Fiber intake and healthy aging

Christopher Thomas

Christopher Thomas has written 95 posts in this blog.

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Finding your fibre (roughage and aging)

Some elements in our diet are indigestible. But that does not mean that they are useless. In fact, our bodies make use of most things we eat, even if we don’t digest them. One example of this is dietary fiber.

Fiber is only found in plants. It is the indigestible part of plant material (also known as ‘roughage’). There are two types of dietary fiber: those that dissolve in water (soluble fiber) and those that do not (insoluble fiber). Most plants contain a mixture of the two (at a ratio of about 3:1 insoluble to soluble) and both forms are vitally important in our diet.

Good sources of fibre

Insoluble fiber (such as cellulose and lignin) is found in whole grains, particularly in the outer husk or bran (eg. oat bran, wheat bran, rice bran). Milling or refining removes the bran and therefore much of the fiber. For example, wheat flour made from whole grains contains 10 times the fiber as standard white flour. Lower levels of insoluble fiber are also found in nuts, seeds and refined cereals such as flour. Lignin is also found in the skin of fruit and vegetables, such as strawberries, prunes, tomatoes, potatoes and onions.

Soluble fiber (such as gums, beta-glucans, psyllium, mucilages and pectins) is found in most plant foods, with the highest amounts in oats, bran, barley, legumes, nuts, soy products and some yeasts. Fruit and vegetables also contain significant levels of fiber. Fruits high in fiber include plums, Asian pears, raspberries, blackberries, apples and citrus pulp. Nonlegume vegetables high in fiber include cauliflower, zucchini, broccoli, carrots, Jerusalem artichokes and celery. However, these fiber levels are still lower than in legumes.

How much fiber do we need for healthy aging?

Current recommendations say we should aim for more than 30g of fiber each day and we typically consume only about half this amount. One reason for this is that the most common cereals we eat are heavily refined, meaning that the bran and germ (which contain most of the good bits) have been removed and only the inner starchy part of the grain has been left behind. Many of our other staples are only rich in starch, which unlike fiber is readily metabolized and used to generate glucose, fat, and obesity.

Why do we need fiber?

• Improve blood sugar levels – Soluble fiber slows the absorption of glucose from the foods we eat which creates a sustained energy release and lowers the strain on insulin production.
• Reduce bad (LDL) cholesterol levels – about a  10% reduction is seen with psyllium supplements.
• Improve weight management – consuming fiber-rich foods can make us feel satisfied sooner and feel full for longer (and therefore less likely to feel hungry or snack between meals). Soluble fiber can also reduce the absorption of nutrients (including sugars, fats and proteins), meaning their energy is lost to our metabolism (to the gain of our healthy gut bacteria). Even the extra chewing time of high fiber foods helps slow the intake of food and reduce the amount (of calories) we consume.
• Reduce the risk of heart attack – significant cardiovascular benefits are seen in diets rich in insoluble fiber beyond lowering cholesterol. For example, lignins like sesamin and sesamolin from sesame seed have beneficial effects on the immune system and can reduce oxidative stress. The bran and germ of whole grains are also rich in minerals, vitamins, antioxidants and other phytochemicals that have positive effects on heart disease.
• Improves bowel health – insoluble fiber makes the stool more soft and bulky, allowing it to move more easily through the intestine and colon. This is useful for the prevention and management of constipation. Fiber makes the urgency of chronic diarrhea more manageable by sucking in the fluid and bulking the stool.
• Helps the work of our  gut  bacteria – dietary fiber is fermented by the gut bacteria of the large intestine. This process releases gas, as well as a number of beneficial compounds like short-chain fatty acids. These help the absorption of minerals and contribute to lower rates of bowel cancer for those on a high fiber diet.

Options to increase dietary fiber

• Buy a book with a fiber counter so you’ll educate yourself on better fiber choices
• Dietary fiber absorbs water so increase your water intake when you increase your fiber intake
• Make sure you eat 3 fruits and 7 vegetables per day
• Eat brown rice instead of white rice
• Eat rolled oats instead of processed, microwave or instant oats
• Use oatbran in cooking. Substitute some of the flour in baking for oatbran; add to meat rissoles or meat loaf; use as a coating for crumbed fish or chicken
• Eat whole grain bread i.e. whole rye, whole grain spelt, whole grain kamut, whole grain barley, sunflower, linseed (flaxseed) or bulgur
• Eat breakfast cereal that says ‘whole grain’ not just wheat
• Use whole grain wheat flour compared to white ‘all purpose’ flour for baking (it has ten times the fiber content per 100g)
• Buy bread from a bakery that uses whole grains or wheat alternatives such as spelt or kamut
• Eat brown or wild rice rather than white rice
• Include more barley in soups, casseroles, risotto, salads
• Eat whole fruit instead of fruit juice
• Consider chickpeas, lentils and soybeans instead of steak mince for your next nachos night!
• Consider taking fiber supplements. The most commonly used supplement is psyllium made from ispaghula husks – take 2 tsp daily. Fiber supplements containing inulin or fructans can also be used as a sugar substitute
• Include dried fruit and nuts as a quick, high fiber snack

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