Is Butter Back? Making Sense of the Latest Research on Fats

By Kathleen M. Zelman, MPH, RD

There is no question about it, dietary fats are misunderstood – from complex terminology to misperceptions – fats are a complicated topic and a source of confusion. All fats have the same number of calories, but they all function diff erently in the body.

Over the past several years, new evidence has mounted on dietary fats challenging age-old wisdom. Recent media coverage is giving us the green light to eat butter and saturated fats but it is not that simple.

Butter may be better than stick margarine but it still needs to be limited. Unsaturated fatty acids continue to be the healthiest fats to consume regularly. Man-made trans fats need to be eliminated and when it comes to saturated fats, there appears to be a shift in thinking.

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Fats 101

There are two basic types of fats: good fats and bad fats. Good fats are the unsaturated polyunsaturated and monounsaturated fats although all fats are a mixture of saturated and unsaturated fats.

Often called the bad fats are saturated and trans fats. Why? Saturated fats have long been demonized due to the impact on total and LDL (bad) cholesterol increasing the risk of heart disease.

Decades of research point to the heart health benefit of replacing most of the saturated and trans fats in the diet with unsaturated fats. The 2010 Dietary Guidelines for Americans recommends limiting saturated fats to 7-10 percent of calories and replacing them with the healthy monounsaturated fats and polyunsaturated fats.

Trans fats should be eliminated or limited to 1 percent of total calories from industrial sources such as anything made with partially hydrogenated oils because they lower HDL (good) cholesterol and increase LDL.

Monounsaturated Fats Polyunsaturated Fats Saturated Fats  
Avocados Fatty Fish Animal
Olives Nuts And Seeds Products
Oils: Canola, Nuts, Olive Oils: Corn, Cottonseed, Safflower,
Sesame, Soybean, Sunflowe
Tropical Vegetable Oils(Coconut)

Recently the 2013 American Heart Association/American College of Cardiology guidelines further slashed saturated fats to 5-6% of calories because fats may help reduce the risk of heart disease and type 2 diabetes risk.

New Thinking on Saturated Fats

Challenging the saturated fat recommendations is the fact that there are multiple factors affecting heart disease risk. In addition to LDL cholesterol, other risk factors include blood pressure, lifestyle, overweight, obesity and waist circumference.

Understanding how saturated fats impact health is complicated. One factor is that there are several different types of saturated fats. Coconut oil, for example, is the most highly saturated fat yet it does not contain cholesterol like saturated fat from animal sources. However, it is not recommended over unsaturated fats because of all the evidence supporting the health benefits of unsaturated fats.

Saturated fat in dairy products may not impact blood fats the same as other saturated fats. One study found that eating whole fat dairy in the context of a healthy diet was not typically associated with an increased risk of weight gain, heart disease or type 2 diabetes.

Impact of Saturated Fat Replacements

Advice to lower fat intake for heart health has led Americans to eat less saturated and total fat and the hope was that it would lead to eating more fruits and vegetables. Unfortunately, instead it led to an increase intake in refined carbohydrates and added sugars.

Replacing fats with refined carbohydrates may actually be worse than eating saturated fats. Studies suggest it may lead to escalating rates of obesity, diabetes and impact heart disease more than saturated fats.

When saturated fat is replaced by healthy unsaturated fats, outcomes may be more favorable. Monounsaturated fats appear to be the most beneficial, followed by polyunsaturated fats and then whole grain carbohydrates.

Is the low fat diet passé?

When it comes to fats, quality appears to be more important than quantity. A low-fat diet is not necessarily low in calories or the ideal diet for good health. For decades followers of the Mediterranean diet have shown that a high-fat diet rich in unsaturated fats can be heart healthy and good for weight control.

The amount of fat in a food does not necessarily define if it is as healthy or not. For example, nuts are 90 percent fat but it is unsaturated and they are nutrient rich. Sweetened beverages, on the other hand, are fat free but most lack nutritional goodness.

Bottom Line

Some experts insist that more important than saturated or total fats is making healthy food and beverage choices that are rich in nutrients. After all a diet containing only 5-6 percent saturated fat is not necessarily healthy, especially if it's loaded with simple sugars and refined carbs.

When it comes to saturated fats, the debate continues. Control portions and choose ones that are a good source of nutrition such as lean meat, poultry, eggs and dairy.

Recent guidelines emphasize the importance of a plant-based diet rich in vegetables, fruits, whole grains, low-fat dairy, poultry, fish, legumes, nontropical vegetable oils and nuts while limiting sweets, sugar-sweetened beverages and red meats. The Dietary Guidelines recommend using oils to replace solid fats and increase the amount and variety of seafood.

When you focus on an overall healthy diet, saturated or total fat don't really matter. It's more important to eat a wide variety of good-for-you food within your calorie budget and get your weight under control. Think about your overall diet, lifestyle and habits such as regular physical activity and not smoking.

Sources

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2. Siri-Tarino, P. et al. AJCN, Jan. 2010 Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease

3. Jakobsen, M.U., O'Reilly, E.J., Heitmann, B.L., Pereira, M.A., Balter, K., Fraser, G.E., et al., "Major Types of Dietary Fat and Risk of Coronary Heart Disease: A Pooled Analysis of 11 Cohort Studies," American Journal of Clinical Nutrition, 89, 2009, pages 1425?1432.

4. Mozaffarian D, Micha R,Wallace S . Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and " "meta-analysis of randomized controlled trials. PLoS Med 2010;7:e1000252.

5. Siri-Tarino, P et al. Saturated fat, carbohydrate, and cardiovascular disease March AJCN, 2010, vol 91: pp 502-509.

6. Hu, Frank. Are refined carbohydrates worse than saturated fat? Am J Clin Nutr June 2010 91: 6 1541-1542

7. FAO/WHO Expert Consultation in Fats and Fatty Acids in Human Nutrition, Nov. 2008. Annals of Nutrition & Metabolism [55(1-3) 1-308 (2009)]

8. U.S. Department of Agriculture, U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2010. Washington, D.C.: U.S. Government Printing Office; 2010.

9. Hooper L, Summerbell CD, Thompson R, et al. Reduced or modifi ed dietary fat for preventing cardiovascular disease. Cochrane Database Syst Rev. 2012 May 16;5:CD002137

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11. Position of the Academy of Nutrition and Dietetics: Dietary Fatty Acids for Healthy Adults. Journal of the Academy of Nutrition and Dietetics, Volume 114, Issue 1 , Pages 136-153, January 2014

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