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Low Fibre Diet

by Penny Crowther(more info)

listed in ibs, originally published in issue 146 - April 2008

In recent years, fibre has rightly been touted as a healthy addition to our diet. Fibre is highly beneficial because of its ability to absorb water in the intestines, softening and bulking out the stool and preventing constipation. Other benefits of fibre are controlling blood sugar levels, by extending the time it takes for the stomach to empty so that sugar is released and absorbed more slowly, balancing the intestinal pH which creates an environment for healthy bacteria, speeding up the removal of toxic waste from the colon and reducing cholesterol.

There is no doubt that fibre is an essential part of a healthy diet. However many people do not realize that all fibre is not the same. My experience from working with clients with IBS is that reducing certain types of fibre can greatly help alleviate their symptoms. In my last column, I talked about the benefits of a low starch diet for some people with IBS. For other IBS sufferers, adjusting the fibre content of the diet is enough to bring relief and is less restrictive than omitting starch.

Like starch, plant fibre is also a polysaccharide, but unlike starch, none of it is digested and absorbed in the human small intestine. There are two types of fibre: soluble and insoluble. Many plant foods contain a mixture of both, but it’s best to choose the foods that are predominantly soluble fibre. Insoluble fibre, such as cellulose, is tough material from the plant wall; and this type of fibre is most likely to be problematic for many IBS sufferers. Soluble fibre on the other hand, such as gums and pectins, is usually better tolerated. Soluble fibre is fermented by the bacteria in the large intestine and metabolized to highly beneficial SCFAs (short chain fatty acids) which are a source of energy. Insoluble fibre is metabolized to a much smaller extent which means that there will be more of it lying around in the gut.

Food Sources of Insoluble Fibre

  • Wholegrain bread (wheatmeal, wholemeal, wholewheat, granary);
  • Wheat bran;
  • Wholemeal muffins, chapattis and pitta bread;
  • Wholegrain breakfast cereal especially wholewheat cereals and wheat bran;
  • Wholemeal flour or pasta;
  • Ryvita or wholemeal crackers;
  • Brown rice;
  • Maize;
  • Nuts and seeds;
  • Tomato skins;
  • Green beans, cauliflower, zucchini, celery.

Food Sources of Soluble Fibre

  • Oat or rye bread;
  • Porridge oats and oat bran
  • Oatcakes;
  • Spelt pasta or bread;
  • All fruit without skin especially apples and berries (and bananas although
  • problematic for some as they are very high in resistant starch);
  • Most vegetables especially roots such as peeled potatoes, carrots, yams and onions;
  • Ground almonds;
  • Barley;
  • Beans, peas and lentils (also a source of insoluble fibre and may be problematic for IBS sufferers. Best omitted initially and then try reintroducing);
  • Flax seeds (ground and soaked overnight);
  • Psyllium husks (must be taken with plenty of water).

For the health conscious person, not surprisingly, the concept of reducing fibre is sometimes a hard one for them to get their head around. Whilst it is more common for me to see clients who are eating too little fibre, I do see people who are eating what is essentially a very healthy diet rich in fibre yet are experiencing IBS symptoms. For these clients, a reduction in their fibre intake as well as paying careful attention to the type of fibre they are eating, brings about a reduction in symptoms.

It’s important not to go to the other extreme and eat too little fibre. However this should not be a problem as when selecting foods from the soluble fibre list, it is not difficult to achieve the UK recommended daily fibre intake of 18g daily. As a rough guide, an orange contains 2.7g fibre, 80g cooked cabbage contains 1.7g, three oatcakes contains 3g, a 70g bowl of porridge contains 7.7g, 25g ground almonds contains 1.8g, a medium baked potato 4g, a 90g portion of white pasta penne contains 2.3g and a slice of white bread 0.8g. White flour products should always form a very minimal part of the diet, but counter intuitive as it may seem, they are often well tolerated by IBS sufferers. If you fall short of your fibre quota, top up with a supplement of Psyllium husks which are 66% soluble fibre; they contain around 4g fibre per rounded teaspoon. However, they may cause bloating in some people so should be treated with caution.

I use B-complex supplementation for low starch diets to ensure against deficiency, since grains are a rich source of these vitamins. The liquid from soaked flaxseeds helps prevent constipation, an occasional side effect of the diet. However, the large amounts of salad, vegetables and fruit usually maintains regularity in most people and supplies a vast array of minerals. People with blood sugar imbalance also do very well on the diet because of the frequent protein containing meals.


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About Penny Crowther

Penny Crowther BANT CNHC qualified as a nutritional therapist in 1997 and has been in clinical practice ever since. She has seen several thousand clients over the years, at her practice in London and online. Penny now specializes in nutrition for women in their 40s and beyond, particularly around peri and post menopause. Mid Life for women can be a time when fluctuating hormones play havoc with your wellbeing. In the midst of all the publicity around HRT, it's easy to forget just how powerful diet and lifestyle changes can be when it comes to navigating the menopausal years.

Penny will guide and support you through specific changes to your diet, targeted to you specifically, in midlife. She provides practical, easy to follow menu plans with easy and delicious recipes. The food you eat affects every cell and system in your body. It optimizes how you look and feel, both mentally and physically.

To book an appointment view consultation options here >>

As well as being a regular columnist for Positive Health, Penny has written for Holland and Barrett, and contributed to articles for the Daily TelegraphThe Times Literary supplement, Pregnancy & Birth and Marie Claire. She has been featured in the Daily Express, Daily Mirror and on local radio.

Penny is a registered nutritional therapist with standards of training endorsed by BANT (British Association for Applied Nutrition and Nutritional Therapy) and CNHC. This includes completing 30 hours of continuing professional development, annually.

Penny’s approach to health is holistic, and takes into account emotional, mental and environmental factors as well as nutrition. She has trained in coaching and studied many complementary therapies before qualifying as a nutritionist, which provides a broad foundation of knowledge in her nutrition practice. Penny may be contacted on Tel: 07761 768 754;

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