Dietary Fiber: The important non food

We know we should eat whole grain cereals, wholewheat bread and the magical five a day, as they are a good source of dietary fiber, but what is it and what does it do for us?

Fiber is the the part of plants our digestive system can't break down and use, so in reality it passes through us and provides no nutritional value, essentially a non food. There are two types of fiber in our diet, soluble and insoluble. Pectin and gum are water-soluble fibers found inside plant cells. Cellulose, hemicellulose and lignin are fibers found in the plant's cell walls are water insoluble. Each type of fiber serves a different purpose in our gut.

Water soluble fiber dissolves in water to form a gel-like material. It can help lower blood cholesterol and glucose levels. Soluble fiber is found in peas, beans, citrus fruits, carrots, barley, oats and apples.

Insoluble fiber helps ease the movement of material through your digestive system, a diet without enough fiber can result in diarrhea or constipation. Whole-wheat flour, wheat bran, nuts, beans and vegetables, such as cauliflower, green beans and potatoes, are good sources of insoluble fiber.

Current research indicates that for optimal benefits you should eat around 14g of fiber per 1000 calories, reducing this slightly if you are over 50.

	....	Under 50	Over 50
Men		38g	30g
Women		25g	21g

Tips for eating more fiber

Considering a fist sized, 250g baked potato has five and a half grams of fiber, consuming 38g a day can be quite an effort. Here are a few tips for how I try to cram in the fiber.

Whole grains, this is the obvious one, eat whole grain cereal and bread.

Add flax meal to your food, as one table spoon contains nearly two grams of fiber. I add it to baked beans on toast, soup, bolognese and chilli, by stirring in one or two tablespoons just prior to serving. You can also stir into things like yogurt and coleslaw, but I haven't tried these yet.

A glass of citrus fruit juice with your breakfast, a typical 200 ml glass of OJ gives you and extra half a gram of fiber plus counts towards one of your five a day.

Add chopped fruit to a yogurt, not only does it add fiber, but add a little extra bulk to your snack, which will keep you full longer.

Porridge is not only a good source of fiber, but add in a table spoon of sliced almonds, a table spoon of raisins and some flax meal sweetened with a little honey, gives you a filling low calorie breakfast with nearly four and a half grams of fiber.

Don't peel fruit and veg with edible skins, rather just wash and eat whole.

Lentils or split peas can be added to stews, bolognese or chilli in smallish amounts without effecting the taste, and will add a fiber boost. Or just try split pea soup, maybe with a little lean ham chopped up for added protein. 

Beans on toast is a 'classic' British dish, but this humble staple of student life, when made with wholewheat or wholemeal bread, contains over 16g of fiber. Add a spoon full of flax meal and you can get well over half your daily fiber in one meal.

One word of caution, add fiber to you diet slowly over a number of weeks. Don't just jump from a low fiber diet of burger and chips to wholegrain everything with a side salad over night. Your gut won't have time to adjust, leading to cramps, gas, diarrhea or constipation.


The Science:
The Mayo Clinic: Nutrition and healthy eating
Food and Nutrition Board: Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. September 5, 2002