A user guide to saturated fat

For decades, consuming saturated fat has been considered an unhealthy practice that can lead to heart disease. This is based mostly on the finding in experimental trials that replacing saturated fat with unsaturated fat lowers low-density lipoprotein (LDL) cholesterol, and that LDL cholesterol itself is linked to heart disease.

But is this harmful reputation warranted?

Better quality research has demonstrated that saturated fat’s effect on heart disease is a lot more complicated. Factors that need to be considered include individual responses to saturated fat intake, food sources of saturated fat, and how the rest of the diet changes when a person increases their saturated fat intake.

Highlighting these points, 19 leading researchers concluded that evidence does not support the general advice to reduce saturated fat intake, and that the topic is far more nuanced than commonly reported.

A similar article was also published in a major mainstream cardiology journal in 2020.

All of this is further confounded by the fact that most studies combine all sources of saturated fat together. That means saturated fat from a steak is counted the same as saturated fat in cookies, cake or other baked goods, which have a combination of saturated fats, trans fats and sugars.

How can someone make sense of all this? This guide explains what is known about saturated fat, discusses the scientific evidence regarding its role in health, and explores whether we should be concerned about how much of it we eat.

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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 fats don’t have any double bonds between their chain of carbons, allowing more hydrogen atoms to be attached to the carbon atoms. This means they are “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 in our guide, Healthy fats on a low-carb diet.

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Which foods contain saturated fat?

Saturated fats are found in both plant and animal products. The 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 (200 grams): 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.

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Saturated fat and health risks: the evidence to date

Guidance to reduce saturated fat is based on studies which show 1) a causal link between saturated fat and LDL cholesterol and 2) a causal link between LDL cholesterol and coronary heart disease.

However, convincing evidence for a direct link between saturated fat and heart disease is lacking.

Let’s take a closer look at what systematic reviews of observational studies and intervention trials tell us about saturated fat intake and the risk of coronary heart disease (CHD), other diseases, and death from any cause.

• A 2009 meta-analysis of 28 cohort studies and 16 randomized controlled trials (RCTs) concluded “The available evidence from cohort and randomised controlled trials is unsatisfactory and unreliable to make judgment about and substantiate the effects of dietary fat on risk of CHD.”
• A 2010 meta-analysis of 21 cohort studies found no association between saturated fat intake on CHD outcomes.
• A 2014 systematic review and meta-analysis of observational studies and randomized controlled trials found that the evidence does not clearly support dietary guidelines that limit intake of saturated fats and replace them with polyunsaturated fats.
• 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.
• A 2017 meta-analysis of 7 cohort studies found no significant association between saturated fat intake and CHD death.

Two systematic reviews of clinical trials — considered the strongest, most reliable evidence — found that replacing saturated fats with unsaturated fats may slightly reduce the risk of heart attack and other cardiovascular events. In the latter review, this effect was found to apply only to men, however, and the intervention had no impact on total mortality or death from heart disease.

Other extensive and similarly high-quality reviews have failed to establish any benefit.

The 2012 Cochrane review of RCTs cited in the previous paragraph was updated in 2020, again finding a small reduction in cardiovascular events with lower saturated fat intake. As before, it also found no difference in cardiovascular death or all-cause death.

An observational study of high-risk subjects from Italy, France, and Scandanavia reported a minimal association between saturated fat intake and progression of carotid intima-media thickness (CIMT, a measurement of subclinical vascular disease), but this association disappeared when all other potential variables were taken into account. The conclusion, therefore, was that there is no evidence that saturated fat intake causes a progression of vascular disease.

Mente and colleagues published a large observational 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 heart disease 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). The study also found that replacing saturated fat with unsaturated fat improved some markers while making others worse, while replacing saturated fat with carbohydrates simply had an adverse effect on blood lipids.

However, as with many epidemiology studies, this study had significant flaws, including not measuring trans fat and inadequate measurement of the quality of carbohydrate. It also measured dietary intake on one occasion, in contrast to most epidemiological studies which have serial dietary data collection points.

Finally, as noted in the introduction, recent data have demonstrated that we need to be much more nuanced when considering the effect of saturated fat on heart disease. We’ll explore the most important nuances next.

Replacing nutrients

The food or nutrient which replaces saturated fat determines whether the switch might be beneficial, neutral or even harmful.

If you think about the studies which reduced saturated fat intake – what did they replace it with? Carbohydrates (such as whole grains vs. refined grains), unsaturated fats, or protein? This really matters.

It’s now clearer that replacing saturated fat with refined carbohydrates does not improve heart disease risk, whereas replacing saturated fat with polyunsaturated fat might, although the evidence is not strong.

This nuance could explain some of the conflicting results from meta-analyses.

There may be little point recommending a person reduce their saturated fat intake if they just end up replacing it with sugary cereals and white bread.

Food sources of saturated fat

A variety of foods are rich sources of saturated fat, including red meat, butter, cheese and coconut oil. Most studies combine all sources of saturated fat together. That means saturated fat in cream is counted the same as saturated fat in yogurt or cheese.

Many foods, including meat and dairy, contain other nutrients and non-nutrient components which can influence heart disease risk, such as probiotics, magnesium, potassium and vitamin D. They also contain other types of fats.

For instance, most beef products have nearly equal amounts of saturated and monounsaturated fats. Therefore, even though meat, yogurt and butter are relatively high in saturated fat, their effects on heart disease may be divergent due to these “confounding” factors.

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.

On the other hand, there are a number of controlled studies showing that cheese is much less likely to raise LDL-cholesterol than is butter.

Further, dairy fat from yogurt and cheese may be protective against heart disease, as suggested by both observational studies and randomized controlled trials.

As leading scientists claimed in their 2020 review paper, we should be discussing health implications of specific foods, rather than lumping them all together as “saturated fats.”

Overall diet

As described above, the whole diet is important. Most people eating a high-carb diet get their carbs from refined grains and sugars, which themselves may be harmful to health. If a low-carb (but high-saturated fat) diet helps them to omit the harmful types of carbs and consume more non-starchy vegetables, then this could be a net health benefit.

In other words, processed foods that are manufactured to replace naturally occurring saturated fats with refined carbs and sugars are rarely a healthier choice.

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

Someone following a typical low-carb or keto diet might 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 (about 22 grams a day) and American Heart Association (13 grams).

Is that a problem? We don’t know for sure, but for many people, probably not. In general, the effect of one nutrient on any outcome is very small.

It’s also important to consider all other factors which might influence a person’s risk of heart disease, and how an increase in saturated fat in the context of a low-carb diet might affect them.

For example, if by eating a low-carb diet (which happens to be high in saturated fat) a person is able to lose 10 lbs (4.5 kilos) of weight, improve their blood sugars, and lower their blood pressure, a small rise in LDL cholesterol should be unlikely to result in a net increase in heart disease risk.

In fact, weight loss intervention studies that have used low-carb, high-fat diets (including saturated fat) have shown on average no significant change in LDL cholesterol.

Instead, they have shown an overall improvement in risk markers for heart disease. This is why considering individual responses is important.

In summary, for many or even most people, increasing saturated fat intake in the context of a healthy low-carbohydrate diet should have a negligible impact on their heart disease risk.

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Conclusion

An across-the-board recommendation to limit your consumption of saturated fat to a small percentage of daily calories isn’t based on sound scientific evidence. In general, focusing on your whole diet is a better health strategy than limiting a single nutrient like saturated fat.

Many low-carb whole foods that provide valuable nutrients and help you feel full — such as meat and full-fat dairy products — are also rich in saturated fat. For people with metabolic conditions that can be improved with a low-carb diet, the benefits of these foods may be more important than a risk that may or may not exist.

On the other hand, the relationship between saturated fat intake and LDL-cholesterol concentration, particle number, and particle size seems to vary quite a bit among individuals, particularly when monitoring the response to a low-carb diet. It’s important that both you and your health care provider are aware of this.

You can read more about LDL cholesterol in our evidence based guides:

Low carb LDL hyper-responders
Is elevated LDL cholesterol harmful?
Cholesterol and low carb diets

/ Franziska Spritzler, RD