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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. I would think the pros far outweigh the cons in this case as the lead would be in minute amounts at most.

    You are exposed to more lead in your drinking water, baths, showers, etc

    • That’s definitely a generalization. I drink, bathe, shower, wash clothes, wash dishes, etc, with water filtered to a very high degree of purity. I am concerned about contaminants of any kind in anything that’s within my awareness.

  2. In the study, organic chickens were used. As we know, organic chickens could be fed soy & corn. So i wonder if soy contains lead? Or even if each ingredient in the supplemental feed needs to be tested for lead first. If we are what we eat, then we need to look at what the animals are eating too, don’t we?

  3. I was also wondering Chris if you could comment on msg being formed when broth is boiled. Can you even bring your broth to a boil at the start and then simmer without forming msg’s. After it has cooled overnight I thought it was always safer to bring it to a boil again before simmering.
    Also would there be less or more lead if you drain the broth and continue to simmer it with new water. Could this be a solution to get rid of the first broth?

  4. My children were severely poisoned by lead while consuming lots of bone broth on GAPS diet. No other sources of lead were found. The broth was made from pastured bones and meat in a steel pot. This has been devastating. People need to stop discrediting main stream medicine for everything. Children’s lives can be ruined. Our environment is much more toxic than our grandparents. Not every food is perfect.

    • Just out of curiosity how do you know the lead in their body was from the broth? And did you do a metal test on your kids?

      You know mothers can pass metals to their children at birth?

  5. With regards to toxicity, what the EPA considers safe, and HOW it considers something safe, is highly objectionable at best, and flat out erroneous at worst. It becomes a matter of the blind leading the blind.

  6. Lead and other toxic metals are rapidly sequestered into tissues and therefore, blood levels of lead and other toxic metals are extremely misleading and are of little to no diagnostic value.

  7. Nice overview and thanks for that. Came across this as I was checking up on pork bone broth.

    It might be an occupational hazard, but as a trained philosopher I am however a little concerned about your choice of frame of reference when it comes to allowed lead levels. Why should anyone take these sources serious, when they are the same who are telling us to eat (whole)grains and fruit all day long? Why use one piece of information from them, when we know that industry largely dictates the contents of their advice? It is not good practice to pick a piece when it is suitable and reject the source in other contexts as fundamentally flawed and misguided. You can’t hold onto something at the same time as you are pusing it away – at least not for long, have you ever tried, often happens in relationships, for instance?

    Finally, to return to some positive critique, I think you are right to point out the environmental factor: where did the animal in question live and grow? What did it eat? And, in extension of that, does grain act as an accumulator of heavy metal, even if it is not grown with petrochemical agents?

    • Thanks for calling out Chris on citing sources he sometimes disdains and other times uses to support his arguments. I concur, too, on distrust of toxicity guidelines without knowing more about the underlying research.

  8. http://www.westonaprice.org/blogs/kdaniel/2013/03/12/bone-broth-and-lead-contamination-a-very-flawed-study-in-medical-hypotheses/

    “To that end, we would like to announce the results of testing performed by The National Food Lab on bone broth from grass-fed beef and pastured chicken from California.65 These two broths were prepared in stainless steel soup pots by the Three Stone Hearth Co-op in Berkeley. As tested on February 14, 2013 at a Minimum Detection Level of 10 parts per billion and again on March 1, 2013 with an MDL of 5 parts per billion, the results were as follows:

    Grassfed beef broth. No lead detected
    Pastured chicken broth: No lead detected
    Reverse osmosis water: No lead detected”

  9. Melkat, I just think distilled water is bad from reading this… http://www.mercola.com/article/water/distilled_water.htm

    “Fasting using distilled water can be dangerous because of the rapid loss of electrolytes (sodium, potassium, chloride) and trace minerals like magnesium, deficiencies of which can cause heart beat irregularities and high blood pressure. Cooking foods in distilled water pulls the minerals out of them and lowers their nutrient value.

    Distilled water is an active absorber and when it comes into contact with air, it absorbs carbon dioxide, making it acidic. The more distilled water a person drinks, the higher the body acidity becomes.”

    Perhaps it does not matter what water you use for broth as long as it is clean filtered water but I never drink distilled water, I always feel weird when I drink it. Just my thoughts…

    • Mercola frequently publishes information of dubious quality. When I read something about making the body more acidic or alkaline, I know it’s BS.

  10. Maybe adding a little zeolite to the bone broth will lock up the lead and flush it out the body.

  11. Hi! Just curious to hear what the results were on the pasture raised chicken broth. Any news?? Thanks for writing this!

  12. I wouldn’t worry about the lead levels in bone broth. Humans encounter toxins every day from car fumes, pollution, tap water, cigarette smoke, or just breathing. The human body is very resilient in detoxifying (even with a poor diet) so this is why one must consume lots of green vegetables etc that can detox the body. This study (I quickly read it) fails to note the quality of water used and contamination levels or Volatile Organic Compounds present in the water. Tap water (I NEVER consume/use for cooking because the injected fluoride, chlorine, lead, pharmaceuticals, etc present in the water.

    When cooking stock, always use filtered mineral water or water undergone Reverse Osmosis (NEVER use distilled). Simple carbon filters filter very little and many contaminates still pass through the carbon and this is why one should use a system with an RO membrane (with carbon filters) as many contaminate molecules are too large to penetrate through the RO membrane.

    Only realize the bone broth you consume is very beneficial to the human body and the there are many health benefits such as helping/treating skin disorders and myriad of other ailments. It is liquid bone marrow you are drinking after all 🙂

    • Josh, can you elaborate a little on why one should NOT use distilled water for broth?

      And what if one adds back in some minerals?
      Thanks for a little more information.

  13. I may need to retread your post and analysis in case I missed it, but were they all cooked for the same amount of time on the same heat? Presumably the water (control) boiled off as much as the broths did, so the concentration of the tap water and its original contents stayed the same across all of the variables?

  14. I recently started making bone broth. I’ve started only with chicken broth. I’ve made four batches and the last three times, I’ve gotten headaches that start after I eat the broth and continue for a couple days. I noticed I had a headache probably the second time I made broth and thought maybe there could be a correlation. I want to keep making broth (because of the health benefits, and it’s also good, useful and healthier than packaged broth/stock), but I also wanted to see if I got headaches again, and yes it did happen each time I’ve made broth. I didn’t use the cheapest chicken, but it also wasn’t ‘pastured chicken’. I used organic chicken from Trader Joe’s and also tried another type from Whole Foods. Yeah, the chickens get some corn and soy feed, I’m sure, and likely aren’t outside much if at all. I know ‘pastured’ chicken is the best, but it’s really hard to find and very pricey (seems that pasture-raised chicken is more expensive than grass-fed/finished beef). I used legs and thighs to make the broth, but I assume pastured chicken parts are also expensive, if even available.

    I want to keep making broth, but I’m concerned now that I’ve experienced these strange headaches after consuming this broth (I used reverse osmosis filtered water, btw). I will read through comments here and see if I can glean any info., but I’m a little hesitant to keep making broth. May need to try to find better chicken?

      • Jen, have you been blood tested for food allergies? My daughter is intolerant of soy at a moderate level. And she gets severe abdominal distress and headaches with soy consumption. It would be worth checking out.

  15. Instead f lead you should me worried amount the fact the bone broth has very little or no calcium in it. Do your research, people. Even if you buy canned bone broth/stock there is little to no calcium unless fortified. The bioavailability of calcium from making bone stock is next to zero, even if you add wine/vinegar to the pot. Sorry, I know the truth hurts sometimes.

  16. Maybe consuming 2-3 cups @ 9.4ppb is not unhealthy, but you gain minute lead exposure from several other sources as well. If you add that to a water supply that is 7.5ppb, and other environmental exposures, it can add up.

  17. What do you think about the grassfed gelatin powder from Great Lakes? It comes from the skin, connective tissue, and bones of animals.