In any human body there are around 30 trillion human cells, but our gut microbiome is an estimated 39 trillion microbial cells including bacteria, viruses and fungi that inhabit our gastrointestinal tract, and have a major influence on our metabolism, body weight, propensity to illness, immune system, appetite and mood. These microbes mostly live in our lower intestine (the colon) and outnumber all the other cells in our body put together.
According to research, the richer and more diverse the community of gut microbes are, the lower our risk of disease and allergies. This has been shown in animal tests and also in human studies comparing the microbes of people with and without particular diseases. Examples from recent work at King’s College London include studies of diabetes, obesity, allergy and inflammatory diseases like colitis and arthritis.
Eating as many types of fruits and vegetables as possible, and eating seasonally is beneficial for our gut microflora. The variety may be as important as the quantities, as the chemicals and types of fibre will vary, and each support different microbial species. It’s better to pick high fibre vegetables. Good examples are artichokes, leeks, onions and garlic, which all contain high levels of inulin (a prebiotic fibre). Some vegetables like lettuce have little fibre or nutrient value. Fruits and vegetables rich in polyphenols and antioxidants act as fuel for microbes which is beneficial for the gut microflora.
Fruits and vegetables are also rich in flavonoids, a group of polyphenols, famous for their rich diversity of colour-providing pigments (including the deep blue of blueberries and rich red of raspberries).
Flavonoids derives from the Latin word flavus meaning “yellow.”
Flavonoids could positively shape the gut microbiota by inhibiting pathogens and boosting beneficial bacteria such as Bifidobacterium and Lactobacillus; these in turn could improve gut health by reducing the endotoxin production, increasing the conversion of primary into secondary bile acids, maintaining gut immune homeostasis, and promoting nutrients absorption.
So, it is so true to follow the well-known advice “Eat the rainbow” …
- 15 tips to boost your gut microbiome (2020) https://www.sciencefocus.com/the-human-body/how-to-boost-your-microbiome/
- List of polyphenol rich vegetables, fruits, herbs and juices https://www.gardeningchannel.com/fruits-vegetables-high-polyphenols/
- Difference Between Flavonoids and Polyphenols (2018) https://www.differencebetween.com/difference-between-flavonoids-and-polyphenols/
- Flavonoids and Best 9 Foods Rich in Flavonoids http://recipeofhealth.com/articles/healthy-food-recipes/flavonoids-and-best-9-foods-rich-in-flavonoids
- Flavonoids and gut health (2020) https://www.sciencedirect.com/science/article/pii/S0958166919301569