The most popular vegetable in the United States is a blood-sugar-spiking starch, a nightshade vegetable, and a commonly genetically modified food.

Potatoes are quickly converted to glucose, and can spike blood sugar and insulin levels.

I love potatoes and consider them a comfort food. But a friend recently told me that there are some nutritional problems with potatoes—and even health risks from eating them. From a nutrition and health standpoint, what are the most important things to know about potatoes? 

 You ask an important question because potatoes are the most popular vegetable in the United States. Many people eat them without a thought and without any knowledge of nutrition problems or health risks associated with them. 

Potato Facts

• Potatoes seem like a harmless vegetable, but they are quickly converted to glucose. They can spike blood sugar and insulin levels, and may contribute to weight gain, which is why many people on low-carb or low-glycemic diets avoid potatoes.
• The potato is a nightshade vegetable that contains glycoalkaloids, which have been implicated in the development of intestinal permeability, digestive trouble, and joint pain in some people.
• Unless you buy organic, the chances are good that the potatoes you eat are genetically modified (GM), because GM potatoes are now widespread in the U.S. food supply. The creator of GM potatoes, Dr. Caius Rommens, recently wrote a book, Pandora’s Potatoes: The Worst GMOs, warning about potential dangers from GM potatoes.

What types of potatoes are most nutritious?

There are many different varieties of potatoes, and each of their nutritional profiles vary. 

• Russet baked potatoes are good sources of potassium, vitamin C, vitamin B, folate, niacin, iron, and manganese, but they rank high on the glycemic index, meaning that their carbohydrates are quickly broken down into sugar, causing blood sugar and insulin levels in the body to rise rapidly. 
• Red potatoes, on the other hand, contain fewer calories and carbohydrates, and slightly more niacin. And they rank moderately on the glycemic index.

Do potatoes cause weight gain?

A few studies have implicated potatoes in weight gain. A 2009 study from the Journal of the American Dietetic Association that followed 42,696 participants over a five-year period found that eating potatoes was associated with an increase in waist circumference in women.

Another study in the New England Journal of Medicine that looked at the dietary patterns of more than 120,000 participants found that potatoes and processed potato chips were the two biggest contributors to weight gain, with each serving per day leading to an average weight gain of 1.3 pounds and 1.7 pounds, respectively. Other studies, however, have found no link between potato consumption and waist circumference or obesity.

Nightshades and intestinal permeability

Although few people realize it, potatoes are members of the nightshade family, which contain toxic substances such as glycoalkaloids that increase intestinal permeability, or “leaky gut.” A leaky gut is believed to set off an autoimmune reaction when various proteins, which should stay inside the digestive tract, make their way into the bloodstream and the body attacks them in response. In one study from Digestive Diseases
and Sciences, researchers fed potato skins (where high concentrations of glycoalkaloids lurk) to mice with inflammatory bowel disease, and found that gut inflammation was significantly increased.

There is virtually no published evidence on potatoes causing joint pain and inflammation in healthy individuals, but there are numerous anecdotal accounts. For example, Mark Sisson, author of Primal Blueprint and blogger at Marksdailyapple.com, found that eating potatoes on a regular basis led to joint pain in his feet and ankles. But that doesn’t happen when he eats other starchy foods, such as yams or squash.

The New Risk: GMO Potatoes

Since the introduction of genetically modified versions in 2015, the potato has become one of the most common genetically modified organisms (GMOs) available in the U.S. So much so that they were recently added to the High-Risk list of the Non-GMO Project Standard.

Unlike many genetically modified vegetables, the GMO potato isn’t designed to produce its own pesticides or to resist herbicides. Instead, the GMO potato developed by J.R. Simplot is engineered so that its flesh stays white when it’s exposed to air or light, or even when it’s bruised or diseased. The trait that prevents the potato’s natural discoloration was achieved by silencing its melanin gene. The potato still gets damaged, but the symptoms are hidden from view—and from the consumer.

GMO potato developer Rommens now heavily criticizes the crop he created, and says the newfangled potatoes are not really bruise-resistant but bruise-concealing. In his book, Rommens explains that concealed bruises can accumulate certain toxins that can compromise the food safety and nutritional quality. For example, the abnormal amino acid tyramine can accumulate in damaged potato tissues. Some people have a poor ability to break down, or are sensitive to, tyramine, and excessive tyramine intake in sensitive people may lead to a dangerous rise in blood pressure, or to nausea, vomiting, quickened heart rate, or severe headache. So, it’s possible that an unsuspecting consumer who is sensitive to tyramine could unknowingly eat bruise-concealing GMO potatoes in combination with other tyramine-rich foods, such as blue cheese, beer, sauerkraut, sausage, soy sauce, or tofu, and end up in the emergency room.

Another toxic effect of the trait that prevents discoloration in the GMO potato is the concealment of infections. Consumers may eat potatoes that look perfectly healthy but actually contain fungal or bacterial pathogens, which often produce toxins and allergens. Rommens is so concerned about the toxic effects that develop in GMO potatoes that he calls the potatoes “the worst GMOs ever commercialized.”

Bottom-Line Advice

It’s important to weigh out the information and decide for yourself if potatoes are a good addition to your diet. Here are some tips:

• Look for potatoes that are labeled Non-GMO Project Verified or, better yet, USDA Organic. Seeking out organic potato products is the best way to avoid both GMO potatoes and potatoes that aren’t sprayed with synthetic chemical pesticides.
• If you are overweight or have high blood glucose levels, avoid potatoes to determine if doing so helps you lose weight or reduces elevated blood glucose levels.
• If you have a known autoimmune disease, a leaky gut, or inflammatory bowel disease—or are sensitive to nightshades, including tomatoes, peppers, and eggplants—try eliminating potatoes from your diet, because they are also nightshades that may be aggravating your condition.
• If it’s better for your health to shun potatoes, there are plenty of vegetables that work as a healthier substitute (see table below). Also be sure to avoid convenience foods that have potato-based ingredients (such as potato starch) in them.
• If you don’t think you need to stay away from potatoes to improve your health, it’s still prudent to increase your intake of other vegetables that provide more nutrients and less carbs than potatoes