Saturday, March 9, 2013

The risk of lead contamination in bone broth diets, 2.

The risk of lead contamination in bone broth diets

Here's a photo from the report published in Medical Hypotheses:


1) They used carcasses of organic chickens.
2)  The fourth sample consisted of tap water boiled with the same apparatus and for the same length of time, controlling for the possible concentration of lead by route of water evaporation.
3) The fact that the broth made with chicken bones contained more than 7 times as much lead as tap water, and the broth made with chicken cartilage and skin contained more than 9 times as much lead as tap water, clearly illustrates the effect of bioconcentration of contaminants.  The higher you eat on the food chain, the more contaminants you consume.
4) Consider that if broth made from chicken skin and cartilage contain 10 times the concentration of lead found in tap water, the skin and cartilage themselves must have a much, much greater a lead concentration, because making broth released the lead from the chicken parts into a vat of water, diluting what occurred in the chicken parts.

Organic farming advocates would consider vegetables and animals grown on lead-contaminated soil "organically grown" so long as the producer followed organic protocols.  Animals always concentrate contaminants found in the environment; the higher on the food chain the animal lives, the greater the concentration.

Pasture is not immune to lead contamination, as lead is an airborne contaminant.  Combustion of fossil fuels and smelting metals releases lead into the atmosphere, where air currents can carry it to pastures. 

A study in Hong Kong found soil and vegetation lead content was inversely proportional to the distance of the soil from motorways.  [1]   This suggests that chickens raised in urban areas will have higher lead contamination levels than chickens raised in remote rural areas. 

Humans exposed to lead accumulate lead in their bones.  One study found that bone lead content increased in Mexican men with age, with the result that  "Bone, especially trabecular one, proved to be a significant endogenous lead source for blood and semen burdens in reproductive aged men."[2]

A study in Boston found that  "ingestion of lead-contaminated tap water is an important predictor of elevated bone lead levels later in life."  [3]  This study found an increase in bone lead in men who consumed more than one glass daily of tap water containing at least 50 mcg lead/liter, levels five times greater than found in the cartilage/skin broth and seven times higher than found in the bone-only broth in the Medical Hypotheses study.

Nevertheless, any increased dietary lead presents an increased risk of lead accumulation in your bones.

One study found an increased risk of hypertension associated with greater bone and blood lead levels. [4]  Another study found lead exposure positively associated with left ventricular hypertrophy and that "halving of the population mean blood lead level would reduce myocardial infarctions by approximately 24,000 events per year and incidence of all cardiovascular disease by over 100,000" [12]

Another study found that "long term accumulation of lead is associated with an increased uric acid level in middle aged and elderly men."[5]

One U.S. study found that low-level lead exposure increased the risk of kidney impairment. [6] A review of 23 studies found the same. [7]

In children, low level lead exposure is linked to intellectual deficits. [8]  One study found that children's "IQ declined by 7.4 points as lifetime average blood lead concentrations increased from 1 to 10 μg per deciliter."[8]

A senior health scientist with the National Toxicology Program seems not to agree with the promoters of bone broth, who think that its claimed benefits outweigh the risk presented by increasing lead intake: 

"There does not appear to be a really safe level of lead exposure," said Andrew A. Rooney, a senior health scientist with the National Toxicology Program who coordinated the review of existing research. "The best course of action," he added, "is to eliminate all lead exposure from our environment." [9]

The CDC doesn't agree with the belief that low levels of lead exposure have no consequence or that we can correct the effects with zinc, calcium vitamin C, or any other nutrient:

"Protecting children from exposure to lead is important to lifelong good health. Even low levels of lead in blood have been shown to affect IQ, ability to pay attention, and academic achievement. And effects of lead exposure cannot be corrected." [10

On a page detailing the adverse effects of lead exposure on children and adults, the CDC's Agency for Toxic Substances and Disease Registry states:

"Lead serves no useful purpose in the human body, but its presence in the body can lead to toxic effects, regardless of exposure pathway.
  • Lead toxicity can affect every organ system.
  • On a molecular level, proposed mechanisms for toxicity involve fundamental biochemical processes. These include lead's ability to inhibit or mimic the actions of calcium (which can affect calcium-dependent or related processes) and to interact with proteins (including those with sulfhydryl, amine, phosphate and carboxyl groups) (ATSDR, 2005).
"It must be emphasized that there may be no threshold for developmental effects on children.
  • The practicing health care provider can distinguish overt clinical symptoms and health effects that come with high exposure levels on an individual basis.
  • However, lack of overt symptoms does not mean “no lead poisoning.”
  • Lower levels of exposure have been shown to have many subtle health effects.
  • Some researchers have suggested that lead continues to contribute significantly to socio-behavioral problems such as juvenile delinquency and violent crime (Needleman 2002, Nevin 2000).
  • It is important to prevent all lead exposures.
"While the immediate health effect of concern in children is typically neurological, it is important to remember that childhood lead poisoning can lead to health effects later in life including renal effects, hypertension, reproductive problems, and developmental problems with their offspring (see below). The sections below describe specific physiologic effects associated with major organ systems and functions."[11]
 To emphasize:  "It is important to prevent all lead exposures."

Which nutrients protect against lead exposure?

Regarding the effect of nutrients on lead absorption and excretion, the CDC has these remarks [13]:

Iron:  "Although iron may help prevent lead absorption in animals, studies of the association between iron deficiency and BLLs in children have produced inconsistent results. There is little evidence that iron promotes a clinically important increase in lead excretion."

Vitamin C: "In summary, although there is fairly strong evidence to support giving vitamin C to adults with EBLLs, there is insufficient evidence to recommend for or against vitamin C supplementation for children with EBLLs." 

Calcium:  "The results of both animal studies and human laboratory studies provide good evidence that dietary calcium competitively inhibits lead absorption." 

Zinc:  "Some evidence from animal studies suggests that high levels of dietary zinc inhibit the absorption and retention of lead in animals (56). However, in one small clinical study in which zinc was given with and without vitamin C to lead-exposed workers, the zinc had no demonstrable effect on their BLLs (36). As with calcium, we do not recommend adding zinc supplements to the diet of children with EBLLs."

Other nutrients:  "Many other factors have been evaluated as mediators of lead absorption and excretion in adults or animals. These factors include vitamins (thiamin, pyridoxine, vitamin D), minerals (phosphorus), dietary chelators (phytatic acid, alginates, oral EDTA), and frequency of meals. These were not included in this review because of a lack of evidence to determine their efficacy in children."

Of these nutrients, only two get CDC endorsement for countering lead exposure:  vitamin C and calcium.  Plants and sun exposure provide all of the listed nutrients without the concentration of lead found in bone broth.  In fact, phytatic acid and alginates occur primarily in plants (grains and legumes, and sea vegetables, respectively), not animal products. 

Lead in plant foods

According to the University of Minnesota Extension Service:

"In general, plants do not absorb or accumulate lead. However, in soils testing high in lead, it is possible for some lead to be taken up. Studies have shown that lead does not readily accumulate in the fruiting parts of vegetable and fruit crops (e.g., corn, beans, squash, tomatoes, strawberries, apples). Higher concentrations are more likely to be found in leafy vegetables (e.g., lettuce) and on the surface of root crops (e.g., carrots)."[14]
According to Cornell University Cooperative Extension:

"Lead in soil is not particularly mobile; that is, it isn't easily taken up by plant roots. However, if there is sufficient lead in the soil, it can be absorbed by plant roots and leaves of vegetables but is largely excluded from the fruiting parts of these plants (e.g. tomatoes, corn, beans, squash, eggplant, pepper). We found that by knowing the amount of lead in a particular soil it is difficult to predict whether vegetables grown in that site will contain corresponding amounts of lead. This is due to several factors. By far the most important factor was the amount of organic matter in the soil. Lettuce plants grown in soils with low levels of organic matter took up much more lead than those grown on soils with high levels (greater than 25%). With soils of very high organic matter content (40-50% or greater), no lead uptake was found even if the lead present in the soil was as high as 3,000 ppm."[15]

If you want to minimize the potential effect of lead on your health or that of your children, I see three reasonable steps:

1) Reduce lead exposure by removing unnecessary sources of lead from your diet and environment.
2) Eat diet based on fruits, legumes, nuts, seeds, and vegetables.
3)  Get sun exposure.
 I don't know about my readers, but given the choice between two sources of calcium, iron, and other minerals, one that contains 10 times more lead than tap water, and one that contains virtually none, I will choose the latter.  I feel fairly confident that I have lower levels of lead exposure and accumulation eating a plant-based diet rich in all essential nutrients than I would eating a diet rich in all essential nutrients but also including significant lead sources like bone broth.   If you want to reduce your lead exposure or body lead levels, why would you ingest a non-essential item that increases your lead exposure?


Charles Grashow said...

The lead concentration in the broth reached 9.5ug/L. That is the same as 9.5 parts per billion (ppb). 15ppb is the EPA’s current legal limit for lead in drinking water. The FDA considers 23ppb to be the ‘level of concern, and there is an upper limit of 50ppb. Lead and arsenic have been found in fruit juices with the lead coming is at around 5ppv. Of course, the FDA did not voluntarily find that lead in juices, rather a lawsuit forced their hand. To me, that makes every food suspect. There is no government “watch dog” for heavy metal contamination.

George Henderson said...

Lead is a natural trace element which is never absent. I used to buy purified laboratory reagents which would have a lead content in ppb listed; these included distilled water and ether, which had passed through an evaporation stage, and were as pure as it is possible to make them.

All lead exposure cannot be eliminated from our environment. If you don't eat bone broth after this report, are you then going to assay the lead content of everything else you might eat instead?
Of course not.

If the EPA considers 15ppb the upper limit for drinking water, consider how much water people drink. Even bone broth drinkers consume a lot more water in other ways. Taking this, and the presence of lead in all other foods, into consideration, the contribution of bone broth to their total lead intake might be insignificant.

While you were worrying about lead in my broth some e. coli crept onto your lettuce leaf.

George Henderson said...

These acupuncturists have confused ppm with ppb, but correcting for that, they seem to say that 10ppb is an acceptable lead content for TCM herbs. I just hope the chemists they're relying on know the difference a few decimal places can make.

"It should be noted that lead is an organic substance occurring in soil, lakes, rivers and oceans and that no soil is lead-free. It is naturally present at an average of about 10 ppm (parts per million), and in general, is usually less than 50 ppm.

The legal limit for lead in pharmaceutical and herbal products has been set at 10 ppm and for mercury at 3 ppm, though most dried Chinese herb material measures well below these levels. American herb companies run sensitive tests measuring these subparts per million of heavy metals in order to assure that no herbs with excessive lead or mercury concentration go on to be sold to the public."

Yeah right. Run them on every batch, do they?

This page is worth reading, defending Chinese herbs against over-zealous lead restrictions:

"After surveying all the science available, Kyle Steenland, PhD and Paolo Boffetta, MD, in their article Lead and Cancer in Humans: Where Are We Now (The American Journal of Industrial Medicine, September 2000, vol. 38, issue 3, pages 295 - 299), conclude that the evidence that lead causes cancer in humans - is weak.

This doesn't mean that lead is safe for us. Far from it, lead is toxic to humans because it can replace other metals in our body such as calcium, zinc, and iron, creating abnormal molecules in our enzymes which then fail to carry out normal body functions.

The typical American diet is said to contain 15 – 25 micrograms or more of lead daily, mainly originating in fruits and vegetables. Other exposures to the air, water, and industry can result in up to 200 millionths of a gram consumed daily. Typical doses of herbal medicine can add 3 to 15 millionths of a gram per day.
Though these figures might sound high, they are actually quite low. The amount of lead in our bodies today is actually the lowest in recorded history. Ten years ago we absorbed ten times as much lead as we do today. In 1970, when lead was still in gasoline and paint, we absorbed 20 times as much. Despite this feast of lead, there is absolutely no evidence that our parents or grandparents suffered from mental retardation, cancer, birth defects or any ailments whatsoever because of their exposure to atmospheric lead. If lead really did cause cancer, as Proposition 65 warnings suggest, might not the precipitous decline in lead exposure result in a similar decline in cancer rates? On the contrary, while lead exposure has declined, most cancer rates have risen. Is it possible that fears of lead may have been inflated, and that lead may not be the environmental bogey man we have presumed it to be.

No one doubts that lead is bad for you at toxic levers, but at what levels? Chinese herbal practitioners know that lead can actually be good for you in certain instances. Lead has a long history of cautious use as medicine. The herbal formula “Lead Special Pill” harnesses the “weight” of lead to settle the lungs in certain cases of asthma. The formula is prescribed at precise doses for periods of no longer than two weeks, and is not given to children or pregnant women. It has been in use safely since the year 1040."

Charles Grashow said...

"Indeed, this study, published online Sunday in The Lancet, found atherosclerosis in 29 of the 76 Egyptian mummies examined.

But the researchers also found the disease in 13 of 51 Peruvian remains dated between A.D. 200 and 1500, two of five ancestral Pueblans who lived between 1500 B.C. and A.D. 500, and three of five Aleutian Islanders who lived in the 19th and early 20th centuries.

Over all, 38 percent of the Egyptians and 29 percent of the other mummies had definite or probable evidence of atherosclerosis, the scientists concluded.

The senior author, Dr. Gregory S. Thomas, a cardiologist and medical director at Long Beach Memorial Medical Center in Long Beach, Calif., said that among the mummies of people age 40 and older, 50 percent had atherosclerosis.

Diet and climate varied among these four groups. The Egyptians may have eaten a diet high in saturated fat. The Peruvians farmed corn, potatoes and beans, and they kept domestic animals. Ancestral Pueblans grew corn and hunted rabbits, deer and sheep, while the Aleutian Islanders subsisted on a diet of fish, shellfish, seals, sea otters and whale."

George Henderson said...

The Egyptians may well have eaten a diet high in saturated fat, as they are always depicted as being fashionably slim in their hieroglyphs.

Peter said...

Excellent article, Don. I really enjoyed reading this.


HealthLongevity has already replied to your nonsense mummy paper in detail, see his comment section.

My friend has eaten a whole-food, plant-based diet for two years now. 3 warm meals per day; dietary staples are same as mine: oatmeal, whole-grain pasta (both penne and spaghetti), brown rice, rye bread with organic Danish tahini, beans, lentils, tomato sauce, cold-pressed canola oil in moderation (the lowest SFA content of oils), broccoli and onions. He received his lipid panel precisely today:

TC = 112 (2.9mmol/l)
LDL = 50 (1.3mmol/l)
HDL = 46 (1.19mmol/l)
Trig = 70 (0.8mmol/l)

My own LDL-C is 1.8mmol/l (70mg/dl) and TC 3.2mmol/l. I am bit more lavish with my approach compared to my friend, but I quite satisfied with my digits.