Why Your Gut Health Is Fundamental To Immune Health

You almost certainly already know that a highly contagious, potentially deadly pathogen is on the loose: coronavirus, cause of Covid-19 disease. But, are you focusing on your health, to be your best self, should you need to fight it? Learn how improving the health of billions of microbes in your gut can actually help your immune system

Diet and Our Health

It will come as no surprise to many, that changing what you eat could have the quickest and greatest positive impact on your overall health. No amount of exercise can fix bad eating habits and guarantee good health. While regular gym goers probably already appreciate just how much sweat it takes to burn off a sweet treat! But, the link between health and food is not limited to cutting back on stuff we know is unhealthy – like alcohol or excessive salt – or controlling weight by choosing lower fat or calorie foods. Everything we eat plays a role in supporting or impacting our health. Not least, because of the overwhelming contribution of our digestive system to our immune system.

Your Gut is 70% of Your Immune System

Your gut wall houses approx. 70 percent of your cells that comprise your immune system. It’s easy to understand why: your digestive tract is a major entry port for all sorts of foreign invaders, on or in our food. But, it’s also home to archaea, fungi, good bacteria and ten times more viruses. This ecosystem of foreign bodies is called the Microbiota. Its cell count outnumbers your own and it is increasingly considered part of your immune system by scientists.

The microbiota plays a fundamental role on the induction, training and function of the host immune system. In return, the immune system has largely evolved as a means to maintain the symbiotic relationship of the host with these highly diverse and evolving microbes.

Yasmine Belkaid and Timothy Hand Role of the Microbiota in Immunity and inflammation

In nature, we see how ecosystems deliver balance. The selfish actions of individual players from the smallest bug to the apex predator self-regulate. No single species triumphs or fails. It’s the same in a healthy gut. Every archaea, fungi, bacteria and virus is doing what it does, interacting with each other and with your immune system and the net result is harmony. Some viruses are helping to regulate bacteria. While some bacteria are helping to regulate your own immune response. Regulating immune response reduces inflammation and the likelihood of auto-immune disorders (where the body attacks itself), scientists increasingly believe. Incredibly, a bacteria cured mice of peanut allergy when it was introduced into their guts in an experiment.

Good bacteria help us get more from our food as well. You have bacteria that help you digest stuff; they have genes we don’t possess that do tricks we can’t, metabolising things we’d otherwise struggle to breakdown – like complex carbohydrates. For example, many Japanese people carry a bacteria in their gut called bacterioides plebeius. This bacteria enables them to better digest seaweed.

Gut Bacteria Prevent Infectious Disease

Native bacteria also help keep invasive or unhelpful bacteria at bay. Strong colonies of healthy bacteria make it more difficult for undesirables to grow out of control. You may not realise that 1 in 30 of us carry a nasty bacteria called Clostridium difficile around in our digestive system. We only experience unpleasant symptoms of diarrhoea when they multiply out of control. This often happens because the balance of bacteria in the gut has been upset by antibiotics.

Microbes in the gut also coach the immune system, helping to prevent infectious diseases. Deficits in the microbiota (this non-human gut ecosystem) lead to the incomplete development of the immune system. In animal testing, germ-free mice (without a gut microbiota) showed broad decreases in T cells throughout their bodies – not just in the gut. Plus, their capability to secrete antibodies and immune response capability are significantly impaired compared with healthy but not germ-free mice. It seems that through the constant interaction with microbes in your gut, your immune system learns and builds capability.

Your Gut is More Unique Than You

You’re more microbe than human and your microbiome is more unique than you are!

We each host around 30 to 50 trillion ‘foreign’ cells, in addition to our own 30 trillion or so cells. This hosted ‘microbiome’ is more unique than you are: 99.9% of your DNA is shared with everyone else; we only share 80-90% of our gut microbe genes. Indeed, variety is the key to a healthy microbiome; we should aim to play host to a broad and diverse ecosystem. One where no single actor runs out of control. Scientists are linking the absence or balance of different microbes in our microbiome to obesity, auto-immune diseases, depression and mental health, cancer and much more.

What we eat can harm or help our gut biome, with all the positive or negative effects already explained. As with any diet, eating right means eating more of the good stuff and less that’s unhelpful. Briefly, the good stuff is: fibre, vegetables, fruit (in moderation), prebiotics – that’s onions, garlic, leek, banana, asparagus, kelp, etc – and fermented foods like kefir, kimchi, tempeh, yoghurt, miso. These foods contribute to the diversity and health of your gut for your good health. The next article will detail more about these foods and why we need them. Then we’ll discuss what you should be avoiding in your diet.

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