Bone Broth and Lead Toxicity: Should You Be Concerned? | Chris Kresser
Last Chance – ADAPT Health Coach Training Program Enrollment Ends May 26   Learn more

Bone Broth and Lead Toxicity: Should You Be Concerned?

by Chris Kresser

Last updated on

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.

Calcium

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)

Iron

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.

268 Comments

Join the conversation

  1. I have researched many articles about the “healthful benefits” of bone broth. I have had collagenous and lymphocytic colitis since 1999. SO, I wanted to heal my gut, of course.
    I went out and purchased two organic chickens-to my deep consternation-as I’ve been a vegetarian since 1988. I was so desperate to see a radical change in my gut health.
    I slow-cooked the bones for about 26 hours, as suggested. I allowed it to cool, skimmed off the fat, and used two cups of broth to make noodle soup. During the early night, about 12:20 A.M. I began to heave and heave and at the same time felt an urge to run to the bathromm with the worst diarrhea of all time.
    The weird thing is that when I threw up, it was the most ghastly looking stuff I’d ever seen. Now, I’m a Registered Nurse with 32 years of hospital experience, and I have NEVER seen vomit like that it my life!!! Words could not describe it-so I won’t even go there.
    So, this morning, I began further research…..not one article mentioned excess glutamtic acids until I specifically asked if drinking long-cooked bones could make you REALLY sick. But when I specifically asked that question on Google, I found dozens of articles that talked about it.
    I can tell you for certain, personally, I may never be able to look at chicken again! It was one of the worst experiences I’ve ever had and kept me awake all night with nausea, vomiting, and diarrhea. As I did further research (after the incident) I read that people with an autoimmune disease, such as Inflammtory Bowel Disease (All types of Colitis) should not use long-cooked broths. I doubt that after that experience I’ll be able to try the short-cooked broth now. (Perhaps after the memory of last night as long disappeared?)

    • Does anyone know about levels if fluoride in the bones of animals used, and tap water raising levels of FLUORIDE?
      Any concern? Pesticides are high in fluoride and animals do eat …
      I am trying to lower fluoride.
      High levels in organic chicken sausage *mechanically removed from bones? Buy free range organic fed chick bone in breast and make my own? Go vegetarian?
      Impossible to find the info I seek. Please help

  2. Just wanted to share my experience… I got really into bone broth for 6 months while living in Thailand. I would get rotisserie chickens from the grocery store and then use the bones to make the broth in a slow cooker. Well, after about 5 months of this my hair started falling out, I was incredibly tired, and my gut issues weren’t getting any better. I started working with a functional medicine doctor and found out I have 13x the amount of lead I should in my body…hard to say just how I got levels so high but I have a strong hunch that it was the bone broth in large part due to the timing of it all.

  3. This is a really old thread but I hope Jannie from Denmark is still monitoring responses. I have had similar issues extreme food intolerances to the point where the only thing I could tolerate for years was raw milk. My leaky gut was causing histamine intolerance to probiotics. My condition has improved quite a bit by doing liver and gallbladder cleansing. I started passing gallstones after years of doing colon cleansing, coffee enemas and lots of magnesium supplements. So I researched and found out about olive oil gallbladder flushes. They work great for some people but I had to modify it to get it to work for myself. I do an apple juice fast once a week (at least 24 hours) and then follow with 3-4 TBSP of coconut oil. I found that coconut oil worked better for me. I would try both. Lecithin has also helped me dissolve a lot of stones. It has been about a year for me and stones are still coming out. I can only get them to come out slowly (I believe because my gallbladder is severely congested) but my digestion improves more and more as my GB gets cleaner. My histamine intolerance has improved as well.

    • Show me the actual scans showing all the stones in your gallbladder.. Stones coming out for years? How big do you think the Gallbladder is LOL!

  4. PLEASE READ THIS: I became very sick consuming 3 glasses of bone broth per day for around a year. Not just physically sick but terrible depression, anxiety, suicidal thoughts since I couldn’t go on this way. I stopped bone broth, and got better overnight. Interestingly though, I had a hair tissue analysis, and the results showed tin which was off the chart and copper toxicity which was 75% as high as the tin, not lead. Please note that I cant give any advice as I’m not a health professional – just warn of my own experience, which has significantly damaged my life. e.g. couldnt work and am now unemployed, tried to plead with my doctor who thinks I must have psych problems since its not something he recognises.

    • Sorry to hear about your experience.
      You could be reacting to the Histamines in the bone broth. Very common with people who have gut issues….

  5. I have been on the bone broth diet for a month now. Just the past couple of days I have developed a metallic taste in my mouth after I eat it…is this a symptom?

    • If you are on a a very low carb diet you could be producing more ketones which you can test for in your urine with urine strips.

  6. Chris: thank you, as always, for the abundance of information you so generously share with everyone—this article is no exception. On the subject of lead exposure and bone broth, I wanted to share something that I learned recently, and I was shocked: If one uses a CROCK POT, as I do, with the standard ceramic liner, the liner may release lead into your food as it cooks! I’m still researching this, but it makes me very reluctant to use my crock pot—and I count on it because I simmer my broth for 36-48 hours as I don’t want to leave my stove on that long. Do you have any insights into this, or am I being paranoid? Thank you so much!

    • Susan, any reputable brand of crock pot will not have ceramic glazed with lead or cadmium contaminated glazes. You can buy a test kit called LeadCheck to test your enameled cookware.

  7. I made a batch of beef bone broth for a whole day and want to enjoy it. So- just don’t over do it will help with the question of toxicity? I take calcium every day. 600 mg.

  8. 50 years ago my mother would not make soup from cow bones as she said waste matter like urin and acid from the bone marrow would seep into the soup. Any truth in that?

  9. I started making beef bone broth last month and wondered if anyone has tested the beef bones for their lead levels. Personally, chicken bones are too dense and therefore I use beef bones. Can you provide test results for these animals? I’m sure the benefit of the bone/chicken broth outweighs the negative. As a precaution, it wouldn’t hurt to have the lead monitored via (blood work) during yearly physical exam.

  10. I would really like to know the source of the chickens before I would believe that all chickens have that level of lead in them. We know fish have high levels of lead toxicity because of environmental factors and we also know that “organic” doesn’t mean those animals were not fed tap water with high levels of lead or what their environment was like. Wouldn’t it be best to test a non-commercial chicken, grass fed, grass finished with local well sourced water? I would imagine that their levels of lead might be lower unless there was high levels of lead in the water well.

    I always question science articles as sometimes they neglect important steps in testing their theory. For example, it would be better to test multiple brands/sources of organic chickens vs the preparation recipe. After reading the abstract, it seems they may have only used organic chicken from one source and then had three different types of preparation of said chicken. Thus this experiment is more indicative on what areas of the chicken hold higher ratios of lead then it is of lead from chicken bone broth in general.

    They should have also tested from other animals besides chicken as well.

    • They just want people to stop buying Organic chicken….. that’s how I see it! Someone paid them to do this “test” and they didn’t even bother to test other animal’s bones and other brands of chicken and non-organic and “natural” chicken……. I’m pretty sure that Organic in many cases will have less lead! and which organic – is it USDA checked?

  11. If soil is a factor in lead levels, doesn’t it seem plausable that pasture raised may be concern for higher lead levels.

  12. Hi Chris, I really value your opinion and use your blog as a resource all the time. My question is an important one. I have a 5.5 month old who I’ve been giving bone broth to for the past few days. She absolutely LOVES it. What is your opinion on this? Because she only weight about 16lbs should I be concerned about lead? She has been exclusively breastfed until 2 weeks ago and she’s had about 1-2 tbsp of broth per day for the past few days. Looking forward to your thoughts and thank you so much for your amazing blog and all that you do!

    • Hi – I know your comment is from over a year ago but this may still be relevant to you. Although the EPA has an action level of 15ppb, Washington DC (where I live) has an action level of just *2* ppb. When the pre-k in our district tested at 3 ppb in the drinking countenance, the school required all children to bring filtered water from home, for nearly a year until they had remediate the problem. So for small child, the levels of sad that this study identifies in bone broth could be very problematic. 10 PPB is 500% higher than the lead action level in Washington DC. If my home taps produced that level of lead, I would remediate them immediately.

      • Whoops – I made some dictation typos! Drinking fountains, not drinking “countenance.” And levels of LEAD, not levels of “sad.”

  13. The solution to the lead/heavy metal issue is simple: take iodine with your broth. Iodine will bind to the metal and flush it out. You should take selenium and Vitaming C with your iodine to balance it and help flush out toxic metals.

Leave a Reply

[if lte IE 8]
[if lte IE 8]