Indigestible Starches (1)
Starchy foods, such as raw potatoes, unripe (green) bananas, plantains, and some legumes contain large amounts of resistant starch – a type of starch that is very slowly or incompletely digested in the small intestine.
By eating raw/uncooked potatoes, green bananas or uncooked plantains, large amounts of indigestible starches pass through the small intestine almost intact. When they reach the large intestine, colon bacteria feed on it producing gas.
Please note that while the resistant starches have shown to exert various health benefits when used in small amounts as supplements (2), the amounts of resistant starch of over 30g (equivalent to a medium size potato of approximately 250g) may cause gastrointestinal symptoms such as abdominal pain, discomfort, bloating, flatulence and cramps. (3)
If you decide to use a raw potatoes as a supplement, and are not accustomed to resistant starch, start with small amounts and increase gradually. A commonly used method is to shred uncooked potato into food.
Cooking potatoes and plantains and ripening bananas breaks down the cellular walls of these resistant starches, making them digestible.
Bacteria such as Listeria, E. coli and Salmonella are found in water and soil. Potatoes may absorb some of these bacteria while growing, as well as during harvest or packaging. Cooking the potatoes destroys the bacteria. Eating the potato raw may cause abdominal cramps, diarrhea, fever and an upset stomach.
Two toxic chemicals (steroidal glycoalkaloids) solanine and chaconine are naturally present in potatoes and are important components of their resistance against pests and pathogens. They can be, however, toxic to humans when taken at high levels.
When subjected to stress (sunlight, incorrect handling or bruised, sprouted or damaged in any way) potatoes release these toxins in potentially harmful amounts that can be deadly. Any form of cooking does not reduce the amount of these toxins, and only up to 30% is removed by peeling them. (read more..)
What about juicing potatoes?
As long as the potato does not contain harmful doses of glycoalkaloids, juicing fresh, peeled potatoes removes most of the resistant starches and is considered safe, at least there are no studies showing otherwise. It is even claimed to be beneficial for the digestive tract by many natural medicine practitioners.