Our food mantras around fat and cholesterol have changed dramatically over the past decade. When medical professionals supported “low fat, low cholesterol” as the way to heart health, food scientists quickly reformulated their products. But, as Americans attempt to cut more fat and cholesterol out of the diet, waistlines keep increasing, as does the rate of heart disease. It is estimated that, in 2009, 785,000 Americans will have a new coronary attack, 470,000 will have a recurrent attack, and 195,000 will have their first heart attack (Free Radical Biology & Medicine, 2007; 43:1,374-6).
Blood lipids rising
What is causing this rise in blood lipids? The first study to make a connection between saturated fatty acid (SFA) intake and coronary heart disease (CHD) was “The Seven Countries Study.” This study demonstrated that a population’s intake of SFA was strongly correlated with serum cholesterol levels in the population; countries consuming more than 15% of total calories from SFA had the highest CHD mortality. SFAs elevate blood cholesterol with a dose-response between the SFA and LDL-C, with the most hypercholesterolemic SFAs being lauric (C12:0), myristic (C14:0) and palmitic (C16:0) acids.
Fat-free, low-fat, trans-fat free. After having these phrases thrown at them, no wonder it’s hard for consumers to swallow the new recommendations to enjoy healthy fats. But research has come a significant distance over the last decade regarding dietary fats and heart health. In 2006, the “Women’s Health Initiative Dietary Modification Trial,” published in Journal of the American Medical Association (2006; 295(6):655-666), demonstrated virtually identical rates of heart attack, stroke and other forms of cardiovascular disease in women who followed a low-fat diet and in those women who didn’t. The Nurses’ Health Study, which supported the same conclusions, also found that replacing 80 calories of carbohydrates with 80 calories of either polyunsaturated or monounsaturated fats lowered the risk for heart disease by about 30% to 40%, while replacing just 30 calories of carbohydrates (7 grams) every day with 30 calories of trans fats (4 grams) nearly doubled the risk for heart disease.
Consuming just 3% of daily caloric needs from trans fatty acids (TFA) will raise low-density lipoprotein (LDL) levels, and consuming 6% of daily needs from TFA will additionally lower HDL cholesterol levels. With this research, the American Heart Association, Dallas, continues to recommend total fat intakes at less than 30% of total daily calories, while the National Heart, Lung and Blood Institute, Bethesda, MD, recommends that total fat intake comprise 25% to 35% of total energy, with less than 7% coming from saturated fat.
Consuming cholesterol
As studies discovered that high cholesterol levels are associated with heart disease, health professionals began encouraging their patients to eliminate or drastically reduce their intake of dietary cholesterol. However, many studies show a weak relationship between a person’s dietary intake of cholesterol and their serum cholesterol level. Most people, on average, produce more cholesterol in their body than actually absorbed from dietary cholesterol. There is, however, a small percentage of the population that does experience a strong rise and fall in their serum cholesterol in direct response to their dietary cholesterol intake. Unfortunately, there is no way to identify this population, except by trial and error. This causes health professionals to continue recommending, as a healthy precaution, that the general public limit their daily consumption of cholesterol.