Concerns About Bone Broth

There are toxicological issues associated with production and processing of meat, such as the presence of various toxic contaminants—from dioxins and PCBs to cooked meat carcinogens. Carcinogenesis, the development of cancer, may be the main concern, but there are a number of other toxic responses connected with the consumption of meat products. Lead, for example, can be toxic to the nerves, gastrointestinal tract, bone marrow, and kidneys.

Where is lead found in the food supply? In general terms, the highest levels of lead, as well as arsenic and mercury, are found in fish. Sardines have the most arsenic, but tuna may have sardines beat when it comes to mercury and lead.

The problem is that “fish-consumption advisories related to human health protection do not consider the fish by-products fed to farmed animals,” like farmed fish. If some tilapia are fed tuna by-products, they could bioaccumulate heavy metals and pass them onto us when we eat them. Researchers found the highest levels in frozen sole fillets, averaging above the legal limit for lead.

Lead exposure has been shown to have adverse effects on nearly every organ system in the body. Symptoms of chronic exposure range from memory loss and constipation to impotence and depression. These symptoms present after pretty hefty exposure, though. However, we now know that “[b]lood lead levels in the range currently considered acceptable are associated with increased prevalence of gout and hyperuricemia” (elevated levels of uric acid in the blood). According to the Centers for Disease Control and the World Health Organization, a blood lead level needs to be less than 25 micrograms per deciliter to be “non-elevated.” You’d assume that at values under 25, there’d be no relationship with health outcomes, but even throughout this “acceptable” range, lower lead means lower uric acid levels and lower gout risk. So, even blood lead levels 20 times below the acceptable level can be associated with increased prevalence of gout. “These data suggest that there is no such thing as a ‘safe’ level of exposure to lead.” 

Once lead gets into the body, it tends to stay in the body. It builds up in the bones such that it may take 30 years just to get rid of half. The best strategy? Don’t get exposed in the first place.

If lead builds up in bones, though, what about boiling bones for broth? As I discuss in my video Lead Contamination in Bone Broth, we know bones sequester lead, which can then leach from the bones. So, researchers suggested that “the bones of farmyard animals will sequester lead, some of which will then be released into broth during its preparation.” Who eats bone broth? Bone broth consumption is encouraged by many advocates of the paleo diet. Online, you can learn all about purported “benefits” of bone broth, but what they don’t tend to mention is the theoretical risk of lead contamination—or at least it was theoretical until now. Broth made from chicken bones was to have markedly high lead concentrations, up to a ten-fold increase in lead. Researchers concluded, “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.”

But what if you only use bones from organic, free-range chickens? They did use only bones from organic, free-range chickens.


For more on the paleo diet, see:

Other products contaminated with lead include Ayurvedic supplements, protein powders, wild animals shot with lead ammunition, dairy products, and tea from China:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

How to Make Your Own CoQ10

Chlorophyll is the green pigment that makes green leaves green. If you search for chlorophyll in the medical literature, a lot of what you find is about fecal fluorescence, a way to detect the contamination of carcasses in the slaughterhouse with feces to reduce the risk of food poisoning from pathogens harbored within animal feces. Fecal matter gets on meat either “with knife entry through the hide into the carcass, and also splash back and aerosol [airborne] deposition of fecal matter during hide removal”—that is, when they’re peeling off the skin. If, however, the animals have been eating grass, you can pick up the poo with a black light. As you can see in my video How to Regenerate Coenzyme Q10 (CoQ10) Naturally, a solution of chlorophyll is green, but, under a UV light, it lights up as red. So, if you have a black light in a chicken slaughter plant, you can get a drop on the droppings. The problem is most chickens aren’t outside anymore. They’re no longer pecking at grass so there’s less fecal fluorescence. We could let them run around outside or we could save money by just adding a chlorophyll supplement to their feed so we can better “identify areas of gut-spill contamination” on the meat.

The reason I was looking up chlorophyll was to follow-up on the data I presented in my Eating Green to Prevent Cancer video, which suggests that chlorophyll may be able to block carcinogens. I found a few in vitro studies on the potential anti-inflammatory effects of chlorophyll. After all, green leaves have long been used to treat inflammation, so anti-inflammatory properties of chlorophyll and their break-down products after digestion were put to the test. And, indeed, they may represent “valuable and abundantly available anti-inflammatory agents.” Maybe that’s one reason why cruciferous vegetables, like kale and collard greens, are associated with decreased markers of inflammation.

In a petri dish, for example, if you lay down a layer of arterial lining cells, more inflammatory immune cells stick to them after you stimulate them with a toxic substance. We can bring down that inflammation with the anti-inflammatory drug aspirin or, even more so, by just dripping on some chlorophyll. Perhaps that’s one of the reasons kale consumers appear to live longer lives.

As interesting as I found that study to be, this next study blew my mind. The most abundant energy source on this planet is sunlight. However, only plants are able to use it directly—or so we thought. After eating plants, animals have chlorophyll in them, too, so might we also be able to derive energy directly from sunlight? Well, first of all, light can’t get through our skin, right? Wrong. This was demonstrated by century-old science—and every kid who’s ever shined a flashlight through her or his fingers, showing that the red wavelengths do get through. In fact, if you step outside on a sunny day, there’s enough light penetrating your skull and going through to your brain that you could read a book in there. Okay, so our internal organs are bathed in sunlight, and when we eat green leafy vegetables, the absorbed chlorophyll in our body does actually appear to produce cellular energy. But, unless we eat so many greens we turn green ourselves, the energy produced is probably negligible.

However, light-activated chlorophyll inside our body may help regenerate Coenzyme Q10. CoQ10 is an antioxidant our body basically makes from scratch using the same enzyme we use to make cholesterol—that is, the same enzyme that’s blocked by cholesterol-lowering statin drugs. So, if CoQ10 production gets caught in the crossfire, then maybe that explains why statins increase our risk of diabetes—namely, by accidently also reducing CoQ10 levels in a friendly-fire type of event. Maybe that’s why statins can lead to muscle breakdown. Given that, should statin users take CoQ10 supplements? No, they should sufficiently improve their diets to stop taking drugs that muck with their biochemistry! By doing so—by eating more plant-based chlorophyll-rich diets—you may best maintain your levels of active CoQ10, also known as ubiquinol. “However, when ubiquinol is used as an antioxidant, it is oxidized to ubiquinone. To act as an effective antioxidant, the body must regenerate ubiquinol from ubiquinone,” perhaps by using dietary chlorophyll metabolites and light.

Researchers exposed some ubiquinone and chlorophyll metabolites to the kind of light that makes it into our bloodstream. Poof! CoQ10 was reborn. But, without the chlorophyll or the light, nothing happened. By going outside we get light and, if we’re eating our veggies, chlorophyll, so maybe that’s how we maintain such high levels of CoQ10 in our bloodstream. Perhaps this explains why dark green leafy vegetables are so good for us. We know sun exposure can be good for us and that eating greens can be good for us. “These benefits are commonly attributed to an increase in vitamin D from sunlight exposure and consumption of antioxidants from green vegetables”—but is it possible that these explanations might be incomplete?


This blog post has it all: a mind-blowing mechanism, practical applicability, and poop. What more could you want?

Interested in learning more about the potential downsides of cholesterol-lowering statin drugs? I’ve produced other videos on the topic, including Statin Cholesterol Drugs and Invasive Breast Cancer and The Actual Benefit of Diet vs. Drugs.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Meat is Heat: The Effects of Diet on Global Warming

One of the most prestigious medical journals in the world editorialized that climate change represents “the biggest global health threat of the 21st century.” Currently, chronic diseases are by far the leading cause of death. Might there be a way to combat both at the same time? For example, riding our bikes instead of driving is a win-win-win for the people, planet, and pocketbook. Are there similar win-win situations when it comes to diet?

As I discuss in my video, Diet and Climate Change: Cooking Up a Storm, the foods that create the most greenhouse gases appear to be the same foods that are contributing to many of our chronic diseases. Researchers found that meat (including fish), eggs, and dairy had the greatest negative environmental impact, whereas grains, beans, fruits, and vegetables had the least impact. And not only did the foods with the heaviest environmental impact tend to have lower nutritional quality, but they also had a higher price per pound. So, avoiding them gives us that triple win scenario.

The European Commission, the governing body of the European Union, commissioned a study on what individuals can do to help the climate. For example, if Europeans started driving electric cars, it could prevent as much as 174 million of carbon from getting released. We could also turn down the thermostat a bit and put on a sweater. But the most powerful action people could take is shift to a meat-free diet.

What we eat may have more of an impact on global warming than what we drive.

Just cutting out animal protein intake one day of the week could have a powerful effect. Meatless Mondays alone could beat out a whole week of working from home and not commuting.

A strictly plant-based diet may be better still: It’s responsible for only about half the greenhouse gas emissions. Studies have suggested that “moderate diet changes are not enough to reduce impacts from food consumption drastically.” Without significant reduction in meat and dairy, changes to healthier diets may only result in rather minor reductions of environmental impacts. This is because studies have shown that the average fossil energy input for animal protein production systems is 25 calories of fossil energy input for every 1 calorie produced—more than 11 times greater than that for grain protein production, for example, which is around 2 to 1.

Researchers in Italy compared seven different diets to see which one was environmentally friendliest. They compared a conventional omnivorous diet adhering to dietary guidelines; an organic omnivorous diet; a conventional vegetarian diet; an organic vegetarian diet; a conventional vegan diet; an organic vegan diet; and a diet the average person actually eats. For each dietary pattern, the researchers looked at carcinogens, air pollution, climate change, effects on the ozone layer, the ecosystem, acid rain, and land, mineral, and fossil fuel use. You can see in the video how many resources it took to feed people on their current diets, all the negative effects the diet is having on the ecosystem, and the adverse effects on human health. If people were eating a healthier diet by conforming to the dietary recommendations, the environmental impact would be significantly less. An organic omnivorous diet would be better still, similar to a vegetarian diet of conventional foods. Those are topped by an organic vegetarian diet, followed by a conventional vegan diet. The best, however, was an organic vegan diet.

The Commission report described that the barriers to animal product reduction are largely lack of knowledge, ingrained habits, and culinary cultures. Proposed policy measures include meat or animal protein taxes, educational campaigns, and putting the greenhouse gas emissions information right on food labels.

Climate change mitigation is expensive. A global transition to even just a low-meat diet, as recommended for health reasons, could reduce these mitigation costs. A study determined that a healthier, low-meat diet would cut the cost of mitigating climate change from about 1% of GDP by more than half, a no-meat diet could cut two-thirds of the cost, and a diet free of animal products could cut 80% of the cost.

Many people aren’t aware of the “cow in the room.” It seems that very few people are aware that the livestock sector is one of the largest contributors to greenhouse gas emissions. But that’s changing.

The UK’s National Health Service is taking a leading role in reducing carbon emissions. Patients, visitors, and staff can look forward to healthy, low-carbon menus with much less meat, dairy, and eggs. “Evidence shows that as far as the climate is concerned, meat is heat.”

The Swedish government recently amended their dietary recommendations to encourage citizens to eat less meat. “If we seek only to achieve the conservative objective of avoiding further long-term increases in [greenhouse gas] emissions from livestock, we are still led to rather radical recommendations” such as cutting current consumption levels in half in affluent countries—“an unlikely outcome if there were no direct rewards to citizens for doing so. Fortunately, there are such rewards: important health benefits…” By helping the planet, we can help ourselves.

There are tons of articles on diet and sustainability. It’s such an important topic that I may review the new science once every year or two. When the U.S. Department of Agriculture entered these waters, the meat industry appeared to freak out, and the Dietary Guidelines debate continues.


What about just cutting down on meat in terms of health impacts? See my video, Do Flexitarians Live Longer?.

What are the health and food safety consequences of buying organic? See my video series that includes:

For information on GMOs, check out: 

I’m thrilled to announce that the How Not to Die Cookbook is out today(!), and there’s a great burger recipe in there that I’m sharing as another sneak peek into the book. Get the recipe here. The book is available at all major outlets now. 

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: