The term probiotic literally means ‘for life’ and is used to describe the benefits of ‘friendly’ bacteria and yeasts found in fermented foods such as live Bio yoghurts, fermented milk drinks and probiotic supplements. Many probiotic supplements claim to offer benefits, but you need to select the right strains for different needs.
The most common probiotics are bacteria that produce lactic acid such as Lactobacillus acidophilus, Bifidobacterium longum and related strains. Because these are acid and bile tolerant, a significant number survive passage through the stomach and small intestines to reach your large bowel.
Health benefits of probiotics
According to the World Health Organisation, probiotics are, by definition, ‘live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host’. Yet, the European Food Safety Authority have so far rejected all health claims for probiotic supplements – not because they lack evidence of effectiveness (they didn’t get as far as considering the studies) but because of difficulties in accurately identifying the particular strains of bacteria for which the claims were filed.
Different probiotic bacteria offer different health benefits and it’s important that these are assigned to the right strains. So when checking labels, you will now often see species identified according to genetic markers and, instead of plain Lactobacillus acidophilus or Bifidobacterium lactis, for example, you will see specific strains such as Lactobacillus acidophilus La-14 and Bifidobacterium lactis HN019. This will help you select the strains with the best research evidence to support their use.
Your bowel bacteria
There are more bacteria in your colon than there are human cells in your body and, together, these bacteria typically weigh an astonishing 1.5 kg and make up around half the bulk of your bowel motions. This will depend on your diet, as every gram of fibre you eat, which fuels the growth and division of bacteria, increases the weight of bowel motions by 5grams.
Probiotic bacteria play an important role in maintaining digestive health by:
- Producing lactic acid and acetic acid to suppress the growth of less acid-tolerant bacteria, including those that cause gastroenteritis such as Bacillus cereus, Salmonella typhi, Shigella dysenteriae, Staphylococcus aureus, Clostridium difficile and Campylobacter species
- Secreting natural antibiotics known as bacteriocins to suppress the growth of harmful bacteria
- Competing with other bacteria for attachment sites on intestinal cell walls – literally crowding them out so they pass through your intestines without gaining a foothold
- Competing with harmful bacteria and yeasts for available nutrients to suppress their growth
- Secreting vitamin K, B group vitamins, biotin and folic acid which you can absorb and use
- Secreting short-chain fatty acids such as butyrate (the main energy source for your colon cells), and propionate which has beneficial effects on the liver to reduce inflammation and improve cholesterol balance
- Stimulating your own immune production of natural antiviral substances such as interferons
- Priming and stimulating your immune reactions against harmful bacteria.
Ideally, at least 70 per cent of your bowel bacteria should be healthy ‘probiotic’ strains of Lactobacilli and Bifidobacteria, and only 30 per cent should be other bowel commensals such as E. coli. In practice however, the balance is usually the other way round.
Lack of probiotics
A surprising number of scientists are prepared to sieve, culture and analyse human stool samples to assess the presence or absence of certain bowel bacteria. These studies suggest that lack of probiotic bacteria in the colon is common, and can result from:
- physical or emotional stress
- previous antibiotic treatment
- gastrointestinal infections
- poor dietary habits
- smoking and alcohol consumption.
Lack of probiotic bacteria in the intestines creates an unhealthy environment that allows other, potentially harmful organisms – viral, bacterial and fungal – to thrive. This disrupts digestion of fibre, increases production of gas and bowel irritants, and frequently leads to symptoms such as those associated with irritable bowel syndrome.
When a lack of probiotic bacteria leads to clinical symptoms, the abnormal intestinal balance is described as a dysbiosis.
Dysbiosis has been linked with the development of a number of health problems, including food intolerance, bloating, flatulence, diarrhoea and constipation. It also increase the chance of developing long-term intestinal problems such as irritable bowel syndrome, diverticular disease, and possibly even inflammatory bowel disease.
Replenishing your probiotic strains
Dietary sources of probiotic bacteria include live Bio yogurt, fermented milk drinks and probiotic supplements in tablet or capsule form. While probiotic dairy and juice-based drinks are available, many people prefer to take their probiotics in supplement form.
Probiotic supplements contain live probiotic bacteria which are held in suspended animation through modern techniques such as freeze drying, spray-drying or microencapsulation. Once they are rehydrated, they will re-activate within the bowel.
These supplements have the advantage of providing a blend of four or more strains of different bacteria, rather than just the one or two that can survive together in a dairy-based medium.
Probiotic capsules are virtually calorie-free as they do not need to provide sugar to keep their ‘hibernating’ bacteria alive. They have a significantly longer shelf life and many do not need refrigeration, making them especially useful for travelling abroad.
Supplements also provide a guaranteed potency of live probiotic bacteria. In contrast, the active bacteria found in yoghurt and fermented drinks are fragile and, after being kept in a fridge for several days, or even weeks, will contain less live bacteria than when they were freshly prepared.
How to select a good probiotic supplement
Each species of probiotic bacteria occupies a different niche among the trillions of bacteria within your bowel, and each offers different health benefits.
When selecting a probiotic supplement, there are 3 main things to look for:
- How many strains are included? You want a product that supplies at least 4 different strains for optimum benefits.
- Is each strain individually identified? For example, instead of plain Lactobacillus rhamnosus, does it contain Lactobacillus rhamnosus NCIMB 30174 or another characterised strain?
- How many of each strain are present? Look for the CFU (colony forming units) number as this tells you how many live bacteria are provided in suspended animation per dose – ideally guaranteed at the time of expiry, rather than the date of manufacture.
If you haven’t taken probiotics before, it’s usually best to start with a relatively low dose, such as 5 billion CFU, and increase slowly, if needed, to 10 billion CFU, then 20 billion CFU and even 50 billion CFU or more, if your symptoms have not resolved.
There are two reasons for this. The most important is that it takes a while for your bowel to adapt to a sudden change in bacterial balance. If you suddenly take a very high dose of 50 billion CFU, some people (but not everyone) will develop side effects such as bloating, abdominal cramps or diarrhoea. The second reason is that probiotic supplements are not cheap, and the higher doses are more expensive. If a lower dose solves your bloating or constipation or Candida, then you will save money.
Never take more than the manufacturer’s recommended dose.
Which are the most beneficial probiotic species?
The main probiotic bacteria included in supplements, in various combinations, to provide all-round digestive and immune health benefits are specific strains of:
- Lactobacillus acidophilus
- Lactobacillus paracasei
- Lactobacillus plantarum
- Lactobacillus brevis
- Bifidobactaerium bifidum
- Bifidobacterium lactis
- Bifidobacterium longum.
Different manufacturers will provide different specific strains (identified by tags such as La-14 or Bl-04). Where possible, select a supplement that identifies these individual strains as this shows the species is well researched, characterised and scientifically validated.
Probiotic bacteria and irritable bowel syndrome
Loss of probiotic bacteria and increased numbers of gas forming bacteria are associated with irritable bowel syndrome (IBS). Replenishing your level of probiotic bacteria can significantly improve associated symptoms such as bloating, discomfort, constipation and diarrhoea.
These benefits are thought to result from a combination of suppressing the level of gas-producing bacteria, reducing gut permeability, reducing perception of intestinal contractions and raising the sensitivity threshold for bowel stretch and pain receptors.
Data from 16 clinical trials, comparing 700 people with irritable bowel syndrome (IBS) who took probiotics and 575 who took placebo, showed that twice as many taking probiotics experienced a greater than 50% reduction in IBS symptoms compared with those taking placebo (53.3% versus 27.7%). Improvements were seen in less than 8 weeks treatment and greatly improved quality of life.
Another analysis of 1793 people with IBS focussed on abdominal pain scores and found that those taking probiotics were almost twice as likely to respond as those on placebo and, in studies looking at distension, bloating, and flatulence, symptom severity was 2.57 fold less with probiotics than with placebo.
Click here to read my review of Enterosgel for treating diarrhoea-predominant irritable bowel syndrome.
Beneficial strains for IBS: Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus casei, Lactobacillus helveticus, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus rhamnosus GG, Bifidobacterium breve, Bifidobacterium infantis, Bifidobacterium lactis, Bifidobacterium longum
Probiotics and traveller’s diarrhoea
Probiotics can help to prevent or reduce the severity of intestinal infections (gastroenteritis) when travelling, including those that cause serious vomiting and diarrhoea, such as Bacillus cereus, Salmonella typhi, Shigella dysenteriae, Staphylococcus aureus and Campylobacter species. Even if you don’t take probiotics at any other time, you should definitely consider them when travelling to foreign countries – especially those where hygiene is less controlled.
Multi-strain products will offer the widest range of protection against acute infectious diarrhoea.
Beneficial strains: Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus rhamnosus GG, Bifidobacterium breve, Bifidobacterium infantis, Bifidobacterium longum
Probiotics and antibiotic-associated diarrhoea
Broad-spectrum antibiotics can be life-saving when they eradicate harmful bacteria. But they also kill beneficial probiotic bacteria, and can produce intestinal side effects such as antibiotic-associated diarrhoea and secondary Candida yeast infections.
Data from 23 studies show that, compared with placebo, probiotics can reduce the risk of antibiotic-associated diarrhoea by 54% in children, while data from 30 clinical trials show that taking a probiotic supplement can reduce the risk of antibiotic-associated diarrhoea by 31% in adults aged 18 to 64 years.
No significant effects were found in older people, however. Currently, the most researched strain for preventing antibiotic associated diarrhoea is Lactobacillus rhamnosus GG.
Beneficial strains: Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus bulgaricus, Lactobacillus paracasei, Lactobacillus rhamnosus GG, Bifidobacterium infantis, Bifidobacterium lactis, Bifidobacterium subtilis
Probiotic bacteria for allergies
When taken during pregnancy, probiotic supplements may reduce the development of allergic conditions in the offspring, by stimulating the production of antibodies rather than allergic reactions associated with atopic conditions such as eczema and asthma.
Results from 17 trials, involving 2947 infants, suggest that when probiotics are both taken prenatally and given to the infant after birth could reduce the risk of the infant developing atopy by 29%, and the risk of food hypersensitivity by 23%.
Beneficial strains: Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus paracasei
Probiotics for lactose intolerance
Because lactic acid bacteria ferment milk sugar (lactose) and convert it to lactic acid, they may improve symptoms associated with lactose intolerance. Research findings are conflicting, however. One review of 9 studies that measured breath hydrogen (to confirm lactose intolerance) found that 3 showed benefit, 3 showed no effects, and 3 were inconclusive. In seven studies that measured symptoms, only one yielded positive results.
Beneficial strains: Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus rhamnosus, Lactobacillus salivarius, Lactobacillus paracasei, Bacillus coagulans, Bifidobacterium bifidum, Bifidobacterium lactis, Bifidobacterium longum
Probiotics for immunity against colds
The immune system is primed within the lining of the small intestine within areas called Peyer’s patches. It’s therefore not surprising that even low doses of probiotic supplements can boost immunity against infections.
Results from 11 clinical trials, involving 2417 children aged 10 or below, found that probiotics significantly reduced fever, cough, runny nose and middle ear pain compared with placebo, shortened the duration of the cold by around 1 day, reduced the need for antibiotics, and decreased the occurrence of new colds, with no safety concerns.
A cochrane analysis of 12 trials, involved 3720 children and adults also found that probiotics were better than placebo, and reduced the chance of experiencing at least one to three acute upper respiratory tract infection by 47%, shortened a cold by 1.89 days, reduced antibiotic prescription rates by 35% and days off school.
Beneficial strains: Lactobacillus acidophilus, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus rhamnosus GG, Bifidobacterium lactis
Click here to read my full review on natural cold remedies that really work.
Probiotics plus multivitamins
Vitamins, minerals and probiotics have a synergistic effect on immunity, as most micronutrients – especially vitamin E, iron and selenium are needed to boost the production of antibodies and other infection-fighting chemicals.
The combination of probiotic bacteria plus a multivitamin and mineral supplement can significantly reduce the severity of colds, and reduce the duration of common cold and ‘flu episodes by almost 2 days, compared with those taking multivitamins and minerals alone. The researchers felt this was most likely through an effect on the activity of T-lymphocytes – the cells that regulate immune responses.
Taking a supplement that provides probiotic bacteria plus vitamins and minerals for at least three months during winter and spring was also found to reduce the severity and the incidence of common cold infections. Those taking the combination supplement were 13.6% less likely to develop cold and ‘flu symptoms than those taking inactive placebo (none were vaccinated against influenza). Symptom severity was also reduced by 19%, and the number of days with fever was reduced by more than half. Blood tests showed that all immune cells (leukocytes, T-lymphocytes and monocytes) showed increased activity, suggesting that this combination of supplements can stimulate cellular immunity.
Probiotics for lowering cholesterol
Probiotics secrete anti-inflammatory substances and fatty acids that are absorbed into the circulation and travel directly to the liver, where they can have beneficial effects on cholesterol production.
Results from 30 trials, involving 1624 people found that, compared with placebo, taking probiotics reduced total cholesterol by 7.8 mg/dL and ‘bad’ LDL cholesterol by 7.3 mg/dL. Another analysis of 11 clinical trials confirmed that probiotic supplements (fermented milk products and probiotics) reduced total cholesterol by 0.17 mmol/L, ‘bad’ LDL-cholesterol by 0.22 mmol/L to help reduce the risk of cardiovascular disease. No effects were seen on ‘good’ HDL-cholesterol or triglycerides.
Beneficial strains: Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus reuteri, Bifidobacterium lactis
Probiotics for urinary tract infections
Nine out of ten urinary tract infections are caused by the bowel bacterium, Escherichia coli, which find their way from the bowel into the bladder. By suppressing their growth, probiotic bacteria may help to protect against urinary infections. Many women in particular find probiotic supplements beneficial, but the results from clinical trials is mixed.
Data from 2 studies, involving 127 women, found that certain Lactobacillus strains did reduce the risk of urinary tract infections compared with placebo.
Another analysis of data from 9 studies, involving 735 people, compared the effects of probiotics against inactive placebo, no treatment, or against antibiotics. Compared with placebo, taking probiotics reduced the relative risk of a urinary tract infection by 18%, but this was not statistically significant. Compare with antibiotics, there was no significant reduction in the risk of recurrent urinary symptoms, which is hardly surprising.
Click here to read my full review of cranberry supplements for urinary infections.
Beneficial strains: Lactobacillus rhamnosus GR-1, Lactobacillus reuteri B-54, Lactobacillus reuteri RC-1
Probiotics for bacterial vaginosis
Bacterial vaginosis is a common condition in which there is a loss of probiotic bacteria in the vagina. This can lead to unpleasant symptoms such as discharge, soreness, irritation, painful sex and a strong odour. having bacterial vaginosis during pregnancy can also increase the risk of miscarriage and preterm delivery.
Taking a probiotic supplement and/or using probiotic pessaries are the quickest way to replenish vaginal probiotic bacteria, and can be used together with specific antibiotics (eg metronidazole, clindamycin) designed to eradicate the other bacteria present.
The results from 12 trials, involving 1,304 women with BV showed that taking probiotic supplements significantly improves the cure rate for BV by 153%.
Click here to read my full review of how to overcome bacterial vaginosis.
Beneficial strains: Lactobacillus acidophilus, Lactobacillus plantarum P176530
Probiotics for Candida yeast infections (thrush)
Candida yeasts are normally present in the vagina without causing problems. Occasionally they can overgrow to cause a soreness, itching, and a cottage-cheese like discharge. Probiotic supplements and/or pessaries can help to suppress Candida overgrowth.
A study involving 436 women with recurrent vaginal Candida albicans infection compared the effects of antifungal medications with or without the use of ten local applications of a vaginal probiotic preparation. In those using the antifungal medication, symptoms continued in 79.7% of women. In those also using the probiotic treatment, symptoms continued in 31.1%.
Investigations may also be needed to exclude an iron deficiency and diabetes.
Click here to read my full review of dietary approaches to overcome recurrent Candida.
Beneficial strains: Lactobacillus acidophilus, Lactobacillus plantarum P176530 Lactobacillus reuteri, Lactobacillus rhamnosus, Streptococcus thermophilus, Lactobacillus delbrueckii bulgaricus
Probiotics for weight loss
There is a lot of interest in how gut bacteria can affect appetite, food choices and weight loss. As it is such a new area, data remains scant. Analysis of the results of 4 studies which compared the effects of probiotics with placebo found only small reductions in body weight (1.77kg) and body mass index (0.77 kg/M2 reduction) which was not statistically significant.
However, there is evidence that one particular strain, Lactobacillus rhamnosus CGMCC1.3724 may offer benefits.
Beneficial strains: Possibly Lactobacillus rhamnosus CGMCC1.3724
Probiotics for inflammatory bowel disease
Inflammatory bowel diseases such as ulcerative colitis, Crohn’s disease, diverticulitis and pouchitis are serious conditions in which the integrity of the intestinal wall is breached. AS a result, intestinal bacteria and bowel toxins can enter the circulation, causing immune reactions and potentially serious complications such as sepsis.
Beneficial probiotic bacteria have the potential to reduce symptoms but must be well researched and shown to be safe when the bowel wall is inflamed and ulcerated.
A blend of 8 different probiotic bacteria is widely recommended by gastroenterologists to treat inflammatory bowel diseases. This is given in very high dose to flood the bowel with beneficial bacteria and suppress other species. This supplement, known as VSL#3 should only be used under medical advice and supervision to treat inflammatory bowel diseases.
When added to conventional therapy it was safe and more effective than conventional therapy alone in improving mild to moderately active ulcerative colitis, Crohn’s disease and pouchitis. In fact, probiotics even appear to have similar effectiveness to prescribed drugs (5-aminosalicylic acid) in maintaining remissions of ulcerative colitis.
Beneficial strains: VSL#3 contains a blend of 8 different strains of probiotic bacteria: Lactobacillus acidophilus DSM 24735, Lactobacillus plantarum DSM 24730, Lactobacillus paracasei DSM 24733, Lactobacillus delbrueckii bulgaricus DSM 24737, Bifidobacterium longum DSM 24736, Bifidobacterium breve DSM 24732, Bifidobacterium infantis DSM 24731, Streptococcus thermophilus DSM 24731
Probiotics and safety
Taking normal doses of probiotic bacteria has not raised any safety concerns across several hundred human clinical trials in healthy adults. If you have a condition that suppresses your immunity, however, or which is associated with intestinal bleeding or increased intestinal permeability, only take probiotics under medical advice and supervision.
Prebiotics and bowel health
Prebiotics are non-digestible fibres that acts as food for probiotic bacteria and selectively stimulate their growth. These ‘resistant’ fibres are not digested or absorbed within the small intestines, but travel intact to the large bowel where they provide energy for probiotic bacteria but cannot be fermented by other, less beneficial bowel bacteria.
Prebiotics include substances known as fructo-oligosaccharides (FOS) which are found in some foods such as oats, barley, wheat, garlic, onions, bananas, honey and tomatoes.
Probiotics and prebiotics are now increasingly used together, in a practice known as synbiotics or, sometimes, symbiotics.
If you have irritable bowel syndrome, however, you may benefit from AVOIDING prebiotic fibres and following a low FODMAP diet.
Few safety concerns are associated with prebiotics, but if you take too many they can themselves cause bloating, so only take small amounts (eg 5 grams or one teaspoonful) at a time.
The small amount included in some probiotic/prebiotic capsules is unlikely to offer any great benefits.
Prevention is better than cure
However you choose to obtain your probiotics, they should ideally be taken every day to replenish those naturally flushed from your body. There are no serious problems associated with continuous treatment, even at high dose, for healthy people.
If you have an inflammatory bowel disease, or a condition that lowers your immunity (such as cancer or HIV) seek individual medical advice before taking a probiotic supplement.
Replenishing your probiotic bacteria can improve your general sense of well-being, as well as helping to maintain a healthy digestion, immune system and circulation.
I firmly believe that everyone would benefit from taking probiotics, but they are especially helpful for those who:
- eat a nutrient-poor diet
- lead a busy, stressful lifestyle
- are currently on, or recently taken, antibiotics
- experience recurrent viral infections such as colds
- are travelling and at risk of gastroenteritis
- have been diagnosed with diverticular disease, irritable bowel syndrome, functional constipation or functional diarrhoea
- recurrent Candida or bacterial vaginosis.
Probiotics may also prove beneficial if you have an inflammatory bowel disease, and for some people who are recovering from a serious illness or surgery. If you are being treated for a medical or surgical condition, however, always seek individual advice from your doctor before taking any supplement – including probiotics – and only take them under medical supervision.
Have you taken probiotic supplements? Did you find them helpful? Please share your experience via the comments below.