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Bone Broth and Lead Toxicity: Should You Be Concerned?


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bone broth lead, lead in bone broth
Are there toxic levels of led in bone broth? Vladislav Ageshin/Hemera/Thinkstock

Yesterday I became aware of a study published in the journal Medical Hypotheses called “The risk of lead contamination in bone broth diets.” (1) The authors mention that consumption of bone broth may be increasing because it is recommended by advocates of both the GAPS and Paleo diets. It’s well-established that farm animals (and humans, for that matter) can be exposed to lead via food, water, air, dust and soil, and that it progressively accumulates in bone. The researchers wanted to find out whether the bones of farm animals might sequester lead, which would then be released into broth during its preparation.

Does bone broth contain toxic levels of lead? Tweet This

To find out, they prepared chicken broth (using organic chickens) three different ways:

  • using chicken bones;
  • using cooked chicken meat without the bones;
  • using chicken skin and cartilage without the bones after the whole chicken had been cooked.

In each case the same tap water, cooking utensils, cookware and cooking time was used. They also included a fourth control preparation, where they followed the same procedure but used only tap water heated for the same length of time. The lead concentrations in the four different samples were as follows:

  • chicken-bone broth: 7.01 µg/L
  • bone broth from chicken meat (without bones): 2.3 µg/L
  • bone broth made from skin and cartilage off the bone: 9.5 µg/L
  • control (tap water): 0.89 µg/L

As you can see, the levels of lead in bone broth made from chicken bones was a little over 7x higher than the tap water, and a little over 10x higher in broth made from chicken skin and cartilage. As the authors point out, lead has “adverse medical effects on the central nervous system, peripheral nervous system, haemopoietic system, gastrointestinal tract, renal system, cardiovascular system, endocrine system and reproductive system”. In short, too much lead wreaks havoc on every system of the body.

Does this mean it’s time to quit the bone broth? Not so fast.

How Much Lead Is Safe?

The authors of the study express alarm about the “high” levels of lead found in the bone broth preparations they made. However, the US Environmental Protection Agency (EPA) has established a safety threshold of 15 parts per billion (ppb, which is equivalent to 15 µg/L) for lead in drinking water. On their page discussing lead and water, they explain that:

Most studies show that exposure to lead-contaminated water alone would not be likely to elevate blood lead levels in most adults, even exposure to water with a lead content close to the Environmental Protection Agency’s (EPA’s) “action level” for lead of 15 parts per billion (ppb). Risk will vary, however, depending upon the individual, the circumstances, and the amount of water consumed. For example, infants who drink formula prepared with lead-contaminated water may be at a higher risk because of the large volume of water they consume relative to their body size.

If drinking water consistently throughout the day with lead levels of 15 µg/L (ppb) does not pose a problem for human adults (and children with the exception of infants drinking formula), then why would drinking 2-3 cups of bone broth with lead levels of 9.5 µ/L pose a problem? I don’t think it would.

That might be the end of the argument right there. But there are additional factors to consider that may make lead in homemade chicken broth even less of a concern.

The Importance of Nutrient Synergy

There’s no doubt that it’s smart to minimize exposure to toxins as much as possible. But in an environment where toxins are found in foods that also contain beneficial nutrients, we must always balance the benefits of those nutrients against the potential harms of the toxins. What’s more, some nutrients protect against the harmful effects of toxins.

For example, I’ve written on the blog and talked on my podcast about how selenium protects against mercury toxicity in fish. More specifically, the reason mercury is toxic is that it damages selenium-dependent enzymes that play a crucial role in protecting us from oxidative damage. This is why you’ve heard so much publicity about the dangers of consuming fish with mercury. However, what these reports neglected to consider is that if a food you consume contains more selenium than mercury, or if background selenium intake is high, mercury won’t be able to destroy all of your selenoenzymes and you’ll be protected from its toxic effects.

As it turns out, certain nutrients like calcium, iron, vitamin D, vitamin C and thiamin (B1) have a similar protective effect against lead toxicity. These nutrients are abundant in Paleo and GAPS diets, and in the case of calcium, abundant in bone broth itself. Let’s take a closer look at how two of these nutrients, calcium and iron, protect against lead toxicity.


Both animal and human studies have shown that low calcium intake increases the risk of lead toxicity. In one rat study, researchers found that rats ingesting a low calcium diet had blood-lead concentrations four times higher than rats on a normal calcium diet, although the quantities of lead ingested were equal. The mechanisms by which calcium protects against lead toxicity involve complex interactions among lead, dietary calcium, intestinal calcium binding proteins and vitamin D, especially 1,25 D (the active form). (2) In fact, the interaction between calcium and lead is quite similar to that of selenium and mercury: one of the ways lead causes harm is by interfering with the beneficial effects of calcium. Lead is known to mimic calcium in biological systems or to alter calcium-mediated cellular responses, compete with calcium in enzyme systems, impair calcium metabolism, or inhibit 1,25-D-mediated regulation of calcium metabolism. (3) Calcium has also been shown to reduce the absorption of lead in the gastrointestinal tract. (4)

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Studies have also shown that susceptibility to lead toxicity is influenced by nutritional iron status. A study in the early 70s found that rodents fed an iron-deficient diet experienced increased susceptibility to lead toxicity. In humans, low iron status of adults has been reported to increase gastrointestinal absorption of lead. (5) As is the case with the lead-calcium and mercury-selenium interactions, lead has been shown to interfere with iron’s physiological functions. For example, lead inhibits three major enzymes that are involved with the production of heme, the ferrous (iron-based) component of hemoglobin, which is the protein that transports oxygen to the cells and tissues of the body. (Mahaffey) Studies also suggest that insufficient iron intake increases the gastrointestinal absorption and soft tissue concentration of lead. (6)

What about vitamin D, vitamin C and thiamin? Though less is known about how these nutrients protect against lead toxicity, vitamin D appears to modify lead distribution once it has been absorbed, preventing its incorporation into bone. (Cheng). Vitamin C has been shown to have chelating properties which help remove lead from the body. And thiamin (B1) appears to inhibit the uptake of lead into cells and promote lead excretion. (7)

We Are What We Eat — and Animals Are No Exception

It’s also plausible that the diet and living conditions of the animals we use to make bone broth will significantly influence the levels of lead their bones, and thus the broth, contain. Food, water, soil and dust are the largest sources of exposure to lead in farm animals. It appears that cereal grains contribute most to dietary exposure to lead. (8) Although I have not seen any comparative data on this, it’s thus reasonable to assume that pasture-raised chickens who eat a combination of forage and grain-based feed would have lower lead levels than conventionally-raised chickens that eat only grain-based feed.

I hope to have some data that will help answer this question in the coming weeks. Jessica Prentice, one of the worker-owners of the Three Stone Hearth community-supported kitchen in Berkeley, CA, has sent samples of their bone broth in to get tested for lead. They make their broth with pasture-raised chickens, so we’ll have at least one example of lead levels in pastured chicken broth to draw from.

That said, given that the levels of lead in the chicken broth tested in the Medical Hypotheses study were below the EPA established safe upper limit for drinking water, and given the protective effect of several nutrients abundant in Paleo/GAPS diets (and even in broth itself), it seems to me that it’s quite safe to consume 2-3 cups of bone broth per day. This is likely to be even more true if your broth is made from pasture-raised chickens. I recommend Kettle & Fire bone broth as a source of lead-free bone broth.

I’ll continue to investigate this issue and report back if I learn anything that changes my opinion.

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Join the conversation

  1. For those who say they are sensitive to gelatin, it might be worth doing blood work to see if you have a true allergy. Gelatin allergy is actually common (there was an outbreak in Japan) because it is used an ingredient in vaccines. The adjuvant in the vaccine can sensitize you to the gelatin and cause subsequent allergic reactions. Unfortunately.

    • Mary Ann, your comment reminds me of the fact that isolated nutrients can cause far more problems than the whole food(s) they’re taken from. Whole foods, properly raised, are nutritionally synergistic, whereas, isolates are stripped of that functionality and benefit. That is true of many food components. Another example that I was thinking of is caffeine, which is far more detrimental as an isolate than as a normal part of coffee or tea (it can even lead to caffeine poisoning). Part of that is because the isolate is added to things in higher amounts than one would likely ever consume in coffee or tea. Just because man can isolate something, doesn’t mean he should. IMO. Thanks!

      • Sorry, I meant to say too, in regard to the benefits of foods being synergistic: Remember some years back when eggs were villainized because of their cholesterol content? Well, some years later someone finally discovered that because of the lecithin that eggs also contain, the synergistic effect is that eggs are a healthy food.

  2. Thanks Chris! My thoughts were similar about the concentrations observed. It’s the dose that makes the poison and not necessarily the concentration. Also, the dosage to cause effects has wide variations among individuals. Your explanation about the interaction with other nutrients makes good sense in accounting for this variation. There is too much evidence, even if it’s mostly anecdotal, that bone broth is a healing and nutritious food. A better scientific study would be to compare the health outcome of those treated with bone broth versus those treated with a placebo. But who will pay for this study???

  3. Could someone please tell me how to UN-notify me of followup comments via email? I am getting 20 emails an hour.

  4. Since my water is filtered to take .99 of everything out (including fluoride) then I am not consuming the 0.89 µg/L in my 8 glasses of water per day. Evidently, that amount is acceptable for everyone to drink on a daily basis. Also, I use the filtered water for my broth so that would bring the lead content down by 0.89 µg/L. So, if I drink a mug or two of broth a day I am on par with those not drinking broth but drinking the “safe” tap water PLUS I have the nutrients of the broth. I am ok with that trade off. We rarely drink any water but our own filtered water and have plenty of glass bottles and jars to take with us when not at home.
    This does bring up up a good point of making sure that one eats from several different farms when possible as animals/produce from each will have a slightly different nutrient profile based on the ground, vegetation, farming practices, breeds, etc., of that particular farm. The same holds true with pollutants and toxins: they will vary from farm to farm and region to region, their land use history and local industries. We buy from several different farms in roughly a 200 mile radius, some to the north, east and south of us. We also make sure we are eating a variety of animals. Again, they will each have their own nutrient profile as well as pros/cons. The majority of the meat we eat is beef and chicken but we make sure to also have lamb, some pork, turkey, bison, deer, elk, duck and goose. We have some of these seasonally and some of these only several times throughout the year due to expense but we do try to have a variety. Lastly, we make sure we eat a variety of cuts. We eat the whole bird, a variety of cuts of the rest as each cut has its own nutrient profile.
    I share these ideas as they go along with not over doing any one food, even if it is nutrient dense. Eg. beef liver is awesome but too much will probably leave you with too much copper. Eating all beef cuts proportionately (how often would a farm family have eaten a liver 100 yrs ago? At most a couple times a year as only so much liver per cow and only a few butchered each year per family.) But eating the liver is great and then eating the roasts will even out the trace minerals.
    Same thing with the lead content – I am hoping! A variety of well raised animals from a variety of locations, eating a variety a cuts and not overdoing any one food, such as broth, over too long of a period and reducing toxins from all unnecessary sources (food is a necessary source!) and it should work itself out….right?
    Thanks for the article. I had already read the study and had become concerned! Glad you thought about it and helped me reason through this issue!

    • I eat liver at least once a month, sometimes twice or three times a month. My plasma copper level recently tested was at the low end of the normal range 14.8 umol/L {11.0-22.0} (zinc was just outside of the lower end of the range 9.1 umol/L {10.0-17.0). I know a RBC measurement would be more accurate but it’s not often tested for around here.

  5. I like your points. Why would anyone go to the trouble of testing this? There are big problems out there. No need to conjure something up. It’s like a war aginst health. I wonder if the chicken used in the testing was free-range and what they were fed. Is this info correct? It looks like the broth made w/ skin and cartilage & no bone has more lead than bone broth.
    chicken-bone broth: 7.01 µg/L
    bone broth from chicken meat (without bones): 2.3 µg/L
    bone broth made from skin and cartilage off the bone: 9.5 µg/L
    control (tap water): 0.89 µg/L
    You taught me something new about the relationship between mercury and selenium.

  6. I think the “more is not necessarily better” applies to just about anything these days. I think I’ll continue to NOT drink bone broth daily but use it for my soups and stews as I’ve always done.

    On another note… I notice that nobody seems to make broth from pork bones. Why? Is it because pigs don’t sweat and so accumulate more toxins, which will be released into broth?

    • Oh, yes – when I make pea soup I always simmer the ham hock first to make broth to cook the peas in. And all the pork chop bones, etc. go into the stock pot.

      One question I have is how does one standardize the soup making method to make the results comparable since the proportion of bones etc to water can vary so much? Also remember that the figure are per liter, but most folks don’t consume nearly that much in a day.

  7. I have had reactions to beef bone broth that were not pleasant. One cup a day brought on diarrhea. Stopped and tried again. Same thing a few weeks later. It is intense. I used pastured/grass fed bones. Biochemical Individuality has a lot to do with reactions. I now cook with organic legs/thighs for broth and am Ok even with 2 cups a day. After bringing to a boil I only simmer for 4 hours. That helps and maybe would reduce exposure to lead that results in long term cooking of bones. I have found the chicken broth soothing and healing. (this method also gives you a soft, delicious,and easily digested chicken meat)

  8. We started making lots of bone broth this winter and love it; however, every time I eat it, my face breaks out. I’m 58 and this is definitely tied to the bone broth because once I stop eating it my skin heals up in a day or so. I use organic chicken or grass-fed beef and have a reaction to both. I’ve read that it may have something to do with the fluoride in the bones. Any ideas, Chris? Thanks

    • Hi, I have the same problem with getting a rash after consuming the bone broth that I make from pastured animals from a local farm, totally organic GMO free etc. I was wondering if it was some sort of detox reaction. For example when taking iodine to detox bromides it is common to get a rash. If there is a detox rash from bone broth, just what am I detoxing? Any thoughts anyone? Also am going to try K2 as that was an important companion nutrient to iodine during that detox.

  9. What about fluoride? I’ve always wondered if bone broth is high in that too, given that it also accumulates in bone.

    • I’m also wondering about fluoride, I’ve heard it was concentrated in bones and leached out when you made broth.

  10. There is no safe level of lead. It’s a bioaccumulator which does damage at any level.

    You need to compare the benefits of the dietary change against the downsides of slow heavy metal toxicity.

    Here is what the ACCLPP voted to present to the CDC based on their new report:
    “Based on new information as well as new understanding of old data, the committee’s report asserts that there is no safe lead level for children — that many of the consequences of early lead exposure are irreversible. The adverse effects extend beyond the neurodevelopmental realm into cardiovascular, immunological, and endocrine effects. The report documents numerous studies that show the negative effects of lead levels as low as five.”


  11. About a year ago I decided to do a fast using bone broth so I had a lot of it. I ended up with diarrhea so severe, I passed out on the toilet, but not before I called to my husband and he was able to catch me, fortunately. I thought I had an intestinal bug, but couldn’t figure out how I would get one since I never go to restaurants. That’s right – never. Anyway, the diarrhea continued less severely when I started eating again, but didn’t go away because I was still having broth. After about a week I went to my Chinese medicine guy and he said cut way back on the broth – too rich. Then I read something On Paul Jaminet’s site to indicate more is not necessarily better so now I just cook my vegetables in small amounts of bone broth and don’t have any trouble. I can tell I’m more sensitive to beef broth than chicken.

  12. Thanks Chris, could the lead be leaching from the crock pot in which the bone broth is being cooked in? Isn’t that a possibility? I have been concerned about lead in the first place as I cook a lot of food in my crock pot & I do drink a cup of bone broth per day. Thanks!

    • No, because they used a control where they just simmered the water in the cookware, and the lead levels were far lower in the water than in the broth. That suggests the lead is coming from the skin, cartilage and bones of the chicken — which makes sense, since lead is known to accumulate in the bones of animals and humans.

      • Actually, it might not be as simple as that.

        The bone broth has all sorts of compounds in it, that water does not. If there is lead in the glazing of a crockpot, it is possible that broths, especially if you add acids like vinegar/lemon juice/kombucha could leach stuff out that plain water doesn’t.

        Some cheap cast irons – from you know where – can also have lead in them that could leach out, under certain conditions.

        To really test this, the bone broth would need to be cooked side by side in a crock pot, and a non lead vessel.

        All that said, I think we are splitting hairs here – it’s just not a problem.

      • Dear Chris,

        Great article. Thanks for writing it. Can you confirm from the study that the number of chickens used in this “experiment” was one; that they used the skin, cartilage and bones from one chicken to make three broths?


  13. can we test the calcium and other minerals along with the protein assay of the bone broth? Both Lamb/ chicken would be interesting to quantify what actually goes into the water? A

  14. Thanks Chris, your an invaluable source of high quality information as always…

    I have the same question as a lot of people do. I also understand you don’t have the answer right now but an update, when you do find out, would be great!

    I always use ethically/pasture raised cow or lamb for my broth, any thoughts on bone lead levels of these animals?! Or does it again come down to nutrient density and benefits out weighing the toxic negatives…

    Thank you.
    Peter O.

  15. I don’t have a comment about bone broth. A lab for silent inflammation profiling is what I am trying to find. Thank you.

  16. Chris,
    Under IRON….”In humans, low iron status of adults has been reported to increase gastrointestinal absorption of iron”. Did you mean to say absorption of iron…… or lead? I don’t understand the statement. Thank you for the article.

    • Wow thanks very much for the links! I have been looking for something like this.

    • The first link is comparing broth with milk or human milk as baby’s food so emphasis is on the protein and calories. We all know we are not looking at broth as a major energy source. The second link is a discussion about how to evaluate broth nutrient, which is kind of blank area. I would say bone broth are nutritious and we just do not have a measured number yet how good. Do not want people get distracted by your comments.

  17. Here we go again: mainstream medical science warning us away from yet another nutrient dense food. Haven’t they done enough damage telling us to avoid saturated animal fats, cholesterol, organ meats, raw milk, seafood, oh- but make sure you eat plenty of whole grains and lowfat soy milk. Be sure you eat lots of heart healthy canola oil and wonderful soy, and corn oil. So good for you. (They have nothing but the most sincere concern for our health and welfare.) Don’t forget to use plenty of hand sanitizer to get rid of all those scary germs while you are at it. Maybe take a prophylactic antibiotic between meals. Needless to say, keep up on your flu vaccines – every 6 months now! Pfffffffllllllllptttt!!!

    Thanks Chris for the article.

    • Your comments are refreshing after reading this article and all the paranoia about a healthy alternative to use in homemade soups. isn’t that better than supermarket soups and stock?

    • WELL SAID………you forgot the raw milk the banned.
      Why isn’t alcohol and cigarettes banned…doesn’t make any sense

      • It makes a lot of sense. It is a perfect scenario. As our old friend Terence used to say, quoting from memory:

        All cultures define themselves by the drugs they promote and the drugs they prohibit. Sugar, alcohol, and tobacco are perfect assembly line drugs, they are the drugs of capitalism. So, it makes perfect sense.

        • Not capitalism. Fascism perhaps. Genuine capitalism would leave the farmer and his customers to produce and consume raw milk unmolested to their hearts content!