They are one of the most versatile and widely used root vegetables in the world. Because they are inexpensive and fairly easy to grow in rich soils worldwide, potatoes have long been a staple food for many cultures.
In fact, in the mid-19th century, most farmers in western Ireland and parts of the Scottish Highlands relied so heavily on potatoes that a blight on the crop caused widespread famine throughout the nation, and contributed to a wave of emigration within the UK and to the Americas.
Yet, the humble potato has also been the subject of quite a lot of controversy in recent years. While vegetables are typically considered to be healthy food choices, potatoes – because of their high starch content – are often vilified by health and diet experts.
The truth is that, when cooked and dressed properly, potatoes provide many nutrients and can be a healthy choice when eaten in moderation.
A quick history of the potato
Believed to have been first domesticated in what are now southern Peru and northwest Bolivia between 8000 and 5000 BCE, the potato would have been the principal staple carbohydrate for many early South American civilizations.
Archaeologists have found tuber remains dating back to 2500 BCE in Peru, where many varieties were grown by the indigenous peoples. The crop was introduced to Europe following the Spanish conquest of the Inca civilization in the early 16th century, and then brought by European travellers to other ports throughout the world.
Thousands of different varieties of potato still thrive in the Andes, with hundreds sometimes occupying the same valley, and a dozen or more different cultivars might be raised by one Andean farming family.
There are nearly 4000 known varieties of potato, each with their own agricultural and nutritional characteristics. Their sizes also vary from one variety to another with some being the size of a ping-pong ball and others as large as a brick or even bigger – the world record for the largest potato goes to a specimen grown in the UK in 2011 that weighed almost 11lb (4.98 kg).
Over the years, many potato varieties have been selectively bred for their skin or flesh colours, which can range from light golden yellow to red, purple, and even blue.
Today, potatoes are the fourth most consumed crop in the world, ranking below only rice, wheat, and corn.
For agricultural purposes, potatoes are generally categorized by their physical characteristics; the main groups are purple potatoes, red potatoes, russet potatoes (with a rough, brown skin), white potatoes, and yellow potatoes (which are also called Yukon potatoes).
The culinary world, however, typically classifies potatoes by their waxiness. A floury or mealy potato is best for baking and typically contains 20-22% starch – more than the waxier boiling potatoes which usually have only 16-18% starch content.
In fact, potatoes have two different starch compounds: amylopectin and amylose. Amylopectin, the more highly branched starch molecule, helps the potato retain its shape after being boiled in water whereas potatoes higher in amylose, which diffuses from the starch molecule when cooked in water, are best for mashing.
We also sometimes refer to chipping potatoes, those that are best suited to holding their shape when crisp-fried.
The good, the bad, and the scary
Potatoes have been at the centre of a dietary controversy for the past few years: historically, in the United States and many other developed countries, we ate fresh potatoes.
But more processed options – like French fries or hash browns – have grown considerably more popular as we’ve become better able to freeze and transport these products.
Though they may be tasty and convenient, these processed potatoes product are often prepared in ways that can lead to weight gain, and illnesses such as diabetes or heart disease.
And while many are quick to dismiss them as fatty and high-carb landmines – to be avoided at all costs – it would be wrong to discount all the potential goodness that potatoes can provide.
Nutrients found in potatoes
Like most vegetables, potatoes provide a variety of vitamins and minerals – especially when cooked in certain ways. Though butter, oil, or toppings such as sour cream can all add calories, a plain potato is a relatively low-calorie choice of side-dish.
Baking a potato is the best way to prepare it as it causes the lowest amount of nutrients to be lost, followed by steaming as boiling potatoes can cause as much as 80% of some of their water-soluble nutrients to leach out into the water.
Potatoes provide many important vitamins and minerals when consumed in moderation and as part of a healthy, balanced diet. For example, a medium-sized white potato that is about the size of a computer mouse represents the recommended 3.5-ounce serving and, if baked and eaten with the skin, it typically contains:
Nutritional breakdown of a medium baked potato
- 94 calories
- 0.15 grams of fat
- 0 grams of cholesterol
- 21.08 grams of carbohydrate
- 2.1 grams of dietary fiber
- 2.1 grams of protein
- 0.64 mg of iron
- 27 mg of magnesium
- 75 mg of phosphorus
- 544 mg of potassium
- 12.6 mg of vitamin C
- 0.211 mg of vitamin B6
- 38 mcg (micrograms) of folate
Potatoes also provide choline, niacin and zinc in different quantities according to the variety. For example, a red potato has slightly more vitamin K and niacin than a Russet potato but provides less fiber and contains comparatively fewer carbs and calories.
Plain potatoes contain very little sodium – usually approximately 10 mg per serving, which is less than 1% of the suggested daily limit.
The fiber content in potatoes helps to maintain a healthy circulation and digestion by preventing constipation and promoting regularity. Dietary fibers can also be important factors in weight loss and management; they can increase the feeling of fullness and reduce the appetite.
Further, a protein found in potatoes, known as potato proteinase inhibitory 2 (PI2) can also curb the appetite by enhancing the release of cholecystokinin (CCK) which is a hormone that promotes feelings of satiety.
An interesting nutritional fact about potatoes is that they’re one of the most filling foods available – studies have shown that people are much more satiated after eating similar-sized portions of many other starchy foods, which leads to a lower overall calorie intake.
Potatoes are also high in vitamin C, which acts as an antioxidant, promoting healthy cardiovascular functions and digestion in addition to helping to prevent some types of cancer, as well as cell damage. A single potato serving contains about 20% of the recommended daily intake of vitamin C.
Potatoes are also a good source of other antioxidants such as carotenoids, flavonoids and phenolic acids – antioxidants have been shown to prevent certain types of chronic diseases, like cancer, diabetes, and heart disease.
Cultivars with purple or red skin and flesh tend to contain the highest amounts of polyphenols and potatoes with yellow flesh contain lutein, a carotenoid antioxidant that is believed to boost eye health.
Potassium is the predominant mineral in potatoes – they contain even more potassium than bananas – and one serving of potatoes can provide 15% of your daily allowance of potassium.
Potassium acts as a blood vessel widener so it can help lower blood pressure. It’s concentrated in the skin, so baking or boiling the potatoes with the skins on gives the best benefit.
In fact, the way your prepare your potatoes will drastically change their nutrient content: as mentioned earlier, boiling can leach out nutrients, frying can increase both the fat and calorie content of the potatoes, and dressings like butter, sour cream, or cheese – while tasty – add even more unnecessary fat and calories. And processed potato products are always an unhealthier choice, containing less nutrients pound for pound than their fresh counterparts but more calories, fat and sodium.
Overall, as with most foods, when eaten in moderation – as part of a well-balanced diet – it’s unlikely that whole, unprocessed potatoes can cause a significant weight gain for most people.
The nutrients in potatoes can contribute to a healthy lifestyle when the naturally fat-free tubers are prepared in the right way.
The minerals in potatoes help the body to build and maintain bone structure and strength, and the iron and zinc also play important roles in the production and maturation of collagen – the skin’s support system – with the vitamin C helping to prevent damage caused by pollution, smoking, or the sun.
Potatoes are a good source of choline, which helps with early brain development, learning, memory and mood as well as muscle movement. It can also help absorb fat, maintain the structure of cellular membranes and transmit nerve impulses. A large potato contains 10-15% of the recommended daily intake of choline.
Potatoes also contain folate which plays an important role in DNA synthesis and repair – meaning that it can prevent many types of cancers cells from forming.
The B6 contained in potatoes helps to break down carbohydrates and proteins into glucose and amino acids, which are more easily metabolized into useable energy within the body. B6 also helps to create useful brain chemicals like dopamine, serotonin and norepinephrine – therefore, they may decrease instances of depression, lower stress, and perhaps even help with attention deficit hyperactivity disorder (ADHD).
The Unhealthy Side of Potatoes
But of course, many studies have also determined that eating certain types of potatoes can cause you to gain weight – a 5-year study found that regular consumption of the tubers was associated with an increase in women’s waist circumference.
Processed potato chips are one of the largest contributors to weight gain, with each serving consumed daily causing an average increase of 1.7 lb (0.77 kg). As mentioned above, processed potato products typically contain far more unhealthy ingredients and preservatives than would a whole potato – even perhaps when topped with butter, sour cream, or cheese.
As all starches, potatoes are mainly composed of carbohydrates – complex sugars – though simple sugars such as fructose, glucose and sucrose are also present in small amounts. Potatoes have a high glycemic index (GI), meaning they cause blood sugar levels to rise rapidly and making them an unsuitable choice for diabetics or other people that must follow a low-glycemic diet, such as women with polycystic ovary syndrome (PCOS). In some cases, cooling the potatoes after cooking them may lower their GI by approximately 25%.
Like many vegetables, potatoes are low in protein; however, the main protein in potatoes – called patatin –may cause allergic reactions in some people. Those who are allergic to latex may be sensitive to patatin due to allergic cross-reactivity.
It’s important to keep in mind that the standard serving size for starches is 3.5 ounces and most potatoes are considerably larger than that. The average Russet baking potato contains almost 2 servings of potato, and those served in restaurants can be even bigger.
While potassium is a very important nutrient in the average diet, for some people it may lead to serious health issues: those with kidney damage or lowered kidney function may not be able to filter excess potassium from the blood, which can occasionally be fatal. Heart disease patients who have been prescribed beta-blockers should also avoid excess amounts of potassium.
It’s also important to note that potatoes are members of the nightshade family of plants – along with peppers, tomatoes and tobacco – and these plants contain glycoalkaloids, potentially toxic chemical compounds – specifically chaconine and solanine.
Though reports of poisoning are rare, it can go undiagnosed in many cases as the symptoms are typically mild: diarrhea, headache, nausea, stomach pain or vomiting. More severe cases of glycoalkaloid poisoning can however lead to decreased blood pressure, fevers, increased heart rate and rapid breathing, neurological disorders or even death. Luckily, the average adult would need to consume over 13 cups of skin-on potatoes in one day to reach a lethal dose of toxins.
Green potatoes are especially high in the compounds, as the green coloration means that they’ve been exposed to sunlight – which will also have increased their glycoalkaloid concentrations. These natural pesticides can, when present in high amounts, have serious effects on digestive health as well as other effects such as drowsiness, increased sensitivity, and itchiness.
The highest glycoalkaloid concentration is found in the potato peel – and proper storage of your potatoes is the key to prevent their formation. As well as hilling up your growing tubers to prevent exposure to sunlight, you should also store your harvested crop at lower temperatures and away from light sources.
It’s best to keep your potatoes in a dark, dry environment such as a root cellar – keeping them in the fridge will cause their starch content to be converted to sugar, and can produce an unpleasant flavour. Don’t store them alongside your onions as both vegetables emit natural gases that cause the other to decay; while fully grown potatoes can typically last about 2 months, spoiled tubers will affect those around them, so they should be removed to prevent the rest of the crop from rotting.