tobacco/sgr_tobacco_use.htmPhysicians and other health professionals have the opportunity to implement the public health and clinical approaches to risk reduction through interaction with patients and their families. Even in persons who are not candidates for clinical management of high serum cholesterol, control of other risk factors and preventive efforts convey the broader public health message to the patient. The physician's advice is valued and considered more credible than mass media or non-targeted educational campaigns. The physician can affect the public health arena in many ways. Table V.1-3 compares the role of the physician and other health professionals in the implementation of the public health approach with their role in the clinical management of risk factors through lifestyle changes.Table V.1-3. The Role of the Physician and Other Health Care Professionals in Implementing the Population and Clinical Approaches to Lifestyle ModificationPopulation ApproachClinical ApproachPrinciplesPromote change in lifestyle habits by serving as a role model to patients.Promote targeted changes in individual lifestyle to produce significant reductions in an individual patient's risk.Provide general advice and access to credible sources of information regarding healthy lifestyle habits.Initiate outcome measurements that will be tracked during scheduled follow-up visits. Physicians, dietitians, and other relevant health professionals should go beyond monitoring adherence to actively helping individuals overcome barriers and promote new behaviors.DietBriefly assess dietary intake of saturated fat and cholesterol.Promote ATP III TLC diet using:Promote U.S. Dietary Guidelines (population diet) using pamphlets/handouts and Food Guide Pyramid.Individualized diet counseling that provides acceptable substitutions for favorite foods contributing to a patient's elevated LDL level — counseling often best performed by a registered dietitianReinforcement of dietary principles during follow-up visits at which LDL response to diet is assessedConsideration of readiness to change and level of motivationProvide shopping and food preparation pamphlets/handouts highlighting low saturated fat foods including reduced fat dairy products, leaner meats, lower fat ground meat, and reduced fat baked goods. Make full use of office personnel to promote public health message.Physical activityPromote regular physical activity by taking a physical activity history.Follow Surgeon General recommendations for physical activity.238Provide pamphlets/advice regarding general principles of physical activity.Promote regular physical activity for individuals using: Recommend 30 minutes of regular moderate intensity activity on most, if not all, days of the week.Specific recommendations to increase physical activity based on a patient's cardiac status, age, and other factorsSpecific advice regarding how physical activity could be integrated into the patient's lifestyleFollow-up visits to monitor physical activity level, and follow-up counseling regarding barriers to daily physical activityBody WeightEnsure that weight, height, and waist circumference are measured at every visit.Follow Obesity Education Initiative (OEI) guidelines for weight management.78,79Promote prevention of weight gain:Promote prevention of weight gain:Provide access to tables identifying height/weight categories for BMI in waiting room or exam roomProvide literature relating BMI to health outcomesProvide literature explaining use of Nutrition Facts labeling to identify calorie content and recommended portion sizes of foodsCalculate BMI for every patient at every visitAnticipate high-risk times for weight gain (perimenopausal years, times of significant life stress) and counsel patient on ways to prevent weight gainFollow-up visits to discuss success of weight gain prevention strategiesDiscuss 10% weight loss goals for persons who are overweight:Discuss lifestyle patterns that promote weight lossPortion controlDaily physical activityFollow-up visits to examine weight/BMI and discuss barriers to adherenceCholesterolEnsure that all adults age 20 and over have their blood cholesterol measured and their results explained in keeping with ATP III guidelines.Follow ATP III guidelines for detection, evaluation, and treatment of persons with lipid disorders. Ensure children and first degree relatives of adults in whom a genetic lipoprotein disorder is suspected have cholesterol screening performed.Blood Pressure Ensure that all adults have their blood pressure measured and their results explained in keeping with JNC VI guidelines. Follow JNC VI guidelines for the detection, evaluation, and treatment of persons with high blood pressure.160,161Smoking CessationEnsure that all persons are aware of the health hazards of cigarette smoking by using posters/handouts in the waiting room.Follow U.S. Department of Health and Human Services Clinical Practice Guideline: Treating Tobacco Use and Dependence.621Promote smoking cessation: Query all persons regarding their smoking habits on every visit.Query regarding smoking habitsProvide targeted advice according to patient's knowledge base, e.g., dangers of smoking, benefits of quitting, and tips to quitSchedule follow-up visits to discuss patient's progress in addressing smoking cessation2. General approach to therapeutic lifestyle changes (TLC)ATP III recommends a multifactorial lifestyle approach to reducing risk for CHD. This approach is designated therapeutic lifestyle changes (TLC) and includes the following components (see Table V.2-1):Reduced intakes of saturated fats and cholesterolTherapeutic dietary options for enhancing LDL lowering (plant stanols/sterols and increased viscous [soluble] fiber)Weight reductionIncreased regular physical activityTable V.2-1. Essential Components of Therapeutic Lifestyle Changes (TLC)ComponentRecommendationLDL-raising nutrientsSaturated fats*Less than 7% of total calories Dietary cholesterol Less than 200 mg/dayTherapeutic options for LDL loweringPlant stanols/sterols2 grams per day Increased viscous (soluble) fiber 10-25 grams per day Total calories (energy) Adjust total caloric intake to maintain desirable body weight/prevent weight gain Physical activity Include enough moderate exercise to expend at least 200 kcal per day*Trans fatty acids are another LDL-raising fat that should be kept at a low intake.Reduced intakes of saturated fats and cholesterol and other therapeutic dietary options for LDL-lowering (plant stanols/sterols and increased viscous fiber) are introduced first for the purpose of achieving the LDL cholesterol goal. After maximum reduction of LDL cholesterol is achieved with dietary therapy, emphasis shifts to management of the metabolic syndrome and its associated lipid risk factors (elevated triglycerides and low HDL cholesterol). A high proportion of patients with the metabolic syndrome are overweight/obese and sedentary; for them, weight reduction therapy and physical activity guidance is required to obtain further CHD risk reduction beyond that achieved by LDL lowering. At all stages of dietary therapy, physicians are encouraged to refer patients to registered dietitians or other qualified nutritionists for medical nutrition therapy, which is the term for the nutrition intervention and guidance provided by a nutrition professional.ATP III recommendations for ranges of other macronutrient intakes in the TLC Diet are given in Table V.2-2. Note that the recommendation for total fat ranges from 25 percent to 35 percent of total calories. To improve overall health, ATP III's lifestyle therapies generally contain the recommendations embodied in the Dietary Guidelines for Americans (2000).241Table V.2-2. Macronutrient Recommendations for the TLC DietComponentRecommendationPolyunsaturated fatUp to 10% of total caloriesMonounsaturated fatUp to 20% of total caloriesTotal fat25-35% of total calories*Carbohydrate†50-60% of total calories*Dietary fiber20-30 grams per day Protein Approximately 15% of total calories*ATP III allows an increase of total fat to 35 percent of total calories and a reduction in carbohydrate to 50 percent for persons with the metabolic syndrome. Any increase in fat intake should be in the form of either polyunsaturated or monounsaturated fat.†Carbohydrate should derive predominantly from foods rich in complex carbohydrates including grains—especially whole grains—fruits, and vegetables.The overall composition of the TLC Diet is consistent with the recommendations of the Dietary Guidelines for Americans (2000) (Table V.2-3). The dietary principles delineated in the Dietary Guidelines need not and should not be sacrificed for the purpose of LDL lowering. Furthermore, adherence to Dietary Guidelines recommendations should contribute to a reduction in risk beyond LDL lowering.Table V.2-3. Dietary Guidelines for Americans (2000)241Aim for FitnessAim for a healthy weightBe physically active each dayBuild a Healthy BaseLet the pyramid guide your food choicesChoose a variety of grains daily, especially whole grainsChoose a variety of fruits and vegetables dailyKeep foods safe to eatChoose sensiblyChoose a diet that is low in saturated fat and cholesterol and moderate in total fatChoose beverages and foods to moderate your intake of sugarsChoose and prepare foods with less saltIf you drink alcoholic beverages, do so in moderationFigure V.2-1 presents one model illustrating the general approach to dietary therapy.Download figureDownload PowerPointFigure V.2-1. A Model of Steps in Therapeutic Lifestyle Changes (TLC)During the first three months of dietary therapy, priority is given to lowering LDL cholesterol. In the first visit, the physician should address a few key questions and obtain an overall assessment of the individual's current life habits:Does the patient consume excess calories in the form of LDL-raising nutrients?Is the patient overweight or obese? Is abdominal obesity present?Is the patient physically active or inactive?If the patient is overweight/obese and/or physically inactive, is the metabolic syndrome present? (See Table II.6-1.)To assess intakes of LDL-raising nutrients, the ATP III panel devised a brief Dietary CAGE that may be helpful (Table V.2-4). These questions are not a substitute for a systematic dietary assessment, which is usually carried out by a nutrition professional. CAGE questions can be used to identify the common food sources of LDL-raising nutrients—saturated fat and cholesterol—in the patient's diet. Also in the first visit, advice is given to begin moderate physical activity, but serious attempts to achieve weight loss can be delayed briefly to concentrate first on reducing intakes of LDL-raising nutrients. At any and every stage of dietary therapy, effective dietary modification will be facilitated by consultation with a registered dietitian or other qualified nutritionist for medical nutrition therapy. (Subsequently, the term nutrition professional will refer to a registered dietitian or qualified nutritionist.)Table V.2-4. Dietary CAGE Questions for Assessment of Intakes of Saturated Fat and CholesterolC—Cheese (and other sources of dairy fats—whole milk, 2% milk, ice cream, cream, whole fat yogurt)A—Animal fats (hamburger, ground meat, frankfurters, bologna, salami, sausage, fried foods, fatty cuts of meat)G—Got it away from home (high-fat meals either purchased and brought home or eaten in restaurants)E—Eat (extra) high-fat commercial products: candy, pastries, pies, doughnuts, cookiesAfter approximately 6 weeks, the physician should evaluate the LDL cholesterol response. If the LDL cholesterol goal has been achieved, or if progress in LDL lowering has occurred, dietary therapy should be continued. If the LDL goal is not achieved, the physician has several options to enhance LDL lowering. First, dietary instructions can be reexplained and reinforced. The assistance of a nutrition professional for more formal instruction and counseling (medical nutrition therapy) is especially valuable at this time. Second, therapeutic dietary options for LDL lowering (plant stanols/sterols and increased viscous fiber) will also enhance LDL lowering. Plant stanols/sterols are currently incorporated into special margarines, which are available directly to consumers. The stanol/sterol contents are listed on the food label. They may be available in other products in the future. Viscous fiber can be increased by emphasizing certain foods: cereal grains, fruits, vegetables, and dried beans, peas, and legumes (see Table V.2-5).Table V.2-5. Food Sources of Viscous (Soluble) FiberFood SourceSoluble Fiber (g)Total Fiber (g)Cereal Grains (½ cup cooked)▪ Barley14▪ Oatmeal12▪ Oatbran13▪ Seeds - Psyllium Seeds, Ground (1 Tbsp) 5 6Fruit (1 medium fruit)▪ Apples14▪ Bananas13▪ Blackberries (½ cup)14▪ Citrus Fruit (orange, grapefruit)22-3▪ Nectarines12▪ Peaches12▪ Pears24▪ Plums11.5▪ Prunes (¼ cup) 1.5 3Legumes (½ cup cooked)▪ Beans- Black Beans25.5- Kidney Beans36- Lima Beans3.56.5- Navy Beans26- Northern Beans1.55.5- Pinto Beans27▪ Lentils (yellow, green, orange)18▪ Peas- Chick Peas16 - Black Eyed Peas 1 5.5Vegetables (½ cup cooked)▪ Broccoli11.5▪ Brussels Sprouts34.5▪ Carrots 1 2.5After another 6 weeks, the response to dietary therapy should be evaluated. If the LDL cholesterol goal is achieved, the current intensity of dietary therapy should be maintained indefinitely. If the patient is approaching the LDL goal, consideration should be given to continuing dietary therapy before adding LDL-lowering drugs. If it appears unlikely that the LDL goal will be achieved with dietary therapy alone, drug therapy should be considered (see Section IV).Thereafter, the metabolic syndrome, if present, becomes the target of therapy (see Section II). First-line therapy for the metabolic syndrome is weight control and increased physical activity. Again, referral to a nutrition professional for medical nutrition therapy to assist in weight reduction is recommended.Finally, long-term monitoring for adherence to TLC is required. Revisits are indicated every 4-6 months during the first year of therapy and every 6-12 months in the long term. If a person is started on drug therapy, more frequent visits are advised.The information shown in Table V.2-6 may be helpful for the physician both for dietary and lifestyle assessment and for guidance of the patient adopting TLC recommendations. The table is compiled from current ATP III dietary recommendations, Dietary Guidelines for Americans (2000),241 Obesity Education Initiative (OEI) guidelines for weight reduction,78,79 and the Surgeon General's Report on Physical Activity.238Table V.2-6. Guide to Therapeutic Lifestyle Changes (TLC)Healthy Lifestyle Recommendations for a Healthy HeartFood Items to Choose More OftenFood Items to Choose Less OftenRecommendations for Weight ReductionRecommendations for Increased Physical ActivityBreads and CerealsBreads and CerealsWeigh RegularlyMake Physical Activity Part of Daily Routines≥6 servings per day, adjusted to caloric needsMany bakery products, including doughnuts, biscuits, butter rolls, muffins, croissants, sweet rolls, Danish, cakes, pies, coffee cakes, cookiesRecord Weight, BMI, & waist circumferenceReduce sedentary timeWalk, wheel, or bike-ride more, drive less; Take the stairs instead of an elevator; Get off the bus a few stops early and walk the remaining distance; Mow the lawn with a push mower; Rake leaves; Garden; Push a stroller; Clean the house; Do exercises or pedal a stationary bike while watching television; Play actively with children; Take a brisk 10-minute walk or wheel before work, during your work break, and after dinnerBreads, cereals, especially whole grain; pasta; rice; potatoes; dry beans and peas; low fat crackers and cookiesMany grain-based snacks, including chips, cheese puffs, snack mix, regular crackers, buttered popcornLose Weight GraduallyMake Physical Activity Part of Exercise or Recreational ActivitiesVegetablesVegetablesGoal: lose 10% of body weight in 6 months. Lose ½ to 1 lb per weekWalk, wheel, or jog; Bicycle or use an arm pedal bicycle; Swim or do water aerobics; Play basketball; Join a sports team; Play wheelchair sports; Golf (pull cart or carry clubs); Canoe; Cross-country ski; Dance; Take part in an exercise program at work, home, school, or gym3-5 servings per day fresh, frozen, or canned, without added fat, sauce, or saltVegetables fried or prepared with butter, cheese, or cream sauceDevelop Healthy Eating PatternsFruitsFruitsChoose healthy foods (see Column 1)Reduce intake of foods in Column 2Limit number of eating occasionsSelect sensible portion sizesAvoid second helpingsIdentify and reduce hidden fat by reading food labels to choose products lower in saturated fat and calories, and ask about ingredients in ready-to-eat foods prepared away from homeIdentify and reduce sources of excess carbohydrates such as fat-free and regular crackers; cookies and other desserts; snacks; and sugar-containing beverages2-4 servings per day fresh, frozen, canned, driedFruits fried or served with butter or creamDairy ProductsDairy Products2-3 servings per dayWhole milk/2% milk, whole-milk yogurt, ice cream, cream, cheeseFat-free, ½%, 1% milk, buttermilk, yogurt, cottage cheese; fat-free& low-fat cheeseEggsEggsEgg yolks, whole eggs≤2 egg yolks per weekMeat, Poultry, FishEgg whites or egg substituteHigher fat meat cuts: ribs, t-bone steak, regular hamburger, bacon, sausage; cold cuts: salami, bologna, hot dogs; organ meats: liver, brains, sweetbreads; poultry with skin; fried meat; fried poultry; fried fishMeat, Poultry, FishFats and Oils≤5 oz per dayButter, shortening, stick margarine, chocolate, coconutLean cuts loin, leg, round; extra lean hamburger; cold cuts made with lean meat or soy protein; skinless poultry; fishFats and OilsAmount adjusted to caloric level: Unsaturated oils; soft or liquid margarines and vegetable oil spreads, salad dressings, seeds, and nutsTLC Diet Options Stanol/sterol-containing margarines; viscous fiber food sources: barley, oats, psyllium, apples, bananas, berries, citrus fruits, nectarines, peaches, pears, plums, prunes, broccoli, brussels sprouts, carrots, dry beans, peas, soy products (tofu, miso)3. Components of the TLC Dieta. Major nutrient componentsThe major LDL-raising dietary constituents are saturated fat and cholesterol. A reduction in intakes of these components is the core of the TLC Diet. The scientific foundation for the relationship between high intakes of saturated fat and increased LDL levels dates back several decades and consists of several lines of evidence: observational studies, metabolic and controlled feeding studies, and clinical studies, including randomized clinical trials. These data have been reviewed in detail in previous reports of the NCEP,1,2,5,6 the U.S. Dietary Guidelines Committees,241 and the American Heart Association.393 The other major nutrients—unsaturated fats, protein, and carbohydrates—do not raise LDL cholesterol levels. In developing an LDL-lowering diet for ATP III, consideration was given not only to these long-established factors but also to new and emerging data that support the importance of the appropriate distribution of other nutrients that are related to cardiovascular health as well as general health. Therefore, the rationale for the recommendations for each component of the TLC diet will be described briefly.1) Saturated fatty acidsSaturated fatty acids are a major dietary determinant of LDL cholesterol level.241 The effects of saturated fatty acids on serum total cholesterol (and LDL cholesterol) levels have been studied extensively.622 Several meta-analyses and reviews have been carried out to estimate the impact of saturated fatty acids on cholesterol levels.623,624 These analyses indicate that for every 1 percent increase in calories from saturated fatty acids as a percent of total energy, the serum LDL cholesterol rises about 2 percent. Conversely, a 1 percent reduction in saturated fatty acids will reduce serum cholesterol by about 2 percent. Recent trials confirm the efficacy of diets low in saturated fatty acids for lowering LDL levels. For example, the DELTA Study625 investigated the effects of reducing dietary saturated fatty acids from 15 percent of total calories to 6.1 percent of total calories. On the diet low in saturated fatty acids, LDL cholesterol was reduced by 11 percent. Another study, beFIT,626,627 tested effects of an NCEP therapeutic diet in individuals with hypercholesterolemia with and without hypertriglyceridemia. Compared to the participants' baseline diet, LDL cholesterol levels were reduced on the therapeutic diet by approximately 8 percent. Large-scale randomized controlled trials have been carried out to assess the safety of reduced intakes of saturated fatty acids and cholesterol in children and have found no evidence for compromised growth or development.628,629Evidence statements: There is a dose response relationship between saturated fatty acids and LDL cholesterol levels. Diets high in saturated fatty acids raise serum LDL cholesterol levels (A1). Reduction in intakes of saturated fatty acids lowers LDL cholesterol levels (A1, B1).The beneficial effects of reducing saturated fatty acids and cholesterol in the diet can be enhanced by weight reduction in overweight persons. Several studies have shown that LDL cholesterol levels can be lowered through weight reduction in overweight persons.78,79 And most important, as shown in the MRFIT study, weight reduction will enhance serum cholesterol lowering brought about by a reduction in intakes of saturated fatty acids and cholesterol.630,631Evidence statements: Weight reduction of even a few pounds will reduce LDL levels regardless of the nutrient composition of the weight loss diet (A2), but weight reduction achieved through a calorie-controlled diet low in saturated fatty acids and cholesterol will enhance and sustain LDL cholesterol lowering (A2).Recommendation: Weight loss through reduced caloric intake and increased levels of physical activity should be encouraged in all overweight persons. Prevention of weight gain also should be emphasized for all persons.Epidemiological studies show that populations that consume high amounts of saturated fatty acids and cholesterol have a high risk for CHD.19,632 The evidence that lowering serum cholesterol levels by decreasing intakes of saturated fatty acids reduces the risk for CHD has been demonstrated in the meta-analysis by Gordon.409,410 This analysis included six robust dietary trials, in aggregate including 6,356 person-years of follow up. It showed that lowering serum cholesterol levels by reducing the intake of saturated fatty acids significantly decreased the incidence of CHD by 24 percent. There was also a trend toward a decrease in coronary mortality (21 percent) and total mortality (6 percent). No increase in non-CVD mortality was found.The data from dietary trials, in combination with the results of controlled clinical trials with cholesterol-lowering medications,455,633 document that reducing serum cholesterol and LDL cholesterol by diet alone or with pharmacological means will reduce CHD endpoints. The current American diet contains an average of about 11 percent of total calories as saturated fatty acids. The major sources of saturated fatty acids in the diet are high-fat dairy products (whole milk, cheese, butter, ice cream, and cream); high-fat meats; tropical oils such as palm oil, coconut oil, and palm kernel oil; and baked products and mixed dishes containing dairy fats, shortening, and tropical oils. To maximize LDL cholesterol lowering by reducing saturated fatty acid intake in the therapeutic diet, it will be necessary to lower intakes from the population mean intake of approximately 11 percent to <7 percent of total energy.Evidence statements: High intakes of saturated fatty acids are associated with high population rates of CHD (C2). Reduction in intake of saturated fatty acids will reduce risk for CHD (A1, B1).Recommendation: The therapeutic diet to maximize LDL cholesterol lowering should contain less than 7 percent of total calories as saturated fatty acids.2) Trans fatty acidsTrans fatty acids are those in which double bonds are in the trans configuration. They are generally produced by hydrogenation of vegetable oils but some are found naturally in animal fats. Substantial evidence from randomized clinical trials indicates that trans fatty acids raise LDL cholesterol levels, compared with unsaturated fatty acids.634-646 These studies also show that when trans fatty acids are substituted for saturated fatty acids, HDL cholesterol levels are lower,647 with a dose response effect observed. Recent United States data show that the use of liquid vegetable oil or semiliquid margarine results in the most favorable total and LDL cholesterol levels and ratios of total cholesterol to HDL cholesterol, whereas the use of butter or stick margarine results in the worst lipid levels.634 In addition, evidence from some epidemiological cohort studies suggests that high intakes of trans fatty acids are associated with higher risk for CHD.648-651 Whether this association is due to adverse effects of trans fatty acids on lipoproteins, to other adverse actions, or to confounding variables is uncertain.The mean U.S. level of trans fatty acids intake is about 2.6 percent of total energy (compared with saturated fatty acids intake of ∼11 percent of energy). Major sources of trans fatty acids in the diet include products made from partially hydrogenated oils such as baked products including crackers, cookies, doughnuts, breads, and products like french fries or chicken fried in hydrogenated shortening. Animal sources including dairy products provide smaller amounts of trans fatty acids. Soft margarines, tub and liquid, and vegetable oil spreads have low amounts of trans fatty acids. Some margarines and spreads are now trans-fatty acid free. Some hydrogenation of vegetable oils is the primary technology currently used to provide form to food products, so that they can be eaten out of the hand, rather than with a spoon.Evidence statements:Trans fatty acids raise serum LDL cholesterol levels (A2). Through this mechanism, higher intakes of trans fatty acids should increase risk for CHD. Prospective studies support an associatio
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