DIETARY FIBER IN POTATO HELPS IN DIGESTION

Dietary fiber content in raw potato tuber ranges from 1-2 g/100g FW. Unpeeled potatoes contain more dietary fibers than peeled potatoes. The dietary fiber from potato tuber comes mainly from its cell walls that constitute about 1.2% of the fresh weight of the tubers. To increase the dietary fiber intake, potatoes must be consumed along with its peel. More than half of the dietary fiber in potato is in the form of pectic substances which improves the quality of potato dietary fiber and thus helps in lowering cholesterol levels. One medium potato with the skin contributes two grams of fiber or eight percent of the daily value. Dietary fiber is a complex carbohydrate and is the part of the plant material that cannot be digested and absorbed in the bloodstream. Dietary fiber has been shown to have numerous health benefits, including improving blood lipid levels, regulating blood glucose, and increasing satiety, which may help in weight management.  

Dietary fiber content of raw potato and other foods (g/ 100g edible portion)

Dietary fiber content of potatoes when cooked by different methods (Source: Ezekiel et al (1999) CPRI Technical Bulletin No. 49)

The main components of dietary fiber are non-starch polysaccharides (NSP), lignin, resistant starch and non-digestible oligosaccharides. Potatoes are a good source of resistant starch. Resistant starch are ‘starch and starch degradation products that escape digestion in the small intestine of healthy individuals’. They act in similar fashion as fibers. Resistant starch is found naturally in foods such as legumes, bananas, potatoes and some unprocessed whole grains.

Resistant starch content of different food materials

(Source: Englyst et al (1996) Measurement of rapidly available glucose in plat foods: a potential in vitro predictor of glycaemic response.British J Nutrition 75: 327-337)

Natural resistant starch is insoluble, fermented in the large intestine and a prebiotic fiber (i.e it may stimulate the growth of beneficial bacteria in the colon). Other types of resistant starch may be soluble or insoluble and may or may not have prebiotic properties. Resistant starch appears to exert beneficial effects within the colon. The amount of resistant starch found in potatoes is highly dependent upon processing and preparation methods. For example, cooking and then cooling potatoes leads to nearly a two-fold increase in resistant starch. Even processed potatoes (e.g. potato flakes) appear to retain a significant amount of resistant starch with the potential to confer health benefits. Resistant starch is considered as the third type of dietary fiber, as it can deliver some of the benefits of insoluble fiber and some of the benefits of soluble fiber.