Several modern dietary trends have pushed the poor potato off many paleo, ketogenic diet, or low-carb dinner plates. But there is more to this lowly tuber than just excessive carb count when baked, roasted, or fried. It can even become an important player in a healthy diet if put to use properly.
Here are some interesting aspects about the common white potato:
- Consumed raw, it is a spectacular source of prebiotic fibers that, in the presence of healthy bowel flora species such as Ruminococcus bromii, are converted to butyrate and other short-chain fatty acids that mediate healthy metabolic changes in humans (e.g., lower blood sugar, lower triglycerides, lower blood pressure), as well as nourish and heal the intestinal lining. A medium-sized raw white potato provides 24 grams prebiotic fiber with zero sugars. Bake, roast, or fry this same potato, however, and 21 grams of fiber are degraded to sugar with only 3 grams prebiotic fiber remaining. More and more people are telling me that they enjoy eating raw potatoes sliced thinly, then salted, occasionally with other spices added.
- Potatoes are among the easiest of foods to ferment, as they naturally settle to the bottom of your fermenting vessel, unlike other veggies that float and need to be pushed down with a stone or plate. Fermented sliced or cubed potatoes are also a source of both prebiotics as well as probiotics.
- Raw unmodified potato starch, as in the widely-available Bob’s Red Mill Unmodified Potato Starch, is a convenient source of prebiotic fiber, as it is approximately 50% prebiotic fiber by weight. Even though sourced from raw potato, the dehydration process, typically conducted at 140 degrees F to hasten the drying process, converts some of the fiber to sugars. So go lightly: one tablespoon contains 5 grams prebiotic fiber but also 5 grams sugar, so limit exposure to one tablespoon at a time, certainly no more than 2. (The mix of sugar and prebiotic fiber, however, make it an excellent boost to bacterial reproduction in making our super-duper high bacterial count L. reuteri yogurt.)
- Once heated with breakdown of fiber, cooling allows some proportion of the fibers to reform, a processed called “retrogradation.” Some people have therefore interpreted this to mean that cooled potatoes are therefore a good source for prebiotic fibers. Two difficulties with this: 1) only 12% of starch will retrograde back to fibers, meaning that 88% of starch remains to raise blood sugar, provoke formation of small LDL particles, and fuel liver de novo lipogenesis that creates fatty liver, and 2) the amylopectin sugars are the last to retrograde back to fibers, meaning that the starches that persist in cold potatoes are among the most harmful. If you are going to enjoy some cold potato salad, remain mindful of our net carb limitation (12-13 grams net carbs per 1/2 cup) and recognize the modest prebiotic fiber content (around 3 grams).
- They are a potassium powerhouse. While bananas are often thought to be rich in potassium, potatoes have twice as much, or about 925 mg in a medium-sized potato.
Of course, something potentially good can be made bad by engaging the potato in high-temperature reactions, such as those that occur with deep-frying that provokes formation of high-temperature byproducts such as acrylamides that are suspected carcinogens, also found in potato chips. And buy organic whenever possible, as conventionally grown potatoes have among the highest herbicide and pesticide residues among produce.