The Diet/Heart Disease Evidence Base

Randomized controlled trials, prospective cohort studies, and metabolic and basic science research have shown that numerous diet components favorably impact cardiovascular risk factors and/or endpoints, likely via multiple metabolic and/or direct vascular effects. Moreover, there is Class IA evidence from the Prevención con Dieta Mediterránea (PREDIMED) trial¹ and the Lyon Diet Heart Study,² two landmark studies that reported marked benefits of a Mediterranean-style diet, as well as recent cohort data³ demonstrating that the effect size from combined diet change is significant. The Lyon Diet Heart Study was a secondary prevention trial that reported a 72% reduction in cardiovascular events in the Mediterranean-style diet group compared with the control group following a prudent Western-style diet. The PREDIMED study showed a 30% decrease in vascular events in primary prevention participants on a Mediterranean-style diet high in extra-virgin olive oil or mixed nuts. Consistent with this evidence, contemporary guidelines, including the 2013 ACC/AHA lifestyle management guideline,⁴ now recommend a "whole foods approach" and specific food patterns to reduce cardiovascular risk, as in the Mediterranean diet pattern or a Dietary Approaches to Stop Hypertension (DASH)-type diet pattern, rather than focusing solely on nutrients with specific metabolic effects (e.g., saturated vs. polyunsaturated fat).

Gaps in Patient Diet Adherence and Physician Counseling

American adults, in general, and patients with known coronary heart disease and/or prior myocardial infarction adhere poorly to cardioprotective diet patterns.⁵ Physicians are positioned to help improve dietary adherence because of their role in patient care. Many believe nutrition counseling to be within their scope of practice and patients expect them to be knowledgeable sources of diet information. However, nearly all studies on this topic show that there is little discussion about healthy dietary practices between physicians and patients, indicating missed opportunities for prevention. In 1995, Kushner identified several perceived barriers to diet counseling by physicians.⁶ However, more recent findings suggest that many of these perceptions are unfounded. For example, one perceived barrier to effective diet counseling by physicians is lack of time and compensation.⁷ However, Albright et al. and Kolasa and Rickett suggest that brief nutrition messages provided during teachable moments with referral to dietitians when needed are most effective in changing diet behaviors.^8,9 An example of simple diet messages may be "eat food as it's found in nature," "eat a whole foods diet low in animal fats and added sugars," and "save concentrated sweets for holidays and birthdays."

Data from Kolasa and Rickett also indicate that many physicians perceive patients to be poorly responsive to diet counseling.⁹ However, recent evidence suggests that physician counseling efforts can have significant impacts. An analysis of the 2005-2008 National Health and Nutritional Examination Survey (NHANES) dataset by Pool et al. showed that direct discussion of patients' weight status by their physicians was associated with clinically significant weight loss.¹⁰ Similarly, a 2013 meta-analysis by Rose et al. also showed that physician advice to lose weight favorably affects patients' attempts to change weight-related behaviors.¹¹

Kolasa and Rickett also report that some physicians perceive diet interventions to be less efficacious than drug therapies, a view that may be more common in the statin era.⁹ However, a recent study indicates that patients on statins may, in fact, consume more hypercaloric diets than non-users.¹² This finding, and the possibility that those on statins may also consume more atherogenic diet patterns, suggests that adherence to statin therapy should not preclude regular diet counseling.

Other perceived barriers to diet counseling by physicians are lack of resources and knowledge,⁹ the latter likely related to the low (and shrinking) number of hours devoted to nutrition education during medical school.¹³ Although having knowledge about the fatty acid content or glycemic index of specific foods is helpful, it is not a requirement for effective diet counseling. Simply steering patients toward food patterns associated with reduced vascular risk in randomized trials (e.g., the Mediterranean diet pattern in which the predominant fats are monounsaturated fatty acids [MUFA] from olive oil and polyunsaturated fatty acids [PUFA] from nuts and liquid vegetable oils, and carbohydrates are from whole grains, fruits, vegetables, and legumes) and away from food patterns associated with increased vascular risk in prospective cohort studies (e.g., the Western diet, which is higher in refined carbohydrates, processed meats, and saturated fats), allows providers to avoid the need to have detailed food knowledge. It also limits discussion of controversial studies and/or recommendations about specific nutrients.

Basic Steps For Diet Counseling

1. Gather baseline diet information: Patients would not be treated for high blood pressure, blood lipids, or blood glucose without gathering baseline data, and the same holds true for diet. It might be easiest to obtain this information through a self-administered diet instrument, such as the Rate Your Plate diet tool, a more informal form, or even a 2-minute diet history, in which patients recall what they typically eat for breakfast, lunch, dinner, and snacks. For those with difficulty recalling, prompts can be used to determine how frequently they eat breakfast foods that are less healthy (egg yolks, breakfast meats, sugared cereals, and full-fat dairy products) versus more healthy options (cereals high in fiber/low in sugar, fruit, and low-fat milk); lunches that are less healthy (deli meats, cheeses, white bread, fast or fried foods) versus more healthy (water packed tuna, grilled chicken, whole grain breads, and fruit); dinners that are less healthy (fatty cuts of beef, pork, restaurant or takeout foods, canned vegetables high in sodium, potatoes, and gravies) versus healthy options (lean animal proteins, beans, legumes, fresh or frozen vegetables, and brown rice); and snacks that are unhealthy (sodas, cookies, and ice cream) versus healthy (fruits and nuts).


2. Start with small diet pattern changes: A brief review of the diet information gathered prior to or during a visit will help identify the most appropriate nutrition topic for that visit. For patients who indicate they drink large quantities of soda, 1-2 minutes could be devoted to the importance of eliminating or replacing sugar-sweetened beverages with reduced calorie beverages or water. If the review indicates a low intake of fruits and vegetables, the discussion might focus on the benefits of eating dark fruits and vegetables and how to obtain seven servings per day. For patients who consume an atherogenic dietary pattern, the physician should be honest with their recommendations that major diet changes are needed, but initially recommend only one change or two at a time, including changing just one meal (e.g., breakfast). Finally, for those who gravitate to popular fad diets for weight loss, patients should be instructed on how to recognize unsound diets, such as those that markedly restrict certain macronutrients, like carbohydrates or entire (and important) food groups, like fruits.


3. Use food-based approaches to target specific risk factors: Therapeutic diet changes should be emphasized when needed. Patients with persistently elevated low-density lipoprotein cholesterol on statin therapy should be guided to further limit saturated fat and increase intake of soluble fiber. However, rather than instructing them to reduce saturated fat to less than 7% of calories and consume 25 grams of soluble fiber per day, the better food message is to "reduce intake of cheeses made with full fat dairy products (the largest source of saturated fat in the American diet), butter, whole milk, cream, sour cream and ice cream" and "increase intake of oats, barley and lentils." Reducing saturated fat from 13-14% of calories to less than 7% of calories would be expected to reduce serum cholesterol by about 15 points. Elevations in triglycerides (TG) are usually very responsive to diet change. Those with rare elevations of TG to 1,000 mg/dl or more require a dual intervention and dietitian assistance in order to reduce total fat to less than 15% of calories and limit refined carbohydrates.¹⁴ Those with moderate TG elevations and who are overweight should be counseled to reduce total calories (a weight loss of just 10-15% of calories can reduce TG up to 30 %), refined carbohydrates, and alcohol, and consume whole grains, foods high in omega-3 fatty acids (like fatty fish), and soluble fiber. Patients with elevated fasting blood glucose levels should be counseled to read labels, even of "healthy" foods like whole grain cereals, instant oatmeal, juices, and yogurts, and choose those that are sugar-free or have no more than 5 grams of sugar per serving. For patients with high blood pressure, messages to reduce sodium intake should also be food-based. Instead of recommending a cut-point for sodium intake of 1.5 or 2 grams per day, the focus should be on reducing components of the diet that contribute the most to dietary sodium (among them bread [the number one source], pizza, and cheese).


4. Be sensitive to patient-specific cultural, religious, and economic factors: The benefits of a heart-healthy dietary pattern last only as long as the pattern is followed. Patients should be encouraged and educated on how to adapt the recommended dietary pattern to their personal and cultural preferences. For example, the US Department of Agriculture Food Pattern offers lacto-ovo vegetarian and vegan adaptations. It is also essential that food and calorie label education and handouts are designed to be understood by low literacy audiences, some of whom may not be fluent in English. Immigrants are at high risk of losing the often healthier diet patterns of their cultural backgrounds as they become acculturated to a Westernized society. This presents an opportunity for physicians to encourage healthy dietary patterns that take into account cultural preferences and offer healthy alternatives. Individuals from cultures that include abundant amounts of white rice, pasta, or breads may find switching to whole grain foods a simple modification. This could be followed by information on appropriate portion sizes. Fried foods are popular among some cultures. Rather than eliminate them from the diet, it may be more effective to encourage alternate cooking methods such as baking, grilling, and steaming. Likewise, encouraging individuals to replace butter/lard with vegetable oils and nuts high in unsaturated fats is a simple but effective strategy for improving the diet. Individuals of low socioeconomic status should be encouraged to consume canned (no added sodium or sugar versions) or frozen fruits and vegetables if fresh produce is too expensive or unavailable.


5. Use motivational and behavioral approaches: Behavioral counseling comprises two distinct elements; "Why" and "How." The former entails finding the motivation to initiate and maintain a behavior change; the latter includes the cognitive and behavioral steps needed to accomplish the desired outcome. The latter uses strategies such as self-monitoring (i.e., daily weight and/or food intake monitoring), identifying and helping overcome barriers to selecting a healthy diet (e.g., teaching them how to set goals, batch foods they can quickly grab on a busy morning, eat healthfully while travelling, and add flavor to foods with fresh herbs instead of the salt shaker).
   
   A useful approach for building motivation is motivational interviewing.¹⁵ This approach involves little directive advice and information exchange; instead, it helps patients think about and verbally express their reasons for and against change, and how changes may impact their life and family goals or core values. Through motivational interviewing, ambivalence and the dread of change are explored prior to moving toward action. Specific motivational interviewing techniques include reflective listening, during which the clinician uses statements like "If I heard you correctly, this is what I think you are saying ..." or "where you might be going with this." Such statements demonstrate empathy and understanding and affirm the client's thoughts and feelings. Motivational interviewing assumes that individuals are more likely to act upon that which they voice themselves. This is referred to as change talk. Reinforcing and eliciting change talk has emerged as an essential active ingredient of motivational interviewing.¹⁶ Evidence for the causal role of change talk includes the association between the amount and trajectory of client change talk expressed within a session.¹⁷
   
   Another behavior change tool is the readiness ruler in which the clinician asks two questions: 1) "On a scale from 0 to ten, with ten being the highest, how important is it to you to change [insert target behavior/condition]?" and 2) "On a scale from 0 to ten, with ten being the highest and assuming you want to change this behavior, how confident are you that you could (insert target behavior/condition)?"¹⁵ After obtaining the patient's numeric rating, the physician may ask the following questions to evaluate the importance of personal changes to the patient and his or her confidence about succeeding: 1) "Why are you a [insert number reported] and not a 0?" and 2) "What would it take to get you to a higher number?"


6. Make use of outside nutrition resources: There are numerous resources available for nutrition counseling of patients, including those available via ACC's patient-centered care portal, CardioSmart.org. CardioSmart.org provides "Healthy Living" resources for patients to eat better, know their numbers, lose weight, and move more. CardioSmart Challenges can help you get into habits that can help get you on track towards healthy living. Here are some additional resources:
   
   http://myeatsmartmovemore.com/ includes reference guides, body mass index charts, and simplified diet and other prevention messages.
   Academy of Nutrition and Dietetics (AND): http://www.eatright.org/
   Choose My Plate: http://www.choosemyplate.gov
   American Heart Association http://www.heart.org/HEARTORG/, including: Life's Simple 7™ (seven health metrics identified as key to preventing cardiovascular disease and stroke) and My Life Check®, a free online assessment in English and Spanish that patients may use to enter relevant data and get a Life's Simple 7™ Action Plan.
   National Heart, Lung, and Blood Institute (NHLBI), part of National Institutes of Health (NIH) including (http://www.nhlbi.nih.gov/):
   Dietary Approach to Stop Hypertension (DASH): http://www.nhlbi.nih.gov/health/resources/heart/hbp-dash-index,
   Theraputic Lifestyle Changes (TLC) to lower cholesterol: http://www.nhlbi.nih.gov/health/resources/heart/cholesterol-tlc
   Publications and fact sheets for use with special populations (African American, Asian American, Pacific Islander, Latino and Native American) http://www.nhlbi.nih.gov/health/prof/heart/index.htm
   National Lipid Association (NLA): https://www.lipid.org/
   Center for Science in the Public Interest: http://www.cspinet.org
   Food and Drug Administration: http://www.fda.gov
   Food and Nutrition Information Center: http://www.fnic.nal.usda.gov
   National Institutes of Health: http://www.nih.gov
   USDA Nutrition Information for You: http://www.nutrition.gov
   
   Tools for Dietary and Nutritional Assessment from the Sports, Cardiovascular, and Wellness Nutrition (SCAN) group of the Academy of Nutrition and Dietetics (AND):
   Preventive Nutrition Inventory
   The Preventive Nutrition Inventory is a food frequency tool that assesses daily saturated fat intake. Patients are able to complete the inventory in 10-15 minutes. The tool has been validated and compares favorably with existing food frequency tools and dietary fat surveys.

References

1. Estruch R, Ros E, Salas-Salvadó J, et al; on behalf of the PREDIMED Study Investigators. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med 2013;368:1279-90.
2. de Lorgeril M, Salen P, Martin JL, Monjaud I, Delaye J, Mamelle N. Mediterranean diet, traditional risk factors, and the rate of cardiovascular complications after myocardial infarction: final report of the Lyon Diet Heart Study. Circulation 1999;99:779-85.
3. Li S, Chuive SE, Flint A, et al. Better diet quality and decreased mortality among myocardial infarction survivors. JAMA Intern Med 2013:173:1808-19.
4. Eckel RH, Jakicic JM, Ard JD, et al. 2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014;63(25 Pt B):2889-934.
5. Ma Y, Olendzki BC, Pagoto SL, Merriam PA, Ockene IS. What are patients actually eating: the dietary practices of cardiovascular disease patients. Curr Opin Cardiol 2010;25:518-21.
6. Kushner RF. Barriers to providing nutrition counseling by physicians: a survey of primary care practitioners. Prev Med 1995;24:546-52.
7. Wynn K, Trudeau JD, Taunton K, Gowans M, Scott I. Nutrition in primary care: current practices, attitudes, and barriers. Can Fam Physician 2010;56:e109-16.
8. Albright J, Armstrong S, Christianson L, et al. North Carolina's pediatric obesity clinician's reference guide and tool kit. Presented at: CDC Weight of the Nation Conference, July 28, 2009; Washington, DC.
9. Kolasa KM, Rickett K. Barriers to providing nutrition counseling cited by physicians: a survey of primary care practitioners. Nutr Clin Pract 2010;25:502-9.
10. Pool AC, Kraschnewski JL, Cover LA, et al. The impact of physician weight discussion on weight loss in US adults. Obes Res Clin Pract 2014;8:e131-9.
11. Rose SA, Poynter PS, Anderson JW, Noar SM, Conigliaro J. Physician weight loss advice and patient weight loss behavior change: a literature review and meta-analysis of survey data. Int J Obes (Lond) 2013;37:118-28.
12. Sugiyama T, Tsugawa Y, Tseng CH, Kobayashi Y, Shapiro MF. Different time trends of caloric and fat intake between statin users and nonusers among US adults: gluttony in the time of statins? JAMA Intern Med 2014;174:1038-45
13. Adams KM, Kohlmeier M, Powell M, Zeisel SH. Nutrition in medicine: nutrition education for medical students and residents. Nutr Clin Pract 2010;25:471-80.
14. Jacobson TA, Ito MK, Maki KC, et al. National lipid association recommendations for patient-centered management of dyslipidemia: part 1--full report. J Clin Lipidol 2015;9:129-69.
15. Miller WR, Rollnick S. Motivational Interviewing: Help People Change. 3rd ed. New York: Guilford Press; 2013.
16. Miller WR, Rose GS. Toward a theory of motivational interviewing. Am Psychol 2009;64:527-37.
17. Moyers TB, Martin T, Houck JM, Christopher PJ, Tonigan JS. From in-session behaviors to drinking outcomes: a causal chain for motivational interviewing. J Consult Clin Psychol 2009;77:1113-24.

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