When it comes to diet, cholesterol and heart health, you’ve probably heard something along these lines:
Eating fat raises cholesterol. Cholesterol causes heart disease. If saturated fat raises cholesterol and, cholesterol is supposed to cause heart disease, then eating saturated fat or cholesterol increases the risk of developing heart disease. Therefore, you should avoid foods containing saturated fat and cholesterol, like butter, bacon, red meat and eggs.
The above ideas have been repeated so many times by health and media organizations, most people think they’re proven facts. However, research going back more than 60 years has yet to show saturated fat or dietary cholesterol has any causal effect on heart disease. Studies costing hundreds of millions of dollars have fallen short on the “saturated fat and cholesterol cause heart disease” hypothesis.
More recently, studies on statins have been used to breathe new life into the “cholesterol causes heart disease” belief. The logic is as follows:
↓ Statins lower heart disease risk in some individuals
↓ Statins also lower blood cholesterol levels
↓ Statins must lower heart disease risk because they lower cholesterol levels (this assumes one causes the other, rather than the fact that the two variables are simply associated)
↓ Because statins lower heart disease risk in some people and they lower cholesterol levels, elevated cholesterol must cause heart disease (this further reinforces a cause-and-effect theory that has not been proven)
↓ If elevated blood cholesterol raises heart disease risk, dietary cholesterol should be avoided (this assumes cholesterol in the diet actually impacts blood cholesterol levels)
↓ Saturated fat should be avoided because it can raise cholesterol levels in some people (this begins to blur the line between cholesterol and saturated fat, which are two very different compounds)
↓ Putting all these assumptions together, dietary fat and cholesterol cause heart disease (finally, the first couple points are tied together with the last couple as though there has been a proven cause-and-effect relationship throughout)
There are many unproven assumptions in the points above. In fact, research actually contradicts much of it, yet this logic continues to be promoted. We’re told to eat low-fat, high-carb foods which could be at the core of the heart disease issues we’re facing today. On top of it, many low-fat, high-carbohydrate processed foods are labeled as “heart healthy,” causing further confusion in people.
Fat and Cholesterol
Fat and cholesterol are two totally different substances, but they’re often talked about together. Except in some short-duration studies on saturated fat and cholesterol, most have shown there is no relationship between how much saturated fat an individual eats and the level of his or her blood cholesterol. People who eat very little saturated fat have been shown to have high cholesterol levels or low cholesterol levels. Some who eat lots of saturated fat have low blood cholesterol levels while others have high cholesterol levels. Stephan Guyenet from Whole Health Source wrote a great review of studies comparing saturated fat consumption and blood cholesterol levels. I highly recommend reading the article.
Another review of research last year left authors in The Netherlands Journal of Medicine stating
“We conclude that avoidance of SAFA (saturated fatty acids) accumulation by reducing the intake of CHO (carbohydrates) with high glycaemic index is more effective in the prevention of CVD (cardiovascular disease) than reducing SAFA intake per se.”
Translation: reducing high-glycemic carbohydrates is more effective than reducing saturated fat to prevent CVD.
There is also a total lack of evidence to suggest dietary cholesterol causes heart disease. Reviewing the research available to date, authors in the British Journal of Nutrition recently said,
“Epidemiological data do not support a link between dietary cholesterol and CVD (cardiovascular disease).”
You may be thinking, “Wait a minute! I hear all the time about how one country eats a diet lower in fat and has lower rates of heart disease, or how in the United States, we eat lots of fat and have high levels of heart disease. What gives?”
This is part of the trouble with research so often cited. One could look at Japan, for example, and find they eat less red meat and total fat, and they have less heart disease than the United States. However, there are many other variables between the two countries. We just have an association between the two countries about heart disease and fat consumption or meat consumption. As explained in Will Red Meat Really Kill You?, there can be many other variables that could affect heart disease risk.
It is possible that in Japan they eat more vegetables, or get more sleep, manage stress better, eat less omega-6 fatty acids; the list of possible differences is significant. The problem is, when researchers are convinced something like fat consumption is to blame, they may look at research in a way that only proves their point of view rather than trying to find the actual answer.
Saturated fat doesn’t seem to play a role in the development of heart disease, but what about other types of fat? Trans fats, common in processed foods, lower HDL and raise LDL levels. Beyond lipid levels, they may also increase development of visceral, or belly, fat. Belly fat is more inflammatory than fat stored in other areas of the body. Since chronic inflammation, rather than out-of-range cholesterol levels, may be the major contributor to heart disease and other degenerative diseases, anything that causes the development of belly fat could increase the risk of heart disease.
Omega-3 fatty acids, found in fish, help to reduce triglyceride levels and lower inflammation. Omega-6 fatty acids, high in vegetable oils, tend to increase inflammation and result in oxidation in the body. Soybean oil and corn oil are two common oils in processed foods that should be avoided. Olive oil is a healthy oil, composed of high amounts of monounsaturated fats.
Consuming excessive amounts of carbohydrate can negatively affect blood lipid levels. First, triglyceride levels are clearly related to the amount of carbohydrate people consume, and a high triglyceride level is an independent risk factor for heart disease. A significant reduction in triglyceride levels often follows a reduction in carbohydrate content within weeks of making the change.
High carbohydrate intake also raises insulin levels. Insulin reduces the body’s ability to burn fat. If the body can’t use fat for fuel, lipid levels in the blood may remain elevated.
In general, studies find that when low-carbohydrate and high-carbohydrate diets are compared, low-carbohydrate diets result in far lower levels of triglycerides and higher levels of HDL. These two shifts significantly change the triglyceride-to-HDL ratio we discussed in Cholesterol, Health and Heart Disease, decreasing heart disease risk. Fasting glucose levels also decrease, which can also help lower heart disease risk.
Low-fat, high-carbohydrate proponents point out low-carbohydrate diets do sometimes raise LDL levels. Those who still see LDL levels as a significant heart disease risk will use this as cause against decreasing carbohydrates and increasing fat. As we’ve discussed, the LDL level by itself should not be seen as a risk factor. As researchers Jeff Volek and Stephen Phinney in their book The Art and Science of Low Carbohydrate Living point out:
“Circling back to the question, should you be concerned if your LDL-C does not go down (or even rises slightly) on a low carbohydrate diet? In the big picture, and particularly so for people with metabolic syndrome, LDL-C is more smoke than fire. A small to moderate increase in one's total LDL-C is not worrisome if other lipid and inflammatory markers are dramatically improved in response to reducing dietary carbs. If, for example, your serum triglycerides went way down on a low carbohydrate diet (which they almost always do) then chances are you have also decreased the smaller more dangerous LDL particles even if your total LDL-C concentration is increased.”
Protein consumption has been given little attention in relation to heart disease. If protein consumption is discussed in relation to heart disease, it’s most often discussed in relation to its dietary source. Some may point the finger at red meat, as we saw in last week’s article, suggesting it raises heart disease risk. However, it isn’t the protein, but rather the fat and cholesterol in the meat that takes the blame.
That said, protein can play an important role in helping the body recover from physical stress and repair tissues. It also helps individuals feel more satisfied, which can help them reduce excessive amounts of carbohydrates and processed foods.
Higher-protein diets often result in favorable changes in body composition and lipid levels and blood pressure. Just beware of cereals and granola bars advertising “high protein” as these foods often contain high amounts of carbohydrates and other undesirable ingredients.
Though we don’t talk about alcohol consumption as much as protein, carbohydrates and fat, alcohol does seem to have a positive effect on lipid levels and heart health. Most of the available research on the benefits of alcohol comes from research on red wine. Red wine has the added benefit of containing polyphenols, powerful antioxidants. Hard liquor does not contain these polyphenols, but has little to no sugar. On the other hand, beer and mixed drinks do contain sugars and may not provide the same kind of health benefits.
For women, one serving per day, and for men, up to two servings per day can help increase HDL levels, as well as affect a couple other lesser known heart health markers, adiponectin and fibrinogen. Alcohol consumption has been shown to increase adiponectin, a hormone that helps regulate blood sugar and fatty acid metabolism. It also helps lower fibrinogen. In the case of heart health, high levels of fibrinogen may increase the risk of developing a blood clot.
Over the past several decades, the view of food has changed significantly. Today, we’re told to eat manufactured foods to improve our health and told to avoid many foods in their natural state. For years, we were told to eat egg whites and toss the yolks. We were told to avoid coconut even though some of the healthiest cultures thrive on it. We were told to replace butter with trans fat-filled margarine or to use vegetable oils, which undergo significant processing, over animal fats that require no processing at all.
Most of these recommendations have been made based on a hypothesis of what is healthy. Unfortunately, research has not backed it up and the average American is faced with higher rates of heart disease, diabetes, obesity and a large number of other health problems, than ever before. If you’re confused about what to eat, you’re not alone. Start with our Healthy Way of Life Food Pyramid as a guide. Eat real food. Use high-quality supplements. Exercise and avoid bad lifestyle choices.
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This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.