Potatoes are underground tubers that grow on the roots of a plant called Solanum tuberosum.
This plant is from the nightshade family, and is related to tomatoes and tobacco.
Native to South America, potatoes were brought to Europe in the 16th century and are now grown in countless varieties worldwide.
They are generally eaten boiled, baked or fried. They are prepared in various different ways, but most frequently served as a side dish or snack.
Common potato-based foods and food products include french fries, potato chips, and potato flour.
Cooked potatoes with skin are a good source of many vitamins and minerals, such as potassium and vitamin C.
Potatoes usually come in shades of brown, but various colored varieties also exist, including yellow, red, and purple.
Aside from being high in water (80%) when fresh, potatoes are primarily composed of carbs, and contain moderate amounts of protein and fiber, but virtually no fat.
The table below presents information on all the main nutrients found in potatoes ().
Potatoes are mainly composed of carbs.
Primarily in the form of starch, the carbs range from 66-90% of dry weight (, , ).
Simple sugars, such as sucrose, glucose and fructose, are also present in small amounts ().
Potatoes usually rank high on the glycemic index, making them unsuitable for diabetics.
The glycemic index is a measure of how foods affect the rise in blood sugar after a meal.
However, some potatoes may be in the medium range, depending on variety and cooking methods (, ).
Cooling the potatoes after cooking may lessen their effect on blood sugar, and lower the glycemic index by 25-26% (, ).
Bottom Line: Carbs are the main dietary component of potatoes. Depending on the variety, potatoes may cause unhealthy spikes in blood sugar. Diabetics should limit their consumption.
Even though potatoes are not a high-fiber food, they may be a significant source of fiber for those who eat them regularly.
The level of fiber is higher in the peel, which makes up 1-2% of the potato. In fact, dried potato peel is about 50% fiber ().
Potato fibers are mainly made up of insoluble fibers, such as pectins, cellulose, and hemicellulose ().
They may also contain varying amounts of resistant starch, a type of fiber that feeds the friendly bacteria in the colon and improves digestive health ().
Resistant starch may also improve blood sugar control, moderating the rise in blood sugar after eating potatoes ().
Compared to cooked potatoes served hot, potatoes that have been cooled down after cooking contain higher amounts of resistant starch ().
Bottom Line: Potatoes are not a high-fiber food. However, potatoes that have been cooled down after boiling may contain some resistant starch, a type of fiber that can improve colon health.
Potatoes are low in protein, ranging from 1-1.5% when fresh and 8-9% when dry (, ).
Despite being low in protein, the protein quality of potatoes is very high for a plant, higher than that of soybeans and other legumes ().
The main protein in potatoes is called patatin, which may be allergenic for some people ().
Bottom Line: Potatoes contain small amounts of high-quality proteins, which may be allergenic to some people.
Vitamins and Minerals
Potatoes are a good source of several vitamins and minerals, particularly potassium and vitamin C.
The levels of some vitamins and minerals are reduced with cooking, but this can be minimized by baking or boiling with the skin on.
- Potassium: The predominant mineral in potatoes, concentrated in the skin. Intake of potassium may have benefits for heart health (, ).
- Vitamin C: The main vitamin found in potatoes. Levels of vitamin C are significantly reduced with heating, but cooking potatoes in the skin appears to reduce this loss ().
- Folate: Concentrated in the peel, the highest concentration of folate is found in potatoes with colored flesh ().
- Vitamin B6: A class of B-vitamins that are involved in the formation of red blood cells. Vitamin B6 is found in most foods and deficiency is rare.
Bottom Line: Potatoes are a good source of several vitamins and minerals, including potassium, vitamin C, folate, and vitamin B6.
Other Plant Compounds
Potatoes are rich in bioactive plant compounds, which are mostly concentrated in the skin.
Varieties with purple or red skin and flesh contain the highest amounts of antioxidants called polyphenols ().
- Chlorogenic acid: The main polyphenol antioxidant in potatoes (, ).
- Catechin: An antioxidant that accounts for about one third of the total polyphenol content. Its concentration is highest in purple potatoes (, ).
- Lutein: Found in potatoes with yellow flesh, lutein is a carotenoid antioxidant that may be important for eye health (, , ).
- Glycoalkaloids: A class of toxic phytonutrients, mainly solanine and chaconine, produced by potatoes as a natural defense against insects and other threats. They may have harmful effects in large amounts ().
Bottom Line: Potatoes provide some healthy antioxidants that are responsible for many of their health benefits. The antioxidants are concentrated in the skin.
Health Benefits of Potatoes
In the context of a healthy diet, potatoes with skin may have a number of health benefits.
Hypertension, a harmful condition characterized by abnormally high blood pressure, is one of the main risk factors for heart disease.
Potatoes contain a number of minerals and plant compounds that may help lower blood pressure.
The high potassium content of potatoes is particularly noteworthy.
Several observational studies and randomized controlled trials have linked high potassium intake with reduced risk of hypertension and heart disease (, , ).
Other substances that may promote lower blood pressure include chlorogenic acid and kukoamines (, ).
Bottom Line: Eating potatoes may help reduce the risk of heart disease.
Satiety and Weight Management
Satiety is the feeling of fullness and loss of appetite that occurs after eating.
Foods that are very satiating may contribute to weight control, prolonging the feeling of fullness after meals and reducing food and energy intake ().
Relative to other carbohydrate-rich foods, potatoes seem to be particularly satiating.
One study, which compared the satiety index of 40 common foods, found potatoes to be the most satiating of all ().
Another small trial in 11 men showed that eating boiled potatoes, as a side dish with pork steak, led to less calorie intake during the meal when compared to pasta or white rice ().
It is unclear which components of potatoes contribute to their satiating effects.
However, studies indicate that a potato protein, known as proteinase inhibitor 2 (PI2), may act to suppress appetite (, ).
Even though PI2 may suppress appetite when taken in its pure form, it is unclear whether it has any effect in the trace amounts present in potatoes.
Bottom Line: Potatoes are relatively satiating (filling). For this reason, they may be useful as a part of a weight-loss diet.
Adverse Effects and Individual Concerns
Eating potatoes is generally regarded as healthy and safe.
However, in some cases, people need to limit their consumption, or avoid them altogether.
Food allergies are a common condition, characterized by a harmful immune reaction to proteins in certain foods.
Potato allergy is relatively uncommon, but some people may be allergic to patatin, one of the main proteins in potatoes (, ).
Some people that are allergic to latex may be sensitive to patatin as well, a phenomenon known as allergic cross-reactivity ().
Bottom Line: Potatoes may be allergenic to some people, but this is rare.
Glycoalkaloids, Potato Toxins
Plants of the nightshade family, such as potatoes, contain a class of toxic phytonutrients known as glycoalkaloids.
There are two main glycoalkaloids found in potatoes, solanine and chaconine.
Glycoalkaloid poisoning after eating potatoes has been reported in both humans and animals (, ).
However, reports of toxicity are rare and the condition may be undiagnosed in many cases.
In low doses, glycoalkaloids usually cause mild symptoms, such as headache, stomach pain, diarrhea, nausea and vomiting ().
In more serious cases, the symptoms include neurological disorders, rapid breathing, fast heartbeat, low blood pressure, fever, and even death (, ).
In mice, long-term intake of glycoalkaloids may increase the risk of cancer in the brain, lungs, breasts and thyroid ().
Other animal studies indicate that low levels of glycoalkaloids, likely to be found in the human diet, may exacerbate inflammatory bowel disease ().
Normally, potatoes contain only trace amounts of glycoalkaloids. A 70 kg individual would have to eat over 2 kg of potatoes (with skin) in one day to get a lethal dose ().
That being said, lower amounts of potatoes may well cause adverse symptoms.
The levels of glycoalkaloids are higher in the peel and sprouts, compared to other parts of the potato. Eating potato sprouts should be avoided (, ).
Potatoes rich in glycoalkaloids have a bitter taste and cause a burning sensation in the mouth, an effect that may be a warning sign of potential toxicity (, ).
Potato varieties containing high amounts of glycoalkaloids (over 200 mg/kg) cannot be marketed commercially, and some varieties have been banned (, , ).
Bottom Line: Depending on the variety, potato skin and sprouts may be toxic due to high amounts of glycoalkaloids.
Acrylamides are contaminants formed in carbohydrate-rich foods when they are cooked at very high temperatures, such as during frying, baking, and roasting ().
They are found in fried, baked or roasted potatoes, but not when they are fresh, boiled or steamed ().
The amount of acrylamides increases with higher frying temperatures ().
In comparison to other foods, french fries and potato chips (crisps) are very high in acrylamides, making them the main dietary sources ().
Toxicity to acrylamides, which are used as industrial chemicals, has been reported in people exposed to them in their work environment (, , ).
Although the amount of acrylamides in foods is generally low, it is the long-term exposure to these chemicals that some experts are worried about.
Animal studies indicate that acrylamides may increase the risk of cancer, in addition to having neurotoxic effects (, , , , , ).
In humans, acrylamides have been classified as a possible risk factor for cancer ().
Numerous observational studies have investigated the effect of eating acrylamide-rich foods on the risk of cancer in humans.
Most of these studies have not detected any significant adverse effects (, , , ).
In contrast, a few studies have linked acrylamides with increased risk of cancer in breasts (), ovaries (, ), kidneys (), mouth (), and esophagus ().
High intake of acrylamides may have adverse health effects over time, but the extent of these effects is unclear and further studies are required.
For optimal health, it seems sensible to limit the consumption of french fries and potato chips (crisps).
Bottom Line: Fried potatoes contain compounds called acrylamides, which may raise the risk of cancer. For this reason, consumption of french fries and potato chips should be limited.
French Fries and Potato Chips
Potatoes have been blamed for contributing to obesity, cardiovascular disease and diabetes.
The main reason for this is that potatoes are widely consumed as french fries and potato chips (crisps), foods that are high in fat and contain a number of unhealthy components. French fries are also frequently associated with fast food.
Observational studies have linked the consumption of fried potatoes and potato chips with weight gain (, ).
Fried potatoes and potato chips may also contain acrylamides, glycoalkaloids, and high amounts of salt, components that may have harmful effects on health over time (, , ).
For this reason, high consumption of fried potatoes, especially french fries and chips, should be avoided.
Bottom Line: French fries and chips contain a number of unhealthy components. Their consumption should be limited.
Potatoes are a popular high-carb food that is consumed worldwide.
They are a good source of several healthy vitamins, minerals, and plant compounds, and may be useful for weight management. They may also help prevent heart disease.
This does not apply to fried potatoes (french fries and chips) that have been soaked in oil and cooked under high heat. For optimal health, their consumption should be limited or avoided altogether.