A user guide to saturated fat

For decades, consuming saturated fat has been considered an unhealthy practice that can lead to heart disease. But is this reputation warranted, or has saturated fat been unfairly demonized? This guide explains what is known about saturated fat, discusses the scientific evidence about its role in health, and explores whether we should be concerned about how much we eat it.


First, what is saturated fat?

A fat (or fatty acid) is classified as saturated or unsaturated based on its molecular structure. Every fatty acid contains a chain of carbon and hydrogen atoms.

Saturated and unsaturated fatty acid

Saturated fats don’t have any double bonds between their chain of carbons, allowing more hydrogen atoms to be attached to the carbon atoms, and therefore are said to be “saturated” with hydrogens. This structure makes them solid at room temperature.

By contrast, an unsaturated fat contains at least one double bond between its carbon atoms — notice in the illustration fewer hydrogen atoms attached to the carbons with the double bond. This chain is now “unsaturated” with hydrogen atoms and remains liquid or semi-liquid at room temperature.

Learn more about different types of fats:


Which foods contain saturated fat?

Saturated fats are found in both plant and animal products. Many foods we eat contain a combination of saturated and unsaturated fats. For instance, although olive oil, nuts, and avocados are typically considered unsaturated fat sources, these foods provide some saturated fat as well.

Here are the amounts of saturated fat in some popular low-carb foods:

  • 1 tablespoon (14 grams) coconut oil: 13 grams
  • 3.5 ounces (100 grams) pork belly: 10-12 grams
  • 3.5 ounces (100 grams) ribeye steak: 8-12 grams
  • 1 ounce (30 grams) dark chocolate (70-85% cacao): 7-9 grams
  • 1 tablespoon (14 grams) butter: 7 grams
  • 1 ounce (30 grams) cheese: 5-7 grams
  • 1 tablespoon (14 grams) tallow: 6 grams
  • 1 tablespoon (14 grams) lard: 5 grams
  • 1 ounce (30 grams) macadamia nuts: 4 grams
  • 3.5 ounces (100 grams) chicken drumstick: 4 grams
  • 1 medium avocado: 4 grams
  • 1 tablespoon (14 grams) heavy cream: 4 grams
  • 1 tablespoon (14 grams) olive oil: 2 grams

Keep in mind that many other keto-friendly foods contain at least a small amount of saturated fat.


What do foods’ saturated fat levels mean for the typical low-carber?

Well, it means that you probably consume 30 or more grams of saturated fat most days, which is significantly above the levels currently advised by the US Dietary Guidelines for Americans (DGA, about 22 grams a day) and American Heart Association, (AHA, 13 grams).

Is that a concern? Not really. Available modern evidence basically shows that consuming that amount of saturated fat is not a concern — in fact, it might actually be good for you. Read on to learn more about the 50-year attack on saturated fat and the poor science behind it.

Videos about saturated fat

Why do health authorities advise us to restrict our saturated fat intake?

The belief that saturated fat is unhealthy has been widely held since the 1960s. For decades, we’ve repeatedly heard terms like “artery-clogging saturated fat” and as of 2018, the message hasn’t really changed among mainstream health authorities and their leading spokespeople.

When discussing new recommendations to restrict saturated fat to less than 10% of daily calories in early 2018, Director of the WHO’s Department of Nutrition and Health Development Francesco Branco stated:

“Dietary saturated fatty acids and trans-fatty acids are of particular concern because high levels of intake are correlated with increased risk of cardiovascular diseases.”

Recently, a Harvard professor characterized coconut oil as “pure poison” due to its high saturated fat content.

The fear of saturated fat can be traced back to the diet-heart hypothesis first proposed in the 1950s by American scientist Ancel Keys who promoted his theory that dietary fat raises cholesterol levels, thereby increasing the risk of heart disease.


The diet-heart hypothesis: incriminating saturated fat with weak evidence

After traveling to Europe and conducting informal surveys in different populations there between 1951 and1952, Keys published a paper suggesting that as a country’s intake of fat, saturated fat, and cholesterol increased, its rates of coronary heart disease (CHD) and related deaths likewise increased.1

Importantly, this was based entirely on observational data, which is considered weak evidence unless correlations are strong and have been repeatedly duplicated in other studies. Even then, this type of research can only show that a behavior and an outcome are associated with an outcome but not that the behavior actually caused the outcome.

That, however, wasn’t the only problem with Keys’ research.

In another 1953 paper, he included a graph showing a strong association between fat intake and CHD mortality in residents of six countries.2However, in 1957, researchers Yerushalamy and Hilleboe published data from 22 countries that failed to show a significant relationship between the amount of fat these populations consumed and their rates of CHD mortality.3

Decades later in the late 1980s, Keys and his research team published the results of their “Seven Countries Study” that tracked diet, health and death data in residents of the US, Japan, and Europe over 25 years. In this paper, Keys stated that although total fat and cholesterol intake weren’t associated with death from CHD, saturated fat intake was. He concluded that populations that ate little saturated fat had low rates of CHD mortality, whereas those with higher saturated fat intake (like the US) were at increased risk for CHD and CHD-related death.4 Yet he cherry-picked his findings: data from countries where people consumed high amounts of saturated fat but had low rates of CHD mortality — such as France and Switzerland — weren’t included in the Seven Countries Study.

These results would end up influencing nutrition policy for decades to come.

In 1961, based on Keys’ ongoing research and other papers favorable to the diet-heart hypothesis, the American Heart Association endorsed low-fat diets for the prevention of heart disease. Sixteen years later, a diet low in total and saturated fats was incorporated into the first set of US dietary guidelines.


Other problems with saturated fat research

Although Keys acknowledged that his findings were based on observational evidence, he strongly believed that his findings proved the diet-heart hypothesis to be true. However, a controlled clinical trial is the only way a cause-and-effect relationship can be proved. But when the National Institute of Health began conducting clinical trials on saturated fat, there were other issues — some of which weren’t revealed until several years later.

Results from controlled trials that failed to find any relationship between saturated fat and risk of CHD mortality or death from other causes often weren’t published within a reasonable time frame. In the Minnesota Coronary Experiment, conducted from1968 to1973, more than 9,500 people participated in a randomized study that looked at the effect of replacing saturated fat with linoleic acid (an omega-6 polyunsaturated fat found in vegetable and seed oils). This study has been described as the largest, most rigorous controlled study of its kind to date.

No benefit was found in the linoleic acid group; however, these results weren’t published until 1989.5The Minnesota Coronary Survey In 2016, an analysis of additional, previously unpublished data from the Minnesota Coronary Experiment confirmed the lack of association between saturated fat and CHD, heart attacks, and risk of death. Moreover, although the linoleic acid group experienced a decrease in LDL cholesterol levels, these participants actually had a slightly higher risk of CHD mortality. The 2016 researchers stated this was likely due to adverse metabolic changes resulting from intake of linoleic acid, which is known to be inflammatory when consumed in high amounts.6

Similarly, in 2013 an analysis of uncovered data from the Sydney Diet Heart Study conducted between 1966 and 1973 found that replacing saturated fat with linoleic acid slightly increased the risk of death from CHD and other causes.7

Fact or Fake concept, Hand flip wood cube change the word, April fools day


Saturated fat and health risks: the evidence to date

A few years ago, we shared some interesting WHO statistics that revealed that people living in European countries with the highest consumption of saturated fat have the lowest risk of dying from heart disease.

And what do systematic reviews of observational studies and controlled studies — considered the strongest, most reliable evidence — tell us about saturated fat intake and the risk of CHD, other diseases, and death from any cause?

  • A 2009 meta-analysis of 28 cohort studies and 16 randomized controlled trials (RCTs) found no significant association between saturated fat intake and CHD events or CHD mortality.8
  • A 2010 meta-analysis of 21 cohort studies found no association between saturated fat intake on CHD outcomes aside from a slightly lower risk of stroke.9
  • A 2015 meta-analysis of 17 observational studies found that saturated fats had no association with heart disease, all-cause mortality, or any other disease.10
  • A 2017 meta-analysis of 7 cohort studies found no significant association between saturated fat intake and CHD death.11

And although two systematic reviews of clinical trials found that replacing saturated fats with unsaturated fats may slightly reduce the risk of heart attack and other cardiovascular events, many other extensive reviews have failed to establish any such benefit.12

Recently, Mente and colleagues published a large study that examined dietary patterns and lipid data from over 100,000 people in 18 countries around the world. Called the PURE study, its data analysis found that higher saturated fat intake was associated with beneficial effects on a number of cardiovascular risk factors, including higher HDL levels, lower triglyceride levels, and – what seemed to be the strongest predictor of CHD risk — a decreased ratio of ApoB (found in LDL particles) to Apo A (found in HDL particles)13

What’s more, although eating a lot of saturated fat was linked to higher LDL cholesterol levels, these elevated values didn’t reliably predict future heart attack events or deaths. Therefore, lowering saturated fat intake in an effort to reduce LDL cholesterol isn’t likely to decrease the risk of cardiovascular events. Additional follow up seven years later in the PURE study revealed no association between saturated fat intake and heart disease but in fact a decreased risk for all-cause mortality and stroke.14

It appears that high saturated fat intake may increase LDL cholesterol concentrations in some people, either modestly or significantly. Additionally, researchers report that myristic acid (a saturated fat found in many foods like coconut oil, palm kernel oil, butter, cream, cheese and meat) has a greater effect on both LDL and HDL cholesterol levels than most other saturated fats.15


Should saturated fat ever be restricted?

Despite strong evidence that saturated fat itself is not harmful, in some instances limiting it might be beneficial. For instance, results from a recent study suggest that in patients with cardiovascular disease, eating a lot of saturated fat might lead to higher concentrations of small and medium LDL particles — changes that could promote disease progression.16 However, response to high saturated fat intake may vary among people with CHD. An earlier study found a beneficial increase in LDL particle size and other improvements in patients with cardiovascular disease who followed a high-saturated-fat, starch-free diet.17

Importantly, experts in the field of lipidology and cardiology disagree about whether elevated LDL cholesterol and particle concentrations increase the risk of CHD when other biomarkers related to heart health, such as inflammation, are within normal limits.


Should you be worried about saturated fat?

In a word – no. Saturated fat is part of our evolutionary history. Many low-carb whole foods that provide valuable nutrients and satiety — such as meat and full-fat dairy products — are also rich in saturated fat. Avoiding these foods may very well do more harm than good.

Aiming for a saturated intake below 10% of calories, as most health authorities recommend, is a difficult task that requires detailed tracking of macronutrients, doesn’t encourage eating naturally, and can diminish pleasure at mealtimes. Limiting fat can also decrease meal satiety and increase hunger and cravings between meals.

Additionally, coconut oil, butter, lard and other saturated fat sources are much more stable for cooking at high temperatures than unsaturated fats like olive oil and vegetable oils.

Based on the large body of high-quality research available, saturated fat intake per se is not linked to greater risk of heart disease, other diseases, or early death from any cause.

What’s more, saturated fat research has typically been conducted in people following all types of diets. There is emerging evidence that consuming a lot of fat on a carbohydrate-restricted diet may be even less of a concern and could lead to overall reductions in cardiovascular risk.18

On the other hand, the relationship between saturated fat intake and elevated LDL cholesterol and particle levels seems to vary from person to person. If your own LDL values increase significantly after adopting a keto or low-carb diet, you may be able to help lower them by cutting back a bit on saturated fat and eating more nuts, olive oil, avocados and fatty fish. By all means, avoid vegetable and seed oils, which are high in linoleic acid.

Conclusion

An across-the-board recommendation to limit your consumption of saturated fat to a small percentage of daily calories simply isn’t based on sound scientific evidence.


Additional resources

Videos

Dietary fat & cardiovascular disease

The demonization and deception in research on saturated fat, cholesterol and heart disease

Articles

The Seven Countries Study, Part 1

Most viewed BMJ paper 2017: Saturated fat does not clog the arteries

/ Franziska Spritzler, RD


Comments

  1. American Journal of Public Health and the Nation’s Health 1953: Prediction and possible prevention of coronary disease [weak evidence]

  2. Journal of the Mount Sinai Hospital, New York 1953: Atherosclerosis: a problem in newer public health [weak evidence]

  3. New York state journal of medicine 1957: Fat in the diet and mortality from heart disease: a methodological note [weak evidence]

  4. The American Journal of Clinical Nutrition 1989: Food consumption patterns in the 1960s in seven countries [weak evidence]

  5. Arteriosclerosis: an official journal of the American Heart Association, Inc. 1989: Test of effect of lipid lowering by diet on cardiovascular risk [moderate evidence]

  6. British Medical Journal 2016: Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73) [moderate evidence]

  7. British Medical Journal 2013: Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis [strong evidence]

  8. Annals Nutrition & Metabolism 2009: Dietary fat and coronary heart disease: Summary of evidence from prospective cohort and randomised controlled trials [strong evidence]

  9. The American Journal of Clinical Nutrition 2010: Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease [moderate evidence]

  10. British Medical Journal 2015: Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies [moderate evidence]

  11. British journal of sports medicine 2017: Evidence from prospective cohort studies does not support current dietary fat guidelines: a systematic review and meta-analysis [moderate evidence]

  12. Public Library of Science medicine 2010: Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: A systematic review and meta-analysis of randomized controlled trials [strong evidence]

    The Cochrane database of systematic reviews 2012: Reduced or modified dietary fat for preventing cardiovascular disease[strong evidence]

    Arteriosclerosis: an official journal of the American Heart Association, Inc. 1989: Test of effect of lipid lowering by diet on cardiovascular risk [moderate evidence]

    British Medical Journal 2016: Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73) [moderate evidence]

    Annals of internal medicine 2014: Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis[strong evidence]

    British Medical Journal 2013: Dietary fatty acids in the secondary prevention of coronary heart disease: a systematic review, meta-analysis and meta-regression[strong evidence]

    Nutrition Journal 2017: The effect of replacing saturated fat with mostly n-6 polyunsaturated fat on coronary heart disease: a meta-analysis of randomised controlled trials[strong evidence]

    Open Heart 2015: Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis [strong evidence]

  13. The Lancet Diabetes and Endocrinology 2017: Association of dietary nutrients with blood lipids and blood pressure in 18 countries: a cross-sectional analysis from the PURE study [weak evidence]

  14. The Lancet 2017: Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study [weak evidence]

  15. The American Journal of Clinical Nutrition 1997: Individual fatty acid effects on plasma lipids and lipoproteins: human studies [moderate evidence]

    Journal of lipid research 1997: Effects of medium chain fatty acids (MCFA), myristic acid, and oleic acid on serum lipoproteins in healthy subjects [moderate evidence]

  16. Public Library of Science one 2017: Effects of a very high saturated fat diet on LDL particles in adults with atherogenic dyslipidemia: A randomized controlled trial [moderate evidence]

  17. Mayo Clinic proceedings 2003: Effect of a high saturated fat and no-starch diet on serum lipid subfractions in patients with documented atherosclerotic cardiovascular disease [weak evidence]

  18. Lipids 2010: Limited effect of dietary saturated fat on plasma saturated fat in the context of a low carbohydrate diet [moderate evidence]

    Public Library of Science one 2014: Effects of step-wise increases in dietary carbohydrate on circulating saturated fatty acids and palmitoleic acid in adults with metabolic syndrome [weak evidence]