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Probiotics are living microbes that are known to be beneficial for health when consumed or applied topically. Most probiotics are lactic acid bacteria, especially Lactococcus and Lactobacillus species. However, other bacteria like Bifidobacterium and Streptococcus thermophilus and a yeast Saccharomyces boulardii, are also considered to be probiotics. When consumed regularly, all of these species act in different ways for improving gut health and the overall health of the body.

The human body has millions of microbes living on the skin and mucous membranes, the inner lining of various organs including the gut, oral cavity, conjunctiva and urogenital tract. These microbes constitute the normal flora of the body. They constantly compete with pathogenic microbes and each other for space and food. Any imbalance in the normal flora will lead to infections and diseases.

To be sure, an infection may be caused by an external microbe or a microbe that is a part of the normal flora. For example, yeasts are normally present in the vagina but an imbalance in the microflora of the vagina could make the yeast population grow quickly and cause vaginal yeast infections. Some microorganisms also produce substances that can aid in the normal functioning of the human body. 

Probiotics help balance the microbial flora of the body so normal functioning can be attained once again. You can obtain probiotics from foods or supplements in the form of pills and tablets or drinks. Certain foods are also fortified with probiotic microbes.

  1. Types of probiotics
  2. Which probiotic foods to eat
  3. Benefits of probiotics
  4. Probiotics side effects
  5. Uses of prebiotics, probiotics and synbiotics
  6. Right time to take probiotics

Depending on the type of bacteria, probiotics can be of different types. Some common bacteria that are used as probiotics are:

  • Lactic acid bacteria: These include Lactobacillus acidophilus, L. paracasei, L. rhamnosus, L. johnsonii, L. casei, L. plantarum, L. reuteri, L. crispatus, Enterococcus faecium, and Leuconostoc mesenteroides.
  • Bifidobacterium species: These include B. lactis, B. adolescentis, B. longum, B. bifidum, B. breve, B. animalis and B. infantis.
  • Other microbes: Bacteria such as Propionibacterium freudenreichii, Escherichia coli strain nissle 1917 (EcN) and yeasts such as Saccharomyces cerevisiae and Saccharomyces boulardii.

Most probiotic products have the name of the microbe it contains on the label. Every probiotic has a specific effect on the body. So, it is best to check with a doctor to know which probiotic is right for you, especially if you are taking probiotics as supplements in certain disease conditions.

Probiotic supplements contain a single or multiple microbes. Experts say that you should consume at least 108 to 1010 probiotic microbes or take supplements with a CFU (colony forming unit) value of 106/mL.

CFU refers to the total number of live microbes in a sample that is capable of replicating and making colonies in a Petri plate.

It is a common mistake to assume that all types of fermented foods are probiotic. While fermented foods do contain good bacteria, including lactic acid bacteria, many foods like sourdough bread, pickles, wine and beer may not have any live microbes left by the time they are cooked or processed.

Furthermore, a lot of bacteria do not survive the low pH (acidic) conditions of the stomach and die before they reach your intestines. Only the strains that are strong enough to pass through the stomach provide the benefits attributed to probiotics.

Dairy products - especially types of fermented milk such as yoghurt and cultured buttermilk (chhachh) - are considered to be among the best probiotic foods - yoghurt is made from Lactobacillus acidophilus and Streptococcus thermophilus. Also, certain foods are now being fortified with known probiotic microbes to improve their health benefits.

Here's a list of probiotic foods you should add to your regular diet:

  • Yoghurt and drinks made with yoghurt such as lassi and chhachh.
  • Tempeh, made with soybeans, apple cider vinegar and a tempeh starter like rhizopus mould.
  • Miso, made by fermenting soybeans and rice koji - a Japanese preparation.
  • Kimchi, a Korean preparation made by fermenting cabbage.

Probiotics have several benefits for the body, both when taken in food and as supplements. Let’s have a look at some of them:

Probiotics reduce cholesterol

Both Lactobacillus and Bifidobacterium species have shown hypocholesterolemic effects (they reduce cholesterol levels) in lab studies. A meta-analysis published in the European Journal of Clinical Nutrition suggested that yoghurt consumption reduces total cholesterol by 4% and LDL (low density or bad cholesterol) by 5%. Yoghurt is prepared with a culture of Lactobacillus acidophilus and Streptococcus thermophilus.

Several mechanisms have been suggested for the hypocholesterolemic action of probiotics. These include deconjugation of bile salts (part of bile fluid secreted from the liver). Bile salts are basically bile acids attached (conjugated) with glycine or taurine (both glycine and taurine are proteins). They help in the absorption of fats in the intestines. On being deconjugated, bile salts are unable to perform their function and are eliminated with the urine. To make up for the lost bile, the liver uses more fats, thus further reducing your total cholesterol levels.

Additionally, probiotics attach some of the cholesterol to their own surface, keeping them from reaching your blood. 

Read more: Foods that reduce high cholesterol levels

Probiotics may help in weight loss

When it comes to the benefits of probiotics in obesity, there are a lot of variables - including the age, sex, and BMI of the person and the dose and duration of intake of the probiotic.

Animal studies show that probiotics affect energy expenditure and the ability of the organism to take energy from food. 

A randomised placebo-controlled study done in Japan found that the consumption of fermented milk that contains 108 CFU/gram of Lactobacillus gasseri starts to reduce adiposity within 12 weeks.

In a clinical trial done in 2014, the administration of probiotics was only found to be effective for women and not men, when combined with calorie restriction and a weight maintenance programme.

More studies are needed to confirm the evidence.

Read more: How to lose weight fast and safely

Probiotics for antibiotic associated diarrhoea

Antibiotics kill some of the good bacteria in the stomach along with the harmful ones. Thus, prolonged antibiotic use often leads to diarrhoea. Antibiotics also increase intestinal motility, which is the contracting and relaxing motion of your intestines that helps push food forward in your gut. Probiotics have proven benefits for reducing the risk of antibiotic-associated diarrhoea. 

A 2015 review indicated that S. boulardii can help prevent antibiotic-associated diarrhoea in children and adults.

A meta-analysis published in the journal Nutrition in Clinical Practice, a peer-reviewed journal published by the American Society for Parenteral and Enteral Nutrition, suggested that probiotic consumption can reduce the risk of antibiotic-associated diarrhoea in adults but not in the elderly (>65 years of age).

Probiotics help manage infectious diarrhoea in infants

Acute infectious diarrhoea is one of the most common causes of hospitalisation and death in children up to five years old, in developing countries. It is characterised by the presence of liquidy baby poop with or without vomiting and fever. The patient usually has more than eight stools within a day. The most common cause of infectious diarrhoea in children is viral infection, particularly rotavirus infection. Diarrhoea is one of the causes of dehydration in children.

A review article published in the Cochrane Database of Systematic Reviews suggested that probiotics used along with rehydration therapy can reduce the duration of diarrhoea in children.

S. boulardii has been shown to be effective in providing symptomatic relief in infectious diarrhoea in children. Though more studies are still needed to confirm the benefits of this yeast in diarrhoea patients.

Probiotics benefits in irritable bowel syndrome (IBS)

IBS patients are often told to take probiotics since an imbalance in gut flora is thought to be one of the possible causes of irritable bowel syndrome - the exact cause of the condition is still unknown.

A meta-analysis of 43 random controlled trials showed that probiotics are effective for the treatment of IBS. In other studies bacteria including Lactobacillus acidophilus, Bifidobacterium breve, and Bifidobacterium longum have been found to be effective in the management of IBS symptoms. 

Clinical studies show that bacteria including Streptococcus thermophilus, Bifidobacterium infantis, B. longum, L. plantarum, L. acidophilus, Lactobacillus bulgaricus and L. casei can be used to reduce flatulence (passing wind) in IBS patients.

However, more studies are still needed to confirm the dosage and duration of treatment required for treating IBS with probiotics. 

Read more: What to eat and what not to eat when you have irritable bowel syndrome

Probiotics for healthy gums, teeth and mouth

Probiotics are effective against various oral health issues which include periodontal diseases like periodontitis, bad breath and dental caries (cavities). Lab studies suggest that Lactobacillus rhamnosus and Bifidobacterium can keep the caries-causing bacteria Streptococcus from adhering to the teeth surface.

An article published in the American Journal of Dentistry argued that the intake of probiotic cheese is suggested to be effective in reducing dental caries. A randomised double-blind placebo-controlled trial found that the consumption of probiotic yoghurt, specifically that contains Lactobacillus reuteri, can reduce the levels of Streptococcus mutans in the oral cavity by up to 80%.

Clinical studies show that intake of probiotics without any other therapy can reduce gum bleeding in periodontitis and gingivitis. However, in most patients, the condition recurs within a few months or a year. 

Similarly, bacteria including Lactobacillus and S. salivarious have shown a reduction in oral malodour on regular consumption.

Probiotics for skin care

Both the oral and topical use of probiotics is said to be good for skin health. Research shows that probiotic bacteria improve skin barrier function by an unknown mechanism, reducing the risk of skin infections. Also, some probiotics release compounds like hyaluronic acid and other proteins that reduce skin dryness and promote skin health.

Intake of Escherichia coli strain Nussle 1917 is found to be beneficial for various inflammatory conditions of the skin. Bacteria like Lactobacillus acidophilus, Bifidobacterium bifidum, L. salivarious and L. casei is suggested to be effective against atopic dermatitis - a chronic condition in which red itchy patches appear all over the skin during a flare-up.

However, most of these studies include different bacteria, dosage, and duration of treatment, so more evidence is needed before probiotics can be used for clinical treatment of skin conditions.

Since most probiotic bacteria are already part of the normal flora of the human body, they are unlikely to cause side effects. Nonetheless, minor side effects like stomach problems and gas may occur in some people.

If you are immunocompromised, it is best to talk to your doctor before taking probiotics since certain strains of probiotics can cause opportunistic infections. 

Also, there have been some cases of severe fungemia (presence of fungus in blood) and bacteremia (presence of bacteria in blood) with regular use of probiotics. So, it is better to consume any kind of probiotic in moderation.

Probiotics are often confused with prebiotics. However, the two are quite different. While probiotics are live microbes that help promote health, prebiotics are complex carbohydrates (usually some types of fibre) that your gut flora uses as food. In other words, prebiotics encourage the natural growth of probiotic bacteria in your gut.

Since prebiotics have a direct impact on the gut flora, they are often given in combination with probiotics to reap maximum benefits from the combo - synbiotics are the mixtures of probiotics and prebiotics. 

Some of the common prebiotic foods include onions, garlic, wheat, bananas, soybeans, tomatoes, rye, barley, honey and sugar beet.

There isn’t much literature on the right time to consume probiotics. Most probiotics are said to be resistant to stomach acid, so you can take them any time of the day, with or without meals. However, one study suggests that taking fatty food may improve the survival rate of bacteria in your upper gastrointestinal tract, especially if you are taking non-enteric coated tablets. Lactobacillus and Bifidobacterium can be taken about 30 minutes before meals to get maximum benefits.

If your physician has recommended probiotics for you, then it is best to adhere to the timings they have suggested.

References

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