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H E A LT H Beneficial bacteria Bacteria are not something we normally think of as having a positive function. But there are different types of bacteria, and some of them are extremely beneficial to our health. AT A GLANCE Good bacteria. Gut microflora. Probiotics. Probiotics can be defined as ‘live microbial food ingredients that have a beneficial effect on human health’. The term probiotic comes from the Greek ‘for life’. This links with the actions of probiotics. They promote the growth of good bacteria in the body. Some bacterial microorganisms can cause illness or are pathogenic. Bacterial pathogens, or what we might call ‘bad’ bacteria such as salmonella and E.coli, can cause gastro-intestinal upset. Probiotics are non-pathogenic bacteria that do not cause illness. They are also referred to as ‘good’ or ‘friendly’ bacteria. When we are born our digestive system is free of bacteria, but bacteria start to take up residence in our body immediately after birth. There are over four hundred species of probiotic bacteria that can inhabit our digestive tract. Healthy adults will have three to four hundred bacteria species inhabiting their intestines. (Lactobacillus or Bifidobacterium) and then by the specific strain of bacterium (Lactobacillus casei or Bifidobacterium bifidum). See our table on p134 for a list of common lactic acid bacteria used in probiotic products. Some of these bacteria live in our intestines and are classed as resident, while others are transient. They do not take up permanent residence in the digestive tract, but form temporary colonies. Lactic acid bacteria are commonly used in the production of fermented foods such as yoghurts, cheeses and pickled foods such as sauerkraut. Their growth lowers the pH of the food, preventing food spoilage by inhibiting other microbes from developing. This is what gives dairy products, such as cheese and yoghurt, a longer shelf life than milk itself. While these bacteria are used in fermented foods, not all of these are probiotic. Yoghurt is probiotic, but cheese is not (see Probiotic foods). Types of good bacteria Benefits Lactic acid bacteria are the most Report by common bacteria used in probiotic Aisling Murtagh cc foods. They can be classified by species 132 consumer choice APRIL 2008 HEALTH A balance of good bacteria helps our digestive system to function at it best. They can assist the breakdown of fat and protein and in the manufacture of certain B vitamins in the gut. They can increase our body’s uptake of certain nutrients by improving their bioavailability. It has been suggested that many gastro-intestinal problems are related to an imbalance of microflora. When we have a healthy level of microflora in our intestines it helps our body deal with pathogenic bacteria if exposed to them. Some good bacteria produce bacteriocins, which are antibiotic-like substances that suppress the growth of non-beneficial, pathogenic bacteria in the gut. Good bacteria can therefore act as a barrier to pathogenic bacteria. Rather than just looking at probiotics on a general level, particular strains of probiotic bacteria have more specific benefits. L. casei and L. acidophilus have been found to have immune enhancing properties. L. acidophilus also encourages the production of substances that inhibit the growth of the yeast Candida, and is useful in the treatment of constipation. B. bifidum has been found to be anti-pathogenic; it can prevent the growth of undesirable bacteria that can cause digestive upset. Flora imbalance Bacteria inhabit our gut from birth, and it is important to have the right balance of good bacteria for digestive health. Many factors can disrupt our gut flora, such as a bout of gastroenteritis, and even high stress levels. Taking a course of antibiotics kills most bacteria in the gut, whether good or bad. A low fibre diet can result in low levels of good gut microflora. Probiotic foods can help to rebalance gut flora and help repopulate the gut with good bacteria. It is not just bacteria that affect the microflora balance. Other microorganisms, such as yeasts or viruses, also occupy the digestive tract. For example, the yeast Candida, which can lead to infections such as thrush, can also inhabit our digestive tract. Problems occur when this microorganism increases in number and disrupts the balance of microflora. Prebiotics Prebiotics stimulate the production of probiotics. They are indigestible fibres that are fermented by probiotic bacteria in the colon. This then stimulates the growth of good bacteria. Prebiotics include fructo-oligosaccharides (FOS), inulin and citrus pectin. Research in 2007 in the British Journal of Nutrition found that when the nondigestible fibres in wholegrains reach the intestine they have a prebiotic effect. This effect does not occur when the fibre alone is consumed (e.g. wheatbran), but was found to result from consumption of the wholegrain itself. Functional food Foods that are marketed as having a specific health benefit, over and above their nutritive value, are deemed functional foods. Probiotic foods can be classed as functional foods. Some may claim they will benefit the immune system or assist digestion. Other probiotic foods, such as biolive yoghurts, may just state they are probiotic and not promote the specific benefits of the bacteria they contain. Even if a probiotic product makes no particular health claims, it will generally promote a good microflora balance and depending on the bacteria present, may have more specific benefits. Research carried out by the European consumer group BEUC, of which the CAI is an active member, found that consumers read and trust health claims used in the marketing of functional foods. BEUC also suggests that health claims are often based on one attribute of the product, which does not reflect its overall health value. In relation to probiotic drinks there is an element of truth in this statement. Some probiotic drinks can have a high sugar content, so it is important to check the ingredients if concerned about sugar intake. A sweet taste can assist consumer taste acceptance of a product. However, this can take away from its overall health value. It is also thought that a diet high in sugars can support the growth of unfavourable microorganisms that disrupt microflora balance, such as yeasts like Candida. Probiotic drinks that are high in sugar thus seem somewhat contradictory. Safety Probiotic foods are not new. These bacteria have been used in certain foods since the beginning of civilisation. They even got a mention in the Bible. But new strains of probiotic bacteria have been developed for use in foods. Consumers may be familiar with the lactic acid bacteria such as those found in Danone Actimel L. casei defensis or Danone Activia Bifidus ActiRegularis. These strains are developed, patented and owned by the manufacturer. Recent research from Holland has led to some questioning of the safety of probiotics. They were used in the treatment of patients with pancreatitis and more patients died from the group where probiotics were used. In this case probiotics were used as a drug (introduced directly into intestine through feeding tube). This can be alarming for consumers, but we consume probiotics very differently. They are consumed as a food or food supplement and not used as a drug. The novel food legislation (Regulation 258/97/EC) governs the introduction of a food or food ingredient that has not been available on the EU market prior to 1997. Because probiotic foods have been around for a long time, they are not considered novel foods. If they are used in a non-traditional way, they must be assessed under the novel food regulation. PROBIOTIC YOGHURTS AND DAIRY DRINKS Manufacturer Product Size Price (€) Price per 100g (€) Bacteria Danone Actimel drink 12x100g 4.99 0.42 orange L. casei defensis Danone Activia yoghurt 500g 1.99 0.40 Bifidus ActiRegularis L. bulgaricus Streptococcus thermophilus Glenisk Organic natural yoghurt wholemilk 500g 1.84 0.37 L. casei B. bifidum (bifidus) L. bulgaricus Streptococcus thermophilus Old McDonald Functional live low fat yoghurt plain 500g 1.99 0.40 L. acidophilus B. longuum L. bulgaricus Streptococcus thermophilus Onken Natural yoghurt 500g 1.41 0.28 L. acidophilus B. longuum Streptococcus thermophilus Rachel’s Dairy Organic yoghurt vanilla low fat 450g 1.99 0.44 L. acidophilus Bifidobacterium L. bulgaricus Streptococcus thermophilus Yakult Probiotic drink 7x65g 3.99 0.88 L. casei shirota B. breve B. infantis Useful contacts Irish Nutrition and Yeo Valley Organic natural yoghurt 500g 1.69 0.34 L. acidophilus Bifidobacterium Dietetic Association Yoplait Everybody drink 8x100g 3.95 0.49 L. rhamnosus GG Kill Avenue Yoplait Essence healthy digestion drink 6x60g 3.99 1.10 Bifidobacterium BB 12r Dun Laoghaire Yoplait Essence immunity boost drink 6x60g 3.99 1.10 Bifidobacterium BB 12r email [email protected] HEALTH APRIL 2008 consumer choice Ashgrove House Co. Dublin www.indi.ie 133 But some new strains of probiotic bacteria have been developed. The novel food regulation is currently being revised. It has been questioned by some European consumer organisations whether new strains of probiotic bacteria should be subject to approval under the revised novel food regulation. The European Food Safety Authority does not currently assess the safety of probiotics used in food. Probiotic foods Common probiotic products include yoghurts and dairy drinks. These products contain different strains of probiotic bacteria. See our table for an overview of a range of probiotic products on the market and the bacteria they contain. But not all yoghurts are probiotic. Consumers will see bio-live, live or probiotic on the label if they are. The transient bacteria, L. bulgarius and Streptococcus thermophilus, often act as starter cultures in the yoghurt making process. These bacteria can be listed as ‘active bacteria’ in the yoghurts ingredients as they are not thought to survive passage through the digestive tract to the gut. Other probiotic cultures can be added to probiotic yoghurts, such as L. acidophilus, L. casei, B. bifidum and B. longum. These probiotic cultures can survive better, and the yoghurt itself protects them from damage during digestion. The specific bacteria that the yoghurt contains can be shown on the yoghurt label, or in the ingredients lists, but is not always displayed. Probiotic yoghurts listed in the table are slightly more expensive than nonprobiotic yoghurts. On average, a 125g pot of yoghurt costs about sixty cents and a 500g pot around €1.80. Some of the probiotic dairy drinks were more expensive than the yoghurts. There are a number of organic yoghurts listed in the table. It seems that organic yoghurts are also often probiotic. For a product to claim it is probiotic it must have a minimum concentration of colony forming units (CFUs). Most probiotic products will name the probiotic cultures present, but do not give the exact concentration. The greater the concentration of probiotic bacteria, the greater the chances of their survival when they reach the gut. Testing of yoghurts that claim to be probiotic and the inclusion of the number of bacteria that should be present in the yoghurt 134 consumer choice APRIL 2008 HEALTH choice comment If consumers wish to consume probiotics, it can be hard to know which products are best. Some companies who produce probiotic products emphasise the benefits of a specific probiotic in their product, when consumed regularly. While these claims are often supported by research, let us be clear that this is also a defined sales strategy. Regular consumption means increased sales and profits. could provide consumers with clearer information on the quality of a probiotic product. Specific bacteria have specific proven benefits, but a balance seems to be more beneficial to overall health. Consuming a range of different probiotic products could help this balance, as these products will often contain different probiotic cultures. We may also see the term ‘synbiotic’ on yoghurts. These products combine prebiotics and probiotics that work in symbiosis to encourage the growth of good gut bacteria. Beneficial bacteria enter a hostile environment When we ingest probiotic bacteria, they have to survive an environment where digestive juices, such as acids and bile, can damage them. An important function of our digestive juices is to destroy pathogenic bacteria that can cause illness, but this can also lead to the destruction of good bacteria. However, some are more resistant to digestive juices than others. More resistant bacteria will often be chosen for use in probiotic products. It is recommended that probiotic bacteria which are used in probiotic foods should be acid and bile tolerant, capable of withstanding technological processes and have a long shelf life. Probiotic supplements Probiotics can also be purchased in supplement form. Probiotic supplements will most often state the number of bacteria present. This number is usually measured on manufacture of the product. The number of probiotic bacteria present will decline with time. Some manufacturers will differentiate between the number of bacteria at manufacture and the number expected to be present by the products expiry date. Consumers may find that probiotic supplements are kept refrigerated in retail outlets. Probiotic bacteria are living microorganisms. Storing them at lower temperatures will prevent the number of each probiotic bacteria in the supplement from declining. There is debate as to how well probiotics survive digestion when taken in this form. It is best to take probiotic supplements on a full stomach. Some probiotic supplements can be enteric coated, which protects them from being damaged by digestive juices. They should then reach the intestine more efficiently. No RDA There is no recommended amount of probiotic bacteria that we should consume on a daily basis. If we never consume probiotics this does not mean we will have low or no gut flora. There are many factors that influence the development of the correct balance of gut flora. Sometimes gut flora need rebalancing, such as after taking antibiotics. In some instances they can be more important than others. LACTIC ACID BACTERIA Species Strain Resident or Transient Lactobacillus L. acidophilus Resident L. casei Resident L. rhamnosus Resident L. bulgaricus Transient L. salivarius Resident B. bifidum Resident B. breve Resident B. infantis Resident B. longum Resident Streptococcus thermophilus Transient Bifidobacterium Other lactic acid bacteria