Cod Liver Oil – Healthy or Dangerous? By Dr. Michael Teplitsky

July 27, 2010 · 60 comments

Blue Ice Royal

Common sense health guide (2) Today Dr. Michael Teplitsky, author of The Common Sense Health Guide, helps to clear up some of the confusion surrounding cod liver oil, which happens to be my favorite supplement – I always say that if you can only afford one, cod liver oil should be it.  Although it’s actually not a “supplement”, it’s a very traditional food.  Be sure to read all the way to the bottom where I’ve added more links all about cod liver oil that you may not have seen yet, and I’ll also tell you one of the reasons I love it for our family.

Cod liver oil has been used for thousands of years.

Ancient Egyptians knew that it could improve night vision. It was given to Roman soldiers as part of their rations. Many of my older patients remember their mothers giving them cod liver oil, especially in the winter. My mother did the same to my sister and me.

Natural cod liver oil is a great supplement.

It contains omega 3 fatty acids, universally acknowledged as being beneficial for the brain, heart, circulation, and joint health.

It is also a very good source of natural vitamins A and D and other important fatty substances. Both A and D are necessary for healthy immune system and for many other functions. Lack of vitamin D has been linked to increased risk of heart disease, cancer, Alzheimer’s disease, asthma, and increased risk of death.

But lately there have been reports of side effects associated with the use of cod liver oil.

How can that be? The answer has to do with how the cod liver oil is made.

Traditionally, cod liver oil was made using a process called fermentation. This is the same process that turns milk into yogurt and cabbage into sauerkraut. What you do is cut the cabbage, put it in a jar, add some salt, and close the lid. Come back 2-3 weeks later and you have sauerkraut.

This is how cod liver oil used to be made – put cod livers in a jar, add some salt, close the lid and come back 2-3 weeks later to find cod liver oil. This natural oil contained the omega 3 fatty acids, natural vitamins A and D, and other useful fatty substances.

But this process is not very efficient. It leaves a lot of oil behind and it takes too long. So the cod liver oil producers have come up with a more efficient way to extract the oil, using high temperature and chemical solvents.

They heat cod livers to 400-500 degrees and add a chemical solvent to bind to the oil. Then they add another chemical to remove the first one, but traces of both remain in the final product. They deodorize the oil using diatomaceous earth. Finally, they purify the oil using very hot water vapors.

This method produces a lot more oil than the old-fashioned fermentation. The problem is that this oil is nutritionally DEAD. It does not contain natural vitamins or other beneficial substances. They are all gone.

To compensate for the loss of vitamins, oil producers add synthetic vitamins A and D to the oil. And they are still able to call it “natural” because it comes from a natural source.

Practically all cod liver oil supplements sold in US are made using chemical extraction and synthetic vitamins. Because of that, they are largely useless.

But there is at least once manufacturer who uses the old-fashioned method.

Their product is called Blue Ice Fermented Cod Liver Oil. I use it myself and recommend it to all my patients, especially during the winter months when you need more vitamins A and D.

Dr. Michael Note from Kelly:  This is the CLO that we have taken for years now.  We take it daily, and then if the kids start acting like they’re coming down with something, I’ll give them extra and almost every time they’re fine the next day.  I always give it with a meal that includes plenty of pastured butterRead why that’s important.  Please let us know if you’ve noticed anything like that, too!

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    { 56 comments… read them below or add one }

    1 Staci January 11, 2003 at 5:08 am

    Our Amish natural foods store carries the full line of Blue Ice CLO products and at a very competitive price (and no shipping, of course). Not sure if any of you live in or near Lancaster County PA, but the store is Miller’s Natural Foods in Ronks, PA. Google it for directions. Great store. I’m very fortunate to have it nearby.


    2 KitchenKop July 27, 2010 at 10:57 pm

    Wow, you are very lucky! :) Thanks for letting us know that it CAN be found in stores!


    3 Anita July 27, 2010 at 5:25 am

    Hi Kelly,
    We’re using the Green Pastures FCLO too, & I think it’s helped us a lot during this Oz winter. Less colds, sniffles, etc., much better all round.


    4 Christy July 27, 2010 at 7:10 am

    Do you happen to know if Cod Liver Oil will help with eye health? I’ve been noticing my eyes hurting when I read for a while and was wondering if CLO might help with that. Also, is there a difference in effectiveness between Blue Ice gel caps, liquid or the emulsified stuff?



    5 Joy December 23, 2011 at 12:14 pm

    Yes, CLO can be good for vision (ps I’m not a doctor, this isn’t medical advice, etc). My understanding is that it can be especially good for light sensitivity. Check out this thread on the celiac forum (I’m “domesticactivist” on the celiac forum):
    Of course with any vision issues it’s a good idea to see an ophthalmologist as well. When you visit your doctor, my post might help:

    As for the various ways of taking it, I don’t know about difference in effectiveness between the different styles. We’ve done both liquid and emulsified, and the main difference we noted was texture.


    6 Christy July 27, 2010 at 7:33 am

    I would also like to know how the chocolate cream flavored gel tastes compared to the cinnamon tingle gel. We had the cinnamon tingle once and it was still pretty hard to get down.


    7 KitchenKop July 27, 2010 at 7:45 pm

    Hi Christy,

    As far as eye health I’m not sure, but it wouldn’t hurt to try, I know it’s beneficial in so many ways, it wouldn’t surprise me if it does help.

    The caps or liquid are a matter of your preference, effectiveness is the same.

    I’ve heard the chocolate is terrible, I don’t think the cinnamon tingle is so bad, really!



    8 BRB July 28, 2010 at 2:22 pm

    I tried the chocolate at the last WAPF conference and it was really bad. I think out of all of the flavors they had, it was the worst by far. I think chocolate may be misleading as it isn’t sweet at all. They should call it cocoa flavored.


    9 Kylie NZ July 29, 2010 at 7:14 pm

    I bought a sample of the chocolate FCLO, thinking it would be amazing, as I love chocolate! Tried it, and I found it absolutely repulsive. Mediteranian is BY FAR my favourite and the only one I consume!


    10 jennie July 27, 2010 at 8:26 am

    Kelly – I take the Blue Ice. My Vit D had been at 17, and now I am up to 35. What do you think the optimum Vit D blood level is? I read a recent study that said that people that have a level OVER 40 are at a greater risk of pancreatic cancer. Also, doesn’t Blue Ice make a tablet that also has Butter Oil in it? Thanks for clarifying! Jennie


    11 Michael Teplitsky, MD July 27, 2010 at 4:52 pm

    Many experts believe that the optimal vitamin D level is above 50. In some studies, they designate people with 75 or more as sufficient, less than 75 as borderline, and less than 50 as deficient.
    I have not seen any reports that link high vitamin D level with pancreatic cancer or any other cancer. There are many studies that show just the opposite


    12 KitchenKop July 27, 2010 at 7:46 pm

    To answer your other question, Jennie, yes Green Past. does also make a CLO/butter oil combo. :)


    13 Tash July 27, 2010 at 8:38 am

    Thank you so much for this post! I take cod liver oil religiously – and thought I was taking good stuff…very glad to know about the way it’s processed. Will definitely switch!


    14 Martha July 27, 2010 at 11:50 am

    We’ve been taking the same CLO for about a year now. I think it has made a difference in our ability to be in the sun with out burning. Kelly, I never thought of upping the dose when someone is coming down with something. I’ll definitely try that next time. The kids will hate me for it, except for the youngest. lol Christy, we tried the chocolate cream gel and it was AWFUL. The taste itself was bearable, but I would never buy a gel again. I had to wash dishcloths multiple times to get the smell out. We have friends who found the same thing. They have discontinued it since it wasn’t popular.


    15 Genevieve July 27, 2010 at 12:38 pm

    I actually don’t mind the chocolate cream since I can hide it in The Nourishing Gourmets fudge recipe and my daughter will eat it. (mind you since she’s started liking the Fish Gummies she does not ask for the fudge anymore) It does taste a lot stronger (like a dark, dark chocolate) so I find the taste stays in my mouth a lot longer than just the flavor free.


    16 Quinn July 27, 2010 at 1:02 pm

    How timely! I’m in the process of shopping for CLO and this one made the final cut! Thanks for sealing the deal for me.


    17 Divina July 27, 2010 at 1:56 pm

    Interesting. I will look into Blue Ice Cod Oil next time I go to the health food store.


    18 KitchenKop July 27, 2010 at 7:48 pm

    Divina, I’ve never seen it at health food stores, it’s only available via mail order as far as I know. (Just thought I’d save you the search!)


    19 KitchenKop July 27, 2010 at 10:58 pm

    See above, I found out I was wrong about this! (Somehow a newer comment ended up way at the top.)


    20 Sarah, The Healthy Home Economist July 27, 2010 at 3:05 pm

    The fermented cod liver oil is great for when you get an ant bite or bee/wasp sting. Take a big spoon of it immediately after getting bit or stung. It stops any mild to allergic reaction you might have!!


    21 Michelle July 27, 2010 at 10:00 pm

    I’m currently looking for a good CLO, but had a question about taking it in the summer. I live in GA and our family gets a lot of sun over the summer months. I’m worried that our sun exposure combined with the CLO might give us too much vitamin D. Should that be a concern?


    22 KitchenKop July 27, 2010 at 10:59 pm

    I think the only way to know for sure about this is to be tested…


    23 susan grimes July 27, 2010 at 10:52 pm

    take a look at
    there is some great info for asthma sufferers


    24 Jenn V. July 28, 2010 at 10:14 am

    I just started taking the Blue Ice CLO. Meanwhile, I saw this one at Wegman’s for a good price, and it seems to fit the bill as a good one (naturally occuring vitamins only), wondering what others think?


    25 WordVixen July 28, 2010 at 6:03 pm

    Jenn- According to the Weston A Price Foundation website, Nordic Naturals wouldn’t be a good choice because of how much vitamin D is lost in the deodorization process.

    If you scroll about 1/3 of the way down, you’ll find this: “They suggested that modern cod liver oil is low in vitamin D because the deodorization process removes the vitamin while manufacturers fortify the oil with only a fraction of the original amount. As an example, they cited cod liver oil made by Nordic Naturals, advertised as containing only


    26 KitchenKop July 28, 2010 at 8:23 pm

    The other thing to keep in mind, though, is that there’s so much more in the fermented CLO than just what’s in other brands. You’re getting so much more bang for your buck (healthy bacteria from fermentation, CoQ10, and lots more), so you can’t really compare it to other CLO brands. There’s more about this at my post on why fermented CLO is better.



    27 Chris @ Natural Health Goodies July 29, 2010 at 5:54 pm

    Amazing, and frustrating another story of a very good for you product being destroyed by modern practices. I just checked my CLO (Nordic Naturals as well) and it even has Vitamin E from refined soybean oil! What a crock! Are there other good brands other than Blue Ice that you know about, and what kinds of terminology should we watch out for on the label?


    28 Kelly the Kitchen Kop July 30, 2010 at 7:56 am

    Chris, Blue Ice is the only brand I know of that manufactures CLO in the tradional way.


    29 amy July 8, 2011 at 12:34 am

    Well are there any that are recommended that are not fermented? I have tried FCLO and it was the worst substance I’ve ever tasted and just can’t imagine trying it again.


    30 KitchenKop July 8, 2011 at 12:53 am

    Amy, have you tried it recently? The formula has gotten a *lot* better in recent months, it’s not great but really not that bad either…
    I take the cinnamon. You could always take the caps if necessary, too.



    31 Jenn V. July 28, 2010 at 8:02 pm

    Thanks so much for the response. You good researchers really bless me! :) I appreciate it.


    32 Zoe July 29, 2010 at 5:01 pm

    I read recently that you should not take CLO while pregnant at risk of consuming too much Vit A. I have stopped taking my fermented CLO since I found out I was pregnant but I wanted to double check and see if anyone else had been told this directly or read this in a reliable source. I hate to go without if not strictly necessary.
    Any feedback would be appreciated!


    33 Kelly the Kitchen Kop July 30, 2010 at 7:54 am

    I took extra when I was pregnant, when I could get it down anyway. Your baby NEEDS you to take this so their brains can grow well.

    Follow my link to my CLO posts index above & there’s one there that discusses this concern specifically. Basically it says that when A & D are in correct proportions you don’t have to worry about the A being toxic, and in Blue Ice they are in the perfect proportions because they’re only natural, not synthetic.


    34 Jenn V. July 30, 2010 at 11:59 am

    Has anyone tried the Blue Ice gummies for their kids? I currently give my 4yo daughter the unflavored oil in a smoothie, but I really have to sweeten it to hide the taste and I hate doing that… My husband and I do the oil straight, and my teen I gave in and got the capsules…


    35 KitchenKop July 30, 2010 at 5:28 pm

    I tried a CLO gummy once and almost lost it. I’ve heard of kids who love them, though. I think Ann Marie’s daughter begs for them.


    36 Martha July 30, 2010 at 5:42 pm

    Our 2 year old loves them, but the rest of us preferred the liquid form.


    37 Jenn V. July 31, 2010 at 2:43 pm

    Haha Kelly that made me laugh. OK, maybe I’ll stick with the liquid… and maybe I’ll try a flavored one next time…


    38 Lisa August 5, 2010 at 6:16 pm

    I’ve been researching cod liver oil and the butter oil combo and found this site…great info. Is there an advantage to taking the cod liver oil/butter oil combo vs just the cod liver oil? I wanted to order some of the Blue Ice and haven’t found a preference one way or the other. What would the advantage be for one vs the other?
    Thanks for the info!!


    39 KitchenKop August 7, 2010 at 11:24 am

    Hi Lisa,
    Weston Price found that when CLO is taken with butter from *grass-fed* cows, the benefits of the CLO are greatly increased. We eat plenty of pastured butter so we don’t take the combo, but it is a nice way to be sure you’re getting both, and if I had a health condition, I’d seriously consider it.


    40 Alex Walden December 6, 2010 at 1:25 am

    Any insight on giving the Blue Ice CLO liquid to my 6 month old who is just starting solids? I’m sold on all the benefits after reading quite a bit from WAPF, but will he tolerate the taste?


    41 KitchenKop December 6, 2010 at 8:32 am

    Now is the best time to start! Just give him a couple drops a day for now and later a few more and then I believe the normal child dose is 1/4 t. but I don’t have it in front of me now, so check that before you take my word for it.


    42 Wendell October 30, 2012 at 1:09 am

    I just went on the blue ice website for the FCLO, but it is pretty expensive. The local Whole Foods market I go to sells Carlson’s Cod Liver Oil. Is that okay for me to consume?


    43 KitchenKop October 30, 2012 at 11:29 pm

    Hi Wendell,

    The FCLO daily serving is fairly small, though, so a bottle lasts a long time. Personally, I’d stick with the FCLO because I know that it’s made with only natural vitamin A & D and I haven’t researched the others.



    44 Marcene November 26, 2012 at 9:34 pm

    I want to get some FCLO for my son who is having some digestive issues. Can I hide the product in his morning breakfast smoothie or does it need to be taken on it’s own?


    45 KitchenKop November 26, 2012 at 9:45 pm

    It can be taken either way, but the taste is not hidden well. He’ll notice it almost for sure.

    Just wanted to warn you about that.



    46 amy November 27, 2012 at 2:15 am

    I bought my children the “kid friendly” emulsified FCLO, peppermint flavored and my kids do not mind it at all. was shocked, after having a very poor first experience with unflavored FCLO. I now also only take the kid friendly version.


    47 Marcene November 27, 2012 at 8:51 am

    amy, is that a product from green pastures as well? I didn’t notice that one on their site.


    48 KitchenKop November 27, 2012 at 2:43 pm

    Hi Marcene,

    Yes, that’s from GP. It’s the one that my son says “tastes like candy” at this post:



    49 Wendy September 15, 2013 at 9:13 pm

    My husband and I just started taking the Green Pastures Blend with cinnamon flavor and we take it with a spoonful of flavored Greek Yogurt and just swallow. I then follow that with something else to eat – I am finding it easier and easier to take, but its still pretty nappy. But I’m determined to take it formy health. I haven’t tried it on my kids yet. :)


    50 Debbie November 25, 2013 at 11:18 am

    We use the “Oslo orange” flavored fclo from green pastures. At first it wasn’t exactly what I was thinking when tasting it, but I can get it down, and my 3 year old son asks for it. So not too bad :) I usually mix it with a half of teaspoon of elderberry syrup ( because it’s sweet with honey) or take a little following the fclo. Thanks Green Pastures!


    51 ARLY December 20, 2013 at 2:14 pm

    How would Cod Liver Oil affect a person diagnosed with Lymphoma? Would it be safe to take?


    52 KitchenKop December 21, 2013 at 11:23 am

    I would think it would be a good idea, but suggest you contact a good naturopath or ask your doc to be sure first.



    53 Nadine March 17, 2014 at 1:42 pm
    54 Nadine March 17, 2014 at 1:49 pm
    55 Muhammad Mazid April 14, 2014 at 2:12 am

    My eye sight is week if i eat cod liver oil capsules my eye sight become normal


    56 Evan Endelson April 23, 2014 at 1:02 pm

    According to, it’s a very healthy supplement but this article makes me think twice about over-consumption. Thanks for the good information on this.


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