In my previous posts on carbohydrates, I have discussed sugars (monosaccharides & disaccharides). I have also discussed the role of glucose, fructose and table sugar (or sugars in general) in the genesis of chronic diseases like heart attacks, diabetes and high blood pressure.
In this post, I will discuss about fiber and its role in health and diseases.
During a discussion on processed foods, one of my colleague asked me whether he can consume junk foods and add psyllium to the diet to compensate for lost fiber. Since fiber has been projected as protective against heart diseases, cancers and diabetes etc, people believe that the major role of fiber is to add bulk to food and lack of fiber can be compensated by taking some commercially available fiber like psyllium, flex seed powder etc (to add bulk to food).
The answer to the question by my colleagues is a big NO. In the fibrous layer of the food, major nutrients are present. Removal of fiber (specially during processing) also leads to removal of various nutrients. Lets take example of wheat, which is consumed globally. Wheat grain in natural form is powerhouse of nutrition. It contains proteins (15-20 gm/100 gm). Refining it to white flour causes loss of vitamins; Thiamine (77%), Riboflavin (80%), Niacin (81%), Vitamin B6 (72%), Folic acid (67%), and vitamin E (80%). 30% proteins are lost and starch concentration increases by more than 230% (review by Morteza Oghbaei et al ). The food becomes totally unbalanced. Consumption of products of white floor raise blood sugar quickly, leading to insulin resistance and its later effects (see article on insulin resistance). Wheat bran is the storehouse of nutrients. but a common household practice is to sieve flour to remove bran. The branded wheat flours in India are akin to white flour only due to lack of bran. Unfortunately branded flours are preferred by home makers, as it relieves them from the job of sieving the flour to remove bran. Our eating habits also alter the fiber content of foods. A large number of people remove skin of apple before consuming it. Skin of apple is full of fiber and micronutrients. The old saying ‘An apple a day, keeps the doctor away’ is applicable only if apple is eaten with skin. Removal of skin makes it an unbalanced food, full of sugar. Converting fruits to fruit juices is not a good idea for health. Milling of rice causes loss of fiber and nutrients. The finely milled white rice is full of starch without fiber and micronutrients. Starch from freshly prepared milled rice or potato is quickly absorbed from intestine raising blood sugar quickly and promote insulin resistance and obesity. High consumption of milled rice may be responsible for high prevalence of diabetes in South India. Diabetes are often advised to refrain from eating rice and potatoes. However, cooked and overnight cooled rice and potatoes, undergo a irreversible change from soluble fiber to insoluble fiber and can be consumed liberally by diabetics .
When foods are taken in natural form, body has to work hard to release nutrients from the fiber present in the food. Sugars and other items are released slowly into blood stream giving satiety and protection against sugar & insulin surges. Fiber is also protective against cancers.
Undigested food (insoluble fiber) enters large intestine and acts as food for intestinal bacteria. These bacteria play a beneficial role in our health. They synthesize Vitamin B 12, Vitamin K, butyric and other short chain fatty acids. Consumption of processed foods have deprived these bacteria of their food and disrupted the balance of good and bad bacteria in the gut. Adequate fiber in the diet keeps good bacteria in a happy mode. Lack of fiber in large intestine causes migration of bacteria in small intestines leading to SIBO (small intestine bacteria overload).
Men require around 30-35 gm and women require 20-25 gm of dietary fiber. Consumption of whole grains cereals, millets, fruits and vegetables contributes to fiber in food and must be part of our daily food intake. Indians should not bother about fiber, since cereals, pulses, fruits and vegetables are consumed daily in meals, which are high in fiber. Fiber is required if the diet is full of processed foods. Too much fiber may lead to flatulence. It may also interfere with absorption of iron, calcium and zinc. Refined and processed foods (breads, biscuits, bakery, ice creams, breakfast cereals, fruit juices etc) lack fiber and should not be ideally consumed by health conscious people.
Fiber content of some foods in gm per 100 gm of food items are:-
Cereals/Millets
Rice-7.6 gm Wheat-17.6 Sorghum-14.3 Bajra-20.3 Ragi-18.6
Pulses and Legumes
Green gram -13.5 Black gram-14.3 Red gram-14.1 Bengal gram-13.6
Takeaway Message
-Addition of commercially available fiber doesn’t add value to your meal
-Eat food in natural forms with minimal processing.
Hope you liked the article. Your comments, criticism and suggestions are welcome.
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In the next blog posts, series of articles on Fats will be discussed.
