Dear Mark: CLA Supplements

Today’s question comes from Ola and regards CLA, or conjugated linoleic acid. What is CLA? CLA is the “good” trans-fat that occurs naturally in meat and dairy, especially from grass-fed animals. In the stomach of ruminants like cows, sheep, or goats, millions upon millions of bacteria help the animal digest its food. They also help convert dietary linoleic fatty acids into saturated fatty acids. Well, that conversion takes several steps, and one of the steps is the creation of CLA, some of which never gets fully saturated and instead shows up in the animal’s body and milk fat. 28 different CLA isomers, or structural arrangements of the molecules, appear in CLA-rich animal fat. It’s very complex and quite different from trans-fat created by partially hydrogenating vegetable oils. Those lab-created trans-fats have definite negative metabolic and health effects, while the panoply of various CLA isomers from grass-fed dairy and meat seem to be beneficial. With that said, let’s get to the question.


Thank you for this great and informative website. I have been primal for about a year now. I still don’t seem to get rid of those last 5 lbs so I read a bit about CLA supplements. What is your take on them? You have commented briefly on them and promised to write a more detailed piece about supplements.

If you don’t recommend CLA, what do you recommend for me? I lift “heavy things”/ push ups etc.. but I don’t sprint as much as I probably should! Thank you!


Conjugated linoleic acid production is a booming industry with many players. You’ve got the new guys creating the stuff on a massive scale, getting their hands dirty in the lab, converting linoleic acid derived from safflower or sunflower oil into various isomers of CLA. Then there are the stalwarts, those ruminant stomachs filled with microscopic bacterial sweatshops toiling away as they convert unsaturated fats to saturated fats and make various CLA isomers in the process. An isomer called cis-9, trans-11 (or c9, t11) isomer is the primary one. CLA with a trans-10, cis-12 isomer is also evident, but in far scanter quantities. Same type of molecules – different arrangement. In fact, c9, t11 CLA  accounts for between 80-95% of the CLA in ruminant and dairy fat, with t10, c12 showing up in trace amounts. Supplement makers have the luxury of focusing on other isomers, of course, so they typically produce CLA supplements containing equal amounts c9, t11 and t10, c12.

Why would they try to improve on an impossibly complex and delicately balanced natural system millions of years in the making by messing with the ratios?

Heh. Do I really have to answer that?

It turns out that the t10, c12 isomer has performed well in some studies. T10, c12 can inhibit the growth of human colon cancer cells in vitro (with c9, t11 having no effect). In another in vitro study, this time connective tissues isolated from human body fat, t10, c12 inhibited lipogenesis, or (something analogous to) body fat creation, while c9, t11 did not. It also showed promise as a promoter of lean mass versus fat mass in humans.

In a totally unsurprising twist, however, results change when you start feeding the stuff to live organisms and paying attention to the full effects (beyond just “does it result in 2% more fat loss?”).  Let’s take a look at a few examples.

Healthy humans taking trans-10, cis-12 CLA supplements had increased triglycerides, LDL-HDL ratios, and total cholesterol-HDL ratios when compared to patients taking supplements based on cis-9, trans-11. In both wild-type and lab mice, the t10, c12 isomer stimulated mammary tumor growth, while c9, t11 isomers had a neutral effect.

As Stephan Guyenet points out in a blog post, CLA loses a head-to-head match with safflower oil (!). The safflower oil group saw improved insulin sensitivity, higher HDL, and lower inflammation. The CLA was 50% trans-10, cis-12 and 50% cis-9, trans-11. In other words, it wasn’t CLA as you’d get from grass-fed butter or pastured lamb shoulder chops. Stephan also cites two other studies using t10, c12 and c9, t11 at a 50:50 ratio that had similarly negative results – here (t10, c12 supplements worsened metabolic syndrome in men) and here (increased c-reactive protein and insulin resistance). If you can’t beat safflower oil, you should probably just throw in the towel.

Another study found that while t10, c12 supplementation decreased fat mass, it also raised LDL, lowered HDL, and overall worsened the cholesterol profile, as well as increased insulin resistance, blood glucose levels, and insulin. C9, t11, on the other hand, improved lipid metabolism overall.

In post menopausal women, high t10, c12 CLA supplementation increased inflammatory markers and lipid peroxidation when compared to CLA “supplementation” with milk (containing, remember, mostly c9, t11).

Mice fed t10, c12-enhanced diets experienced reductions in liver fatty acid oxidation and liver detoxification enzymes. In short, t10, c12 CLA gave mice fatty liver and reduced the liver’s ability to do its job. It had similar effects on hamster livers.

T10, c12 led to dysregulated glucose and lipid metabolism.

Are you noticing a pattern? Again and again, individual CLA isomers appear to be protective or beneficial in isolated studies, usually in vitro, but when you actually feed an animal or a human a CLA supplement with the same isomer ratios, the benefits either disappear or get counterbalanced by a negative effect. You might burn some body fat, but you’ll also become insulin resistant. You may keep off the baby weight, but your breast milk will contain less fat as a consequence. I’m a big supporter of supplementation, but in my opinion, CLA supplementation simply isn’t worth it.

The right CLA supplement employing the right isomers in grass-fed ruminant-fat proportions could be helpful, but after taking an admittedly brief look at the top CLA supplements results on Amazon, I couldn’t point you toward any that fit that description. They may exist. Heck, they probably do exist, but it’s not obvious. I think you’d be better served simply eating grass-fed animal products: butter, cheese, and meat with fat intact.

And as for what you should do to lose the last five pounds read this, this, this, and see this. Grok on!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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55 thoughts on “Dear Mark: CLA Supplements”

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  1. A couple of months back I went on a quest to find some CLA that WASN’T safflower derived. I went so far as to write the manufacturers of some that didn’t explicitly state they were safflower derived to ask if they had a product that was animal derived. I didn’t hear back from any of them.

  2. Its amazing how there is a supplement for every damn nutrient. I am sick of it. Sure, I take fish oil because I don’t eat a lot of fish. I don’t eat as much as I would like because I can’t afford it.

    Everyone that eats food can afford grass-fed butter. Its cheap. When you figure the cost per calorie its a measly 12.5 cents for me. This means I can have a heart healthy eggs cooked in butter with a side of bacon meal for under $2. I’ll add a handful of blueberries or 1/2 grapefruit for more nutrition and awesome taste.

    I’ll take the grass-fed butter and beef please.

    1. Its not sold at local grocery stores here in southwest Houston. Whole Foods might have it, but that automatically means a severe mark-up in pricing.

      1. What about farmers markets? I can buy grass-fed butter from my farmers market for $4 per lb. Texas has farmers markets open all year long. It would seem like at least one farmer would have grass-fed butter. No?

      2. That’s not true. HEB has Kerrygold butter for reasonable prices. I usually go to the one on Buffalo Speedway

        1. FWIW, as near as I can recall, it was not obvious to me from the packaging that Kerrygold is grass fed. (I’m not disputing you, I’m just saying why Andy T might think there isn’t any.)

  3. Tim Ferriss refers to Blue Ice Royal Butter Oil/Fermented Cod Liver Oil Blend. It has high vitamin butter oil mixed with fermented fish oil. Does the butter contained in this product speak to what you are advising?

    1. The High Vitamin Butter Oil is a natural source of CLA, and mixed with FCLO it’s a potent combo of vitamins A, D and K too.

      I’ve been taking it for a while and I like it a lot, check out for more info…

  4. interesting read…
    Watras A, Buchholz A, Close R, Zhang Z, Schoeller D. The role of conjugated linoleic acid in reducing body fat and preventing holiday weight gain. International Journal of Obesity. March 2007;31(3):481-487.

  5. Just out of curiosity, how much are you all paying for your grass- fed butter? There’s a great local one available here, but it’s like $9 a pound.

    1. I pay $4 per lb at my local farmers market.

      Jewel Osco in Chicago, more specifically in Wrigleyville, has Kerrgold Grass Fed butter for $12 per lb. When I was there for Easter they made a huge mistake and I got it for $6 per lb 🙂

      1. Kerry Gold is usually about $4 a half pound at the Trader Joes on Lincoln just north of Addison, Primal Toad. (And you can shoot South down Lincoln to Paulina Meat Market and pick up the best bacon in the World!)

    2. I pay $5.50/lb for local and grass fed (I stock up in the spring when they’re on the best pasture–no pastured dairy in winter in western Oregon or Washington). If I’d been more on the ball, I’d have gotten in on a group buy and would have my freezer stocked with some for closer to $4/lb. Be $6.50 or so for Organic Valley pastured butter through Azure Standard.

  6. Im paying 10$ a pound here in Ottawa, Canada,

    but im getting my ground grass fed beef for 4$ a pound from the same place!


  7. Isn’t worrying about the “last 5 lb” kind of silly? Isn’t it just a number on a scale? Worry about your energy level, your stamina, your health in general. Let your body and mind be healthly. Be “fit”, not “132 lbs” or “105 lbs” or whatever. Be “healthy”. It’s a lifelong journey, not a destination.

    1. Exactly…besides I always thought that mother nature puts a slight padding on healthy individuals to have a ‘nutrient bank’ for bad times.
      That’s what my Veterinarian told me about my dogs when I told him that I wish my dogs were rib cage thin eating raw, and they’re not. It isn’t healthy running around with a 5% body fat.
      If you can’t get that last 5 lbs down, obviously your body is fighting hard to have it on for some reason in the first place.

      I’m female and I know why I can’t get rid of the last 5 lbs…because when body fat drops under a certain % my hormones get out of wack and my menstruation stops. I would think the same law of nature counts for men…xept they got nothing to messure their hormones on.

    2. Hey, some of us are morbidly emotionally-obese. Definitely not suggesting that Ola is, but my point is that some of your fellow readers carry around tons of psychological baggage. So let’s try not to come off as glib, okeydoke?

    3. Why wouldn’t I worry about the last 5 pounds?

      When Mark posts pictures of himself he posts ones where there is no extra 5 pounds … just look at the picture up there at the top of the page … no extra 5 pounds …it’s natural for people to want to look good.

  8. Mark, I wonder what happens with CLA over fermentation? Will kefir and yogurts still carry same amounts as the original grass fed raw milk?

  9. Primal Toad…you can afford blueberries??? Wow!!! If man has F#*@k’d with it I don’t eat it. (period)
    Plants and animals; Wild when possible.

  10. Looks like CLA supplements aren’t something to be to thrilled about, too bad they’re so popular.

  11. Another very interesting blog. Tracking through some of the links, I have a question about getting fitter. Does anyone have any tips for those of us with fibromyalgia – I came into BP because I was a late diagnosed coeliac – the diet side is easy because anything else makes us feel rubbish – but getting fitter when even 10 minutes of exercise can result in muscle pain is tricky! Any ideas?

    1. I have several clients with FM (I’m a personal trainer). Primal eating often helps as it reduces the systemic body inflamation that I think pays a big role in FM cases. What I’ve found to be the best thing is the isagenix product range, making sure to incorporate the extra whey protein. Just letting you know what has worked for them, also helped for chronic fatigue.

  12. I tried CLA…supposed to help you lose fat. NONSENSE!!! I gained weight and broke out with severe acne. It’s garbage – threw it out.

  13. My favorite CLA loaded fat is grass fed pemmican (dried beef and tallow). I live on that stuff. You get a whole ton of CLA because it’s like 80% fat.

  14. Peggy–do you make your own, or do you buy it? Would you be willing to share the recipe?

  15. Oh, and JennyW . . . That sucks. FM and celiac run in my family, though I’ve dodged the bullet so far. Based on watching my mother, I’d say, don’t overdo it in terms of pushing yourself to lift heavy at first. You have to go slow. If ten minutes is what works for your body, start there and work your way up. I’d say a light, short weight routine interspersed with walking, yoga, or tai chi would be ideal–though I’m not an expert and neither my Mom nor my Grandmother ever followed an ideal routine!!

    If you tolerate salicylates, you can also try eating foods high in them–it’s a great way to reduce theinflammation and possibly pain associated with weight training. Blueberries and cranberries are two of the best, but other fruits and a few veggies have them too– you can find lists online.

    Best of luck.

  16. I was thinking.. maybe we should work harder to increase awareness. One thing I was thinking is why not have some local walks? If people could see all the people doing this and how healthy they are it might be a step in the right direction. Along with some booths (including LOCAL farms!) with more information and tons of Primal Food! We could use the local farms to sponser the events. Maybe someone from each area (ie Boston, NY, Maimi, LA, Washington DC, etc) Can organize it and we can try and do it on the same weekend. It may have to be somewhere just outside the cities..but it could work. We could make a special T-Shirt for it. Maybe in September?

  17. Audra, I also broke out terribly! I took my last doses yesterday and I don’t plan on going back to it anytime soon once my face clears up.

    1. Wow! Awesome paneestrtion. I’m so glad I found this post (I think via Pathable?) Your paneestrtion is so spot on! Scary. Glad I’ve been leery of those location-providing things (although they look like fun!) I’ve also been guilty of some of the privacy crimes this is info my students need! KUDOS!

  18. I actually been taking CLA and has worked pretty good for me my body is more toned than before, I also read that if you take a fish oil supplement with CLA it cancels the effect of insulin resistance so imbdoing that.

  19. I wouldn’t recommend CLA supplements. My health declined after I started taking CLA pills. They were only part of the picture as I was doing a lot of dumb stuff but I think they were the tipping point that sent me sprawling over the edge. Long story short: just eat natural.
    But for more details:
    A couple years ago I wanted to get as toned as possible so I started taking CLA pills. I was also taking Xenadrine (partially for increased metabolism and partially because it kept me wired) and consuming lots of caffeine, mostly from energy products. I was hooked on other pills that stunt hunger and increase metabolism (kind of like a painkiller and a stimulant combined), tripping out just about every day. That stuff was all before CLA so I didn’t have much fat to begin with, though I was staying at a fairly stable weight, probably thanks to lots of omelettes and trail mix. I wasn’t eating very well overall because I was loading up on free junk and pop during long workdays and only ate relatively healthy at home. I thought with so much metabolism-cranking and fat-burning stuff going into my system combined with working out I’d end up big and ripped. What happened is I did get quite toned fast but was soon noticing a decrease in energy and shortly after I was also losing muscle mass, even though I tried to eat more. Instead of getting big and ripped, which was the plan, I basically got skinny. I was more toned but less fit and healthy. I lost strength and endurance. I also got sick and that lasted about a month so during that time I had barely any energy to exercise and after work I’d bike home, crash on the couch, eat, and then go to bed, just to wake up and force myself to get to work and do it all over again, cleaning up crap and dealing with toxic chemicals for 10 hours at a time, with my head spinning in the clouds. That didn’t help my situation. My immune system must have been in shambles and I bet I was nutrient-deficient. All of that was followed by a whole bunch of shelter-hopping, welfare, jail time, and eating donated “food” to survive and general turmoil etc. which made being healthy and fit hard to accomplish. In some ways I’m not in as good shape as I was two to three years ago.
    Moral of the story: supplement wisely and be very mindful about everything you put in your body. Everything has a consequence. If you want to get more toned you’re better off tinkering with your calories or doing some fasting than taking pills to burn more fat.
    Now, being a bit older and wiser (and Primal! – makes a big difference), I’m exercising and eating well, doing a bit of fasting, supplementing only with vitamins, fish oil, ginseng, and bee pollen (when I can afford them or when my parents are willing to buy them) and occasionally protein powder and power bars (thanks to my brother who shares), and keeping my vices in check (well, compared to before.. for example I replaced energy drinks with coffee or tea and raw honey), I’m steadily getting good results and becoming a more capable creature rather than just a stronger and bigger bodybuilder. This could change soon since my parents want to kick me out as soon as I can get on welfare again or get a crappy job. I’ll just have to do my best to Grok on!

  20. quero saber o que realmente o cla suplemento faz no nosso organismo

  21. darn. now I need to cancel my order. Excellent research and summary! If you do find one that has the profile of natural sources could you post it here? grass fed cannot be found where i live, whatever the price

    1. High Vitamin Butter Oil from grass fed cows. “the oil extracted from the milk of dairy cows grazing on natural green pastures.” “When butter is cold pressed and centrifuged, the solid fats separate from the oils, yielding a skim of high vitamin butter oil that is the most nutrient-dense source of Vitamin K2, or Activator X, available. The liquid and butter wax are removed, leaving a concentrated High Vitamin Butter Oil devoid of moisture, lactose, and milk protein. It is done at a raw temperature, which preserves the delicate vitamins and the low chain fatty acids that are denatured when heated.”

      Delivers a natural, organic source of Vitamin A, Vitamin E, & Vitamin K.
      Includes natural CoQ enzymes
      Promotes regularity and can help relieve constipation.
      Provides an Antioxidant boost for maintaining overall good health.
      Strengthens Teeth and Bones, preventing decay and breaks.
      Moisturizes skin and balances natural oils to prevent breakouts.
      Contains the Dr. Oz-recommended weight loss booster, Conjugated Linoleic Acid, (CLA).
      Enhances absorption of digestive nutrients.
      Demonstrates compounded health benefits when combined with Cod Liver Oil.”

  22. It works for some, it doesn’t work for others.. particularly those who are muscular. I am 160 lbs and it helped me lose body fat and see my abs.. and I know this because in the past, I have not seen a decrease in body fat through healthy eating and exercising alone. There was one study about insulin and CLA and now everyone hates it. Please..

    Disagree with your article.. atleast the ending anyway. Very informative though.

    1. It worked for me as well. I was already eating healthy and take krill oil daily. Within 2 months my belly was basically gone and I dropped those last 10 lb. I do not like that CLA supplements come from safflower,known for higher omega 6’s than wise, however I do not eat processed foods as a rule nor grains. I am a nut, veggie, fruit, fish, legumes eater mostly.
      It may have had something to do with my cutting back on grains. Yet, cutting grains before never worked for long. I believe CLA gave me the energy to cope with that.

  23. And the person who posted about tripping on a bunch of pills.. you can’t blame CLA supplements cause you overdosed on 30 other pills.

  24. For a purely dairy-derived CLA, check out Dr Mercola. His is sourced exclusively from grass-fed dairy herds.

    1. I’ve just gone to Mercola web site and found CLA but it doesn’t say if it is cis9 trans11 that those CLA products contain. Do you have a link or can you point me in the right direction? Where i live there is no grass-fed anything. Very frustrating!

  25. Is CLA in Greek yogurt? I love the stuff, and its really good for your digestive tract. It says dairy, so I didn’t know what kind of dairy.

  26. Hi Mark,

    I have an autoimmune kidney disorder (iga nephropathy) so eating a lot of grass-fed beef and dairy is hard on my damaged kidneys.

    Is there I way I can get a healthy dose of CLA through supplementation?

    Best, Martin

  27. Yet there is no point in trying to increase your dietary CLA naturally because, even if all the theoretical benefits were confirmed, a person would have to consume at least 500g of fat, mostly saturated, each day to get meaningful amounts, which is at least three grams. That is over 4,500 fat calories each day just from eat CLA rich foods [11]. Therefore if you want to boost your conjugated CLA intake to the levels used in scientific studies, you must use CLA supplementation.

  28. I have been buying CLA from GNC for a few years. Recently learned where GNC and Walmart have been putting all sorts of phoney ingredients in their products and frauding the consumers. Does anyone know if the CLA from GNC is actually made from Safflower oil, or is it the real thing? I’m starting to become concerned that they are using Valvoline 10w40 motor oil or something.

  29. How about Mercola’s? Does any one of you guys know if his CLA supplement is derived from grassfed animals?

    1. Mercola now has CLA that is derived from grass-fed cows. I have been using it for about a month or two now. We also eat grass-fed beef and grass-fed butter. I avoid other dairy because of some sensitivities to dairy. I take enough CLA to make my daily total (from foods + supplements) high enough to help with my health issues.

  30. Mercola’s CLA is safflower derived, just like every other brand’s…

    Just got the confirmation from Mercola’s Consumer Services.