That feeling in your stomach about making a decision. Butterflies before giving a speech or taking an exam. Upset stomach if nervous. What we feel in our gut is not a coincidence, it’s inextricably linked to our mental state. Professor Mary Tabacchi looks at the evidence and how to create good gut health...

Why does a person sometimes get an upset stomach from eating and sometimes not? When does a diet become inflammatory versus healing and the ability to build up the immune system? When does food store up energy, so the body functions efficiently, so we can do physical work with ease?

Researchers have long suspected a strong gut-brain connection. In 1822, at a Northern Michigan military outpost, Dr William Beaumont studied a soldier who had been shot in the abdomen. He discovered that when the patient was angry his stomach produced more acid and when relaxed he could digest readily, with no pain.

This explains why heart disease, inflamed veins and arteries, allergic reactions, rashes and joint pain all happen according to the emotional state. The brain can trigger emotions and emotions may determine whether the food is readily digested or causes a stomach ache or diarrhea. Equally a healthy gut sends neuro peptides to the brain which calm us and create a positive mental outlook.

The spleen, liver, lymph and blood bone mechanisms are well known immune centres, however, for more than 20 years, scientists have suspected there is a gut immune connection. We know the human microbiome found on skin and the so called fecal excretory system influences health.

Our skin and our guts are part of our personal microbiome, which is the larger picture concerning bacteria and the body. Research suggests gut microbiota influence growth, body size, immunity, lifespan, obesity, heart disease, diabetes, allergies, skin health and so-called lifestyle diseases.

The microbiota may weigh one to five pounds in the average person. They outnumber human cells by 10 to one. Microbiota have traditionally been poorly understood by scientists and physicians, which led to an over emphasis on cleanliness, but we need to encounter some dirt for our health. Children need to play in the mud, or on the grass, in order to be healthy: it increases the microbiota for their gut health. While it might be a good idea to use hand sanitiser outside the home during the time of Covid, in the house we don’t need to use it much.

How it all works
Unsurprisingly, diet strongly effects the gut-brain connection and generally a high fibre diet benefits the gut and promotes healthy skin. Dietary fibre is composed of soluble and non-soluble components, both of which have positive effects upon blood cholesterol, triglycerides (a fat which enters our body after a meal) and other blood lipids (fats). Insoluble fibre is in wholegrains, dried peas, beans and nuts and stimulate intestinal transit which prevents constipation and stimulates production of immune factors.

The reactions between the fibre and the gut microbiota create prebiotics and their action in the gut causes the formation of probiotics: part of our microbiome and the good bacteria which fight off bad bacteria.

The ratio between monounsaturated (omega-3) oils and polyunsaturated (omega 6 oils) in our diet is also a crucial element of a healthy gut. Most Americans don’t have a healthy balance between the two and, on average, eat 10 times more omega 6 fats than omega 3. Omega 3 fats can help protect the heart and blood vessels from disease, lower triglycerides, improve circulation and prevent blood clots. Fish is the best source of omega 3 oil but it is found in nuts and seeds.

Unfortunately, many people misunderstand the role of complex carbohydrates and gluten-free diets are now an expensive industry. These diets can often disavow complex carbohydrates, but fibre is an essential complex carbohydrate and starch is a complex carbohydrate. Only about 1 per cent of people are truly gluten enteropathy and must remain gluten free. Fibre and low fibre complex carbohydrates are essential parts of physiology.

Digestible complex carbohydrates are enzymatically broken down slowly, especially when eaten with other foods which means glucose is steadily delivered into the blood, to the cells. The misunderstanding of the glycemic index is that few people eat carbs alone. Uninformed consumers think bananas are too high on the glycemic index. Not so.

What to eat
The Mediterranean Diet is ideal for gut health. A lifestyle rather than a diet, it includes many vegetables and fruit, of various colours, which are anti-inflammatory. Think about spinach, carrots, tomatoes, oranges, peaches, raspberries and blueberries among others. Vegetables and fruits are also very nutritious as they contain the precursors of many vitamins. The Mediterranean lifestyle is a high fibre regimen. It contains less meat, so is very environmentally conscious and if families can’t afford fresh vegetables and fruits, frozen and canned items are excellent.

We thought we had escaped the disastrous results of Covid, but now we must prevent the infectious Omicron virus. Of course it is very important to have the vaccines, but just as important is the gut-mind connection. It gives us a powerful immune response. As well as eating well and exercising, we must relax.

In 1987, Herbert Benson and Joan Borysenko discovered that a relaxed and positive mindset is tremendously important. Eat nutritious food, take exercise and sleep well. If meditation works for you, please do it. I tend to meditate when I am hiking. Nature is a great healer, so hike in a forest or green space if you are able to. I can’t stress exercise enough, maybe push yourself a little. The mind-gut connection is real and very important. Our mental states can be related to foods as well as the proper amount of exercise.

Since we have established the microbiome is critical, especially in the intestines, the gut-brain connection is key. You are not only what you eat, but what you think. The state of mind influences the gut and the immune system. Physiological and neurological sciences intertwined. We are beginning a new era in psychoneuroimmunology.