By Geoffrey Harris, MD
Before I was Dr. Geoffrey Harris, MD, I was just Geoff Harris. (Geoff is pronounced like Jeff. The spelling is a result of my mother’s preference for the British spelling, and likely largely affected by the fact that she was an English teacher before I was born.) Throughout high school, I took most of the honors classes that my school offered. During the last semester of my senior year, I convinced my parents that I should be able to take a contemporary literature class instead of the honors writing class offered during that spring. The contemporary literature class was great since I could read Ian Fleming and Anne Rice books and follow the adventures of James Bond and the vampire Lestat. But, I digress…
During the honors writing class that I chose not to take, the students were assigned to carry around a potato for a week and write journal entries about the potato. I never got to write about a potato back then. But, here I am, potato in hand, writing about a potato. You might ask, “Why is he writing about a potato?” Potatoes are not a SuperFood and most of the time I am adamantly against people eating potatoes. French fries, potato chips, baked potatoes soaked in butter and sour cream, and potato skins covered in cheese, bacon, and ranch dressing are all on my list of foods not to eat. Many experts blame these processed potato dishes for our countries high rates of obesity, heart disease, and diabetes. But the potato is a good-food-gone-bad, a fallen SuperFood. Understanding the potato can help us understand how to eat and how not to eat.
Understanding the Potato
For the purposes of this article, I would like to focus on the Russet potato. The Russet potato is the “Idaho potato” or baking potato and has brown skin and white pulp. It is the common potato for baking, boiling, mashing, and making into French fries. Believe it or not, a baked Russet potato with the skin is low in sodium, high in potassium (more than a banana), is a good source of fiber, has no fat, and no cholesterol. One baked, medium Russet potato (6.5 ounces raw, about 5 ounces after baking) only has 135 calories and has 3 to 4 grams of protein and 3 to 4 grams of dietary fiber. The potato is also a good source of vitamin C, vitamin B6, folic acid (folate), beta carotene, and iron. Actually, in 2004, the USDA (United States Department of Agriculture) ranked the Russet potato number 17 on a list of the top 20 sources of food antioxidants, above plums, black beans, and Gala apples. Spinach didn’t even make their list. Finally, the Russet potato is relatively inexpensive, so you can get a lot of nutritional power for the dollar with potatoes.
At SuperFoodsRx, we tend to choose our SuperFoods based on a food’s phytonutrient antioxidant power. The micronutrients in fruits and vegetables (phytonutrients) work with the classic vitamins and minerals to prevent cell damage, destroy free radicals, protect from disease, and promote health. We look for foods with high antioxidant potential to become SuperFoods. So, how does the potato stack up with regard to antioxidant power?
In 2004, the Journal of Food Composition and Analysis published a USDA study that developed a comparison database for the antioxidant content of fruits and vegetables. The study published ORAC (Oxygen Radical Absorbance Capacity) and TAC (Total Antioxidant Activity) values for 11 fruits, 8 vegetables, 5 nuts, 3 dried fruits, and rice bran. ORAC and TAC are methods for studying the antioxidant activity of food by challenging the food, in a lab, to free radicals and measuring how well they remove the free radicals. This type of testing doesn’t identify specific phytonutrients like anthocyanins or flavins, instead it identifies how well a certain food can fight oxidative stress. Obviously, how a food reacts to free radicals in a test tube doesn’t exactly predict how it would work in our bodies after digestion and absorption into our organs. But, the value of this study is that is can compare different foods’ antioxidant power. Well, the potato did okay.
The common Russet potato had a Total Antioxidant Capacity of 13.2 (blueberries had 62.2). The interesting result is that it ranked higher than carrot, kiwi, watermelon, cantaloupe, radish, and even tomato. Now, as I said, the study didn’t identify phytonutrients or specific antioxidants. The study simply smashed up the food and tested it. The potatoes were baked which would retain their vitamin C activity and tomatoes were boiled which would lower their vitamin C content. Foods with higher vitamin C contents would tend to test better in the study. The study wasn’t perfect, but the potato held its own it the testing.
Has the Potato Gotten a Bum Rap?
If the Russet potato is so healthy, why isn’t the potato a SuperFood? As of late, high carbohydrate foods have been tarred, feathered, and ridden out of town on a rail. The potato has been grouped with white rice, white bread, and pasta as being high in carbohydrate and low in nutrition. It is true that the potato has a high glycemic index, which means it rapidly increases blood sugar (glucose) after ingestion. But, remember that glucose is the main energy source for the brain and we need some carbohydrate for energy. Too much carbohydrate can cause problems but don’t throw the baby out with the bathwater. The fiber and the nutrients in the potato should differentiate it from the other “high carb” foods. The problem with the potato is that it is a vegetable asking to be processed.
One medium, baked Russet potato as part of a balanced meal can be considered nutritious: no fat, no cholesterol, a good source of dietary fiber, packed with antioxidants, and only 135 calories. Peel it or skip eating the skin and you lose out on the fiber. Fry it and the potato will soak up the frying oil turning a no fat food into a high fat food. The potato isn’t picky either. It will soak up trans-fats and saturated fats without prejudice. By adding 2 tablespoons of butter, you add 200 calories and 22 grams of fat. Three tablespoons of sour cream adds 90 more calories and 9 grams of fat. Adding bacon and cheese adds over 300 calories and 15 grams of fat. The other problem is serving size. You can go to the grocery and pick out a huge baked potato to hold even more butter and sour cream. And think of all the peeled potatoes that go into one large order of French fries at your nearest fast food joint. Look at all the ways we can make the potato into an unhealthy food to be avoided.
This is why the potato is not a SuperFood. Instead of enjoying a medium-sized baked potato once or twice a week with healthy toppings, our society peels, fries, and soaks the potato in fat, oil, and butter and shovels it down in massive quantities.
I am fine with my patients eating a potato once in awhile. I prefer that they would choose a medium-sized potato that is baked with the skin. Baked potatoes can be enjoyed with other SuperFoods like plain yogurt, steamed vegetables, or tomato salsa. Just be sure you eat the skin too. If the potato is too bland, try flavoring it with vinegar or spices. Avoid salt, butter, or regular sour cream.
So, that is my potato writing assignment. The potato is a good example of a fallen SuperFood. I’m sure each of the SuperFoods tastes good with lots of butter and sour cream, but don’t cause the downfall of any more fruits or vegetables. Let the potato be a lesson of how a good food can go bad.
1) Store your potatoes in a dark, cool place. Keep them in brown paper bags, not plastic bags. Don’t keep them in the fridge because the cold temperatures will break down the starches into sugar. Separate the potatoes from the onions, because the onion fumes will rot the potato faster.
2) When baking a potato, don’t wrap the potato in foil. Wrapping the potato in foil tends to steam, not bake the potato and the skin will end up soggy. Simply wash them and put them on a baking tray.
3) Don’t eat the potato if it has turned green or started to sprout. Potato plants create a glycoalkaloid, called solanine, that acts as a toxin which causes stomach pain and diarrhea. Cooking doesn’t tend to remove the toxin, so don’t eat potatoes that are turning green.
FYI: When a potato starts turning green it is because the potato is making chlorophyll. The chlorophyll is not toxic, but the solanine tends to be produced and concentrated in the green areas. The potato turns green and produces solanine when it is exposed to light. Most of the potato plant produces solanine to discourage animals from chewing on the plant and repel insects. The root (tuber) of the plant, the potato, is well protected underground and doesn’t typically have a need for the solanine unless it is open and exposed. Don’t eat the green parts or the potato sprouts because of the solanine.