Heart experts have worked for decades trying to help Americans understand the dangers of heart disease. And the plumbing analogy has served them well.
Just as you avoid pouring used cooking oil down your kitchen sink, you should limit your consumption of cholesterol and fat. Otherwise, you will eventually need a cardiologist to clean out your arteries.
It’s a pretty good analogy, and it may have some truth to it. It’s not the whole story about cardiovascular disease, however, and heart experts are now trying to correct some of the misconceptions.
DIETARY CHOLESTEROL is now known to be a non-issue for about 75 percent of people. Unless you are sensitive to the substance (as 25 percent are), you can eat eggs, shrimp and other foods high in cholesterol without worry. They will not affect the cholesterol in your blood.
OF THE MANY TYPES OF CHOLESTEROL carried in the blood, only a few are hazardous, and some are actually helpful in preventing heart disease. Low density lipoprotein or LDL is associated with an increased risk of cardiovascular disease, but high density lipoprotein (HDL) is known as “good” cholesterol because it’s protective.
The American Heart Association recommends keeping HDL higher than 40 milligrams/deciliter and LDL between 100 and 129 mg/dl (lower if you have had a heart attack or are at high risk). Until recently, decisions to treat with cholesterol-lowering medications were based on these numbers, but the 2013 guidelines recommend that doctors consider a patient’s risk factors and overall heart health. That’s not denying the importance of cholesterol but de-emphasizing the numbers and the clogged pipe analogy.
EVEN FATS ARE NOT ALWAYS BAD. There are good fats and bad fats.
Heading the “bad” list are manmade fats known as trans fats. These are found mainly in fried food, fast food, pastries, packaged cookies and other processed foods. Avoid any product that comes with “hydrogenated” or “partially hydrogenated” on the list of ingredients.
Saturated fat, particularly that found in meat, eggs and dairy products, are ordinarily included among the bad fats. But that view is no longer universally accepted. Nuts have somewhat high levels of saturated fat, and they are now considered beneficial.
Nuts also have high levels of unsaturated and monounsaturated fat–both considered good for heart health. Fatty fish, such as salmon, and certain oils, such as olive and canola, are good for your arteries because of their beneficial omega-3 fatty acids. Omega-3 can also be obtained through eating lean red meat from grass fed animals.
Instead of advising patients to eat as little fat as possible, doctors now stress replacing bad fats with good ones.
FINALLY, SOME SAY THE CLOGGED PIPE ANALOGY IS “JUST PLAIN WRONG.” An essay published in the British Journal of Sports Medicine [April 25, 2017] called for scrapping the whole idea of eating less saturated fat and worrying about LDL cholesterol. According to the authors, we should instead focus on reducing inflammation and insulin resistance in the body through diet, exercise, stress reduction and avoidance of smoking.
Studies that the authors used to support this conclusion included:
The PREDIMED study (2014), which found that high-risk patients who ate a Mediterranean-style diet lowered their cardiovascular risk 30 percent more than did those who followed a low-fat diet. This Mediterranean diet was relatively high in fat from olive oil and nuts but also rich in fruits, vegetables, whole grains and fish.
A 2015 review/meta-analysis (De Souza, et al) that found no correlation between consumption of saturated fat and the risk of coronary heart disease, ischemic stroke, type 2 diabetes or mortality.
Some say that the authors of the editorial are basing their views on “selective reporting” rather than the totality of the evidence.
In response, the European Atherosclerosis Society (EAS) released a consensus statement [April 25, 2017] pointing out that “there is a dose-dependent, log-linear association between absolute LDL cholesterol and cardiovascular risk, and this association is independent of other cardiovascular risk factors and is consistent across the multiple lines of evidence.”
The clogged pipe analogy is clearly an over-simplification. Diet is still important, but the focus should be not so much on limiting fats but eating good food-fresh fruits, vegetables, whole grains, fish, nuts and seeds.
Nicole Christel is a dietitian at BAMC.