digestion – Page 5 – Clinical Alimentary

Fibre (or roughage) is a term you may have heard of, but what is it, you may be wondering? Why am I asked to increase, or decrease the amount of fibre I am eating? This is the one area that I give advice about most often.

Fibre is the residue of carbohydrates (starchy foods) that are left in our bowel after we have digested the food that we eat. So it’s waste then? Well not really, it is food for the good bacteria in our bowel and it’s useful for our health to have a good intake of wholegrain starchy foods. Fibre is found in wholegrain and bran based cereals, oats and oat flour, pulses (peas & beans,) lentils, wholemeal, brown & seeded breads, wholemeal pasta, brown rice, nuts, seeds, dried and fresh fruit and vegetables for example.

Two different kinds of fibre are

Soluble fibre – found in oats, golden linseeds, pulses and certain fruit pulps, and vegetables such as Jerusalem artichokes, this fibre is soluble in water. Soluble fibre is food for our gut bacteria and helps lower cholesterol levels.

Insoluble fibre – this is found in wheat bran, rye and other grains and is also the tough outer coatings on fruits, nuts & seeds, this fibre is not soluble in water. Insoluble fibre reduces constipation and promotes gut health.

We are all aware that we need to have at least 5 portions of fruit and vegetables per day, but little is said about wholegrain foods (2-3 servings per day are advised) – to be healthy we should include these in our diet where we can. The UK Committee On the Medical Aspects of food (1999) say that adults should aim for at least 18g up to 24g of fibre per day, this is rather old advice, however we are still as a population not achieving these levels and we have no reason to change this advice. (Levels may be different in other countries and children also have different requirements.)

So, why is this advice so important? Well we all know that those people who have a low intake get constipated, but longer term, low intake of fibre can be more problematic. But rather than focus on negatives, lets discuss the positive aspects. Six good reasons to increase your fibre intake:

1. High fibre foods take longer to leave our stomach, therefore making us feel fuller for longer, good food then, if you are aiming to manage your weight. This idea may be more complex than just adding fibre to processed food or supplements for example; high fibre foods take longer to eat also, which also may have additional effects on satiety.

2. Foods that contain fibre take longer for the available component to pass into our bodies and this can help to achieve a lower blood sugar level after meals, compared with low fibre food, for people who have type 2 diabetes.

3. Some fibre also provides prebiotic action, giving homes and food for the bacteria that live in our large bowel. Helping increases in numbers of ‘friendly bacteria’ is beneficial, these bacteria produce vitamin K and also make short chain fatty acids, which feeds our gut and keeps it healthy. High numbers of good bacteria also reduce the levels of harmful bacteria in our bowel, the ones that result in illness.

4. Having a higher intake of fibre also protects against bowel cancer (which type of fibre is more protective is disputed – Parkin & Boyd 2011.)

5. Fibre also decreases the time it takes for food to pass through our digestive system, reducing constipation (along with a good fluid intake.)

6. Total and ‘bad’ cholesterol levels are reduced with higher fibre diets, by reducing the amount of cholesterol that is reabsorbed into your body, reducing your risk of heart attacks and stroke.

Therefore, as you can see – lots of good reasons to ensure you eat plenty of sources.

All good advice – so why is it I sometimes give advice to reduce the amount of fibre people eat, isn’t this going to be harmful in the future? People who have bowel conditions that may need to reduce fibre intake are often advised to go on a low fibre or low residue diets because fibre stretches the bowel wall, causing bloating and increased pain, also if the bowel is narrowed high fibre residues may cause a blockage. These may be people with crohn’s disease, colitis, cancer, stricturing (narrowing of the bowel) or adhesions from past surgery. Sometimes the type of fibre may be problematic, such as for people with irritable bowel syndrome and advice is provided to eat fibre that does not result in as much bloating, such as following the Low FODMAP diet for example. All these situations need changes to the amount or type of fibre in the diet, but this is usually a short-term measure, and people are advised to increase their fibre intake back to healthy levels post illness or after surgery. They then need to increase the amount slowly initially, starting with fruits without skins or pith & well cooked vegetables, increasing to foods higher in fibre such as wholegrain breads and pulses when tolerated.

So why not try some sources of fibre if you don’t eat it often? It is always advisable to increase the amount you eat slowly, particularly if you are not used to eating large amounts. Start by including one more portion of fruit (about a handful) or vegetables (2-3 tablespoons or a small salad) per day, till you are eating recommended levels or start with a bowl of wholegrain cereal (30g,) then include wholegrain breads, oats, wholegrain pasta/rice – increase by one item per day and see how tasty it is!

http://summaries.cochrane.org/CD002128/dietary-advice-for-reducing-cardiovascular-risk Free article

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3252068/?tool=pubmed Parkin DM, Boyd, L. (2011) Cancers attributable to dietary factors in the UK in 2010 111 – low consumption of fibre British Journal of Cancer 105 (S27-S30) Free article

Click to access revision1.pdf

N. Babio1,2, R. Balanza1,2, J. Basulto1, M. Bulló1,2 and J. Salas-Salvadó1,2 (2010) Dietary fibre: influence on body weight, glycemic control and plasma cholesterol profile Nutr Hosp. 2010;25(3):327-340 Free article

http://www.diabetes.org.uk/Documents/Reports/Nutritional_guidelines200911.pdf Evidence-based nutrition guidelines for the prevention and management of diabetes
May 2011 diabetes UK Free article

Probiotics – what are they and can they help my gut? (clinicalalimentary.wordpress.com)

Probiotics have been around for millennia and are found naturally in certain foods, however does natural always mean safe? This post discusses the various types of probiotics that are home-made and discusses their safety and whether they will actually do what they propose to. This post has been rather challenging to write, it has produced lots of information, but little in the way of clinical evidence to directly prove that home-made products are more or less effective than shop bought, and little direct evidence in how effective they are at reducing gastrointestinal problems. This is perhaps not too surprising.

Home cultured dairy foods including yoghurt, cheese & clabbered milk.

There is nothing wrong in producing your own home-made yoghurts and cheeses, should you wish to. Kits are available on the internet and you may also wish to go on training courses, or review books to get started (will probably help to avoid costly mistakes!) Milk, if left un-refrigerated will sour, some types of milk will take longer to do this depending on the amount of bacteria they contain and the processes they have been exposed too, UHT milk contains very limited numbers of bacteria due to its heat treatment, so it will take longer to sour, for example. Starter cultures are required and can be purchased for this very process, but other ‘live’ milk products can be used as starters.

Kombucha

Kombucha is a Japanese fermented mushroom in tea and sugar, proposed to be taken as a tonic. It contains yeast and bacteria and is anecdotally suggested to reduce constipation and have benefits for myriad of other health complaints. Web & Pinterest searches revealed lots of information about how to make this at home, but it is also available to purchase as a manufactured product. A small number of case studies have reported serious side effects with taking this product as a drink, some of the cases had other medical problems which may have also been implicated, but symptoms have been reported in people who had no health problems too. Kombucha has resulted in jaundice (yellowing of skin and eyes due to damage to the liver,) one case had improvement to the liver after stopping taking kombucha, but one death was mentioned that was attributed to taking this product. We have no evidence that Kombucha improves constipation and although cases of serious side effects are rare and the data is old, it is probably worth avoiding taking home made kombucha as a health tonic, liver damage is a very serious problem that is best avoided. If you do wish to try komucha perhaps try the manufactured products but no evidence is available to suggest it helps with IBS for example.

Sauerkraut

Sauerkraut is a fermented vegetable product based on cabbage its direct translation is sour cabbage! It has reported both prebiotic (food and homes for bacteria) and probiotic actions. It is also a source of vitamin C, which helps your skin, and sauerkraut was used in history as food in winter to prevent scurvy. Sauerkraut also contains a substance called tyramine, some people have problems with tyramine and are informed to avoid this (MAOI diet,) – you will likely know, if you need to avoid this food!!

Sauerkraut has been produced and consumed in European countries for approximately 1000 years, and is widely available as a manufactured product in supermarkets. The bacteria that are found in sauerkraut are lactic acid bacteria and these produce an acid environment leading to its sour taste. When produced correctly it can be kept for several months in an airtight jar but as with all home-made products the possibility of producing pathogenic bacteria should be considered, the not so friendly ones, that can result in illness. unpasteurized (or home-made) varieties will contain more probiotic activity but hygiene and use of a reliable manufacturing method, is very important. Listeria has been found during fermentation of sauerkraut, therefore it may be advisable not to consume unpasteurized sauerkraut during pregnancy or also those people who may be at risk of illness such as those with weakened immune systems, or the very young & the elderly.

Their may be one drawback to this food for your gut, as a consequence of it containing some prebiotic features, due to it being based on cabbage. If you find eating foods containing oligosaccharides (a starchy prebiotic found in beans, cabbage, sprouts, for example!) results in intolerable gas and bloating, then sauerkraut is probably best avoided. But white cabbage has been tested and is low fodmap so sauerkraut based on white cabbage is likely OK to use but do check for other ingredients. However it is a dish that is readily available and is worth eating, if you like it. As for its effectiveness in promoting gut health a search on PubMed (published research papers) did not reveal any direct studies on the effectiveness of this product on gut health, but lots of data on the populations of bacteria and yeasts found in sauerkraut, so an indirect link may be possible, but as with most traditional foods, direct evidence is elusive and needs to be investigated.

Kefir

On a basic Pubmed search an incredible 1,912 studies that mention kefir were found, so for a home manufactured product it seems to have attracted the attention of the scientists and clinical researchers! However in IBS for example non of these research papers have been reviewed systematically, therefore they are likely to not meet the strict criteria for good levels of evidence such as randomised controlled trials. Kefir is a stable cultured dairy product that contains yeasts and lactic acid bacteria of various different types, thirty bacteria species and 15 species of yeast have been identified. It can be purchased as a starter called Kefir ‘grains’ for producing live dairy products at home. Kefir has a large number of bacteria that are suggested to be able to pass into the gastrointestinal tract in beneficial numbers despite passing through the acidic conditions of the stomach (not all bacteria will survive to the small bowel.) It has even been used successfully to replace yeast in producing bread, as a consequence of the yeast species it contains. It is reputed to improve lactose intolerance (increased gas, bloating & diarrhoea when consuming lactose, a sugar found in dairy products) due to the lactic acid fermentation process, but many yoghurts and cheese have lower levels of lactose as a result of fermentation. It is probably best to introduce this food slowly and monitor you symptoms, if you are prone to lactose intolerance and wish to try it. A recent review reported that kefir is an important food and warrants further study, although this review had most of the data from animal studies and in vitro studies (studying the activity in cells, or in test tubes) so the research cannot be related directly to effects in humans. It is certainly and interesting product and does warrant further studies!

Filmjolk

This is fermented milk and is similar to Kefir, it is made using different bacteria lactococcus lactis and Leuconostoc Mesenteroides, and this gives the yoghurt a different taste – less sour than traditional yoghurts. It is also available commercially; searches have not produced much data in English about whether this product is goof for digestive health but if you can read Swedish follow the link to learn more (lots of papers at the bottom of the page)

http://en.wikipedia.org/wiki/Filmj%C3%B6lk

Tofu miso

These are fermented soya foods that do contain bacteria however don’t forget that bacteria may be affected by the cooking process, so how useful the probiotic effect is when these products are exposed to heat, is debatable.

As with all food preparation, food hygiene is vital to produce safe home-made products, ensure you use clean utensils, wash your hands and check the following link:

http://www.nhs.uk/Livewell/homehygiene/Pages/how-to-store-food-safely.aspx

http://www.nhs.uk/Livewell/homehygiene/Pages/Homehygienehub.aspx

Some people are possibly more at risk from taking live products, during pregnancy UK advice is to avoid products containing unpasteurized milk, and soft cheeses that are mould-ripened, such as brie, camembert and chevre and others with a similar rind. Other cheeses you need to avoid are soft blue-veined cheeses such as Danish blue or gorgonzola. These are made with mould and they can contain Listeria, a type of bacteria that can harm your unborn baby. Also if you have been told by your doctor that you have a weak immune system (medically called immunocompromised) you are better to avoid taking live bacteria and food products that contain them.

http://www.ncbi.nlm.nih.gov/pubmed/21390946

Niksic M, Niebuhr SE, Dickson JS, Mendonca AF, Koziczkowski JJ, Ellingson JL (2005) Survival of Listeria monocytogenes and Escherichia coli O157:H7 during sauerkraut fermentation. JFood Prot. Jul;68(7):1367-74 .

Srinvisan R, Smolinski S, Greenbaum D, (1997) Probable gastrointestinal toxicity of kombucha tea J Gen Intern Med 12:643:644

Hertzler, S.R. and Clancy, S.M. (2003). Kefir improves lactose digestion and
tolerance in adults with lactose maldigestion. J. Am. Diet. Assoc. 103:582–
587.

ZEYNEP B. GUZEL-SEYD˙IM1, TUGBA KOK-TAS1, ANNEL K. GREENE2
and AT˙IF C. SEYD˙IM1(2011) Review: Functional Properties of Kefir. Critical Reviews in Food Science and Nutrition, 51:261–268

Oggioni MR, Pozzi G, Valensin PE, et al; Recurrent septicemia in an immunocompromised patient due to probiotic strains of Bacillus subtilis. J Clin Microbiol. 1998 Jan;36(1):325-6

Related articles