Foods for best gut health

By now you probably know that your gut bacteria dramatically influences your health, but what foods ensure you get the best mix of bacteria? Dietitian Paula Norris provides a guide.

One of science’s most intriguing discoveries of recent years is the link between our gut bacteria (or microbiota) and our health. A connection between microbiota balance (good bacteria vs bad bacteria) and weight has been clearly established, but recently, links to our immune system and diseases such as cancer and arthritis have also been discovered. It seems that our gut, and the foods we put in it, is way more critical to our health than we ever expected.

More than just digestion

Gut microbes make nutrients needed to digest carbohydrates for energy, help absorb vitamins in the body and help maintain gut structure, function, cell growth and anti-inflammatory activity. The good microbes help prevent overgrowth of nasty organisms such as salmonella or rotavirus (the cause of gastro or gastroenteritis).

Since the gut houses most of the body’s immune system, with approximately 80% of white blood cells found in the gut, having a good gut microbiota can positively influence your immune system too. Since our gastrointestinal tract is constantly being exposed to antigens and microbes from the outside world, having an internal army to fight the nasties is crucial.

If symptoms of Irritable Bowel Syndrome (IBS) impact on your day-to-day life, then trying to improve your gut microbiota might just be worth a try. Links have been made between good gut microbiota and reduced IBS-type symptoms and improved regulation of bowel movements.

In some places, Gastroenterologists are starting to perform Faecal Microbiota Transplantation (FMT) where healthy and balanced human microbiota is introduced into the bowel of someone with abnormal or unbalanced microbiota in order to kill off as many bad bacteria as possible and restore the balance. FMT is currently being used in some centres to treat conditions such as severe IBS and Clostridium Difficile (C. diff) which causes severe diarrhoea and colitis.

The critical balance

The balance of good vs bad microbes in our gut is critical. With somewhere in the range of 100 trillion microbes in our guts, and combinations of over 10,000 different species, the diversity seems endless.

You will have heard of probiotics, which refers to living “good” bacteria that have some potential benefit to the host. Lactobacilli and Bifidobacterium probiotic strains are the most commonly found strains of probiotics in both food and supplements.

What studies are saying

Early studies, mostly in rats and mice, show links between gut microbiota and the receptors that regulate mood, anxiety and depression, as well as increasing the availability of tryptophan — the precursor to the “happy” hormone serotonin.

It’s been shown that gut microbiota produce up to 95% of the body’s serotonin, which is then communicated back to the brain by the millions of nerve cells in the gut. So as well as nourishing our bodies with loads of nutrients, it seems this could even be the reason why we feel happier when we eat healthier.

Studies are also being conducted investigating the potential link between a healthier gut microbiota and the prevention and treatment of allergies, some cancers, inflammatory bowel diseases, coronary heart disease, asthma, diabetes and arthritis, just to name a few. And when it comes to weight gain, these 100 trillion bacteria also seem likely to play a role in how we convert food into energy and absorb calories. This could have huge implications in the future.

However, it must be stressed that most of the emerging evidence has been conducted in animal studies, and results therefore are not suitable or applicable to humans at this point. However, it is shaping up to be a very exciting area of medicine.

How you can change your gut microbiota

Many factors that we can’t control influence the makeup of our gut microbiota, from our genetics to where in the world we live. There are so many contributing factors, that each of us has our own unique gut microbiota. However, here are a few things that you can do to improve your gut microbiome:

1. Eat prebiotic fibre

Prebiotic fibre stimulates the growth and activity of the probiotic organisms (good bacteria) through the process of fermentation. Many high-fibre foods contain some prebiotics, the most common being FOS (Fructo-oligosaccharide), GOS (Galacto-oligosaccharide) and inulin. Get more prebiotic fibre by eating:

  • Legumes: chickpeas, lentils, red kidney beans
  • Fruit with the skin on: custard apples, nectarines, peaches, watermelon, pomegranate, grapefruit
  • Vegetables: chicory, garlic, onion,
    leek, asparagus, beetroot, green peas,
    snow peas, sweetcorn
  • Wholegrains: oats, barley, rye bread, pasta, cous cous, whole wheat breads
  • Nuts: cashews, pistachios

As well as helping to increase the good bacteria in our gut, prebiotic fibre also increases satiety, helps absorb nutrients, lowers cholesterol, improves bowel function and regularity and can be protective against some cancers.

2. Eat probiotic-rich foods

Eating probiotic-rich and fermented foods can increase the amount of good bacteria in your gut. The obvious and most common source from food is yoghurt. The probiotics found in yoghurt are the lactic acid bacteria, tough enough to make it through the acidic environment in our stomachs to the small intestine.

But not all probiotic yoghurts contain the level of lactic acid bacteria that has been shown to have a positive digestive effect. Look for products where a serving size would give you about 100 million cfu (colony-forming units) each day. Activia, Vaalia and Jalna are some examples of brands available in Australia. Yakult also contains lactic acid bacteria at the required levels for digestive benefits.

Other foods to include are cottage cheese, kefir and fermented foods such as sauerkraut, miso paste and kimchi.

3. Steer clear of processed foods

Improved gut microbiota is just another reason on a long list to steer clear of highly processed foods. High fat and high sugar foods can negatively impact your gut microbiota in a big way.

4. Control your stress levels

In a vicious cycle, just as an unbalanced gut microbiota is likely to increase stress levels, stress levels have also been shown to negatively impact on your gut microbiota by decreasing the amount of organisms and their diversity.

5. Avoid heavy drinking

Excessive alcohol intake has been linked with a reduced amount and lower diversity of gut microbiota.

Should you be taking a probiotic supplement?

Studies showing benefits of taking probiotic supplements have their limitations, and benefits associated to one specific probiotic strain cannot necessarily be applied to other strains. For this reason, there is no hard and fast recommendation around taking a probiotic supplement.

However, as probiotics are generally considered safe, there are some times when temporarily taking a supplement is likely to be beneficial. These times include: after a course of antibiotics, after a bout of diarrhoea, during times of stress, when travelling where food and water-borne illness is a possibility or following the onset of uncomfortable gut symptoms like bloating, constipation or wind. If you choose to take a probiotic then ensure you store it correctly — it’s often recommended that you store them in the fridge so read the label.

While more research is still needed to prove the link between gut microbiota and diseases, the best thing you can do to positively alter your gut microbiota is to implement and be consistent with good dietary practices. It proves to be just one of the many reasons to eat more wholefoods, fruit, vegetables and wholegrains.

Watch this space, but for now, eat well and be happy!


Paula Norris is the inspiration behind popular Instagram account @MovingDietitian, and is passionate about motivating everyone to find healthier and fitter version of themselves. Paula, an Accredited Dietitian, is continually driven to dispel nutritional myths and expose the facts about products that many companies don’t want you to know. Follow her on Instagram and Twitter @movingdietitian and Facebook @movingdietitianAU for the latest on nutrition trends and product insights.