Nutrition and Heart Health: Evidence from the AHA/ACC Lifestyle GuidelineAn expert panel discusses dietary fats and their effects on cardiovascular health in the latest edition of our Emerging Science Series.
Moderators Robert O. Bonow, MD, MACC, FAHA and Linda Van Horn, PhD, RD, FAHA cover cutting-edge research and discoveries with panelists Alice H. Lichtenstein, D.Sc., FAHA, Penny Kris-Etherton, PhD, RD, FAHA, FNLA, and Frank Sacks, MD, FAHA.
The Emerging Science Series can be viewed for a fee.
This webinar was recorded on Thursday, July 24, 2014
No CME/CE credit for this activity is provided.
An Introduction to Nutrition and Heart Health: Evidence From the AHA/ACC Lifestyle Guideline
Penny M. Kris-Etherton, Ph.D., R.D., F.A.H.A., F.N.L.A.
The 2013 AHA/ACC Guideline on Lifestyle Management to Reduce Cardiovascular Risk recommends decreasing an elevated LDL-cholesterol and reducing high blood pressure to lower risk of cardiovascular disease (CVD). A healthy dietary pattern is recommended that is low in saturated fat and sodium. Recently, some have challenged the evidence base for these recommendations. In this webinar we clarify the mixed messages, both in the media and the scientific literature, about these recommendations. Relative to saturated fat, many randomized controlled trials consistently have shown that replacing saturated fat with polyunsaturated fat decreases LDL-cholesterol and cardiovascular events. Similarly, well-conducted observational studies also show that replacing saturated fat with polyunsaturated fat decreases CVD risk. In contrast, replacing saturated fat with dietary carbohydrate, especially refined carbohydrate, resulting in a low fat diet does not affect CVD risk. The evidence base convincingly supports the current dietary recommendation to replace saturated fat with polyunsaturated fat as an important strategy to decrease CVD risk. Thus, a low-fat diet is not recommended. Rather, a moderate-fat diet that is low in saturated fat by replacement with polyunsaturated fat is recommended.
An elevated blood pressure is the leading cause of preventable deaths worldwide. Many studies have shown that dietary sodium increases blood pressure. The DASH (Dietary Approaches to Stop Hypertension) Study showed that the lower the sodium, the lower the blood pressure. Decreasing sodium in an average American diet reduces blood pressure. Moreover, a DASH diet lowers blood pressure further, and reductions in sodium from 3.3 g/day to 2.4 g/day to 1.5 g/day result in a stepwise reduction in blood pressure. The decrease in blood pressure in persons with hypertension is greatest, and is comparable to that achieved with pharmacotherapy. Two long-term clinical trials, one of which was conducted in Taiwan and the other in the United States (Trials of Hypertension Prevention, TOHP), both showed that a reduced sodium diet decreased CVD events and CVD death rate. There are methodological problems in population studies that relate a low sodium intake to higher CVD events. These include errors in assessing sodium intake, potential for reverse causality (i.e., persons with disease were following a low sodium diet because of the disease), major analytic issues including under-adjustment, and the potential for residual confounding. Of the 26 population studies that were reviewed in an AHA Presidential Advisory (2012), there were 2.5 major problems per study. Thus, major methodological issues limit the usefulness of studies that challenge current dietary recommendations for sodium. The estimated benefits of sodium reduction are substantial and warrant major public health efforts to reduce salt intake.
In summary, the evidence is irrefutable that saturated fat should be decreased to 5 to 6% of calories by replacement with polyunsaturated fat to lower LDL-cholesterol and reduce CVD risk. Moreover, it is clear that dietary sodium should be reduced to 1500 mg/day to reduce hypertension, age-related increases in blood pressure, and CVD risk. Collectively, these recommendations should be part of a dietary pattern that emphasizes vegetables, fruits and whole grains; includes low-fat dairy products, poultry, fish, legumes, non-tropical vegetable oils and nuts; and limits intake of sweets, sugar-sweetened beverages and red meats. An important theme of the webinar is to affirm the strong evidence base that supports current dietary recommendations to lower saturated fat and sodium to decrease risk of CVD.
For recommended sources of liquid vegetable oils:
2010 Dietary Guidelines for Americans (PDF)
See Figure 3-3 on page 25.
For information about decreasing dietary sodium:
AHA The Salty Six
For information on saturated fats, including video:
AHA Saturated Fats
Dr. Kris-Etherton is Distinguished Professor of Nutrition in the Department of Nutritional Sciences at The Pennsylvania State University. She has served on many national committees that have established dietary guidelines and recommendations. She is a Fellow of the American Heart Association (AHA) and The National Lipid Association.