Learning Objective
You will learn about the health claims relating to bone broth and read research that offers a critical review on the subject.
![Beef stock](https://thesourdoughschool.com/wp-content/uploads/2020/01/beef-stock-sourdough-scaled-1.jpg)
‘Bone broth is good for the gut microbiome.’ But is it?
Lunch is a good time for conversation. We make a lot of bread, so soup is always on the menu here, and many of my students have been keen to discuss the merits of bone broth, asking for more information on how bone broth is made and if it is good for repairing a damaged gut.
Bone broth is both delicious and inexpensive. It is also a brilliant way to use all parts of a carcass efficiently, known as nose-to-tail eating. By making bone broth, we can consume parts of the animal that are high in gelatine, such as skin, tendons and other gelatinous parts of the carcass. But the studies I had read made me deeply sceptical about many of the health claims, and about the idea of incorporating bone broth into our menu at all.
Our lunches are always vegetarian. I am not personally a vegetarian. I am an ecotarian, so I approach the food I eat mindfully, and I make sure that I use up all the leftovers. Making a bone broth is, without doubt, a sustainable approach to using up every part of our food, and reducing food waste is certainly a key message. But is there actually any evidence that bone broth is good for the gut microbiome?
A quick Google search brings up numerous medicinal claims on dozens of websites saying that bone broth is good for the gut. But when you delve a little deeper, there isn’t any robust scientific research regarding bone broth modulating the gut microbiome.
So where do all these claims come from? There is a tradition of drinking bone broth when you are poorly, and a small study carried out by researchers from Nebraska Medical Center and published in a leading medical journal in 2000 (Chest) reported that ‘chicken soup may contain a number of substances with beneficial medicinal activity’. The researchers noted that participants eating chicken soup had a mild reduction of both inflammation and the symptoms of their respiratory infection. There was a large flaw in claiming that these reductions were the effects of consuming bone broth, though: the chicken soup had other ingredients, including onions, sweet potatoes, parsnips, turnips, carrots, celery and parsley.
Does bone broth contain more nutrients?
In 2017, a study in the journal Food and Nutrition Research analysed bone broth and reported that pork bone broth was not an especially good source of either calcium or magnesium. That said, the authors also noted that different bones from different animals had very different levels of nutrients and that levels of acidity and variations in cooking time would significantly alter the nutritional values of the broth. A long cooking time was also shown to increase levels of gelatine.
Could eating bone broth be harmful?
While there are various levels of minerals and amino acids in broth, the bones are where any heavy metals are stored, in particular lead. So there is a question of whether bone broth might result in lead being released. In 2013, a small study looked at the lead content of bone broth made from organic chicken bones. The broth contained over 10 times more lead than water alone. That said, the 2017 study mentioned above concluded that the risks associated with the consumption of heavy metals found in the broths from their study were low, as the amounts consumed in a bowl of soup are actually too low to be considered toxic.
I asked our in-house gut–brain expert, nutritionist and neuroscientist Miguel Toribio-Mateas for his thoughts. ‘Bone broth made with sustainably sourced bones, ideally from animals that were green-pastured or outdoor-reared in as organic an environment as possible, have been used in traditional cooking from China to the Mediterranean for centuries,’ he said. Miguel added that he is ‘cautious about how much of a miracle food it is, for anything from gut healing to osteoporosis. The existing evidence for [bone broth] being good for gut bacteria is patchy. This doesn’t mean that it may be bad, but there are definitely much better ways to feed your gut bugs and to protect the integrity of your gut. Think fresh, brightly coloured fruit and veg, along with a diversity of fermented foods in small amounts, and as part of a life that makes food a source of pleasure, not just sustenance. So, of course, continue to have bone broth if you enjoy it too. Just take these miraculous claims with a pinch of salt.’
The question of ethics
As I mentioned above, our lunches at The Sourdough School don’t include any meat products. We believe that we have to reduce our total consumption of meat if we are to live within our planetary boundaries, alongside other major changes in the way we approach our food. We choose ingredients in our bread-making that are focused on gut health while also considering our choices and how they affect not just the diversity and health of our own gut microbiome, but also the biodiversity of our planet and agricultural systems by helping to reduce the use of fossil fuels and halt deforestation.
It’s not easy. Although I am conscious that eating or not eating meat is a contentious subject, I am nevertheless going to share our approach, while respecting other people’s views. I have long advocated eating less but better-quality meat. As a family, we have significantly reduced our meat consumption. If we eat meat, we look for organic, grass-fed livestock, which can have benefits for both the climate and the ecosystem. There is absolutely no question that intensively produced, grain-fed meat is negative, in every sense.
Interestingly, grass-fed animals do have a positive impact when outdoor-reared. Our soil is able to hold three times more carbon than the atmosphere, but intensive farming means that the soil actually leaks carbon. Organic and pasture-fed livestock systems both store and sequester carbon. To maintain this system, we need grass-fed sheep and cows. They play a key role in returning carbon to the soil and supporting the soil, as long as they are not overstocked. As it stands, organic farming accounts for less than 3.5% of the farming in the UK.
Building soil fertility is something for bakers to consider
As bakers, we have to look at the whole agricultural system. To grow the grain that we use to make our bread, farmers have to build soil fertility. This is about providing nutrients, especially nitrogen. The current system is to use synthetic nitrogen fertiliser, which contributes to both greenhouse gas emissions and soil erosion, as well as the overgrowth of clogging weed in our rivers.
To farm organically, farmers avoid synthetic nitrogen by rotation of their cereal crop fields. This is usually done over four or five years and with grasslands containing leguminous plants like clover. Clover draws nitrogen from the atmosphere into the soil. It makes sense in every way to give the soil some animals to graze these crops and build organic matter along the way, increasing diversity in the fields. In turn, the diversity of plants contributes to the diversity of wildlife and a balanced ecosystem. To find out more about organic farming and how choosing grass-fed, outdoor-reared meat might support our ecosystems, see the Soil Association website. Here at the School, we are proud members, and the School is certified by the Soil Association.
Conclusion
Incorporating ethically reared meat into our diets is a personal choice and one that is worth consideration when it comes to supporting farmers and a sustainable agricultural system. From the limited research available on traditional bone broth, it is a relatively poor source of nutrients and might well contain components that are harmful to health. So until a robust human study is published to show that bone broth has a positive effect on modulating or improving gut health, we are, literally, taking any claims about bone broth benefiting the gut microbiome with a large pinch of salt.
Learning Outcome
You will understand the complexities involved in deciding whether or not bone broth is good for gut health.