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Can Some Trans Fats Be Healthy?


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This article is part of a special report on Red Meat. To see the other articles in this series, click here.

Trans fats are one of the few food components that are widely accepted as being unhealthy, and for good reason. Industrial trans fats are created by pumping hydrogen molecules into liquid vegetable oil, changing the chemical structure and causing the oil to become a solid fat.

Trans fats are generally considered to be especially harmful because they raise total cholesterol while lowering HDL cholesterol. However, as usual with conventional nutrition advice, there is far more danger to trans fats than simply the effect they have on cholesterol ratios.

Mark Sisson has written a helpful explanation as to why trans fats are best to be avoided.

However, it may surprise you to learn that many of the foods recommended on a Paleo or whole foods diet contain trans fats as well. Dairy fat and meats from grass eating “ruminant” animals contain significant amounts of trans fatty acids, and grass-fed animals actually have higher levels of these trans fats than grain fed animals. (1) In fact, your grass-fed steak contains about 0.5g-1.4g of trans fat per ounce (28.3g) of total fat. (2)

Does this mean we should avoid all grass-fed animal products, cut out red meat, and only eat fat-free dairy if we want to reduce our risk of heart disease? Not at all! These naturally occurring trans fats in ruminant animal products are not at all harmful to our health, and may actually reduce the development of many different chronic diseases.

Are you eating enough healthy trans fat? Tweet This

CLA: How is it different than industrial trans fats?

Naturally occurring trans fats are formed when rumen bacteria in the stomachs of ruminant animals (cows, sheep, etc.) digest the grass the animal has eaten and form trans-rumenic and trans-vaccenic acid via biohydrogenation of polyunsaturated fats in the grass. Conjugated linoleic acid, or CLA, is a trans-rumenic acid that is found abundantly in grass-fed meat and dairy products, and to a lesser degree in grain-fed products. It is also produced in our bodies from the conversion of trans-vaccenic acid (VA) from those same animal products.

Industrial trans fats have slightly different chemical structures than those trans fats found in beef and butter (specifically, the location of the double bond). CLA also has contains both cis- and trans- bonds, whereas most industrial trans fats have only trans bonds. But these minor differences in structure lead to majorly different effects in the body, as has been shown in many clinical and epidemiological studies. (3)

While industrial trans fats are shown to increase the risk of heart disease, cancer, and obesity, CLA and other trans fats found naturally in animal products are actually thought to decrease the risk of those diseases.

Health benefits of CLA

The major difference between CLA and industrial trans fats is the effect they have on heart disease and atherosclerosis. Several clinical and epidemiological studies have been performed, and meta-analysis of these studies suggests that natural trans fats from animal products are not associated with any increased risk of heart disease. (4) These studies have generally have shown either an inverse or no association between natural trans fat intake and heart disease across multiple geographical locations. (5)

While there have been very few highly controlled clinical trials studying the effects of CLA and VA on heart disease and atherosclerosis, the few that exist also support the conclusion that these natural trans fats may actually reduce the risk of heart disease. In animal studies, CLA has demonstrated potent anti-atherogenic effects, preventing fatty streak and plaque formation in the arteries of rodents by changing macrophage lipid metabolism. (67) While more research in humans is needed, it seems that grass-fed dairy and meat products, high in both CLA and vitamin K2, are some of the best foods you can eat if you’re looking to prevent a heart attack.

CLA may also be helpful in preventing the development and improving the management of type II diabetes.

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In rats, CLA has been shown to improve glucose tolerance and skeletal muscle insulin action. (8) Research has also demonstrated that CLA may reduce hyperinsulinemia by increasing the production of adiponectin, a hormone that can lead to enhanced insulin action and improve insulin sensitivity. (9) Epidemiological evidence suggests that there is an inverse association between CLA levels in adipose tissue and diabetes risk, further supporting the hypothesis that CLA may be involved in healthy insulin regulation. (10)

CLA has even been shown to reduce the risk of cancer, in both experimental and case control studies. (11) It appears to work primarily by blocking the growth and metastatic spread of tumors, controlling the cell cycle, and by reducing inflammation. (12) CLA is able to interrupt the omega-6 PUFA metabolic pathway for the synthesis of eicosanoids, preventing the inflammatory processes that promote cancer development. This may be one reason why dairy consumption has been shown to be inversely associated with certain cancers like breast and colorectal cancer. (1314151617) Based on these animal and human studies, it’s possible that CLA plays a role in cancer prevention.

You may have seen CLA supplements advertised as a weight loss promoter. Some research suggests that CLA can help reduce body fat and promote weight loss in overweight and obese individuals. (18) In a few studies, dietary supplementation of CLA has been shown to increase lean body mass, reduce body fat mass, and improve overall body composition in overweight individuals. (192021) It is thought that CLA may promote improvements in body composition by increasing the breakdown and reducing the storage of body fat. That said, this reduction in body fat is small, so CLA may not cause significant weight loss in the way that supplement advertisers would suggest. But it certainly wouldn’t hurt in your weight loss efforts to increase your dietary CLA.

These studies certainly provide interesting food for thought about CLA’s possible health benefits. That said, I think we need more high quality human research before we can be certain about CLA’s role in human health and disease.

The good news is that all of the foods CLA is present in are beneficial in other ways, so you’ll get enough CLA simply by emphasizing grass-fed meat and dairy products (assuming you tolerate dairy).

Dietary Sources of CLA

So now that you know some of the incredible benefits of natural trans fats like conjugated linoleic acid (CLA) and vaccenic acid (VA), how can you increase them in your diet?

As I mentioned earlier, grass-fed dairy and meat are the best sources of CLA and VA. In fact, 100% grass-fed animal products contain from three to five times more CLA than products from animals fed grain. (22) And since CLA is in the fat, the best sources will be fattier cuts of meat, bone marrow, high-fat dairy products like butter and whole milk, and full fat cheeses. Eatwild.com has some great information about CLA in food products, and even has a product directory that allows you to search locally for food made from animals raised on fresh pasture.

Some people may believe that supplementing CLA has the same potential benefits as eating a diet rich in CLA. I disagree, and believe that these supplements could be potentially harmful. Most CLA supplements are derived from linoleic acid in safflower oil, and some studies have shown that CLA supplementation in humans can cause fatty liver, inflammation, dyslipidemia, and insulin resistance. Furthermore, CLA supplements have not demonstrated the beneficial effects seen from dietary intake of CLA in human trials. This may be due to the composition of synthetic CLA supplements; 50% of the product is an unnamed isomer, and is an entirely different fatty acid than the CLA and VA found in meat and dairy products. (23)

It’s always better to get nutrients from food rather than supplements whenever possible, and CLA is no exception. So if you’re looking for a heart-healthy, cancer-preventing diet, be sure to include plenty of grass-fed beef, butter, and cheese. (And don’t worry if your doctor thinks you’re crazy!)

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Join the conversation

  1. Hi,
    I wonder how much lobbying was needed to distort the truth that much!
    The conclusion of (3) is: “Small clinical studies have been conducted to establish cause-and-effect relationships between these different sources of TFA and biomarkers or risk factors of CVD with inconclusive results. The lack of detection of treatment effects reported in some studies may be due to insufficient statistical power. Many studies have used doses of rTFA that are not realistically attainable via diet; thus, further clinical studies are warranted. Associations between iTFA intake and cancer have been inconsistent, and associations between rTFA intake and cancer have not been well studied”.
    So basically, this study is about denying previous studies while not bringing any answer or anything to refute their results.
    If I read another study: http://www.health.harvard.edu/press_releases/natural-trans-fat-less-harmful-than-artificial-version All I can read is again the same, the naturally occuring transfat seem to have a lesser correlation with CVD. http://www.webmd.com/food-recipes/20120120/natural-trans-fats-less-unhealthy-than-manmade-variety It might indeed be related to the chirality, but there is no single scientific argument to say that they are healthy!


    • Hi Bernard, thanks for checking. It’s common to overestimate/oversimply the results of scientific studies. While the article does seem to say that more studies are needed in other places, in the place you pointed out it pretty much says, “But these minor differences in structure lead to majorly different effects in the body, as has been shown in many clinical and epidemiological studies.”
      That statement seems compelling after I read that cis-bonds in unsaturated fats are what makes it healthier than saturated fats. Turns out it’s not true for iTFA and rTFA?

      • Hi Bernard, thanks for checking. It’s common to overestimate/oversimply the results of scientific studies. While the article does seem to say that more studies are needed in other places, in the place you pointed out it pretty much says, “But these minor differences in structure lead to majorly different effects in the body, as has been shown in many clinical and epidemiological studies.”
        That statement seems compelling after I read that cis-bonds in unsaturated fats are what makes it healthier than saturated fats. Turns out it’s not true for iTFA and rTFA? The Harvard article you pointed out does say that there are other reasons to believe that natural transfat are less harmful. I only recently learned that dairy had transfat.

  2. Every thing that seems good about CLA is also what seems good about lowering your carbs and increasing your fat intake. I wouldn’t be surprised if CLA added nothing special to the equation. This is an old article, and I suppose more research might be found.

    But all of this ‘processed’ vs ‘unprocessed’ stuff is bunk. All that matters is the end product. If some trans fats are good, then not all transfats are bad. Which means that I’m not gonna trust the health industry, which has failed us before.., with this research. Some scientist needs to show us exactly what the difference is when a saturated fat is processed, and when a transfat is processed. One of the bad ones. And one of the good ones. Not these meta studies with untold variables. It can be as simple as someone eating a butter and steak diet, vs someone eating a margarine and steak diet.

    I have no problem to ‘when in doubt’, use what nature gives you. But I want science to tell me that a pill form is bad, not some wishy washy sense of how big industry is bad. STUDY it. Determine how Transfats are bad.

    My opinion on transfats: the anti-fat health nuts got egg on their face by trying to link fat to syndromX, even as research was coming in that sugar was to blame. So in order to salvage credibility, they had to ‘determine’ that it wasn’t all fat that was bad — just horrible trans fats, and to a lesser extent saturated fats. And since most transfats are created ‘artificially’, this became an easy sell.

    I want science!

  3. We know that there is a difference between industrial trans fats and natural trans fats. How can anybody think they are the same or would even work in a similar manner in our bodies?

    Good article. Will be interesting to see what research come out in the future regarding natural trans fats.

  4. Chris Kresser have you read the book “The China Study”?
    Just wondering why you would promote a diet that contains most of the items that were proved to be foods not to eat?

    • I thought the China study had been found to have so many holes it looked like they were drilling down to us. There are still many out there who believe all vegetables and “good healthy grains” I guess. Hopefully NuSI will find the truth, what ever it really is. Funny how the obesity epidemic the huge increases in diabetes and Alzheimer’s seem to coincide with the various initialed agencies recommendations to cut out fat and increase grains. AND sugar gets a walk. Also funny that cattle ranchers feed cattle grain (slowly otherwise it makes them sick) because it is cheap and fattens them up, but we are told to eat more because it’s healthy for us. I lived in Italy for a while and there were plenty of fat Italians eating that Mediterranean diet. There are a lot of people finding all we’ve been told the last 50 years or so is baloney.

    • The China Study (the study the book is based on) was an observational study (aka correlation is not causation) that basically showed that the book was wrong.

      Meat, fish and dairy had no correlation with heart disease. The only significant correlation was with wheat and heart disease.

      This page has links to the real facts https://deniseminger.com/the-china-study/

  5. So I was looking at the popular Thai Kitchen brand of coconut milk and I saw that it contained about 0.7 grams of trans fats per can. Is this an additive or is it naturally-occurring? It is a product of Thailand so I’m concerned. I live in Canada by the way where labeling laws are a little more lax than the USA.

    • Dan, coconut has saturated fat naturally. So most likely the trans fat is from the coconut and not an additive.

  6. This article purports to be scientific and scholarly. But the references cited by numbers in the text have no references shown at the end of the paper. So the authenticity of claims cannot be evaluated. Therefore, this is a sham publication and it appears in no peer reviewed journal. It also appears to be heavily biased towards the beef and dairy industry.

  7. Do you have any safety studies not funded by industry?

    The two that you linked which showed no apparent harm were both “Supported by the Global Dairy Platform, Rosemont, IL.”

  8. The simple key to all fats is this.

    There are healthy fats and unhealthy fats. Eat the healthy fats do not eat the unhealthy fats. Don’t worry too much about eating too much fat.

    Another principal of healthy eating is also simple. Natural food good man made “food” bad.

    Combining these two we get. Natural made CLA good; man made CLA bad.

    Thanks I was unaware CLA was a natural transfat.


  9. I had only a few precious belongings in my car and I was unable to bring my desktop PC since it was too bulky. This means the star of the show is a Nvidia Tegra 2 system-on-chip running at 1 GHz.

  10. The last sentence says it all: “Don’t worry if your doctor thinks you’re crazy”.

    Trust Chris, he’s an acupuncturist.

    • “Don’t worry if your doctor thinks you’re crazy”

      Doctors spend most of their time in Med School being brainwashed into the Pathogen Theory of Disease; this requires them to be advocates for the Rockefeller Drug Industry.

      The doctors recently graduated from the Rockefeller funded Medical Schools, who will BECOME good doctors soon realize they have been brain washed and commence learning.

      The very best ones reject the the Pathogen Theory of Disease and covertly treat disease with vitamins and NATURAL means. They do this mostly by educating their patients. Medical Boards generally prohibit natural healing.

      noun \ˈdäk-tər\

      : a person who is skilled in the science of medicine : a person who is trained and licensed to treat sick and injured people

      b : a learned or authoritative teacher

      When we as a society allow our doctors to teach us the TRUTH about our health and how to PREVENT disease and treat MOST disease with natural wholesome foods and exercise this nation will have health.

      Don’t hold your breath waiting, about 3 TRILLION in GNP is being billed by the Rockefeller Medical Industry to KEEP YOU UNHEALTHY or dead before your time.