From the 1970’s until very recently, we were told that all fats were bad, and we should eat as little fat as possible. We now know that polyunsaturated omega-3 fatty acids are not only good for us, they are essential. What is the difference between saturated and unsaturated fats? Are some fats “good” and other fats “bad”?

What is fat?

Fats and oils are large molecules made of carbon, hydrogen, and a little bit of oxygen. Each fat molecule contains 3 “fatty acid” tails attached to a glycerol backbone. The result is called a “triglyceride.” Every fat molecule (or triglyceride) has the same glycerol backbone; it’s the different types of fatty acids attached to that backbone that give different kinds of fats their unique properties. Each fatty acid is essentially a long chain of carbon atoms with lots of hydrogen atoms attached to it along both sides, and an “acid” group on one end.

Fat is good.

We think of fat as bad; as something we want to get rid of. We think that the less we have of it the healthier we are. When we have too much of it, we feel ugly and unhappy. But the truth is that fat is incredibly important. Fat is vital to human life and health.

Fat is our portable battery pack.

Fat is an efficient, lightweight, flexible, and portable source of energy. All animals store energy as fat for these reasons. If we were meant to burn carbohydrates for energy, we would have the ability to sprout big lumps of starch all over our bodies, the way plants do. But Mother Nature is smart. She knows that animals need to move around in the world and can’t afford to be weighed down by heavy potato-like structures. Our bodies can only store hours’ worth of energy as starch (glycogen), but we can store months’ worth of energy as fat.

Fat contains more than twice the amount of energy per pound than carbohydrates do. You probably already know this but may not have thought about it this way: carbohydrate contains 4 calories per gram and fat contains 9 calories per gram. Calories are units of energy. Fat can pack a lot more energy than starch can.

Saturated fat is the preferred fuel of the heart, which is why the heart has some saturated fat wrapped around it.

Our brains are mostly made of fat.

Approximately 60% of the brain is made out of fat. In addition to being an important component of every brain cell membrane, fat also is a major component of myelin, the special insulating material that is wrapped around the electrical wiring pathways of our brain (damage to myelin is the hallmark of Multiple Sclerosis). Myelin is approximately 50% fat and 50% cholesterol.

Fat protects us.

Fat cushions our delicate vital organs so they won’t be bruised or damaged when we run, jump, or fall. Fat is a critical component of our skin—the barrier between us and the outside world—preventing us from randomly absorbing everything we come into contact with. Fats are integral parts of the outer lining (membrane) of every cell in our bodies, forming a water-tight seal that keeps stuff that should be inside the cell inside and stuff that should stay outside of the cell outside. What’s more, inside each cell are mini-compartments, like the nucleus and the mitochondria, that need to keep their contents separate from the inside of the rest of the cell, so they each have fatty membranes, as well.

Fats lubricate our moving parts.

Fats are important ingredients in tears, joint fluids, and other slippery substances that we need to function properly.

Dietary fat is required for vitamin absorption.

Certain essential vitamins, such as A, D, E and K, all require fat in order to be absorbed by our intestines. Fat itself is so important to our health and survival, that we are designed to absorb about 99% of all the fat we eat. This is not true of many plant substances that we think of as so important to our health, such as vegetable iron and beta-carotene.

How much fat do we need to eat?

This is a difficult question. Fat is so important to every cell in our bodies that we can make fat out of anything—we can make it out of dietary proteins from animals and plants, and we can make it out of carbohydrates, like sugar and starch. That doesn’t mean that these are the ideal ways to obtain fats—for all we know, the body would prefer to get its fat directly from the diet so that it doesn’t have to go through the hassle of turning other dietary ingredients into fat—it just means that it’s possible. There are only a few fats (“essential fatty acids”) that we absolutely must eat because we can’t make them ourselves (see below).

What is the difference between saturated and unsaturated fat?

A “saturated” fatty acid has the most hydrogen atoms it can possibly carry—it is therefore “saturated” with hydrogen. Every carbon atom is attached to as many hydrogen atoms as it can hold. Each carbon-hydrogen bond carries energy, so the more hydrogen atoms that are bound to a fat, the more energy you can get out of that fat when you burn it. Saturated fat has more energy, and therefore more calories, per pound.

Unsaturated fats have less hydrogen—at least one of the carbons will have a hydrogen missing. Since there is no hydrogen for that carbon to bind to, the carbon atom forms a “double bond” to a neighboring carbon atom instead. If a fat has one double bond, it is called “monounsaturated” (missing one hydrogen). Oleic acid, the primary fatty acid in olive oil, is a well-known example of a monounsaturated fatty acid, or “MUFA.” If it has more than one double bond, it is called “polyunsaturated” (missing more than one hydrogen). Omega-3 and omega-6 fatty acids (see below) are well-known examples of polyunsaturated fatty acids, or “PUFA’s.”

Most fats occurring in nature contain mixtures of saturated, monounsaturated, and polyunsaturated fatty acids. Olive oil contains approximately 17% saturated fatty acids, 71% MUFA (oleic acid), and 11% PUFA’s. Coconut oil contains more than 90% saturated fat. Beef fat contains nearly equal parts saturated fat and monounsaturated fat (most of which is oleic acid, the primary fatty acid in olive oil) and approximately 5% polyunsaturated fat, depending on what the animal is fed.

Saturated fats, with their full load of energy-packed hydrogen bonds, are straight molecules that pack together efficiently, and are therefore solid at room temperature (like lard, cocoa butter and coconut oil). Unsaturated fats, with their weaker double bonds, are crooked, because double bonds create kinks in the backbone. They do not pack together efficiently and are therefore liquid at room temperature (like olive oil). Imagine a box full of straight straws—they pack easily and you can fit a lot of straws into the box. However you can’t fit as many bendy straws into that same box because they take up more space. They also move around more inside the box. When molecules have room to move around easily, they are more likely to form liquids than solids.

Saturated fats are very stable, whereas unsaturated fats (oils) are fragile. The carbon double bonds in unsaturated fats are weak and vulnerable to chemical attack compared to the strong carbon-hydrogen bonds in saturated fats. This is why unsaturated fats (oils) go rancid (become “oxidized”) when exposed to air, whereas you can leave lard or butter on the countertop for a long time without worrying about it. Ghee, which is butter with all of its proteins removed (pure butterfat), can be stored at room temperature indefinitely.

Are saturated fats unhealthy?

Our bodies need both types of fats—saturated and unsaturated. Saturated fats are good for things like insulation (myelin), cushioning (abdominal fat around our organs), and storage (body fat under the skin) purposes. Unsaturated fats are good for flexibility and fluidity purposes, such as in membranes and body fluids. It doesn’t make sense to think of one kind as inherently healthy and the other kind as inherently unhealthy.

Saturated fats are chemically rather boring—they are quite stable (especially as compared to the reactive PUFA’s) and it is hard from a common sense point of view to imagine them causing the kinds of trouble they are accused of causing—such as burrowing into heart vessel walls and causing inflammatory plaques that rupture into heart attacks. These are by nature long, smooth, non-irritating substances.

You would not want all of your body fat to be unsaturated. All of your fat would be liquid instead of firm and compact. Not only would you sag everywhere, and begin to resemble a Shar Pei, but your body would have to be bigger, because liquid fats take up more space (like the bent straws in the box).

The misguided belief that saturated fats cause heart disease is rooted in a famous study published in 1970 called “The Seven Countries Study”, in which renowned scientist Ancel Keys claimed that people in countries where more animal fat was eaten had more heart disease then people in countries where less animal fat was eaten. Not only was this study an epidemiological study, and therefore incapable of proving a causal link between any dietary factor and any disease, but there have been numerous studies showing no connection at all between saturated fat and heat disease, including a study of 22 countries published by Yerushalmy and Hilleboe in 1957 (see references below).

The hypothesis that saturated fat causes heart disease now stands on very shaky ground; it is now controversial at best, if not obsolete. Researchers are finding much stronger evidence linking cholesterol dysregulation and heart disease to refined carbohydrates than to saturated fats (Halton 2006, Howard 2006, Mente 2009, Astrup 2010, and Jakobsen 2010). If you are interested in a thorough review of the history of this controversy, I would highly recommend Nina Teicholz’s wonderful new book The Big Fat Surprise, and Gary Taubes’ book Good Calories, Bad Calories.

What are omega-3 fatty acids?

Omega-3 fatty acids are polyunsaturated fatty acids (PUFA’s). This means they are each missing more than one hydrogen, and have more than one carbon double bond instead. Omega-3 just means that the first double bond in the fat chain is at carbon #3 in the backbone. They are liquid fats (oils).

Even if you eat a 100% fat-free diet, your body will find a way to make almost all of the important fats it needs out of the protein and carbohydrate you eat, but it cannot make omega-3 fatty acids. There are three omega-3 fatty acids that are often called “essential” to our health: ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid). Because we can’t make them from scratch, we have to eat them. Well, to be more precise, we cannot make ALA.

What is ALA?

ALA is the mother of all omega-3 fatty acids. It is an 18-carbon fatty acid that we can build upon to make EPA (20 carbons), which can in turn be converted to DHA (22 carbons). This process happens in the liver. The problem is that our bodies are not very good at adding carbons to ALA, so we convert only a very small percentage (less than 5%) of the ALA we eat into EPA, and far less of that EPA into DHA. So, the vast majority of the ALA we eat does not turn into precious EPA and DHA; it simply gets burned for energy or stored as fat.

It appears as if ALA itself isn’t required by the body as an important component of any particular cell or molecule; it may only be important as a building block for EPA and DHA. Therefore, if you get enough EPA and DHA in your diet, you may not need any ALA.

What are EPA and DHA?

EPA and DHA, on the other hand, serve important roles in the body. I mention them together because they are almost always found together in nature, and because researchers almost always study them in combination, not individually. Therefore, it can be confusing to try to figure out which one of these compounds is responsible for which benefits. Both EPA and DHA serve as building blocks for anti-inflammatory, pro-healing compounds called “resolvins” and “protectins”, which help to prevent chronic inflammation. They also stabilize the electrical activity of cardiac cell membranes, reducing risk of arrhythmias.

It seems as if DHA may be the most essential of the essential omega-3 fatty acids. The brain and retina require large amounts of DHA for their cells to function properly. It is found in the cell membranes of the brain and retina, helping to keep those membranes fluid and flexible. This is important, because membranes don’t simply act as water-tight walls. They have to be able to wrap around and envelop important nutrients to take them in, or fold outward to let them out. Membranes are very dynamic structures.

What are good dietary sources of ALA?

ALA is easy to obtain because it is found in such a wide variety of plant and animal foods. Interestingly, Americans obtain more of their daily ALA from animal foods than from plant foods. Oils of seeds, grains, nuts, and legumes contain ALA, with the highest concentrations being found in flaxseed oil, walnuts, canola oil and chia seeds. These foods are therefore marketed as being “rich in omega-3’s.” There is also a significant amount of ALA in purslane, an edible succulent green vegetable, and small amounts of ALA in spinach leaves. The problem is that these sources only contain one of the three essential omega-3 fatty acids; they do not contain any DHA or EPA. The body can only convert a very small percentage of ALA into EPA (3-8%) and has an even harder time converting ALA into DHA (0-4%), although there are some studies that suggest that, in the complete absence of dietary DHA (such as may occur for vegans), the body may be able to ramp up its ability to convert ALA into DHA to some extent.

What are good dietary sources of EPA and DHA?

EPA and DHA are synthesized primarily by algae and grasses—things that people don’t tend to eat and don’t digest well:

  • Marine microalgae
  • Seaweed
  • Grasses

However, many land animals eat grasses (or should) and many fish (especially small fish) eat algae. Animals eating these green foods accumulate EPA and DHA in their tissues, especially in their fats, livers, and brains. Therefore, good sources of EPA and DHA include:

  • Meat from grass-fed animals
  • Liver from grass-fed animals (much higher amounts than muscle meats)
  • Pasture-raised poultry meat
  • Liver from pasture-raised poultry (much higher amounts than bird meat)
  • Animal brain
  • Small oily fish (anchovy, herring, sardines and mackerel)
  • Large oily fish that eat small oily fish (bluefish, tuna, salmon, halibut, bass, and trout)—even farmed fish often contain omega-3’s because of what they are fed.
  • Fish liver oils, such as cod liver oil.
  • Oysters

Eggs from pastured poultry contain some DHA but are a poor source of EPA

Full-fat dairy products, especially from grass-fed animals, contain some EPA but are a poor source of DHA.

What are omega-6 fatty acids?

Omega-6 fatty acids are liquid polyunsaturated fatty acids (PUFA’s) just like omega-3’s are, but they have their first double bond at carbon #6 instead of carbon #3. Whereas there are 3 important omega-3 fatty acids for human health, there is only one essential omega-6 fatty acid: Linoleic Acid (LA).

What is Linoleic Acid (LA)?

It is so unfortunate that linoleic acid, the mother of all omega-6 fatty acids, and alpha-linolenic acid, the mother of all omega-3 fatty acids, have such similar names, because many people confuse the two, but so be it. LA is an 18-carbon polyunsaturated omega-6 fatty acid that we can build upon to make other important molecules, most notably, a 20-carbon omega-6 fatty acid called arachidonic acid.

Linoleic acid is present in all of our cell membranes so that it will be available to form arachidonic acid whenever called upon to do so. Arachidonic acid is required for the process of inflammation to begin. You might be thinking that inflammation is a bad thing, but without it, we cannot mount an immune response to things like bacterial infections and physical injuries. Inflammation is our first line of defense and requires specialized molecules that are made from arachidonic acid: prostaglandins, leukotrienes, and thromboxanes.

While you may not have heard of any of those inflammatory chemicals, you have probably heard of the medicines that are marketed to reduce their activity. NSAIDs such as ibuprofen reduce prostaglandin synthesis. Aspirin reduces prostaglandin synthesis and thromboxane activity. Singulair® is an asthma medication that reduces leukotriene activity.

What are good dietary sources of Linoleic Acid?

Our Western diet is loaded with LA, so not to worry. In fact, we get far more LA than we need. Linoleic acid is present in all kinds of plant and animal foods, but it is present in especially high amounts in vegetable oils (nut and seed oils). Animal fats contain approximately 10-20 % LA, whereas seed oils contain between 50-80% LA. We have been told for decades to avoid animal fats and to choose plant oils instead, and the result is that most of us now get far too much LA in our diet.

The omega ratio problem: are you off-balance?

So, the omega-3 fatty acids are used to create chemicals that have anti-inflammatory properties (resolvins, protectins) and the omega-6 fatty acid LA is used primarily to create chemicals that have pro-inflammatory properties (prostaglandins, leukotrienes, and thromboxanes).

All creatures need a proper balance of these two forces in order to defend themselves (pro-inflammatory elements) and heal (anti-inflammatory elements). Mother Nature understood this, which is why we are gifted with both pathways. In fact, these pathways are intricately connected to each other to keep one another in check. It’s a brilliant system. The pathway that leads from the omega-3 ALA to EPA and DHA uses the very same enzymes as the pathway leading from the omega-6 LA to arachidonic acid. The omega-3 and omega-6 pathways have to share these enzymes, so the pathways actually compete with one another.

This is why some scientists believe that it is important to eat a balance of omega-3 and omega-6 fatty acids. There is good evidence to suggest that our ancestors ate diets that contained roughly equal amounts of omega-3 and omega-6, depending on where they lived; at most their diets may have had 2-4 times more omega-6 than omega-3. However, these days our diets contain 20 to 30 times more omega-6 than omega-3, tipping the scale mightily toward inflammation and away from healing. This may be one of the most important reasons why so many people experience chronic pain and inflammation and find themselves turning so often to medications like ibuprofen to turn down the activity of the omega-6 pathway.

The same problem occurs in animals. Grass is high in ALA, the omega-3 parent molecule, whereas grains are high in LA, the omega-6 parent molecule. Therefore, grain-fed cows, for example, have an excess of omega-6 fatty acids and a deficit of omega-3 fatty acids. Grass-fed beef has an average omega-6 to omega-3 ratio of 1.53 to 1, whereas grain-fed beef has a ratio of 7.65 to 1.

Barleans fish oil omega-3 supplementIf you don’t regularly eat foods naturally rich in omega-3, you should consider taking a supplement. There are three forms of omega-3 fatty acids: ALA, EPA and DHA, and supplements vary greatly in quantities of each form. What you want to aim for is about 1000 mg of EPA per day. Fish or krill oil supplements are best. Vegan-friendly supplements derived from algae are available. I use Barlean’s omega-3 fish oil supplement.

Is it possible to eat too much omega-3?

Theoretically, yes.  If you ate a diet consisting only of a high-omega-3 fish, such as mackerel or salmon, your omega-6 intake would be very low in comparison to your omega-3, and it is possible that your ratio could turn upside-down.  Would that be bad for your health?  The theoretical possibilities include increased risk of bleeding and reduced ability to mount an appropriate inflammatory response to injuries and infections.  I found  two studies that can help us to address this question.

In the first study, researchers fed men a diet consisting of unlimited carbohydrate + mackerel for one week, so that mackerel was the only source of fat or protein.  This diet provided 7 to 11 grams of omega-3 fatty acids per day. The number of platelets (blood clotting bodies) in the blood of these men was reduced and platelets were less sticky in laboratory tests compared to platelets of those eating a standard diet.  The authors of the study concluded that these were healthy developments, because they could potentially decrease the risk of blood clots in people who are at risk for strokes and heart attacks.

In the second study, researchers compared one diet containing essentially no omega-3 fatty acids, to another diet containing 10 grams per day of omega-3 fatty acids in the form of salmon and salmon oil. After 3 weeks, in the high omega-3 group, platelet counts dropped (in a couple of cases to below normal–the lowest count was 90,000, whereas the normal lower limit is considered to be 150,000), platelets became less sticky, and bleeding time was lengthened to about 10 minutes on average (normal upper limit considered to be about 9 minutes).  The authors did not conclude whether these findings meant that the high omega-3 diet was healthier or riskier than the omega-3 free diet.

The typical recommended dose of omega-3 fatty acids is between 1 and 2 grams per day. Since the scientific jury is still out about the potential risks involved in taking very high doses of omega- 3, it would be best to use common sense here.  It is nearly impossible to eat a natural diet that is too high in omega-3 and too low in omega- 6. However, eating a diet of 100% oily fish (there are no studies of such a diet) or taking very high doses of omega-3 fatty acids could theoretically throw your ratio off-balance to the point that bleeding and resistance to infection could become problematic.


Healthy fats are healthy for you.

Include healthy animal fats in your daily diet if you can, as these are naturally good sources of EPA and DHA.

Reduce the amount of vegetable oils (nut and seed oils) in your diet to improve your omega-3 to omega-6 ratio.

If you choose to eat a vegan diet, be sure to include some DHA/EPA from microalgae sources, and gravitate towards plant foods that are high in ALA and low in LA.

To learn why dietary cholesterol is not bad for you, read my Cholesterol page.

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  • Des

    So, would eating about 3 ounces of smoked salmon for a few days in a row be okay if I’m eating eggs and other meats as well as fruit?

    • I’m sorry I can’t give personalized dietary advice on this site; it really depends on everything else you’re eating because it’s not just about how much omega-3 you are getting, it’s also about how much omega-6 you are getting.

      • Des

        I understand, thanks for your guidance.

  • Des

    Hi Dr. Ede, Is DPA essential?

    • It is unclear. EPA does seem to be essential, since it is very hard to make it from ALA, and many studies show that EPA supplements are more effective than DHA supplements for brain disorders, despite the fact that the brain uses DHA in high amounts. Giving DHA directly may not be as good as giving EPA and letting the body decide when to turn it into DHA.

  • Des

    Since omega 3 is an unsaturated less stable fat, what is the effect of cooking salmon?

    • Yes, the effect of cooking on meats is already on my to-do list (posted on the homepage), so this is one of the questions that will be covered as part of that future topic.

  • Karen

    There are 2 typos in the article where you have written mg when I am sure you meant grams. First is “In the second study, researchers compared one diet containing essentially no omega-3 fatty acids, to another diet containing 10 mg per day of omega-3 fatty acids..” and also at “The typical recommended dose of omega-3 fatty acids is between 1 and 2 mg per day. “

    • Karen, thanks so much for your sharp eagle eye and brain! I really appreciate it and have made the corrections.

  • rita

    Is butter healthier than olive oil? You keep hearing stories in the media about how olive oil is so healthy but is this vegetable oil really that good? What about butter?

    • Hi Rita
      What a good question. I don’t think anyone knows the answer to this. For people with dairy sensitivities, olive oil should be better, but if there are no dairy issues to worry about, I’m not sure if either one is healthier than the other. We’re not really designed to eat dairy fats, but some of us have evolved the ability to tolerate them. Luckily olives are fruits and not vegetables, so their ingredients, including their oils, are less likely to bother people than veggie ingredients, in my opinion. But I’m not aware of any scientific information that supports olive oil over butter or vice versa…

      • rita

        Ok, thank you Dr. Ede.

      • tpmrussell

        “We’re not really designed to eat dairy fats, but some of us have evolved the ability to tolerate them.”

        What do you mean by this statement? I would imagine that you don’t believe that we were “designed” to eat anything, per se. It all comes down to evolutionary fitness, right? So why the distinction between the terms “design” vs. “tolerate”?

        It is my belief that the lactase persistence enzyme mutation spread so rapidly because it conferred a tremendous survival advantage, meaning those without that mutation as a group were “less fit” evolutionarily. Wouldn’t that suggest that at least some of us were indeed “designed” to eat dairy fats?

        I have looked into this in some detail, and I don’t see any evidence that non-dairy consumers have lower mortality rates or less reproductive health than dairy-consumers.

        There is a suggestion of increased risk of certain types of Cancers by dairy consumers, but that risk seems to be outweighed by protection from other types of Cancers. The overall effect of dairy consumption seems to be protective in terms of heart disease, diabetes, and general metabolic health. As I understand it, the French, who have the greatest longevity in Europe and the highest documented rate of supercentenarians in the world, eat about 4 times the butter and 60% more cheese than the average American. I personally don’t think that’s a coincidence.

        Please don’t perceive this comment as confrontational. I really appreciate your blog and would love to hear more of your thoughts on this topic.

        Thanks very much.

  • John

    This is very useful guide. I’m glad I like sardines and mackerel in olive oil and will try to eat them more regularly .

    • Hi John
      I’m so glad the information has been helpful! May you enjoy your fatty little fishes:)

  • Kaspic

    When you talk about vegetable oils, it is not clear what exactly vegetable oils you mean, and also some clarification about oils whether they are cold-pressed (extra virgin) or refined oils.

    • Hi Kaspic
      Thank you for this feedback. I went back and edited the paragraphs about vegetable oils to make it clear that what I mean is nut and seed oils–thanks for pointing that out. As far as cold-pressed vs refined, I haven’t specifically researched the differences in the quality of fats in these, although I know many others have, and the general recommendation is to choose extra virgin or first-cold-press varieties of oils when possible. However I do not know whether the refining process changes the content or quality of ALA in seed and nut oils. I’ll add this to my list of things to read about!

      • Kaspic

        By refining the oil, it really changes the unsaturated fat and actually destroys everything. Refining can be done in many ways by physical or chemical means. One of the common refining is heating the oil up far beyond the smoking temperature, so that everything is ‘deleted’ and supermarkets could store this oil for ages, and fast food establishments could deep-fry in it. So basically only cold-pressed oils should be considered as healthy and refined oils in the best case scenario should be considered as neutral (if we’re lucky and no trans fats are inside).

        And thanks for the really nice article!

  • Christopher

    i have recently started taking Coconut Oil as a supplement to my diet with every meal after i read about MCT (Medium Chain Triglyceride) and its use in Alzheimer’s and find my brain seems far more alert (65 yrs) and my dietary intake has slowed to about 60% of what i normally used to eat as a natural occurrence not because I tried to reduce it. Could i take Coconut oil if i wanted to start on a Ketogenic diet or would it affect it

    • Hi Christopher
      Many people find coconut oil very useful on a ketogenic diet. I personally am not able to tolerate it, unfortunately, so I can’t comment on how it might affect my own progress, but it is a very popular oil among ketogenic diet followers. So glad to hear you are feeling more alert!

  • Tricia

    Thanks so much for this information! I am interested in the pathway of how LA goes to AA and then to prostaglandins and inflammation. I began taking primrose oil for peri-menopause about two years ago. A few months afterward I begin having symptoms of histamine intolerance. I thought it was another menopause challenge and began reading everything about HIT and changing my diet. I never thought about the EPO as I understood that this is the healthy omega 6. I looked at the bottle and there are 948mg of LA in each capsule, 240 mg GLA. The bottle says healthy prostaglandin levels. I wonder if EPO is very positive for PMS, but also creates high levels of AA and prostaglandins which lead to inflammation and HIT.

  • Da St

    To gauge the quality of this “nutrition science” and “common sense,” let’s point out how Ede does scientifically and ethically. Here’s her key paragraph on the science controversy:

    The misguided belief that saturated fats cause heart disease is rooted in a famous study published in 1970 called “The Seven Countries Study”, in which renowned scientist Ancel Keys claimed that people in countries where more animal fat was eaten had more heart disease then people in countries where less animal fat was eaten. Not only was this study an epidemiological study, and therefore incapable of proving a causal link between any dietary factor and any disease, but the original study actually involved 22 countries, not 7; the data from the other 15 countries having been omitted for undisclosed reasons. When the data from all 22 countries were analyzed, no correlation between fat and heart disease was found (Yerushalmy and Hilleboe 1957).

    The study may be called “The Seven Countries Study,” but its title is “Seven Countries: A multivariate analysis of death and coronary heart disease.” Keys was an author and editor. It wasn’t about animal fat. He was right, though, about the countries. He didn’t claim it proved a causal link–he, unlike Ede, is an epidemiologist, and knows what epidemiological studies can and can’t do.

    “The original study” did not involve 22 countries. But then, by this point in the paragraph, Ede literally does not know what she is writing about. What she thinks is “the original study” is an article, not a study (not even an epidemiological study), titled “Atherosclerosis: A Newer Problem in Public Health,” published in the Journal of Mount Sinai Hospital in 1953. This is not the Seven Countries Study, which was published in 1970. “Atherosclerosis: A Newer Problem in Public Health” did not involve 22 countries, either. It did include a graph showing the relationship between the death rate from degenerative heart disease death rate and fat intake (total fat calories, not animal fat or saturated fat calories, as a percentage of total calories) in six countries. Ede seems to have read neither the actual Seven Countries Study nor the “Atherosclerosis: A Newer Problem…” paper, judging from all the false claims about dates, country counts, and fat types she includes in this one paragraph.

    The Yerushalmy and Hilleboe study was not a study in which “the data from all 22 countries were analyzed.” The reference to “all 22 countries” is spurious. Keys’ paper published in 1953 did not include data from “22 countries,” but from six. (Keys also explained why he included the countries he included and did not include some others; and six is not seven.) The Seven Countries Study was published in 1970, and Yerushalmy and Hilleboe published in 1957–13 years before the Seven Countries Study. Ede did not even notice that she gave a 1970 date for the Keys study that she said Yerushalmy and Hilleboe refuted in 1957. It appears Ede thinks that the 1953 paper by Keys was the Seven Countries Study too.

    Yerushalmy and Hilleboe did use data on 22 countries (data from the World Health Organization and the Food and Agriculture Organization of the United Nations), but it was more countries than Keys’ paper considered, and the data were from different years. There were no “all 22” until Yerushalmy and Hilleboe’s paper used that number of countries. But what they concluded was not that “no correlation between fat and heart disease was found,” but that the association was reduced; that it was not “specific” for fat in the diet but that “the association with heart disease mortality is stronger when animal protein is substituted for fat.”

    The 1953 Keys paper was the one that Yerushalmy and Hilleboe considered. They concluded that Keys’ conclusion was not yet validated, but not that no association existed. The Seven Countries Study published its first results later, after Yerushalmy and Hilleboe published–13 years later. It was begun in 1958, a year after Yerushalmy and Hilleboe published. These two studies have literally nothing to do with each other, contrary to Ede’s mess of an account. The Seven Countries Study showed, among many other findings, that there is a direct and independent relationship between heart attack and stroke risk and death, and total serum cholesterol.

    Before you thank Dr. Ede for this information, you really need to evaluate its quality. In just one paragraph, the quality is abysmal.

  • Trevor

    Hi Dr. Ede,

    Can you talk a bit about trans-fats? What are they? What does our body do with them?


    • Dear Trevor,

      While I haven’t personally researched this topic in detail yet, I can tell you what Dr. Mary Enig says in her excellent book “Know Your Fats.”

      Trans fats are 18-carbon saturated fats containing one “trans” double bond (trans double bonds result in a very slight kink in the shape of the fat molecule, as opposed to “cis” double bonds (found in naturally occurring saturated fats) which result in a big bend in the molecule).

      There is only one naturally occurring trans fat, called trans-vaccenic acid, or TVA, which exists in small amounts in the fats of ruminant animals. TVA has its double bond in the 11th position. These animals turn TVA into another trans fat in their digestive tract called conjugated linoleic acid. There are no known human health risks to consuming this type of trans fat, and some say they are actually beneficial to human health.

      Unnatural trans fats are found in high percentages in man-made partially hydrogenated vegetable oils. Unlike TVA, these fats don’t have their double bond in the 11th position, but elsewhere in the molecule. Apparently, our bodies are unable to metabolize these fats properly due to their unusual chemistry and shape, so they interfere with normal fat processing and membrane function, including platelet activity, breast milk composition, HDL levels, and insulin signaling.

  • Steve Tremblay

    Hi Dr. Ede
    Do you know if fats under my belly are use only for energy or the body also use them also for other purposes ? What I want to say is if other cells in my body needs fats for cell’s duplication or for manufacturing other things (hormones, cell membranes, etc), does my belly will “melt” its fats for other cells or it will say no because these fats are stored only for energy ?

    • Hi Steve

      There are two types of belly fat–“subcutaneous”, which means directly underneath the skin–this is the kind of fat you can pinch with your fingers– and “visceral”, which is the fat deep inside the body, surrounding the organs in the abdomen. Both kinds of fat can be burned for energy, but visceral fat is much harder to burn if you have insulin resistance and are eating too much carbohydrate. If you are having trouble burning excess visceral fat, please see my article about insulin resistance for helpful tips: http://www.diagnosisdiet.com/how-to-diagnose-prevent-and-treat-insulin-resistance/

  • snezana

    Hello, I would like to know if cod liver oil is good too as supplement? It is because I hear of so many supplement needed by the body like vitamin D, vitamine K2 and after searching I find out that cod liver oil has both omega3 and vitamin D and then I searched more and discover Dr Weston price site where it is recommended the fermented cod liver oil which apparently contains all omega 3 + vitamin D and K2. I was planning to take that and give that to the children aswell, but I would like some opinion if somebody knows about it because it is quite expensive..
    thanks for helping

  • Andrew

    I’ve found multiple studies online that claim saturated fats are implicated in colon cancer and IBD. Have you looked at or refuted this at all?

    “High intake of saturated fats are risk factors for ulcerative colitis and colon cancer.”

Last Modified: Oct 4, 2016