NUTRITION
Fibre – Are you getting enough? Gillian Woodward
M
ost typical Western style diets contain only about 15 grams of dietary fibre a day. According to the latest ‘Nutrient Reference Values’ for Australians, adult women should be having 28 grams and men about 38 grams of fibre per day. How do you know whether your diet contains too little/ sufficient/too much fibre? Well, symptoms might give you the answer to this question! If you suffer from constipation, chances are your diet is low in fibre and or fluids. Fibre needs lots of fluid, especially water, to be handled well by your digestive system. If you produce too many bulky stools and perhaps suffer from excessive wind, then you may have too high a fibre intake. This can happen with endurance athletes or those needing to eat large volumes of food to satisfy the energy requirements of all the extra training on top of maintaining a healthy body mass. Back in the 1970s the word fibre was synonymous with wheat bran, which was liberally sprinkled on (usually low fibre) breakfast cereals by those who wanted to have a healthy bowel. Since then, it has been found that due to its high phytic acid content, too much unprocessed wheat bran (ie more than 2 tablespoons) can bind up important nutrients like calcium, zinc and iron, rendering them unabsorbed by the body. Not only is this undesirable, but also it doesn’t make sense to add bran to a fibre-depleted, refined product, when you could enjoy eating wholegrain bread or cereals in the first place. A common misconception is that fibre refers to just one substance, but this is far from the truth. Dietary fibre includes many different types which have different properties and they include lignin, pectin, cellulose, saponins, polysaccharides, gums, mucilages and gels. They are often generally classified as either ‘soluble’ or ‘insoluble’. Another falsehood is that fibre remains undigested in the intestinal tract – wrong! Good bacteria do most of the digesting of fibre in the large intestine, producing valuable byproducts (called volatile fatty acids) which help protect and nourish the bowel wall. Eating plenty of dietary fibre of all types helps to protect us from not only constipation, but bowel cancer, diabetes, gallstones, heart disease, diverticular disease and even obesity. High fibre foods are generally low in fat – another obvious bonus.
So where is this fibre and how do you get enough? It is only in vegetable/plant foods so fruits and vegetables, nuts, seeds, legumes, breads and cereals (particularly wholegrain varieties) are the major sources. They must be combined with sufficient fluid, however, to have their health promoting effects – approximately 1.5 - 2 litres per day. A half-cup serve of vegetable can have as little as 1.5 grams (eg peeled potato, pumpkin) or as much as 6 - 7 grams of fibre (eg corn, peas or lentils). The recommended number of 5 serves of vegetables daily should provide around 10-15 grams of fibre. Fruits also vary in their fibre content, from about 2 grams in a peach to 9 grams in half a punnet of raspberries or blackberries. Dried figs are the highest fibre dried fruit with 9g per 50g of figs. Thirty grams of nuts will provide about 2-4 grams of fibre, while cereals vary from 9 grams per serve in a bran type down to negligible in a refined flakey or popped cereal. A cup of white rice provides 1.4 grams of fibre whereas brown rice, only 2.8 grams of fibre, surprisingly not a lot more. Pasta has about 3.5 grams per half cup serve. From these figures you should be able to see that one has to eat quite a volume of food in a day to achieve the 28 (female) or 38 (male) grams of fibre. Now you can probably see why 2 fruit and 5 veg as well as at least 5 serves of bread and cereals a day have been recommended for a healthy diet. Fibre can well be lacking from a low carbohydrate diet (which seems still to be fashionable lately). But hopefully active athletes like orienteers know that without carbohydrates, their energy stores are quickly depleted and performance levels drop. Too much fibre can sometimes be experienced, as I mentioned earlier, by those who have large energy requirements and therefore eat larger quantities of food. It is wise for these people to perhaps include some lower fibre (white) breads and more refined cereals as well as restrict their fruit intake to 3-4 serves daily (or replace some fruit serves with juice, which has virtually no fibre). Gillian Woodward is a Practising Dietician and has been providing advice in the field for over 25 years. She has been an orienteer since 1984.
Sport Psychology continued… I certainly wish the juniors competing at JWOC all the best. Enjoy yourselves, because if you do, you will probably also produce the best performance you are capable of. Something on your mind? This column has been appearing in the AO for more than two years now covering a range of sport psychology topics such as goal setting, overcoming distraction, focussing on processes and recovering from mistakes. One of the things I’ve tried to do is provide action plans and tips that can be implemented by orienteers in their training, competing or technique generally. Is there anything however “on your mind” when you compete
that you find challenging? If so, I invite you to drop me an email and see if we can address it in the next or subsequent columns. I’m happy to keep your details anonymous if you wish. Please email me on the address below at least a fortnight before AO submissions are required (see submission date on page 2 of this edition). Jason McCrae is a Psychologist in the ACT, currently working for Lifeline Canberra. He has previously worked as a Sport Psychologist at the ACT Academy of Sport which is also Orienteering Australia’s National Training Centre. Email: jason.mccrae@tpg.com.au JUNE 2007 THE AUSTRALIAN ORIENTEER 19
