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Heart Disease - Evidence and Advice
When Patients Ask Whether They Should Limit Carbs or Fat, What Do You Tell Them?
New study apparently flies in the face of American Heart Association recommendations to follow a low-fat diet, but it shouldn’t change your overall message: Take everything in moderation.
Author: Renee Cocchi
Clinical Advisor: Gerrie Gardner, DO, FACC, FACP
You may have more patients ask you what they should keep an eye on when they eat: carbohydrates or fats. That’s because a new study apparently flies in the face of American Heart Association (AHA) guidelines that recommend a low-fat diet and limiting saturated fatty acids. The study found that high-carbohydrate diets led to mortality more frequently than did high-fat diets.
Researchers used the Prospective Urban Rural Epidemiology (PURE) study1 to figure out the relationship between macronutrients and cardiovascular disease. PURE is a 10-year, large, epidemiological cohort study of >135,000 people aged 35 to 70 years from 18 countries. Participants completed questionnaires about their food intake, health status, and sociodemographic factors. Investigators followed them for an average of 7.4 years, looking primarily at total morality and cardiovascular (CV) events. Researchers also assessed myocardial infarction, stroke, and CV- and non-CV–related mortality.
In the end, there were nearly 5800 deaths and nearly 4800 major CV disease events. High carbohydrate intake (>60% of energy) had an adverse impact on mortality and non-CV disease mortality. Meanwhile, higher fat intake was linked with lower risk of total mortality, non-CV disease mortality, and stroke.
Should Your Advice to Patients Change?
So what do you do in practice, given the findings and AHA recommendations to limit total and saturated fat intake each to <30% of energy? In the end, your message shouldn’t change that much: Take everything in moderation.
As for the findings, Geraldine Gardner, DO, FACC, FACP, an invasive cardiologist with Providence Medical Group in Everett, WA, reminds us that PURE is an observational study with patients on many diets from different countries self-reporting food intake.
"PURE trial is certainly causing controversy it the cardiology world," says Dr. Gardner. "We have been enforcing a low saturated fat diet for years. We know that saturated fat raises LDL. Lowering LDL lowers CV risk. This has been well studied over the last 20 years, so lowering saturated fat intake makes sense."
"We also know that processed foods with carbohydrates are poor substitutes for diets high in plant volume," continues Dr Gardner. "The question in my mind is what carbohydrates are beneficial and which ones are detrimental. Fast food carbs are not a substitute for vegetables and fruits."
Dr Gardner says that she agrees with an AHA’s response to the trial that “... a nutrition study of PURE’s scale and scope is extremely challenging,” and it needs to “... be interpreted with significant caution.” The AHA also points to the limits of using food frequency questionnaires, particularly in large, international studies. Finally, the group notes that, while it's important to pay attention to saturated fats and refined carbohydrates, they are just part of the puzzle. Consumers need to focus on balance.
Six Tips for Better Nutritional Counseling
Dr Gardner says that she frequently discusses the importance of eating a well-balanced diet with her patients, but a recent editorial in JAMA3 points out that she is the exception to the rule. “Clinicians seldom discuss nutrition with their patients,” write the editorial’s authors, adding that "... only 12% of office visits include consulting about diet." Even in high-risk patients, "... only one in five receive nutrition counseling" and "... many patients receive most of their nutrition information from other, and often unreliable, sources."
The editorial offers 6 steps to help clinicians incorporate nutritional counseling into their daily practice:
- Use a short, validated screening questionnaire to quickly assess the need for nutritional counseling as a jumping-off point to start the conversation.
- Set the visit up to include the 5As (assess, advise, agree, assist, arrange); this helps engage patients who aren’t committed yet to behavioral changes.
- Make small nutritional changes, one at a time, like incorporating 1 piece of fruit a day in patients’ diets.
- Use available professional resources.
- Don’t do it all at once. Save the last few minutes of a patient visit to review nutrition and offer resources.
- Don’t go it alone. Use other professionals to help.
1Dehghan M, Mente A, Zhang X, et al. Association of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. The Lancet. August 29, 2017. http://dx.doi.org/10.1016/S0140-6736(17)32252-3.
2Hughes S. PURE Shakes Up Nutritional Field: Finds High Fat Intake Beneficial. Medscape. August, 2017. http://www.medscape.com/viewarticle/884937#vp_1.
3Kahan S, Manson JE. Nutrition Counseling in Clinical Practice How Clinicians Can Do Better, JAMA, 2017: September 7: epub ahead of print. doi: 10.1001/jama.2017
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