Does Saturated Fat Increase Risk of Heart Disease?
For the last 40 years, people have believed that eating less fat, specifically saturated fat, is the key action to protect against heart disease and other health conditions. In 1980, the Dietary Guidelines for Americans recommended that people “avoid too much fat, saturated fat, and cholesterol.” Fast forward to 2015, the updated guidelines reversed nearly 40 years worth of focus on restricting total fat and dietary cholesterol. They removed any limitations on total fat consumption and of dietary cholesterol. There is currently still an upper limit recommendation on saturated fats but whether that is based on strong data is an ongoing debate.
It’s estimated that about 80 percent of cardiovascular disease – including heart disease and stroke – is preventable. But the question is: what’s the best route for prevention? How beneficial is it to limit beef, pork tenderloin and coconut oil from your diet in an attempt to reduce saturated fat consumption? Is it helpful to continue choosing low-fat yogurt over full-fat, the leanest steak at the butcher, chicken breast over chicken skin and requesting dressing on the side of a salad?
My Experience and Confusion With Conflicting Viewpoints
These are questions that my mind has tossed and turned over for my entire career as a dietitian. I spent the first five years of my career working for different nutrition departments that had varying viewpoints on dietary fat intake. I first worked for a nutrition department where Dr. Caldwell Esselstyn ran vegan/oil-free nutrition programs for those with coronary artery disease. And I worked with a huge mentor of mine, Dr. Michael Roizen for several years, who advocates for a mediterranean style diet that is rich in plants, extra virgin olive oil and avocado but does not include red meat, coconut oil or egg yolks. Next I worked for several years as a dietitian for Dr. Mark Hyman when we started the Cleveland Clinic Center for Functional Medicine. Dr. Hyman is an advocate of a higher fat, whole foods diet that includes quality red meat, eggs, coconut oil and plenty of vegetables!
As you can imagine, I felt overwhelmed by the contrasting nutrition beliefs. At the time, I had to focus on the similarities between all three approaches for my own sanity. Here is what I determined:
1) Food can reverse disease
2) Eat more vegetables
3) Eat more colorful plants
4) Avoid processed foods
5) Avoid high intake of added sugars
6) Cook as often as possible to avoid outsourcing your meals.
I also learned to let go of the idea that there is a “right” approach to nutrition. I had personally witnessed individuals who experienced transformations with all three nutrition approaches. My early experiences with these experts, in addition to seeing 4,000 patients on my own, shaped my core belief of personalized nutrition: there is no one size fits all approach to food. A person’s genetics, microbiome, health history and overall lifestyle will impact how much their cholesterol levels are impacted by saturated fat intake. But it helps to start out with a better understanding of what is true about saturated fats and what information was based on poorly designed epidemiological data.
The Four Types of Fat
A healthy brain, cell membranes, hormone production, and so much more depend on healthy fat intake. A few fats, including the omega-3 fatty acids in foods like wild-caught seafood and flaxseeds, are even considered essential, meaning the body cannot make them endogenously and you need to get them exogenously from food and/or supplements.
Broadly speaking, fat comes in four “flavors”, defined by their bonds.
1) Saturated Fats
Saturated fats contain single bonds between carbon molecules, but no double bonds. The chain of carbon atoms is “saturated” with hydrogen atoms. At room temperature, foods that are predominantly saturated fat are solid, for example: coconut oil, red meat, butter, cheese, and lard.
2) Trans Fats
These artificial fats can occur naturally but have primarily been produced synthetically by partially hydrogenating oils to make them solid at room temperature and more stable. They are currently being phased out of the food supply because they are a double whammy for risk of heart disease.
3) Monounsaturated Fats
Monounsaturated fats have a single carbon-to-carbon double bond, which means two fewer hydrogen atoms than saturated fat and a bend at the double bond. As a result, many monounsaturated fats are liquid at room temperature, for example: extra virgin olive oil and avocado oil.
4) Polyunsaturated Fats
Polyunsaturated fats have two or more double bonds in its carbon chain. The two main types of polyunsaturated fats, omega-3 fatty acids and omega-6 fatty acids, refer to the distance between the beginning of the carbon chain and the first double bond. Omega 3 fats have been shown to be more anti-inflammatory (think wild salmon and chia seeds) and omega 6 fats, when over consumed can be very inflammatory (an example is industrialized seed oils such as safflower oil, soybean oil, etc.). So while both omega 3s and omega 6s are essential, having an optimal ratio of these two is desirable.
Monounsaturated fats have been touted as heart healthy (think extra-virgin olive oil and the Mediterranean diet), and polyunsaturated fats have been well-studied for their anti-inflammatory and other benefits, specifically omega 3 fats. Omega 6 fats can be inflammatory when consumed in excess, which is extremely common in the US.
Oversimplifying Saturated Fats
Saturated fats have not received that same acclaim. Mainstream sources such as MedLine Plus, an online information service produced by the U.S. National Library of Medicine, classifies saturated fat as “one of the unhealthy fats, along with trans fat.”
Other organizations also subscribe to this thinking. “Eating foods that contain saturated fats raises the level of cholesterol in your blood,” says the American Heart Association (AHA). “High levels of LDL cholesterol in your blood increase your risk of heart disease and stroke.”
Classifying saturated fat as beneficial or harmful, as these and other organizations have, oversimplifies the influence that one nutrient has on health without looking at the comprehensive diet.
A new study published in the Journal of the American College of Cardiology highlighted that the health impact of saturated fats may depend on whether the fats are interacting with naturally occurring food components and nutrients or with unhealthy compounds from a highly processed diet. The biggest key with saturated fats is that they behave differently when you modify your carbohydrate intake. It’s not just saturated fat on it’s own that does the most damage. It’s saturated fats combined with high carbohydrate refined foods and sugars. There appears to be a difference between eating a McDonald’s hamburger with conventional beef, highly processed cheese and a white fluffy bun with french fries compared to eating a grass-fed burger wrapped in lettuce with a kale salad on the side.
Foods Contain Different Types of Fats
Dietary fat is a very diverse molecule that can behave in many ways within the body. Many foods that get labeled as high in saturated fat actually contain a diverse range of fats:
- An egg yolk, which contains the egg’s fat, is slightly higher in monounsaturated fat compared with saturated fat (two grams versus 1.6 grams per large yolk).
- Of the 12 grams of fat in one tablespoon of butter, about seven grams is saturated fat. The rest is monounsaturated and polyunsaturated fat.
- A slice of bacon contains more monounsaturated fat than saturated fat.
- A ribeye steak, one of the fattiest cuts, contains slightly more monounsaturated fat than saturated fat. A three-ounce cut contains four grams of saturated fat and 4.7 grams of monounsaturated fat.
I’m not recommending that you slather butter over your foods or eat a plate of bacon! These examples highlight that food is very complex, and that many foods labeled as high in saturated fat actually contain a variety of fats.
Saturated Fat is a Complex Nutrient
The general synopsis with saturated fatty acids is that they are diverse compounds. Saying all saturated fats are created equal is like saying all carbohydrates are created equal.
Saturated fats are grouped as short-, medium-, or long-chain fatty acids according to the number of carbon atoms. The types of saturated fatty acids in the human diet are stearic acid (18 carbons), palmitic (16 carbons), myristic (14 carbons), and lauric acids (12 carbons). Their length of carbon atoms determine how the fatty acids behave. The body metabolizes saturated fats differently. Most long-chain fatty acids that are common in animal foods are metabolized with specific fatty acid-binding proteins. The body can even convert some fatty acids into others. The body can convert stearic acid, an 18-carbon atom long saturated fat found in animal foods, into a “heart-healthy” monounsaturated oleic acid that is primarily found in olive oil.
Compared with longer-chain fatty acids, medium-chain fatty acids may help improve insulin sensitivity and body weight. Just for reference: coconut oil is made up of about 60% medium chain triglycerides while MCT oil is 100% medium chain triglycerides. Most medium-chain fatty acids found in coconut oil and MCT oil go straight from the intestinal tract to the liver, where they are converted into an instant energy source or as ketones. Research has shown that MCTs are burned off and have the ability to slightly raise a person’s metabolic rate.
The Saturated Fat – Cholesterol Connection
For decades, critics associated saturated fats found in foods with high cholesterol in the body and thus, an increased risk of heart disease. The thinking went that saturated fat can raise cholesterol – more specifically, your low-density lipoprotein (LDL) or “lousy” cholesterol – and increase your risk for heart disease. And while I have seen individuals increase their saturated fat intake and develop high LDL cholesterol, I have also seen the exact opposite–this is again where personalized nutrition comes into play.
But just like with saturated fat, the idea of “good” and “bad” cholesterol oversimplifies a complex molecule. Today, we know that LDL and high-density lipoprotein (HDL) – the so-called “healthy” cholesterol – have different subtypes. These subtypes can be harmless or damaging. Small dense LDL particles or a ‘pattern B’ phenotype are much more susceptible to oxidation and build up along the artery wall, increasing risk of atherosclerosis or coronary blockage. And the primary driver of small dense LDL particles is a diet high in sugar, not fat!
One of the first studies that looked at cholesterol and heart disease was the Framingham Heart Study, which started in 1948 and monitored heart disease in over 5,000 residents of the Massachusetts town to identify the primary risk factors for heart disease.
Interestingly, William Castelli, MD, director of the study, noted its limitations in 1992. “In Framingham, Massachusetts, the more saturated fat one ate, the more cholesterol one ate, the more calories one ate, the lower people’s serum cholesterol,” he said.
One national study published in 2009 found that nearly 75 percent of patients hospitalized for a heart attack fell within the guidelines for LDL cholesterol levels, and nearly half had optimal LDL levels. Likewise, a 2017 study found that most major heart attacks happen in people with normal cholesterol levels.
The Framingham Study – and even how people view saturated fat and cholesterol today – evolved from a researcher named Dr. Ancel Keys, who believed that heart disease was preventable and pushed for larger-scale studies. In 1953, Keys argued that eating too much dietary fat led to heart disease. His Seven Countries Study argued that countries who consumed the most fat had the highest rates of heart disease. Critics noted that Keys had cherry-picked what countries he focused on while conveniently ignoring those that didn’t fit his agenda.
The Concerns with Trans Fats
Health experts like Jonny Bowden, PhD, author of Living Low Carb, states that saturated fat has been looped into trans fats when it comes to impact on heart disease. But by the 1990s it became evident that trans fats are the most harmful type of fat. The harms of trans fats are agreed upon by nearly every doctor and nutritionist across specialties. This is primarily due to the way that trans fats increase levels of low density lipoprotein (LDL or “lousy” cholesterol), especially small dense LDL particles and lowers levels of the “happy” high density lipoprotein (HDL) cholesterol. These trans fats are a byproduct of partial hydrogenation, which converts an oil – usually a vegetable oil – into a solid food such as margarine. These foods, a product of manufacturing rather than nature, are harmful to people’s health.
After years of battling between health experts and the food industry, the Food and Drug Administration (FDA) concluded in 2015, that trans fats are unhealthy, without question. In 2016, the FDA gave food manufacturers three years to eliminate them from the food supply. But prior to that, manufacturers were able to claim 0 grams of trans fats if the food product contained less than 0.5g of trans fats per serving. Even today, the ingredient list is where you want to look to identify any source of trans fats. If you see partially hydrogenated in the ingredients, you know that food contains trans fat. It’s most commonly found in commercially prepared baked goods, boxed mashed potatoes, cinnamon rolls in a box, some pre-made cookie dough batters, and deep fried foods at restaurants.
Replacing Saturated Fat with Vegetable Oils
By 1977, the US Senate Select Committee on Nutrition and Human Needs recommended that Americans reduce their consumption of total and saturated fat. Vegetable oils, margarine, and other unhealthy foods dominated grocery stores, and the low-fat philosophy gained momentum. Meta-analyses from early on demonstrated that replacing saturated fat intake with unsaturated fats, especially polyunsaturated fats, can lower risk of Cardiovascular Disease (CVD). A 2015 review of 11 Randomized Control Trials (RCTs) found that lowering dietary saturated fat was associated with a significant reduction in risk of cardiovascular events by 17% over a mean of 4.3 years.
At the same time, a 2014 meta-analysis of 32 observational trials and 27 RCTs concluded, “Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.” In other words: vegetable oils may not be as optimal as we thought. Most linoleic acid (omega 6s fats) comes from highly concentrated vegetable oils, widely used as cooking and frying oils as well as in many processed and packaged food items. When they are heated, the fat in vegetable oil becomes damaged or oxidized. The linoleic acid in these oils can oxidize in many tissues, contributing to the chronic inflammation that can eventually manifest as heart disease and other health issues.
Well conducted RCTs have not been able to clearly demonstrate that lowering saturated fat and replacing with sugar/refined carbohydrates or vegetable oils will significantly improve heart health or lower your risk of death. “There is no robust evidence that current population-wide arbitrary upper limits on saturated fat consumption in the United States will prevent [cardiovascular disease] or reduce mortality,” researchers in one recent review concluded. Eating some foods high in saturated fat like whole-fat dairy, dark chocolate and unprocessed meats are not likely associated with an increased risk of heart disease or diabetes. Especially in the context of a diet that is low in sugar and rich in vegetables and antioxidants.
Added Sugar is a Bigger Enemy than Saturated Fat
The sugar industry was absolutely involved in making saturated fat the enemy. In 1965, the Sugar Research Foundation – today called the Sugar Association – sponsored a literature review that linked fat and cholesterol with heart disease while downplaying research that showed sugar was also a risk factor.
This study, written by three Harvard scientists and published in 1967 in the New England Journal of Medicine, dismissed the data about sugar and focused instead on demonizing saturated fat. The result: Experts embraced low-fat diets early on while stifling the debate about sugar and heart disease.
Thankfully, that perspective is changing and newer studies reveal that added sugar, not saturated fat, may be a bigger driver for heart disease. A diet high in added sugars may increase risk for heart disease three-fold by increasing the risk of chronic inflammation, blood sugar levels and other risk factors associated with heart disease.
It appears that a diet high in sugar and saturated fats is the most problematic for a person’s risk of disease. If you are going to consume saturated fats in your diet, then it’s optimal to keep your added sugar intake low. Replacing saturated fat with other nutrients like sugar or refined carbohydrates is not nutritious. One meta-analysis of 60 randomized controlled trials found that replacing saturated fat calories with carbohydrate calories did not favorably change the ratio of total cholesterol and HDL cholesterol. Additionally, replacing saturated fat with carbohydrates increased fasting triglyceride levels.
Heart Disease is a Complex Condition
Pinning heart disease – or any disease, for that matter – on one nutrient such as saturated fat oversimplifies a very complex problem. Risk factors for heart disease include:
- Chronic inflammation
- Oxidative stress
- Thrombosis or blood clots
- High blood pressure
- Nutrient deficiencies
- Lack of physical activity
Many of these factors can be attributed to someone’s overall diet and lifestyle. The Nurses Health Study followed 84,129 women without cardiovascular disease, cancer, and diabetes. A 14-year follow-up found that 82 percent of coronary events could be attributed to five factors among these women:
- They didn’t smoke.
- They had had a body-mass index (BMI) under 25. In other words, they maintained a healthy weight.
- They moderately consumed alcohol.
- They engaged in moderate-to-vigorous physical activity for at least half an hour every day.
- They ate a low-glycemic diet high in fiber, omega-3 fatty acids, and folate.
In other words, the heart-healthier women made conscious choices about their diet and lifestyle. Lowering cholesterol or avoiding saturated fat had very little (if anything) to do with being healthy and reducing their risk of heart disease. Focusing on overall diet quality and eliminating processed foods can help improve heart health and overall health as a whole.
Choosing Optimal Saturated Fats
The most common misconceptions and discrepancies about fat stem from variations that aren’t always reflected in the studies, including:
- The source of saturated fat
- The carbon length of the saturated fat (short-chain, medium-chain, long-chain)
- The replacement macronutrient, such as carbohydrates or protein
Saturated fats have the same problem as carbohydrates: They often get lumped into one broad category. Ice cream and cauliflower are both carbohydrates, but one is obviously more nutrient dense than the other.
Instead of lumping all foods into a broad saturated fat category, we need to shift focus to specific foods that are healthful sources of saturated fats. Nutrient-dense sources include:
- Coconut Oil is about 92 percent saturated fat, yet most of that fat comes from two medium-chain triglycerides (MCTs) called caprylic and capric fatty acids. Studies have shown MCTs provide benefits, including weight loss, compared with other fats. Virgin coconut oil also provides nutrients including vitamin E and polyphenols. Lauric acid, the primary fatty acid in coconut oil, has also been shown to support your immune system.
- Grass-fed Ghee has been a staple in Indian cuisine and Ayurvedic medicine since ancient times. Its anti-inflammatory benefits come from butyrate, a fatty acid that supports the immune system, soothes inflammation, can fight viral infections, and helps heal and support the stomach lining. Ghee from grass-fed cows has conjugated linoleic acid (CLA), a fatty acid known for its heart health and other benefits.
- Grass-fed beef. Cows fed a diet of grass are more likely to yield beef with a superior fatty acid and antioxidant composition compared with grain-fed beef. Beef from grass-fed cows is higher in CLA and omega-3 fatty acids. Grass-fed/finished beef is higher in healthy fats and has a lower overall fat content. Grass-based diets also elevate precursors for vitamin A and E, as well as antioxidants including glutathione and superoxide dismutase compared with cows fed grain.
With saturated fat – as with food in general – quality is critical. Most studies do not differentiate between grain-fed beef and grass-fed beef, for instance, revealing further limitations that contribute to the continued misunderstanding about saturated fat.
Determining Saturated Fat Intake for Your Needs
Some experts paint a black-and-white picture about saturated fat, recommending that someone avoid it as much as possible or eat it liberally. I take a more moderate approach, encouraging small amounts but not treating foods rich in saturated fats as “unlimited” foods like non-starchy vegetables.
Tip #1: Limit your Added Sugar & Refined Carbohydrate Intake
Despite popular belief, overconsumption of added sugars and refined grains can be a driving cause of an altered lipid profile. If you want to be able to consume some saturated fats in your diet without being concerned about adverse health outcomes, limiting your added sugar intake is key. Try to reduce your added sugar intake, in addition to starchy foods that break down to sugar such as bagels, pastas, and most breads.
This does not mean that all carbohydrates are off the table! You need whole food, intact forms of carbohydrates to provide dietary fiber, which is absolutely critical for healthy lipids! Think raw leafy greens, non-starchy vegetables, berries, lentils, beans, sweet potatoes, etc.
Tip #2: Be Mindful of How Much Saturated Fat you Consume in your Diet
I’ve had a few clients go too far with ketogenic diets, which can be healthy, adding copious amounts of butter to their steak and coffee. Or they embrace the health benefits of coconut oil by cooking with it liberally or adding it to specific foods or beverages for its health benefits. Even healthy foods can become unhealthy in these amounts. You don’t need to avoid it, but be mindful about how much you consume and its source.
Tip #3: Prioritize Monounsaturated & Some Polyunsaturated Fats But Limit Vegetable Oils
Get most of your fat intake from monounsaturated and polyunsaturated (omega 3s) fats from sources like walnuts, macadamia nuts, almonds, chia seeds, ground flaxseeds, hemp seeds, avocado, wild-caught fatty fish, grass-fed beef, extra virgin olive oil, and avocado oil.
Avoid industrialized vegetable/seed oils that are high in omega 6s that can potentially oxidize such as safflower oil, soybean oil, sunflower oil, peanut oil, corn oil, cottonseed oil, grapeseed oil, rice bran oil, and canola oil.
As always, remember that nutrition is personal! You have to find the right approach that works best for you!