Cod Liver Oil for Kids: Benefits, Risks & How To Choose the Best One

Heather Dessinger

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Cod liver oil in a small glass

When my firstborn was a wee squishy baby, my Facebook feed was filled with photos of toddlers (and older kids) having hilarious reactions to their first taste of cod liver oil. It was considered the original superfood by the mamas in my community,  and “the more the better” was our motto.

Things have changed, though, both when it comes to questions parents grapple with when posting photos of kids online and the thinking regarding cod liver oil.

We now know that it’s possible to get too much of a good thing, and there are factors to consider when deciding whether to even take it at all. Before we get into those details, though, there are some basics we need to cover.

The Difference Between Cod Liver Oil & Fish Oil

Fish oil is extracted from the tissue of oily fish like herring, tuna, anchovies, and mackerel, and cod liver oil is extracted from exactly what you would expect . . . cod livers.

Both types of oil contain docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), but only one is rich the active forms of vitamin A and vitamin D. That may seem like a small difference, but it’s actually huge.

To understand why, let’s say you picked up a copy of 500 Things You Should Know: Instructions for Life From the Everyday to the Exotic, then left it on your nightstand unread. It hasn’t done you much good yet, has it?

Our DNA is the same way. We all have inner blueprints (or books) full of wisdom about how to function optimally, but our bodies don’t “read” them without certain signals. Bioavailable forms of vitamin A and D, which are relatively difficult to obtain in the diet, are precursors to hormones that regulate gene expression. (1)(2)

In other words, they help our bodies access the amazing libraries of information found within our DNA to optimize biological performance (also called genetic potential).

It’s pretty well-known that vitamin D influences over 2,000 genes, but what many people don’t realize is that vitamin A and D are an inseparable team. They’re so crucial to our health that receptors for both are found in every single cell.

In addition to their separate receptors (RAR for vitamin A and VDR for vitamin D), they share a receptor called RXR that allows them to “cross-talk.” (3)

This “conversation” is crucial for health, and unfortunately consuming large amounts of one can cause it to drown out the other, thus causing a functional deficiency. That’s one of the reasons cod liver oil, which is rich in both, has been so highly valued in traditional cultures.

Benefits of Vitamin A

Vitamin A has a profound influence on over 600 genes, including those that affect a child’s:

  • Eyesight
  • Growth and development
  • Immune function
  • Inflammation levels
  • Skin health
  • Tissue and bone repair

Also, parents who have picky eaters, are working to heal leaky gut, or just want to support gut health should know that “Vitamin A has profound effects on the gut mucosal immune system and can calm potent inflammatory molecules.” (4)

According to Michael Ash, D.O. N.D. F.Dip, it may even be “the key to a tolerant immune system,” that impacts “our ability to consume a wide range of antigens (food) and yet not react adversely.” (4) Pretty amazing, right?

As I mention in this article on eating healthy during pregnancy, nutrition labels often say that a food has “X” amount of Vitamin A, but what they really mean is that it contains carotenoids such as beta-carotene.

Unfortunately beta-carotene is not biologically active, and therefore not the same as the bioavailable form of Vitamin A (retinol) found in animal products. Most of us do not possess enough of the enzyme needed to efficiently convert beta-carotene into bioavailable Vitamin A – in fact, this study found that only about 3% is converted, and about 45% of adults can’t make the conversion at all. (5, 6)

True bioavailable Vitamin A is found only in animal products such as liver (or liver capsules if you can’t stomach liver), pastured butter, milk, animal fats such as lard and tallow, and cod liver oil.

Pregnancy nutrition diet

Risks of Synthetic Vitamin A

When shopping for cod liver oil, it’s important to be aware that almost all brands on the market use a process that removes naturally occurring vitamins and replaces them with synthetic ones, which the body doesn’t always recognize or know what to do with.

Synthetic Vitamin A in particular is of concern because of its relative toxicity. You will often find warnings associated with vitamin A consumption, citing its toxicity and risk of birth defects if taken in excess. This is a legitimate concern for all forms of synthetic vitamin A including supplements and fortified foods, but consuming moderate amounts of real food where it occurs naturally is not a problem as long as vitamin D intake is also optimized. Chris Kresser, LAc explains why here.

Benefits of Vitamin D

Often called “The Sunshine Vitamin,” Vitamin D is known as the champion of strong bones and teeth. However, it also plays a crucial role in:

  • Regulating growth
  • Immune regulation
  • Mood
  • Cardiovascular health
  • Blood sugar balance
  • Hormone balance

Unfortunately, a study published in 2009 found that 70% of children in the United States have insufficient levels, which increases their risk of developing food and environmental allergies, diabetes, high blood pressure, cardiovascular disease, and certain cancers. (7) (8) Vitamin D levels have been trending downward for a while, so it’s possible that vitamin D insufficiency is even more widespread now.

There are a few good food sources of vitamin D, including cod liver oil, fatty fish, caviar, pastured butter, and eggs. However, according to MIT Senior Research Scientist Dr. Stephanie Seneff, oral vitamin D cannot fully replace sunshine, and kids (and adults) also need healthy sun exposure to optimize levels.

Benefits of Omega-3 Fatty Acids (And Why More Is Not Necessarily Better)

Fat fuels the 100 billion neurons that make up our brains. It even makes up 60% of the brains overall structure. There’s no question that omega-3 fatty acids, particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have profound benefits for children.

According to this study, “fatty acids are among the most crucial molecules that determine your brain’s integrity and ability to perform.” Getting enough of the right fats during childhood has a huge impact on:

  • Intelligence
  • Eyesight (DHA is astructural component of the retina)
  • Development of executive brain functions like focus and attention, planning and problem solving
  • Social and emotional development (9)


Beyond their important role in building the brain structure, EFAs [essential fatty acids], as messengers, are involved in the synthesis and functions of brain neurotransmitters, and in the molecules of the immune system” (10)

While DHA can be created from plant-derived α-linolenic acid (ALA) within the body, most of us have inadequate levels of the enzymes needed to make the conversion. For that reason, consuming preformed DHA is considered the optimal way to ensure children are getting enough of this brain-building fat.

The best sources of preformed DHA are fatty fish (especially salmon, mackerel, sardines, and herring), caviar, and cod liver oil. Eggs also contain a small amount of DHA.

Why More Cod Liver Oil Is Not Necessarily Better

Something to keep in mind, though, is that the more unsaturated a fat is, the more vulnerable it is to oxidation. The long-chain, omega-3 fats found in fish oil are the most unsaturated form of fat, and therefore the most susceptible to becoming oxidized (rancid).

Unfortunately, with just a few exceptions fish oil supplements are purified using extraction processes that can damage these lipids, causing fish oil to become pro-inflammatory instead of anti-inflammatory.

Oxidized lipids have been linked to a number of health issues, including organ toxicity and accelerated atherosclerosis—the exact opposite outcomes usually desired by those who supplement with fish oil.” (11)

This may be why studies about the health benefits of fish oil (and sometimes specifically cod liver oil) are mixed, with some showing positive effects and others showing negative effects. Other reasons could include:

  • The use of synthetic vitamins A and D in fish oil (discussed above)
  • The use of high doses (more on that below)
  • Bio-individuality (some people may benefit from it, while others may not)

Regarding dosage, it’s often assumed that more of a good thing is always better, but that doesn’t appear to be the case with cod liver oil. Excessive intake may expose us to more polyunsaturated fatty acids (PUFA’s) than are optimal, thus working against us instead of for us.

To minimize PUFA exposure while still getting adequate brain-building nutrients, it’s important to look for an oil that is pure, minimally processed (so that the lipids are intact), and contains a significant amount of DHA in a relatively small dose. The cod liver oil that I buy has an estimated 600-700 mg of DHA per teaspoon, which is good in my opinion. (The vitamin content varies some because the nutrients are naturally occurring.)

Is fermented cod liver oil healthy?

In recent years there has been a lot of controversy surrounding Green Pastures Fermented Cod Liver Oil (FCLO). Some have claimed that it is rancid, while others say it isn’t. After reading all the available information on both sides, I cannot say with confidence that I know for certain that it’s safe.

For that reason, I choose to err on the side of caution and do not recommend it at this time.

Map of the U.S. 37th parallel related to vitamin D synthesis

So, should kids take cod liver oil?

Like most things, there isn’t a one-size-fits all answer. The needs of a child who lives in subtropical or tropical area where they can play outside all year will be different from the needs of a child who lives above the 37 degree latitude line, where it is only possible to manufacture vitamin D from sun exposure in the summer months. For the child who only has summer to generate vitamin D through the skin, supplementation during the fall/winter may be beneficial.

Diet is another consideration. Ideally, a child would be eating clean, purity-tested fish/seafood (especially cold-water fatty fish) a few times a week for DHA, EPA and vitamin D, as well as liver and organ meats for vitamin A. If that’s the case, supplementation may not be beneficial.

On the other hand, if fish and liver (or liver capsules) aren’t consumed regularly, then a cod liver oil rich in DHA and the active forms of vitamins A and D is likely to be beneficial.

As Chris Masterjohn, who has researched considerably on this subject, puts it:

It is easier to add cod liver oil to an imperfect diet than to perfect the diet, and for many people the most balanced approach to obtain all of these nutrients will be to consume a small amount of cod liver oil while also trying to hit the other dietary bases more often than not, allowing the cod liver oil to relieve the need for dietary perfection.” (12)

Chris Kresser, LAc recommends a maximum of 1 teaspoon a day for adults. Because I live in an area with year-round sunshine and access to fatty fish / pastured liver I’m not currently giving my kids cod liver oil, but if I did I would give them 1/4 to 1/3 teaspoon based on their age/body weight compared to an average adult.

For the past several years I’ve used and recommended Rosita cod liver oil. Although we don’t use it daily right now because we now live in a sunny area, I keep some in the freezer to use during illness or for other reasons that might come up. Here’s why they’re my top choice:

  • They use an ancient extraction process that doesn’t use heat. (Remember, heat is part of what contributes to lipid oxidation, aka rancidity.)
  • The oil is then filtered using paper (not heat or chemicals) to remove contaminants and then tested to ensure purity.
  • Unlike most other oils that add synthetic vitamins, nothing is added except for one drop of naturally derived vitamin E and rosemary oil per bottle to maintain freshness.
  • It contains a good amount of DHA and EPA per dose.

If you want to try it out, you can find Rosita cod liver oil here.

Have a question about cod liver oil? Please leave it in the comments below!

This article was medically reviewed by Madiha Saeed, MD, a board certified family physician. As always, this is not personal medical advice and we recommend that you talk with your doctor.

Small glasses filled with cod liver oil

Article Sources:

1. Bikle, Daniel (2017) Vitamin D: Production, Metabolism, and Mechanisms of Action. Retrieved from

2. McGrane, Mary (2007) Vitamin A regulation of gene expression: molecular mechanism of a prototype gene. Retrieved from

3. Levine, Stephen (2010) Why Vitamin D is Not Enough. Retrieved from

4. Ash, Michael (2010) Vitamin A: The Key to a Tolerant Immune System? Retrieved from

5. Kresser, Chris. Why you can’t get vitamin A from eating vegetables. Retrieved from

6. Hickenbottom, Sabrina et. al. (2002) Variability in conversion of β-carotene to vitamin A in men as measured by using a double-tracer study design. Retrieved from

7. Kumar, Juhi et. al. (2009) Prevalence and Associations of 25-Hydroxyvitamin D Deficiency in US Children: NHANES 2001–2004. Retrieved from

8. Albert Einstein College of Medicine (2011) Low Vitamin D Levels Linked to Allergies in Kids. Retrieved from

9. Castle, Jill (2016) DHA Benefits: How DHA Helps Your Child’s Brain. Retrieved from

10. Chang, CY et. al. (2009) Essential fatty acids and human brain. Retrieved from

11. Kresser, Chris (2019) Should You Really Be Taking Fish Oil? Retrieved from

12. Masterjohn, Chris (2015) Weighing in on the Fermented Cod Liver Oil (FCLO) Controversy. Retrieved from

13. Harvard Medical School (2008) Time for more vitamin D. Retrieved from

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Heather is a holistic health educator, herbalist, DIYer, Lyme and mold warrior. Since founding in 2009, Heather has been taking complicated health research and making it easy to understand. She shares tested natural recipes and herbal remedies with millions of naturally minded mamas around the world. 

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136 thoughts on “Cod Liver Oil for Kids: Benefits, Risks & How To Choose the Best One”

      • Just curious if you ever found an answer to this question! I supplement my child with Rosita but I also wonder if I need to add additional K2 because of the D he’s getting in it??!

  1. fermented CLO/BO and systemic enzymes (Vitalzym brand). I assume on a desert Island there are coconuts, so I didn’t say coconut oil.

  2. all those billions of cells have me spinning– can i just give my 2 and 4 year old half a capsule each of the probiotic my husband and i take?

    also, on the CLO, we are about to order from green pasture. which flavors are allowed on gaps? i was thinking about getting the orange liquid (non-emulsified) and figured we could just mix it into our morning fruit smoothies– how do you think that would turn out?

    • Orange doesn’t taste sweetened to me, just slightly orangy. You can try it in a smoothie, might work best if you add an egg yolk to emulsify the oil. My boys and I just shoot ours into the back of the mouth with the syringe, swallow, shudder, and eat some grass-fed butter, raw honey, or a few chocolate chips to take care of the taste and the burn.

    • I recommend the arctic ice over the oslo orange. As for dosage, I can’t really say. Dr. Campbell-McBride’s recommendations are the only ones I know of.

  3. I have been thinking about starting on butter oil/cod liver oil, do you know if the green pastures caps are huge? I have a really hard time swallowing pills, but i guess there is always the liquid version but I am as bad as a kid about that…ew

  4. actually nevermind, I saw that there is a combination cinnamon flavored gel, I will take your tip about mixing it with honey and spread it on some toast in the morning 😉

  5. CLO and Vit. D3! Actually, a desert island is probably going to have plenty of natural D3 and fish… after reading your post I’d definitely say probiotics. I’ve been on and off with giving the kids probiotics, even though I know my son would benefit greatly. This was really informative, especially the part that talks about how many millions of bacteria is recomended. We eat yogurt and some fermented foods, but after reading this I feel you’re right that we could all benefit from more probiotics. I think this will be my next step in improving the health of our family. Perhaps the probiotics will help enough with my sons sensitive gut that we can avoid doing a full GAPS diet. Thanks again! I really enjoy your blog, its like there is someone out there who knows exactly the kind of info I’m looking for. We made marshmallows last night (never been a marshmallow fan, but these are good!) and today we are going to make Christmas ornaments similar to the ones you posted recently (what a great idea for leftover balls of yarn!).

  6. and there would prob be shrimp so no need for Astaxanthin no people so no need for anti virals prob just my Garden of life natual Raw One vits. 🙂 and the Raw one B complex.

  7. Fantastic post! Can’t wait to read more, too! My hubby and I were laughing last night about the idea of fermented clo…I mean, it just SOUNDS nasty! 😉 are capsules a total no-no (for adults, I mean)? 🙂

  8. we are taking FCLO, BO, probiotics and yep we needed to add the magnesium trace oil… not quite two, but I’m good with that 🙂

  9. Hi Heather,
    Thanks for another great post. While I do agree that fermented cod liver oil is probably full of all sort of wonderful, important nutrients, fact is it smells exactly like the garbage truck I was parked behind in the midst of summer heat here in Montreal. It is vile, disgusting and I’m pretty sure it’s not fit for human consumption. I have half a VERY expensive bottle sitting in my fridge and it’s going to stay there FOREVER.

    So, on that positive note, if I do still want to consume CLO but can’t stomach that grossness, what brand do you recommend?


  10. The jury is still out on fish oils for me. Our bodies utilize them but there may be no need to supplement with them. I’m with Russ, give me two opposite sex ruminants. Also, there is evidence that probiotics do not reach the lower intestinal tract. It has been reported that they effect our flora by altering the gene expression of lower GI flora, but not by physically adding to them. Good thoughts, as if you were on said deserted island I guess if that’s all you had…I’d hope for oysters, shellfish, bird, coconut, and plenty of sun.

  11. Hey Heather!

    Do you think that starting a regimen of probiotics complete with die-off symptoms is beneficial even if you do not alter your diet at all? It was my understanding (I thought!) that the introduction of the strong probiotic was most effective when paired with the intro stage of GAPS. ??? Would it still be a good idea to start taking one that strong without starting GAPS? I’ve tried a lot of different “probioics” and acidophilus pills before and found that none of them worked as well as good old fashioned yogurt if I was having stomach trouble.

    • Hi Kaitlin! Yes, I believe probiotics are beneficial for everyone – unless there is someone out there with a very strange medical condition that contraindicates it. But other than that, yes I totally recommend them.

  12. I recently had a friend ask me what the best supplement was for pregnancy. I’m curious to see what you have to say because I like your way of thinking, :).

  13. I thought that FCLO was actually pretty low (or at least not a sufficient source)in omega 3’s and that it was good to take fish oil as well.

  14. Melissa Holloway – There is a liquid, too. That is what we use and mix with honey/butter oil. OR you can just buy the CLO/Butter oil mix!

  15. Kristine Winniford – Yay, I’m glad you liked Jenni’s marshmallows. I tell everyone I can about them 🙂 And I’d love to see pics of your ornaments if you’d be willing to post them on my wall!

  16. Roxanna Farnsworth – We take more than two! These are just the two I consider essential. Other supplements should be tailored to individual needs IMO 🙂

  17. Portia Drantch – Thank you! I’d say it’s the same as for children. The pregnant/nursing mother’s diet listed on is what I followed to get the rest of my nutrients (except some women cannot do dairy and I don’t do grains – other than that I followed it pretty closely)

    • I’m being told that the first thing I need to do, prenatal-wise, is buy pre-natal vitamins with folic acid. I haven’t seen mention of prenatal vitamins in your posts or in WAPF’s pregnant mother’s diet. Do y’all endorse the vitamins too; or is it that if one follows that diet, she shouldn’t need them?
      I’m thinking I’ll see what they offer at my natural foods store, but I’d love to know if you used a certain kind, or none at all.

  18. Mommypotamus, I don’t think the ornaments turned out well. Maybe not enough glue? I think we’ll try again with more glue.

  19. I really want to try Biokult as all your real foodies are recommending it. Do you how many capsules of Biokult should I take? On the bottle it says 2 capsules (=4 billion CFU) per day, but the GAPS book says GAPS adult patients (I have eczema) should take up to 15-20 billion CFU every day. That’s about 7-10 capsules a day and a lot of money!

    At the moment I take Garden of Life Primal Defense Ultra (as recommended by Nourishing Traditions). Each capsule consists of 5 billion CFU, so I only need to take 3 everyday in order to reach Dr. Campbell’s recommendation, and it would be relatively cheaper.

    Did I calculated it right? Would appreciate your advice.

    • HI Carrie! I have an order of Biokult in the mail (it was backordered and hasn’t arrived yet) but none in the house so I can’t check for you. Will try to remember once it arrives!

  20. Phew, this post rocked my world. I’m a natural product advisor, amongst other nutrition-related things, and I have such a soft spot for “natural”-labelled things. I suppose getting caught up in criticizing conventional supplements blinded me somewhat to the bigger picture.

    Thanks for the well researched and interesting post.

  21. Love your blog!!! My son is allergic to fish. What would you recommend as an alternative to cod liver oil? I have given him flax oil before and am currently giving him vit d3. I just hate that he can’t have any fish! Thanks!

    • Hi Cheryl! It might be worth asking your trusted health advisor about dried liver supplements since they could provide the true vitamin A needed to work synergistically with D. Of course, that’s a guess ;/

  22. Hi Heather,
    My two older kiddos have been only taking FCLO and probiotics for the past year. We use Green Pastures FCLO unflavored and Custom Probiotics 11 strain blend. We did temporarily suspend our use of FCLO over the past spring and summer due to finances, but we recently became group buyers for Green Pastures and have an order on its way! I am excited to have it in my home again! I took 1 tsp almost every day of my pregnancy with Micah and I felt great!
    I have a suggestion and a question.
    Suggestion: My two older kiddos (3 and5) always took FCLO with their fresh juice in the morning. Since we get the unflavored it is extra “tasty” if you know what i mean, but they both took it like champs just prior to their fresh juice. I think it helped. I did the same.
    Question: I went with Custom Probiotics 11 strain because I felt it was a good blend. They do make a D-Lacate Free blend (with only 4 strands) that they recommend for kiddos on the spectrum. My older son (5) was diagnosed at 3. Many argue that the diagnosis no longer is applicable (praise the Lord) but we continue to put educational and therapy supports in his life because we know our journey is life long. Of course diet is paramont to those supports actually being worthwhile. Both of our two older kiddos do seem to have underdeveloped guts. Do you think I should switch to the D-Lactate Free blend from Custom Probiotics or can you recommend another manufacturer? I would like to start Micah soon anyway (almost 6 mos) and will need this for him. I do think that perhaps the Custom Probiotics 11 strain may be contributing to my kids ongoing constipation problems…any thought on that? Their colons are always FOS (one of our fav docs says that medical jargon for full of stuff).
    Sorry this is so long.
    I just really respect and appreciate your blog and your opinion
    Thank you

    • HI Jenni! To be perfectly honest I think you know more about specific probiotic blends than I do! I use Biokult because it is recommended for the GAPS diet so I have not researched much further. Regarding constipation, it is my understanding that probiotics tend to help with this issue rather than cause it . . . is there a reason you think they’re the problem?

      • I was the suspecting the D- lactate since I consider my kiddos to have underdeveloped digestive systems. For example both of them are lacking amylase at age 5 and 3 even though this should have developed by now. I don’t know. I get so spun around trying to figure what the real problem(s)…that’s just it…there’s most likely multiple issues. I do know that some probiotics (including Biocult) have been reported to actually increase constipation. Dr. Natasha has wrote that constipation is a typical sign of die-off…but I wonder…are my kids in a perpetual state of die-off?

  23. My kids drink lots of water kefir! Lots and lots. We go through about 2 gallons a week and they even eat the grains sometimes. Since we started this about 4 months ago, my oldest has only gotten 2 little colds, compared to the dozen or so illnesses he had between August and Christmas last year. It’s been fantastic! I know what kefir has a lot of different strains of bacteria. Do you really think that they still need a supplement? (I haven’t ventured in to many other ferments. I did just make whey for the first time, and we do sourdough. But, they aren’t getting probiotics anywhere else.)

    • Everyone is different so I can’t really say, but the ideal would be that we’d all eat variety of fermented foods in substantial amounts rather than supplement. I personally tend to go through cycles where I ferment a lot and where I don’t do anything, so supplementing works for my family 🙂

  24. HI! I just came across your blog 🙂 Though I have heard of CLO, and walk past it every week at my local natural foods store, I can’t say I am well informed about it. I am very interested in using it but one concern I have is mercury contamination. Isn’t it highly contaminated, being it is from cod? I currently take a krill oil supplement along with D3, but I’m considering the CLO if it isn’t badly contaminated.

  25. Ugh, I wish I can use the probiotic on your reference page. My 4 1/2-month-old has food intolerance and can’t do milk. It says that the probiotics are derived from milk. Do you know if the milk protein is still present in them or not. Or do you have a hypoallergenic brand you recommend. I’m currently giving her a probiotic I buy from our local breastfeeding center. It is an infant formula that has 10+billion bacterial cells. She can only tolerate a small dosage of it, otherwise things don’t go well. Also wondering if you know if probiotics are present in my milk. Because of her food intolerance, I took out all dairy, among a lot of other stuff, out of my diet. I started taking a supplement with 5+billion and making water kefir. I also try to eat sauerkraut when I can remember, but I can’t always remember to eat fermented foods. And I can’t eat most fermented foods because of said allergy. So I was wondering if I up my probiotics supplement, buy a stronger brand, if it would benefit the little lady as well. Or should I keep things the way they are so I don’t release toxins into my milk?

  26. Hi Mommypotamus! Thank you for sharing your knowledge with others! I’ve come to value your perspective from reading your blog, so I wanted to ask you why you don’t include a magnesium supplement as a necessity. I’ve been reading that most Americans are very deficient in this. Does FCLO contain lots of magnesium? Or is there a reason it’s not as essential as these others on your list? I’d love to hear your opinion, since I’m trying to decide which supplements my family should be on. This was very helpful, thanks again!

    • I would also like to know about the magnesium.
      For a 4 yr old, myself and my husband.
      Is it necessary to give kids extra magnesium supplement as well? Or would it be enough to give them baths with some epsom salts and magnesium butter foot massage?

  27. I’m currently taking Green Pasture’s FCLO/HVBO blend daily and nursing my 8 week old. This might be a stupid question, but here goes 🙂 Once she hits the 3 month mark, do I need to start giving her her own dose or is what she’s getting through breastmilk sufficient?? Same question goes for probiotics. Can you offer any guidance?

    • Not a stupid question at all! The Weston A. Price Foundation recommends starting with 1/2 teaspoon FCLO around four months. Since Vitamins A & D can be absorbed through skin I rubbed it on my babies bottom rather than give it to them orally until they were over a year old. When to introduce probiotics seems to have more to do with the type of birth the baby had (whether mom had good gut flora that she passed on through the birth canal), whether or not formula was introduced, etc. rather than age. I know some people that introduce probiotics at 1 week old and some that don’t until 6-10 months. Hope that helps!

  28. How much of the FCLO/butter oil blend are we supposed to give to 1 year olds, 3 year olds and 5 year olds? Also, I see that you give your children K2. Do you use Jarrow’s MK-7? if so, for children, do you remove the casing? How do you administer it?

  29. Hi!
    I love your blog! Thank you for the wonderful information. I recently bought fermented cod liver oil capsules from Green Pastures from a health food store in our area. After I bought them, I left them in the warm trunk of our car for 3 hours. I know you are supposed to store them in a cool place or refrigerate. Do you think they are still good? I’m worried it gave the opportunity for something harmful to grow (I don’t know a ton about the oil, except the basics from Sally Fallon…) Thank you so much for your time!

  30. As the Fermented Cod Liver Oil / Butter Oil also contains vit K – why did you add additional vit K supplement?
    Is there not enough in the Green Pasture oil?
    I am just about to start giving it to my 4 yr old son, but was wondering if I need to incl other supplements.
    We will substitute store bought probiotics by milk kefir.
    Many thanks for any advice.

  31. Is there another brand of Cod Liver Oil that you’ve promoted in the past year? I can’t remember if it was on your site, but I’m thinking it was raw and therefore didn’t cause the nausea that some of us encounter with the fermented. 🙂

      • Thanks for replying! One of the things I appreciate about your blog is that you reply to comments long after you’ve posted the article. 🙂

  32. I’m interested in starting a quality probiotic at the “die off” strength that you recommend, but I’m nursing right now. I don’t want my breastmilk to be full of toxins. Should I wait until he weans before beginning the probiotic?

    • Hi Natalie, unfortunately I am not qualified to give advice regarding specific situations. You might try contacting the company to see what they recommend 🙂

  33. Heather, can you give me any guidance about dosage for magnesium and K-2 for a toddler (16 months)? I do have some of the magnesium oil for myself, but it has never occurred to me to use it for my toddler, though it does make sense to do it. But I wouldn’t have any idea how much to use. I’ve also seen some discussion (in reviewers’ comments on Amazon – a great source of info, yes?) about the different kinds of vit K — MK-4 versus MK-7, I think. Do you have any thoughts about the difference and which is better? I also noticed that some of the products (such as MK-7 by Jarrow) have soy, which I’d rather not give to my toddler. One other thing: I take the cinnamon tingle FCLO but haven’t been sure whether that flavor is okay for a toddler. I’ve given him the unflavored, which he previously took gladly but lately has been refusing. Just wondering if I could try giving him the cinnamon tingle, or if the cassia oil and stevia leaf in it would be too much (or unsafe) for him.

  34. Hi,
    This might be a stupid question. I am trying to buy Green Pastures Fermented Cod Liver Oil for my kids. I live in Norway however so the site is all in Norwegian. I can click on the picture to see which bottle I am purchasing however can’t read the description. I cannot find one that specifically indicates it is for children on the bottle. Is there one for kids? Or are they for anyone and you just following the recommended dosing according to the Weston Price link that you gave above? Thank you!

  35. thank you, again, for providing such well-researched and organized information on your site. i am so grateful, over and over, as i continue to browse your pages.

    my question is: how do you count Vitamin K2, Trace Minerals & Magnesium as one supplement (your modified count is now three and not two.) can you find them together as one supplement? if not, what brand K2 supplement of you use? (and is it liquid, capsule, tablet…?)

    • i also just realized that high-vitamin butter oil has a good amount of vitamin K2. is it enough if we use the combo FCLO/BO? and do you feel the dosage should be increased when using the combo rather than straight FCLO? thank you!

  36. What is the importance of FCLO and butter oil being taken together? Is this a must? Thank you!!! Love love love all of this info!!!

  37. Heather,

    What do you think is the best way to get that capsuled probiotic into little ones? Would my 2 year olds get about 2 capsules/day if they are 65 million units per capsule?


  38. Dear Heather,

    I absolutely love your blog! I read your ebook on pregnancy recommendations, and loved it. My son is now 7 months old, and we are doing everything we possibly can to provide him and our family with a WEPF diet. However, I have a question regarding FCLO that I haven’t been able to find anywhere– not on the WEPF site, or, unfortunately on your blog. I introduced my son to FCLO when he was 5 months old, and he took it like a champ. If anything, he loved it. We were doing it daily until some major hectic life event occurred, and I forgot to give it to him for 4 days straight. So, when I remembered to give it to him again, at 6.5 months, he suddenly developed a reaction to it: his outer mouth (possibly even inner, for all I know) and his neck, upper chest were red. It eventually went away after a few hours, and he didn’t seem uncomfortable. I was just wondering if you had ever heard of anything like this before? I just find it strange that he was fine, and now he has a reaction. Haven’t tried since. Maybe that’s what I should do? Try again?

    Thanks so much– not just for taking time to respond to this, but to respond to complete strangers, offer support, kindness and so much knowledge! You are an inspiration!

  39. Hi Heather,

    I am on a mission to try to save my 20 month old’s teeth! I thought I was on the right track nutritionally (much better with him than my 5yr old who has no cavities), but he has 3 teeth with cavities and alot of signs of decay on his front teeth. I have already started fclo/hvbo but want to add the k2 suppmelements. What dosage would you recommend for a nearly 2 yr old? Thanks!

    • Elizabeth, Unfortunately, because I am not a healthcare provider I am unable to make recommendations regarding specific situations. A Nutritional Therapy Practitioner may be able to offer some guidance. My friend Jennifer at 20 Something Allergies (include link) is wonderful.

  40. This post was so helpful. We just received our order of Oslo Orange FCLO today after using Cinnamon Tingle before that. Whoo, is the orange fishy! 🙂

    Do you recommend Biokult over Prescript Assist probiotics? If so, which type of Biokult? And are these effective sprinkled over food for little ones that can’t swallow capsules?


    • I personally prefer Prescript Assist because my family gets lactic-acid based bacteria through fermented foods. Right now I just give them part of a capsule, but PA is supposed to be coming out with a kids chewable soon 🙂

  41. Hi there, just a note on probiotics…instead of buying the ‘supplement’ version, why not just make ur own home grown probiotics? i make keifer from organic keifer grains that makes the enzymes and good bateria needed, turning cows/goats milk into fermented milk…u can also get water keifer which makes natural ‘squash’…one cup a day made into a smoothy and me n my little dude love it! much cheaper, easier than supplements and u know where its come from….what are ur thoughts?

  42. Hi Heather,
    At what age do you usually start your kids on the COncentrace? My son is 20 months old and I’m wondering if I should start that now? Same question about the magnesium oil. I know it stings him, even the lotion one, but I put epsom salts in his weekly bath. And how do you give them the K2? Isn’t it in a capsule?

  43. Our hospital sent us home with a box of commercial liquid Vitamin D supplements we’re supposed to give our newborn, but it’s got junk like ‘caramel coloring’ added. So my Doula suggested this:

    I’d love to give her the most natural, healthy thing I can though, and the WAPF links don’t work anymore. Can you tell me if FCLO is safe for newborns, and in what quantities? She’ll be 4 weeks on Tuesday. Poor thing was born right intime for Winter where we won’t get nearly the amount of natural sunlight as I’d like to give her for it!

    Thank you!

  44. What are your thoughts on the garden of life probiotics for kids in the powder form. I mix some in homemade kumbucha with some liquid minerals. Also they take Catalyn from standard process it has the basic vitamin structure A C D thyromine, riboflavin, and vitamin b6. Is that too much supplementation I side more on whole food supplemetation and lots and lots of butter and grass fed foods organic foods

  45. I had a physical with complete bloodwork + Vit D screen and my Vit D levels are normal. Does this mean I should not supplement with the FCLO? Would I be overdosing if I did? Is there something else I’m missing as a reason to take it? Thanks so much I really appreciate the investigation you and colleagues do for us!

  46. can i give my 2 and 5 year olds the probiotic you recommend here? Should I just give them 1/2 a capsule each? thanks for your guidance.

  47. Great post! I have been thinking of giving my kids food supplements, but I can’t seem to decide what is best for them. Thank you for this very informative post.

  48. Is the probiotic you recommend the one you give your children? If so, how much do you give them a day/week? Thanks in advance.

  49. Hi Heather, I have a very important question: what kind of test can I ask my daughter doctor to order besides iron and vitamin D. She has an appointment on the 17. Thank you, I appreciatte your help.

  50. Or anyone who can help me with my question. I need to check how my daugther is so I am going to ask her doctor to order some blood test, but the ones a can think are iron and Vitamin D, what others can I ask for. Thank you!!!

  51. I have been drinking reverse osmosis water for awhile now since in DC we have a huge water problem (lead pipes, etc). I have heard 2 sides to the argument about trace minerals from water. On one side i heard that the daily value of trace minerals you get from your water is negligible so you don’t need to add just because you’re drinking reverse osmosis water – as long as your food supply provides these. On the other side i’ve heard that you do need it. I was looking into concentrace as a brand and noticed it’s mined in western US which has a huge groundwater contamination problem (lots of arsenic, etc) and there is arsenic in the supplement. It also worries me because other groundwater contaminants can be in it. I am pregnant and unsure of this is safe. Do you have any additional research or thoughts on this?

  52. Hi Heather,
    Wondering if you’ve come across any research for GAPS kids with moderate digestive problems where its seems that it is virtually impossible for them to obtain Vitamin A from fruits and vegetables, and supplements. We’re having this problem with one of my kids and I want us to get better results, especially as we approach the summer months. Thanks again for all of the great research that you share with us!


  53. Hi
    I would like to share my experience with probiotics
    My bb it was only breastfeed and its still
    At 6 months he developed a cow milk allergy very very heavy that we rushed him to emergency and tge only thing he had was organic greek yougurt
    Aftee 2 weeks i tried again and again same story and my pediatrician confirmed its allergy to milk
    Then I researched a lot and decided to out him on Raw Garden of Life kids Probiotics( as i use Primal Defense from them and really reversed my IBS in 2 months) and my son started to have yougurt and home made cheese without having any allergy anymore
    I put my hand on my heart im not do ung advertisement and i dont get any benefit but tgis probiotic did amazing job
    After i started to recommend to my friends that suffer from same and guess what it helped their babies….

  54. I’d love to see you and Vani Hari (aka Food Babe) get together. Maybe do a podcast together or write a few blogs together. I hv been following both of you for many years and the knowledge you two share with your followers is invaluable. I think you two could accomplish great things together.

  55. Concentrace minerals contain beryllium.
    Beryllium is carcinogenic.
    I was seeing a naturopath and she was running tests on me. When she ran a hair test she found beryllium show up in my hair.
    Concerned we deduced it down to the minerals I had added in my diet months back
    I stopped taking them and ran another hair test which show zero beryllium.
    U may want to reconsider When u call this healthy.

    • Heather,
      Thank you for your dedication to sharing your researching. I imagine most comes from researching for yourself and family. You dont have to take your precious family time to help others but you do. For that I am very thankful. Blessings to you and your family.

  56. Do you still recommend Green Pastures FCLO? We like the Arctic Mint flavor, but I was concerned when I saw on the bottle that the ingredients include “spearmint oil, lemon oil, peppermint oil and wintergreen oil”. I called the company to ask if these were essential oils (because I don’t feel it’s safe for my small children to ingest them), but they simply assured me it was “food grade oils”. I’m not sure I feel comfortable giving that to my 3 year old or applying to my infants bottom.

    • Your only supposed to apply the plain fermented cod liver oil to their bottom at night. Not any type of flavored one. The brand she recommended makes both Un and flavored.

  57. We are trying to find a good probiotic for the kids, do you have a new link to help with this choice? The one above just takes us to Amazon now (not a product).

  58. Hey there, you may want to update the cod liver oil section of this particular blog. I enjoy your suggestions and recommendations. Thank you!

  59. The link to fermented cod liver oil does not actually take you to fermented cod liver oil. Can you post the link to where you purchase fermented cod liver oil. Thank you! Also, what about all the studies about it being rancid? Thank you! Love your posts!

  60. Hi Lauren, thanks so much for your question. I no longer recommend fermented cod liver oil due to concerns about rancidity. This post was written so long ago I forgot I’d mentioned it here, so I’ve scheduled some time to update this post.

    • Hi when can we expect this updated post?? I was just about to purchase the recommended green pastures FCLO to help increase vitamin a intake during the measles outbreak (to ease hubby’s mind ) and now I’m confused as to whether I should continue with the purchase. Thank you!

  61. Hi Mommypotamus, I’m wondering about Krill oil. I read online that it has naturally occuring vitamins A, D and E, but when I check the various labels of krill oil supplements, there is no A, D or E listed on any of them (unless it is added separately). Do you have any other info about this? I would like to know if krill oil is as beneficial as cod liver oil.

  62. We use Rosita and I’m curious where you found that you can keep it in the freezer. I just let a bottle expire in my fridge 🙁 because like you we only use it as needed but I like to have it on hand.

  63. I just bought my first bottle of cod liver oil this week, so this article is quite timely:). I’m wondering if it’s a good one? It’s Nordic naturals. I know they are known to be pretty clean?