In recent years, ‘bone broth’ has become popular as a gut-healing, immune-boosting, beauty-enhancing, joint-soothing cure-all. Dietitian Katrina Pace investigates if it’s really all it’s cracked up to be.
Soup, made from a broth of leftover meat, bones and vegetables is a traditional, humble meal eaten around the world since humans harnessed fire. Chicken soup specifically holds a long tradition of being a comfort food for body and spirit.
What are bone broths?
Bone broths are made from simmering animal bones, meat and cartilage. Adding an acid, such as vinegar or lemon juice, helps break down the collagen found in the cartilage and meat. The remaining liquid is what’s reported to have the health benefits.
How does stock, broth and bone broth differ?
Although different, stock, broth and bone broth are often talked about interchangeably. The main difference between them is the length of time they’re cooked for.
Broth is made using meat (which may contain bones) and a few vegetables simmered in water for under 2 hours. This gives a thin liquid to be used in soup or sauces.
Stock is mostly made from bones and a few vegetables in water. It’s simmered for, generally, 2-6 hours and this liquid is used in sauces, gravies, stew and soup.
Bone broth is essentially the same as stock. It’s made by simmering bones, with marrow and cartilage attached, but for longer than a stock — between 16 and 18 hours.
Because it’s simmered for so long, it gives a much thicker liquid because the gelatine has been leached out of the bones and cartilage. It can be used in soups, sauces or drunk on its own.
What claims are made about bone broths?
Bone broths have been promoted as a source of collagen, protein and minerals that help gut healing, boost the immune system, and improve joint health and skin condition.
What nutrients are found in bone broth?
Traditionally, the bones used to make bone broth contain marrow and still had cartilage attached. Both marrow and cartilage are sources of gelatine, a protein produced from collagen. Extra collagen may help to reduce joint pain and improve skin elasticity.
Although much has been said about collagen and bone broths improving gut health, there is no research to support this. Read more about collagen here.
During the cooking of bone broth, minerals such as calcium and magnesium, which are stored in the bones, are leached into the water. The addition of vinegar and the longer simmering time increases the amount of minerals in the broth.
One study found the calcium and magnesium levels in broth were less than five per cent of daily recommended levels, so broth isn’t a good source of these nutrients.
What’s the evidence behind this?
One study found an increased quantity of lead in bone broth. Bones can store heavy metals, which when simmered to make stock, can leach into the water. So, apart from being a flavourful way to use leftover meat bones and veges and a way to make your own base for soups and gravies, take the medicinal use of bone broths with a pinch of salt.
Are there any side effects?
A recent study found that commercially produced bone broth contained far less collagen than the potentially therapeutic dose of 20g that can be found in collagen supplements. In bone broths made to non-standardised recipes there was a highly variable amount of amino acids, meaning that broths are unlikely to be a consistently reliable source of amino acids that are thought to be responsible for the suggested health benefits.
Article sources and references
- Alcock RD et al. 2019. Bone broth unlikely to provide reliable concentrations of collagen precursors compared with supplemental sources of collagen used in collagen research. International Journal of sport nutrition and exercise metabolism 29:265-72https://www.ncbi.nlm.nih.gov/pubmed/29893587
- Hsu DJ et al . 2017. Essential and toxic metals in animal bone broths. Food & Nutrition Research 61:1347478https://www.ncbi.nlm.nih.gov/pubmed/28804437
- Nutrition Research 61:1347478 Monro JA et al. 2013. The risk of lead contamination in bone broth diets. Medical Hypotheses 80:389-90https://www.ncbi.nlm.nih.gov/pubmed/23375414
- Saint-Germain C. 1997. The production of bone broth: A study in nutritional exploitation. Anthropozoologica 25:153-6http://sciencepress.mnhn.fr/sites/default/files/articles/pdf/az1998n25-26a18.pdf