Chicken soup and animal broths have long been thought to provide essential minerals and other nutrients to nourish our bodies and minds. And in fact, studies have shown that traditional chicken soup can affect white blood cell activity.
These days, broths are more popular than ever. The web is filled with recommendations to drink long-simmer bone broth regularly to heal the gut, improve joint health and boost immunity.
Models are reportedly sipping bone broth for the hair, skin and nail enhancing collagen. Bone broth contains a number of amino acids that nourish such as collagen, gelatin, proline, glycine, arginine and glutamine. For this reason, popular gut-healing diets such as the Gut and Psychology Syndrome diet (GAPS) and the Specific Carbohydrate Diet (SCD), Paleo Diets, Keto Diets include bone broth as important steps. We have a wide range of best beef bone broth at Bone Broth
Lead in bone broths
A study was recently published in the journal Medical Hypotheses raising concerns of lead contamination in commercially-available bone broths. Lead toxicity in humans can cause reproductive and gastrointestinal problems, neuropathy, anemia, abdominal pain, memory impairment, and depression, and recent studies suggest that even small amounts of lead exposure can cause trouble.
Lead is stored in bones, and thus it was hypothesized that the lead concentration in bone broths would greatly exceed that of tap water. The researchers investigated three different broths made with tap water and organic chicken bones, meat without the bones, and skin and cartilage without the bones. The tap water used to make the broths had 89 parts per billion of lead. The bone broth contained 700 parts per billion, and the skin and cartilage broth contained 950 parts per billion. This may sound alarming at first, but keep in mind that the legal limit for lead in drinking water is 1500 parts per billion. The benefits of bone broths may surpass the increased exposure to lead, but this is likely both dosage-dependent and individual. It’s also unclear whether pasture-raised animals, preferred in the Paleo Diet, might have less lead in their bones than standard grain-fed animals (organic or not). Certain individuals and populations, like pregnant women, should take greater care to avoid lead exposure.
If you frequently consume bone broths, one prudent measure would be to have your doctor order a blood test for lead and possibly erythrocyte protoporphyrin (EP), which will see if your recent bone broth ingestion pattern has resulted in significant lead exposure.
To understand just how much the answer matters, here’s a quick primer on lead. Lead is a well-known neurotoxin. Studies show that elevated blood levels of lead are associated with deficits in growth, learning, and attention among children. Among adults, studies correlate high lead levels with neuropathy, hyperactivity, depression and anxiety.3,4,5 Plus, because essential metals and minerals compete for absorption in the small intestines, exposure through food could lead to deficiencies that affect hundreds of nutrient-dependent biochemical pathways, and even gene expression.6,7 The bottom line? Lead toxicity has consequences for mood, cognition and stress handling, growth and development, thyroid function, neurotransmitters, sex hormones and more.
Some (albeit limited) research shows that lead can be present in animal bones:
- Lead-exposed cows do store it in their bones – one study tested thirteen cows that were accidentally exposed to lead and found elevated blood levels correlated well to accumulation in their bones and other tissues.8
- A sixteen-year retrospective study conducted by the Veterinary Biomedical Sciences Department at the University of Saskatchewan found 525 cases of acute lead poisoning among the 2,060 samples they analyzed from cattle in western Canada. The researchers refer to lead poisoning as one of the “most common” metal toxicities found among cattle in the region 9.
- In Brazil, one study identified both lead and arsenic contamination among cattle and chicken, attributed partly to a presence in the feed.
With this in mind, we knew we needed to investigate: We initiated a small-scale experiment, to analyze the lead content in three beef bone broth samples. We also tested one sample of hydrolyzed beef collagen because we know time-strapped foodies and smoothie sophisticates often use it as an alternative to bone broth in beverages and recipes.
And there’s more. Looking for beef bone broth ? Look no further! Bone Broth has you covered.
In addition to lead, we measured 36 other toxic and essential minerals and metals in our samples, from calcium to zinc and aluminium to uranium, making this the most extensive profile of both bone broth and collagen powder that we are aware of, published to date. We’re excited to share what we found out and help you make sense of it all.
How much lead is in bone broth?
The health benefits of bone broth (or soup) have been long perceived, but only a decade ago was the remedial effect of bone broth scientifically evaluated. For instance, the generally believed the curing effect of chicken soup against symptomatic upper respiratory tract infection had been found to follow from an increase in nasal mucus velocity or its mild anti-inflammatory effect. More recently, bone broth has been increasingly recommended as part of the diets for gut and psychology syndrome (GAPS) patients, such as those with autism and attention-deficit hyperactivity disorder (ADHD).
Others regard bone broths as an important dietary source of essential elements, such as calcium, which is particularly favoured by those who are intolerant to or cannot access milk products. For example, in some Asian cultures, the consumption of soup made from soaking chicken or other bones in vinegar has been traditionally prescribed for calcium or iron enrichment, especially during pregnancy and postpartum periods. Although dietitians and the media have widely promoted bone broth as a calcium supplement, no or only weak scientific evidence concerning calcium levels therein and preparation methods has been provided.
Animal bones are known to contain trace amounts of toxic metals in addition to minerals. Calcium supplements that are made from a bone meal (finely crushed bone) have a lead level in the range of a few to 10 μg/g, and some even contain cadmium (~2 μg/g). Accordingly, simmered broths of animal bones may be reasonably assumed to contain toxic metals and to cause dietary exposure. However, the presence of toxic metals in bone broth has rarely been studied.
This study investigates the extraction of metals, both essential and toxic, from animal bones into broth, with a view to addressing some of the public concerns about whether bone broths are good sources of nutrient elements and the risks that are associated with the consumption of toxic metals in bone broth/soup.
The ‘Lead’ Study on Chicken Bone Broth
First, let’s look at the study that threw the safety of bone broth into question. In 2013, researchers in the UK got cookin.’ Specifically, they made four different combinations of broth:
- Using just boiled tap water
- Boiled tap water with chicken bones
- Boiled tap water with chicken skin and cartilage without bones – from a cooked chicken
- Boiled tap water with chicken meat
They reportedly used organic chicken cooked in the same type of pots (stainless) and boiled each variation for the same length of time.
Here are lead levels in each variation:
- Using just boiled tap water, .89 µg/L (microgram per deciliter)
- Boiled tap water with chicken bones, 7.01 µg/L
- Boiled tap water with chicken skin and cartilage without bones – from a cooked chicken, 9.5 µg/L
- Boiled tap water with chicken meat, 2.3 µg/L
Lead levels with the skin and cartilage came in at more than 10X that of just the tap water, while broth made with just bones showed more than 7X the amount.
But are those lead levels high? If we go by government guidelines, then no. The US Environmental Protection Agency (EPA) set its safety threshold at 15 parts per billion (the same as µg/L).
A 2017 Study on Pig and Cow Broth
That 2013 study, unfortunately, remains the only one I could find that measures metals in chicken bone broth. However, a 2017 study assessed levels in pig and cow bone broths.
The Taiwan-based study used pig legs and ribs from Taiwan, and cow femurs from Australia boiled for 12 hours.
Here’s what they found:
- The amount of lead in these broths came in at 6.14 µg/L and 7.12 µg/L for pig leg and pig rib bones, respectively, in acidified water (with vinegar added)
- In un-acidified water with pig legs, lead levels were just 2.6 µg/L
- The amount of beneficial minerals such as calcium and magnesium increased with cooking time
The researchers concluded: “…nutritional values, and particularly calcium levels, have attracted attention, but systematic evaluations of methods of their preparation and the range of calcium concentrations are few, as are the health risks associated with the ingestion of toxic metals such as lead that commonly accompany bone minerals.”
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 the lead of 15 parts per billion (ppb). The 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 a lead in the homemade chicken broth even less of a concern.
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.
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. Bone Broth has a wide range of best beef bone broth in Melbourne
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 the 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). 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. Calcium has also been shown to reduce the absorption of lead in the gastrointestinal tract.
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. 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.
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 the bone. 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.
Is Broth Beneficial Even with Some Lead in It?
In a best broth scenario then, people replete in calcium would not suffer ill effects from lead in the broth. Such people would also benefit from the ample quantities of the amino acid glycine in the broth because glycine — along with the cysteine and glutamic acid also found in broth — are needed by the body to produce the powerful antioxidant glutathione, which helps us dispatch lead and other heavy metals.
Unhappily, that beneficial broth scenario does not hold unless people already have a healthy gut. It is far less likely to be the case in those already suffering from digestive disorders and compromised gastrointestinal integrity. This is the case with children who have autism and other disorders, and unfortunately, these are the very children being given broth as part of their gut healing. As already pointed out, even normal children can absorb up to 50 per cent of the lead in food. Furthermore, as Dr. Russell Blaylock has pointed out, a lead will magnify the possibility of excitotoxicity fueled by glutamic acid.
Although the body needs glutamic acid, people who are highly sensitive to MSG may have to limit the direct consumption of even glutamic acid from food. This is the probable reason why many GAPS practitioners have observed that people often do better if they start their healing journeys with meat broth and later move on to full fledged broth that has also been made with skin, cartilage and bones. Check out our Melbourne best beef bone broth here.
It’s very unlikely that drinking or eating bone broth could cause harm unless you’re consuming it in large amounts. “Animal bones are known to contain trace amounts of toxic metals along with minerals,” Jones says. “When bone broth is cooked, lead may be released. A small study conducted in the United Kingdom in 2013 looked at the lead content of bone broth made from organic chicken bones. The broth contained over ten times more lead than the water alone.” But a 2017 study conducted in Taiwan found that commercial bone broth had minimal amounts of lead, as well as being a relatively poor source of calcium and magnesium.
You can go ahead and use bone broth for soups and stews (the way humans have historically done), but know that drinking huge amounts of it is unnecessary, and may even be harmful.