What Sugar Do Potatoes Have, and Is It Healthy?

November 24, 2025 •

4 min read

While most people consider potatoes a starchy vegetable, they also contain small amounts of simple sugars, such as sucrose, glucose, and fructose. This might come as a surprise to those who think of all sugar as inherently unhealthy, but the overall nutritional profile and carbohydrate composition of potatoes is more nuanced than a simple sugar count suggests.

Quick Summary

An exploration of the sugars in potatoes, focusing on the roles of complex carbohydrates (starch) versus simple sugars. It details how the body processes these sugars, how preparation methods influence their impact on blood glucose, and the health implications for a balanced diet.

Key Points

Potato Sugar Content: Potatoes contain primarily complex carbohydrates (starch) and only small amounts of simple sugars like glucose, fructose, and sucrose.
Digestion Process: The body breaks down potato starch into glucose, which is absorbed into the bloodstream; the speed depends heavily on cooking and variety.
High Glycemic Index: Despite being starchy, some potato preparations, like baked or instant mashed, can have a high glycemic index, causing a fast blood sugar spike.
Resistant Starch Benefits: Cooking and then cooling potatoes increases resistant starch, a form of fiber that improves gut health and lowers the food's glycemic impact.
Cooking Methods Matter: How you prepare a potato is crucial; boiling and cooling is more beneficial for blood sugar control than baking or mashing.
Nutrient-Dense Complex Carbs: Plain, prepared potatoes are a nutrient-dense food rich in potassium and Vitamin C, offering a good source of complex carbohydrates.

The Dominance of Complex Carbohydrates

Despite the presence of simple sugars, potatoes are overwhelmingly composed of complex carbohydrates in the form of starch. Starch is a polysaccharide, meaning it consists of long, linked chains of glucose molecules. Your body must break down these long chains during digestion before it can absorb the glucose. This process is different from consuming a simple sugar, like table sugar (sucrose), which is a disaccharide that is broken down and absorbed much more quickly.

Starch vs. Simple Sugars

The digestion rate is a critical distinction between the energy from starch versus simple sugars. When you eat potatoes, the glucose is released into your bloodstream over a longer period, providing a more sustained energy source compared to the rapid spike and crash associated with simple, refined sugars. The amount of simple sugar present in a typical potato is quite low. For example, a 100-gram serving of boiled potato contains only about 0.9 grams of sugar, compared to over 20 grams of total carbohydrates, most of which are starch.

The Role of Resistant Starch

A particularly interesting aspect of potato carbohydrates is resistant starch. As the name suggests, this type of starch resists digestion and functions more like dietary fiber. When potatoes are cooked and then cooled, some of the digestible starch converts into resistant starch, which offers several health benefits. This process is known as retrogradation. Reheating cooled potatoes does not eliminate the resistant starch, meaning you can still benefit from it. Resistant starch supports gut health by feeding beneficial bacteria and can also help regulate blood sugar levels.

How Preparation Affects Potato Sugar and Digestion

The method of preparing a potato has a profound impact on its glycemic index (GI), a measure of how quickly a food raises blood sugar levels. While a potato is a complex carbohydrate, certain cooking methods can lead to rapid starch breakdown and a higher GI.

Glycemic Index Variations in Potatoes

Different cooking methods can drastically change the GI of a potato:

Baked Potatoes: Typically have a high GI, with values often in the 80s or 90s, especially for starchy varieties like Russets. The high heat and process can make the starch more easily digestible.
Boiled Potatoes: Generally have a lower GI than baked potatoes. Their GI can be further reduced significantly by cooling them after boiling.
French Fries and Chips: The added fat in these preparations slows down digestion, but the high-heat frying also makes the starches more accessible, and the products can have varying, but often high, glycemic loads.
Instant Mashed Potatoes: These have one of the highest GIs among potato products because the processing breaks down the starch granules, making them very quick to digest.

To minimize the impact on blood sugar, boiling and then cooling potatoes is the most effective method, as it increases resistant starch content. Eating potatoes with the skin, which adds fiber, and pairing them with other foods containing protein and fat can also help slow digestion.

Starch vs. Table Sugar: A Surprising Glycemic Comparison

Many people are surprised to learn that a potato can sometimes raise blood sugar more quickly than an equal amount of table sugar (sucrose). This is because the glucose units in a potato's starch are rapidly digested into pure glucose, while sucrose is a disaccharide of glucose and fructose. Fructose is processed differently by the body and does not impact blood sugar as directly as glucose. This does not mean potatoes are "worse" than sugar, but rather highlights that the glycemic response is not simply determined by the perceived sweetness of a food.

Comparison: White Potato vs. Sweet Potato

When comparing white and sweet potatoes, their sugar and starch profiles differ significantly. This is important for those managing blood sugar or simply looking for variety in their diet.


Characteristic	White Potato (e.g., Russet)	Sweet Potato	Health Implication
Primary Carbohydrate	Mainly starch	Mix of starch and simple sugars (mostly sucrose)	Sweet potatoes have more simple sugar, but also higher fiber, balancing the glycemic response.
Total Sugar (per 100g)	Low (approx. 0.9 g)	Higher (approx. 4.2 g)	Despite lower total sugar, white potatoes can spike blood sugar faster due to rapid starch digestion.
Glycemic Index (GI)	Typically medium to high, depending on preparation	Usually lower to medium, depending on preparation	Sweet potatoes generally lead to a slower, steadier rise in blood sugar.
Resistant Starch	Can be increased significantly by cooking and cooling	Found in some varieties; also benefits from cooling	Resistant starch is a fiber-like carb that benefits gut health and blood sugar control.
Vitamin A	Very little	Excellent source (often over 100% of daily value)	Sweet potatoes offer a significant vitamin A boost not found in white potatoes.

Conclusion

In summary, the question of what sugar do potatoes have reveals a lot about how we perceive carbohydrates. Potatoes have very little simple sugar in their raw form. Their carbohydrates primarily consist of starch, a complex sugar made of long glucose chains. While the body eventually breaks this starch down into glucose, the rate of digestion is heavily influenced by preparation method. By boiling and cooling potatoes, you can increase their resistant starch content, which in turn lowers their glycemic impact and offers additional health benefits. The key to including potatoes in a healthy diet lies in understanding this complexity, choosing less processed options, and paying attention to preparation.

Where to Learn More

For further information on the role of starch and sugar in nutrition, the Harvard T.H. Chan School of Public Health provides comprehensive resources on carbohydrates and the glycemic index. Learn more at The Nutrition Source

Frequently Asked Questions

No, potatoes are not primarily a sugary food. They are predominantly composed of complex carbohydrates known as starch, with only trace amounts of simple sugars like glucose and fructose.

No, potato starch is not the same as table sugar. Starch is a complex carbohydrate made of long glucose chains, while table sugar (sucrose) is a simple disaccharide. The body digests starch more slowly, releasing glucose gradually.

Potatoes can affect blood sugar significantly, especially when cooked in ways that make their starch easily digestible, like baking or mashing. However, boiling and cooling them increases resistant starch, leading to a slower rise in blood sugar.

Yes, the potato variety matters. Starchy potatoes like Russets have a different carbohydrate profile and typically a higher glycemic index than waxy potatoes like red or fingerling, which have a lower GI.

Yes, resistant starch is healthy. It acts like fiber, feeding beneficial gut bacteria and improving blood sugar control. You can increase resistant starch in potatoes by cooking and then cooling them.

Yes, people with diabetes can eat potatoes in moderation. They should consider the portion size, preparation method, and pair them with protein, fat, or other fiber-rich foods to help manage blood sugar response.

Baked potatoes can have a high glycemic index because the cooking process breaks down the starch granules, making them easier and faster for the body to digest and convert to glucose.