Are Saturated Fats Bad For You?

The Saturated Fat Wars Heat Up Again

Author: Dr. Stephen Chaney

Are saturated fats bad for you?

I feel your pain. It is so confusing. Just a few months ago we were being told our fears of saturated fats were outdated. Saturated fats were fine. It was carbohydrates we needed to avoid.

Then, just last week the headlines blared: “Hold your horses. Saturated fats are bad for you. You need to avoid them.” No wonder you are confused!

Last week’s headlines were based on a recently published Presidential Advisory by the American Heart Association (F.M. Sacks et al, Circulation. 2017;135.00-00. DO!: 10.1161/CIR.0000000000000510). A Presidential Advisory is the AHA’s highest-level health advisory. It is meant to guide public health policy by government agencies such as the US Surgeon General’s office, the USDA, and the CDC.

However, the warnings about the dangers of saturated fat are very much like the warnings about the dangers of global warming. They have their believers and their deniers, and both sides passionately defend their positions. I understand the passion of saturated fat deniers. Foods high in saturated fat are an integral part of our heritage and our culture. It is only natural to want to believe those foods are good for us.

Because of this, I knew the AHA advisory would be controversial. After all, if someone is telling us we need to give up the foods we love, they better have darn good evidence to back up their recommendations.

I knew you, my readers, would want a scientifically accurate evaluation of the evidence, so I carefully analyzed the research studies the AHA presented in support of their recommendations. Here is what I found.

How Was The Analysis Done?

This report was put together by the top heart disease experts, both physicians and research scientists, in the country. They examined over 50 years of research studies. They also examined meta-analyses that combined the results of multiple research studies. In short, they examined the entire body of scientific evidence on diet and heart disease.

The AHA committee used very rigorous criteria in selecting the best studies for their analysis. They only included randomized clinical trials that:

Had actual cardiovascular end points – heart attack, stroke, and deaths due to heart disease. Studies looking at things like LDL, HDL, particle size, inflammation etc. only give you part of the picture. They may, or may not, accurately predict risk of dying from heart disease.
Lasted two years or more. The fats we eat determine the fat composition of our cell membranes, and that is what ultimately determines our risk of dying from heart disease. This is the one instance it is true to say: “We are what we eat.” However, changing the fat composition of our cell membranes does not occur overnight. It takes 2 years or more to achieve a 60-70% change in the fat composition of cell membranes.

It also takes time for any intervention to meaningfully impact heart disease risk. For example, with statin drugs it takes 1-2 years before there is a significant reduction in heart disease risk. Thus, for a variety of reasons, studies of less than 2 years duration are doomed to fail.

Showed the subjects stuck with the new diet for the duration of the study. Subjects find it difficult to adhere to a diet to which they are not accustomed long term and often revert to their more familiar diet. This requires either very close monitoring of what the subjects are eating or measurement of fat membrane composition to verify diet adherence, or both. Studies that only measured what the subjects were eating at the beginning of the study and then looked at outcomes months or years later may or may not be valid. Without any measurement of diet adherence, it is impossible to know.
Carefully controlled or measured what the saturated fats were replaced with. The importance of this criterion will be clear when we look at the results of their study.

They then did a meta-analysis of what they referred to as “core randomized trials” that met all 4 criteria. In short, this was a very rigorous and well-done analysis.

The main finding of the report was:

Replacing saturated fats from animal products with polyunsaturated fats from vegetable oils decreased the risk of heart disease by 29%. This is equivalent to statin therapy, without the side effects.
The conclusions of this report applied equally to the saturated fats that come from meats and dairy products.
About 50% of the risk reduction could be due to lowering of LDL cholesterol. The rest came from reduced arterial inflammation, increased flexibility of the arteries, increased membrane fluidity and other factors.
When the replacement of saturated fats with polyunsaturated fats occurred in the context of a heart healthy diet such as the Mediterranean diet, heart disease risk was reduced by 47%.

What the saturated fats are replaced with is critically important. The authors of this report calculated what would happen if we were to replace half of our saturated fat calories with equivalent calories from other foods. Replacing half of our saturated fat intake with:

Polyunsaturated fats (vegetable oils and fish oil), lowers heart disease risk by 25%.
Monounsaturated fats (olive oil & peanut oil), lowers heart disease risk by 15%.
Complex carbohydrates (whole grains, fruits & vegetables), lowers heart disease risk by 9%.
Refined carbohydrates and sugars (the kind of carbohydrates in the typical American Diet), slightly increases heart disease risk.
Trans fats, increases heart disease risk by 5%.
The authors did not address the relative value of omega-6 and omega-3 polyunsaturated fats in their report. However, I have addressed the heart health benefits of omega-3s in a previous report, Fish Oil Really Snake Oil.

Why Is There So Much Confusion?

You are probably saying: “If saturated fats are so bad for me, why do I keep seeing diet books and news headlines saying I have nothing to fear from saturated fats?” The answer is pretty simple. The studies that have given rise to misleading headlines about the safety of saturated fats ignored one or more of the criteria described above that are needed to assure a valid conclusion. For example:

Some recent headlines claiming that saturated fats did not increase the risk of heart disease were based on studies in which saturated fats were replaced by refined carbohydrates and sugars. Other headlines were based on studies that did not measure what the saturated fats were replaced with.
The popular high saturated fat-low carb diets are not backed by any studies looking at their effect on heart attacks, stroke, or heart disease deaths. They are only backed by studies looking at their effect on LDL cholesterol and other imperfect markers of heart disease risk.
In contrast, the Mediterranean diet, which lowers saturated fat intake and contains healthy carbohydrates (whole grains, fruits and vegetables), significantly decreases the risk of heart disease. Please reference Mediterranean Diet for Heart Health.

What Are The Saturated Fat Deniers Saying?

The saturated fat deniers have wasted no time trying to discredit the American Heart Association advisory. Maybe they can’t bear the thought of having to give up their favorite fatty foods. Or maybe they just can’t bear to admit they were wrong.

However, their claims just don’t hold water. Let me give you some examples.

The AHA (American Heart Association) is a tool of the pharmaceutical industry. If the AHA were a tool of the pharmaceutical industry, I hardly think their report would have stated that replacing saturated fats with polyunsaturated fats was as effective as statin drugs at reducing heart attack risk.
The AHA is a tool of the food industry. If the AHA were a tool of the food industry, I hardly think they would have recommended replacing fats from meat & dairy with polyunsaturated fats.
The AHA advisory was based on associations, which do not show cause and effect. False. The AHA committee based their recommendations on randomized clinical trials, the strongest kind of evidence. They merely said that studies looking at the association between saturated fats and heart disease were consistent with their analysis of randomized clinical trials.
The AHA advisory was based on LDL cholesterol, which is an imperfect predictor of cardiovascular risk. False. Again, the AHA committee based their recommendations on randomized clinical trials of cardiovascular outcomes, not on LDL levels. They merely estimated that LDL cholesterol levels contributed to about 50% of the risk they observed.
The AHA committee ignored an early study in which replacing butter with polyunsaturated fats increased cardiovascular risk. False. That study actually replaced butter with margarine. It was the first study showing that trans fats are worse for us than saturated fats.
The AHA committee ignored recent studies that did not fit their hypothesis. False. They developed a valid set of scientific criteria for evaluating clinical studies. As described above, they simply eliminated those studies whose design does not permit a definitive conclusion.
The AHA recommends low fat diets containing refined carbohydrates and sugary foods, which are even worse. False. The AHA has consistently recommended low fat diets with complex carbohydrates (whole grains, fruits & vegetables). It is the food industry that corrupted their message. More to the point, this AHA Presidential Advisory specifically recommended lowering saturated fats in the context of a heart healthy diet like the Mediterranean diet.
The AHA recommends replacing saturated fats with omega-6 polyunsaturated vegetable fats, which can be harmful if consumed in excess. I have some sympathy with this argument. I would have preferred to have seen more emphasis on omega-3 oils in their report. There should also have been some discussion of the importance of antioxidants to protect against free radicals generated by polyunsaturated fat metabolism. However, their final recommendation to replace saturated fats with polyunsaturated fats in the context of a healthy diet like the Mediterranean diet goes a long way towards satisfying both concerns.

In short, the saturated fat deniers have no persuasive counter-argument. The evidence that saturated fat causes heart disease is simply overwhelming.

What Does This Mean For You?

The time for debate is over. The evidence is overwhelming. It should be obvious to any reasonable person that saturated fats increase our risk of heart disease.

It should also be obvious that any diet that claims saturated fats are heart healthy is a myth. There are no long-term studies to back up that claim.

It is time to consider what it would mean if everyone in this country were to follow the AHA recommendations and replace half of the saturated fat in our diet with polyunsaturated fat. That would decrease our risk of heart disease by 29%.

800,000 Americans die of heart disease each year. 232,000 lives would be saved.
Heart disease costs our nation $316 billion each year. $92 billion health care dollars would be saved.
Heart disease costs are expected to exceed $1 trillion by 2035. $290 billion health care dollars would be saved.

What if we decreased our risk of heart disease by 47% by coupling decreased intake of saturated fats with a heart healthy diet like the Mediterranean diet?

376,000 lives would be saved.
$148 billion health care dollars would be saved.
$470 billion health care dollars would be saved by 2035.

Each of us has the ability to save our health and our lives by what we put into our mouths every day.

In addition, our health care system will soon become financially non-viable if we continue to focus on disease treatment rather than prevention. Each of us also has the ability to save our health care system by what we put into our mouths every day.

The Bottom Line

The link between saturated fat and heart disease risk is like global warming. It has its believers and its deniers, and both sides passionately defend their viewpoints.
The American Heart Association (AHA) recently released a Presidential Advisory on the relationship between saturated fats and heart disease. Because I knew their report would be controversial, I analyzed its scientific accuracy very carefully.
The AHA report was prepared by the top heart disease experts in the country. They reviewed over 50 years of clinical studies and used a very rigorous set of criteria to decide which studies to include in their analysis and which to exclude. In my judgement, the criteria they used were valid. Studies that fail to meet one or more of these criteria may not provide valid results. Unfortunately, several of the studies that have generated some of the recent controversy did not meet those criteria.
From a meta-analysis of “core studies” meeting these criteria, they concluded:
- Replacing saturated fats from animal products with polyunsaturated fats from vegetable oils decreased the risk of heart disease by 29%. This is equivalent to statin therapy, without the side effects
- The conclusions of this report applied equally to the saturated fats that come from meats and dairy products.
- About 50% of the risk reduction could be due to lowering of LDL cholesterol. The rest came from reduced inflammation, increased flexibility of the arteries, and other factors.
- When the replacement of saturated fats with polyunsaturated fats occurred in the context of a heart healthy diet such as the Mediterranean diet, heart disease risk was reduced by 47%.
The AHA recommends replacing half of the calories from saturated fat with healthier choices. From a detailed analysis of the data, the authors concluded which foods replace the saturated fat is very important. Replacing half of our saturated fat intake with:
- Polyunsaturated fats (vegetable oils and fish oil), lowers heart disease risk by 25%.
- Monounsaturated fats (olive oil & peanut oil), lowers heart disease risk by 15%.
- Complex carbohydrates (whole grains, fruits & vegetables), lowers heart disease risk by 9%.
- Refined carbohydrates and sugars (the kind of carbohydrates in the typical American Diet), slightly increases heart disease risk.
- Trans fats, significantly increases heart disease risk.
The saturated fat deniers have already started trying to discredit the AHA advisory. I have reviewed their claims and found them to be baseless.
The evidence is overwhelming. It should be obvious to any reasonable person that saturated fats increase our risk of heart disease. It should also be obvious that any diet that claims saturated fats are heart healthy is a myth. There are no long-term studies to back up that claim.
If everyone in this country were to follow the AHA recommendations and replace half of the saturated fat in our diet with polyunsaturated fat:
- Between 232,000 and 376,000 lives would be saved next year.
- Between 92 and 148 billion health care dollars would be saved next year.
- By 2035 between 290 and 470 billion health care dollars would be saved annually.

In short, each of us has the ability to preserve our health and save our lives by what we put into our mouth every day.

So, are saturated fats bad for you? The answer is a resounding “yes.”

For more details, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.