Potatoes

Aside from being high in water when fresh, potatoes are primarily composed of carbs and contain moderate amounts of protein and fiber — but almost no fat.

The nutrients found in 2/3 cup (100 grams) of boiled potatoes — cooked with the skin but without salt — are:

Calories: 87
Water: 77%
Protein: 1.9 grams
Carbs: 20.1 grams
Sugar: 0.9 grams
Fiber: 1.8 grams
Fat: 0.1 grams

Carbs
Potatoes are mainly composed of carbs, primarily in the form of starch. The carb content ranges from 66–90% of dry weight (2, 3, 4).

Simple sugars — such as sucrose, glucose, and fructose — are also present in small amounts (5).

Potatoes usually rank high on the glycemic index (GI), making them unsuitable for people with diabetes. The GI measures how foods affect your rise in blood sugar after a meal.

However, some potatoes may be in the medium range — depending on the variety and cooking methods (6Trusted Source, 7Trusted Source).

Cooling potatoes after cooking may lessen their effect on blood sugar and lower their GI by 25–26% (8Trusted Source, 9).

Fibers
Even though potatoes are not a high-fiber food, they may provide a significant source of fiber for those who eat them regularly.

The level of fiber is highest in the skin, which makes up 1–2% of the potato. In fact, dried skins are about 50% fiber (10Trusted Source).

Potato fibers — such as pectin, cellulose, and hemicellulose — are mainly insoluble (11Trusted Source).

They also contain varying amounts of resistant starch, a type of fiber that feeds the friendly bacteria in your gut and improves digestive health (12Trusted Source).

Resistant starch can also improve blood sugar control, moderating your rise in blood sugar after meals (13).

Compared to hot potatoes, cooled ones offer higher amounts of resistant starch (8Trusted Source).

Protein
Potatoes are low in protein, ranging from 1–1.5% when fresh and 8–9% by dry weight (10Trusted Source, 14).

In fact, compared to other common food crops — such as wheat, rice, and corn — potatoes have the lowest amount of protein.

However, the protein quality of potatoes is very high for a plant — higher than that of soybeans and other legumes (10Trusted Source).

The main protein in potatoes is called patatin, which may cause allergic reactions in some people (15Trusted Source).

SUMMARY
Carbs are the main dietary component of potatoes. Those cooled down after boiling may provide some resistant starch, which can improve gut health. Potatoes also contain small amounts of high-quality protein.

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 drop during cooking, but this reduction can be minimized by baking or boiling them with the skin on.

Potassium. The predominant mineral in potatoes, potassium is concentrated in the skin and may benefit heart health (16, 17Trusted Source).
Vitamin C. The main vitamin found in potatoes, vitamin C is significantly reduced with cooking — but leaving the skin on appears to reduce this loss (16)

Folate.

Concentrated in the peel, folate is mostly found in potatoes with colored flesh (18Trusted Source).
Vitamin B6. A class of B vitamins involved in red blood cell formation, B6 is found in most foods. Deficiency is rare.
SUMMARY
Potatoes are a good source of several vitamins and minerals, including potassium, folate, and vitamins C and 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 polyphenols, a type of antioxidant (19).

Chlorogenic acid. This is the main polyphenol in potatoes (19, 20Trusted Source).
Catechin. An antioxidant that accounts for about 1/3 of total polyphenol content, catechin is highest in purple potatoes (19, 21Trusted Source).
Lutein. Found in potatoes with yellow flesh, lutein is a carotenoid antioxidant that may boost eye health (10Trusted Source, 16, 22Trusted Source).
Glycoalkaloids. A class of toxic phytonutrients produced by potatoes as a natural defense against insects and other threats, glycoalkaloids may have harmful effects in large amounts .

SUMMARY
Potatoes harbor some healthy antioxidants that are responsible for many of their health benefits and mostly concentrated in the skin.

Heart Health
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 link high potassium intake to a reduced risk of high blood pressure and heart disease.

Other substances in potatoes that may promote lower blood pressure include chlorogenic acid and kukoamines (25Trusted Source, 26Trusted Source).

Fullness and Weight Management
Foods that are very filling may contribute to weight control, prolonging the feeling of fullness after meals and reducing food and calorie intake.

Relative to other carb-rich foods, potatoes are particularly filling.

One study of 40 common foods found potatoes to be the most filling.

Another small trial in 11 men showed that eating boiled potatoes as a side with pork steak led to less calorie intake during the meal when compared to pasta or white rice .

Thus, potatoes may aid weight loss by helping you reduce overall intake.

Studies indicate that proteinase inhibitor 2 (PI2), a potato protein, may 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.

SUMMARY
Potatoes are relatively filling. For this reason, they may be useful as a part of a weight loss diet.
Safety and Side Effects
Eating potatoes is generally healthy and safe.

However, in some cases, people need to limit their consumption — or avoid them altogether.

Potato Allergy
Food allergies are a common condition, characterized by a harmful immune reaction to proteins in certain foods.

Potato allergy is relatively rare, but some people may be allergic to patatin, one of the main proteins in potatoes.

Those who are allergic to latex may be sensitive to patatin as well due to a phenomenon known as allergic cross-reactivity.

Potato Toxins
Plants of the nightshade family, such as potatoes, contain a class of toxic phytonutrients known as glycoalkaloids.

The two main glycoalkaloids in potatoes are solanine and chaconine.

Glycoalkaloid poisoning after eating potatoes has been reported in both people and animals .

However, reports of toxicity are rare and the condition may go 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 the low levels of glycoalkaloids likely found in the human diet may exacerbate inflammatory bowel disease (IBD).

Normally, potatoes contain only trace amounts of glycoalkaloids. A 154-pound (70-kg) individual would have to eat over 13 cups (2 kg) of potatoes (with the skin) in one day to get a lethal dose.

That said, lower amounts may still cause adverse symptoms.

The levels of glycoalkaloids are higher in the peel and sprouts than other parts of the potato. It’s best to avoid eating potato sprouts.

Potatoes rich in glycoalkaloids have a bitter taste and cause a burning sensation in your mouth, an effect that may be a warning sign of potential toxicity.

Potato varieties containing high amounts of glycoalkaloids — over 25 mg per cup (200 mg per kg) — cannot be marketed commercially, and some varieties have been banned.

Acrylamides
Acrylamides are contaminants formed in carb-rich foods when they’re cooked at very high temperatures, such as during frying, baking, and roasting (45).

They are found in fried, baked, or roasted potatoes, but not fresh, boiled, or steamed ones..

The amount of acrylamides increases with higher frying temperatures.

Compared to other foods, french fries and potato chips are very high in acrylamides.

These compounds are used as industrial chemicals, and acrylamide toxicity has been reported in people exposed to them in the workplace.

Although the amount of acrylamides in foods is generally low, long-term exposure may be harmful.

Animal studies indicate that acrylamides may increase cancer risk and harm the brain and nervous system.

In humans, acrylamides have been classified as a possible risk factor for cancer (45).

Numerous observational studies have investigated the effect of eating acrylamide-rich foods on cancer risk, and most did not detect any significant adverse effects.

In contrast, a few studies have linked acrylamides with an increased risk of cancer of the 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 your consumption of french fries and potato chips.

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 — high-fat foods that harbor a number of unhealthy compounds. French fries are also frequently associated with fast food.

Observational studies link the consumption of fried potatoes and potato chips to weight gain (68Trusted Source, 69Trusted Source).

Fried potatoes and potato chips may also contain acrylamides, glycoalkaloids, and high amounts of salt, which all may be harmful over time (45, 70Trusted Source, 71Trusted Source).

For this reason, high consumption of fried potatoes — especially french fries and chips — should be avoided.

SUMMARY
Potatoes may contain a number of unhealthy compounds — particularly when fried. Limit your consumption of french fries and chips, and never eat potato sprouts.