Probiotics – got a gut feeling?

| 21 August 2018
minute reading time

The food and drink we now consume is far-removed from that of our ancestors, whose food and water were contaminated with soil bacteria. This constantly replenished their gut flora with a healthy population of beneficial bacteria.

Today, it’s a different story. Stress, illness, poor diet and antibiotics can all disrupt the delicate balance and lead to a whole string of conditions – allergies, coeliac disease, Crohn’s disease, diarrhoea, inflammatory bowel disease, gastric cancer, obesity and type 2 diabetes. However, when our gut flora becomes unbalanced with high levels of harmful bacteria, probiotics can help restore the balance.

Probiotic means ‘for life’ and is a term used to describe the ‘friendly’ bacteria and yeast found in certain foods and supplements. The World Health Organisation defines probiotics as: “Live microorganisms which when administered in adequate amounts confer a health benefit on the host”. Most probiotics are bacteria commonly used ones are Lactobacillus and Bifidobacterium. The yeast Saccharomyces boulardii has also been used to combat inflammatory bowel disease and diarrhoea.

Probiotics are available in tablets, capsules, powders and drinks and they are also found naturally in some fermented foods such as sauerkraut, miso soup, tempeh and kombucha tea, as well as live yoghurts. However, obtaining probiotics from food can be tricky as manufacturers are not required to say how much in the way of bacteria they contain. Eating live yoghurt for your probiotics may be pointless as one pot usually contains just a few million organisms and you would need to consume dozens of pots to obtain the number of bacteria required to match a good probiotic.

Don’t confuse probiotics with prebiotics, which are the ‘foods’ that probiotic bacteria thrive on, plant-based foods such as leeks, garlic and onions or extracts from them – lactulose, lactitol, fructo-oligosaccharides and inulin.

Good bacteria benefit your health in different ways. They may stick to your intestinal cell walls, forming a protective barrier; they may regulate the immune system, helping it respond to viruses and substances that trigger allergies. Probiotic bacteria can knock out harmful bacteria by producing antimicrobial substances or by creating a hostile environment such as making the gut more acidic. Some may produce useful enzymes or beneficial metabolites while others may affect your nervous system, altering pain responses and promoting pain relief.

Probiotics are often recommended following a course of antibiotics as antibiotics kill off bacteria indiscriminately and probiotics can re-populate the gut with friendly bacteria. However, up to 90 per cent of the probiotic bacteria in yoghurt drinks may not survive the journey through the stomach because of gastric acid and bile salts. Because of this, the food industry is now developing capsules that protect probiotics from stomach acid.

There are many different causes of diarrhoea, including antibiotics, infection and illness. Probiotics such as the yeast Saccharomyces boulardii and the bacteria Lactobacillus casei, L. bulgaricus and Streptococcus thermophiles, can be effective against antibiotic-associated diarrhoea. If you’ve recently taken antibiotics or suffer from an imbalance of gut bacteria, probiotics may help. However, using fewer antibiotics is the obvious and best method for prevention.

Asthma, eczema and hay fever have dramatically increased worldwide, especially in industrialised countries. Evidence suggests that probiotics may help reduce the risk, particularly of eczema. However, many people are allergic to, or intolerant of, cow’s milk and dairy products so probiotic dairy foods are obviously not advisable.

Probiotics may produce a modest reduction in blood pressure and cholesterol levels, maybe because they can increase the absorption of nutrients and plant hormones which can help to widen blood vessels. They may also help reduce blood glucose levels and so delay the onset of diabetes. A reduction in body weight also helps to lower blood pressure and probiotic studies are showing promising results.

Of course, you could just eat healthier foods that naturally lower cholesterol, such as soya protein (tofu and soya milk), oats, nuts, vegetable oils and fibre. There’s no question that the key foods for good health are fruit, vegetables, wholegrain foods and pulses such as peas, beans and lentils. A big plus is that they also reduce your risk of obesity and diabetes.

Unhealthy gut flora can increase the risk of inflammatory bowel disease (IBS), which in turn can increase the risk of colon cancer. Probiotics such as Lactobacillus casei have helped alleviate IBS in some people, reduced nausea, indigestion, abdominal pain, bloating, flatulence and disrupted bowel movements. The jury is still out on constipation and Crohn’s disease but some studies suggest probiotics can help.

In general, probiotics may offer significant health benefits by reducing inflammation, boosting the immune system and decreasing the activity of enzymes which produce cancer-causing compounds in the gut. This is a new and exciting area of research but more studies are needed before it’s possible to give reliable recommendations.

Probiotics are generally regarded as safe but if your immune system is weakened by illness or medication, probiotics could have a negative effect and even some healthy people experience diarrhoea when they take them. People with lactose intolerance should obviously avoid dairy products containing probiotics and caution is advised when using probiotics in premature babies or those with an immune deficiency.

Good bacteria may be boosted by probiotics but eating a plant-based diet does the same thing. Gut flora is strongly affected by diet and as vegans have the healthiest diet, their gut flora tends to have lower levels of the harmful bacteria that cause disease and higher levels of protective bacteria. Reduced inflammation may be the real key that links vegan gut flora with greater health benefits. It doesn’t take a long time either as the benefits of changing your diet can happen fast.

If you need to bring out the big guns to repopulate your gut after taking antibiotics then a probiotic supplement may help. It’s best to take it before you eat, before your stomach fills up with acid. If you are taking antibiotics, try to space out the time between taking the antibiotic and the probiotic. Check the potency and choose the right ones for what you are hoping to achieve.

If you are simply trying to be the healthiest you can, then populating your gut naturally with good bacteria can certainly be achieved with a healthy, vegan diet. The prebiotic fibre you naturally eat on this diet will feed the healthy bacteria in your gut – it’s a win-win situation!

About the author
Dr. Justine Butler
Justine joined Viva! in 2005 after graduating from Bristol University with a PhD in molecular biology. After working as a campaigner, then researcher and writer, she is now Viva!’s head of research and her work focuses on animals, the environment and health. Justine’s scientific training helps her research and write both in-depth scientific reports, such as White Lies and the Meat Report, as well as easy-to-read factsheets and myth-busting articles for consumer magazines and updates on the latest research. Justine also recently wrote the Vegan for the Planet guide for Viva!’s Vegan Now campaign.

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