Over the past few months a bunch of people asked us if we tested our bone broth for toxic heavy metals. When we get the same question a lot, we of course look into it.
My first question was --- Is there an issue with toxic metals in bone broth? As it turns out, yes, there "can" be an issue!
Heavy metals are naturally present in our environment. We need the "good" heavy metals to thrive: iron, zinc, magnesium, copper, etc. But, we can 100% do without the toxic heavy metals: arsenic, cadmium, lead, mercury, etc.
Too many toxic heavy metals can lead to a host of pretty awful issues: nervous system damage, cardiovascular issues, cancer, endocrine disruption, kidney damage, and so on.
Our body is designed to excrete heavy metals through urine (and a little bit through sweat, hair, and breastmilk too)... but only so much. There's a limit. If you're overloaded, your body will store those heavy metals in your bones, blood, tissues, and organs.
Similarly, if an animal is exposed to heavy metals via food, water, air, dust, or soil, those heavy metals accumulate in the bones. Maybe the farm's soil or air is contaminated from a nearby factory. Maybe the pipes for the water has lead solder connecting them. Maybe the feed a farm is buying was grown on contaminated soil or processed on contaminated equipment.
And, of course, a main purpose of bone broth is drawing out as much as possible from the bones. If there are heavy metals in bones, they will make their way into the broth. This is especially true when you pre-soak with apple cider vinegar and simmer for 48 hours to make it thick and gelatinous (like our broth).
And that led me to my second question --- Should I be concerned about every bone broth? Where is the fear coming from? Well... it seems it might be a little political.
There was a study done in the UK in 2013 that scared a lot of people. It's titled "The Risk of Lead Contamination in Bone Broth Diets". This study found high levels of lead in organic chicken bone broth, which is quite concerning. And, in fact, this one study is still cited in articles written today!
Let's dig a little deeper. Let's go farther than the short abstract.
Here are the broths tested in the study and their test results for lead:
(9.5 parts per billion): Broth made from tap water plus skin and cartilage(7.01 parts per billion): Broth made from tap water plus bones(2.3 parts per billion): Broth made from tap water plus meat(0.89 parts per billion): Tap water alone cooked for the same amount of time as a control.
But, they only used organic chicken from one farm. And, there's zero information about that farm, their practices, the feed, and the broth recipe. Did they use vinegar or wine in the broth? Was the chicken's water contaminated with lead? What was the quality of the feed and the soil? Were the chickens raised indoors or outdoors? So many unanswered questions! All we get is that it was one "organic chicken" that created a lead issue with broth.
Another curious thing is that the broth with skin and cartilage contained more lead than the broth made with just bones. Bones are where lead is stored, so why wouldn't the broth made with bones only contain more lead? It's an odd result.
Moreover, the abstract of the study specifically called out "bone broth diets" like GAPS and paleo. They even go so far as to write, "In view of the dangers of lead consumption to the human body, we recommend that doctors and nutritionists take the risk of lead contamination into consideration when advising patients about bone broth diets."
That's quite curious. Why are they worried about these diets? Are the researchers anti healing through food? Who funded the research? Is it political?
My opinion? This study is not comprehensive. It does not speak to all bone broths. But it does cover a potential issue if the water or animals are overloaded with heavy metals.
What I glean from this study is that we need more research. We don't need fear to spread and people to stop drinking broth from this one study.
Regardless of whether the fear was fabricated or legit, we tested our bone broth anyway. After all, it's always nice to validate that your food choices are as clean as you think.
For Miller's, here were my concerns before testing:
What if there's mercury in the fishmeal in our chicken feed?What if the soil that our animals live on is contaminated?What is the well water that the broth is made with is contaminated?What if the Celtic sea salt has lots of heavy metals?
We got the test results back. I was super excited. But, I was also confused.
At face value, it appeared that our bone broth tested NEGATIVE for arsenic, cadmium, lead, and mercury.
You can find the test results right here!
You'll notice that, for every sample, the results are "<0.01 mg/kg" and "<0.02 mg/kg".
I asked the lab what the "<" means. They said that it indicates their limit of quantitation (LOQ), the lowest concentration that can be accurately tested using the test procedure in that sample type. So the results simply report that none of the metals tested were found in the sample above the specific reporting LOQs. Whether or not they were present below this LOQ is information that is not provided by the test.
When talking to the lab, I told them what we needed and assumed that this test would go below a 1 ppb. So, when the results came in, I assumed that a "mg/kg" was the same as a part per billion (ppb). Ummm... that math wasn't write! A "mg/kg" is actually a part per million (ppm).
That means that the test we ran had results saying that the broth had less than 0.02 ppm (or 20 ppb) of arsenic and lead. And, it had less than 0.01 ppm (or 10 ppb) of cadmium and mercury.
For some reference, the EPA says that less than 15 ppb of lead is safe in drinking water. Not saying that I agree, but it's a good reference point.
These results are good. It means the broth definitely isn't overloaded with toxic heavy metals. But, it's not good enough!!! We need to test again!
We really need to a lower LOQ. We need to know the results with an accuracy of as low as 1 ppb. It looks like the lab we sent the original samples to doesn't have an LOQ that low. So here I am on the hunt for a lab to do it again. As soon as I can, I'll send samples in again and paying for more expensive testing to get the info you deserve. Stay tuned! I hope to have the new results in by the end of April 2025.
Do you worry about toxic metals (or other junk) in your food? Where have your fears stemmed from?
I'd love to hear from you. You can comment below (no account required) or contact us 😊
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Sources
The risk of lead contamination in bone broth dietsBone Broth and Lead Toxicity: Should You Be Concerned?Bone Broth and Lead Contamination: A Very Flawed Study in Medical HypothesesBone Broth, Collagen, and Toxic Metals: A Research Review
