How to improve gut health: feed the bacteria that work for you.

To improve gut health, start with your plate: more variety of plants, fibre built up slowly, a fermented food if you tolerate it, less sugar, processed food and alcohol. Then sleep and stress, which affect your gut too. Your gut microbiome, the bacteria living there, shifts with every meal.

You've just finished antibiotics, your stomach changes daily and your energy comes and goes. I see it often in the people I work with: the first move is nearly always a trip to the chemist.

What are the signs of poor gut health?

The signs go beyond your stomach. Bloating and irregular bowels often come with others.

• You crave something sweet. Mid-afternoon you want it even when you're not hungry.
• Your head goes foggy. In long meetings you struggle to stay on track.
• You catch every cold going. There may be a link: between 60 and 70% of your immune system lives in your gut.

What damages your gut bacteria?

Mostly the way you eat and live. Sugar, ultra-processed food, alcohol, stress, poor sleep and some medicines, such as antibiotics, change your gut bacteria: doctors call it dysbiosis.

What ferments matters. Good bacteria work slowly on fibre and make butyrate, the fuel that keeps your gut lining tight. Too much sugar speeds fermentation up and lets opportunistic bacteria take over: the lining can loosen and low-level inflammation simmers on.

It does more than you think. Your gut makes much of your serotonin, which helps regulate mood and appetite, and your gut flora recycles some hormones your liver sends out in bile. A disrupted microbiome is also one of the twelve recognised mechanisms of ageing.

Eating the same things. In a comparison of older people, those with a varied diet had richer gut flora and were less frail. The same desk sandwich all week matters more than it seems.

How to improve your gut flora, at the table and beyond

Thirty plants a week. Vegetables, fruit, pulses, nuts, seeds, herbs and spices each count once. A five-ingredient salad with walnuts and almonds already makes seven.

Fibre, a step at a time. Aim for 20-30 grams a day from vegetables, pulses and whole fruit. Add a portion at a time, with more water: double it overnight and your gut complains.

A fermented food, if it agrees with you. Sauerkraut, kimchi or plain yoghurt, if dairy suits you. In a comparison of two groups, a diet rich in fermented foods increased gut bacteria variety and lowered signs of inflammation more than fibre alone, in the short term. Start with a spoonful.

Take away before you add. Fizzy drinks, packaged cakes and snacks contain emulsifiers and sweeteners that can upset your gut flora. Protein bars and shakes that replace a real meal starve your good bacteria of fibre.

Protein, spread out and chewed well. Protein that reaches your lower gut poorly digested ferments badly and leaves toxic by-products. Better 20-40 grams a meal than a huge steak at a client dinner, wolfed down.

Drink, sleep, stress. Alcohol harms your good bacteria. Short nights and constant stress upset your gut flora too.

The mistake nearly everyone makes. After antibiotics, buying probiotics and carrying on with lunch on the go, drinks after work and five hours' sleep.

Start with this week's shop: more colours, less packaging. In a month, notice how you feel mid-afternoon.