Potato vs Sweet potato - Health impact and Nutrition Comparison
It is easy to assume that sweet potatoes and potatoes are different types of the same vegetable. However, despite the similarity of the names and looks, these vegetables are not even closely related. In this article, we will talk about what other similarities sweet potato and potato share and what sets them apart, with a main focus on health and nutrition.
Sweet potatoes and potatoes are tuberous roots of underground plants called root vegetables.
Botanically, plants of sweet potatoes and potatoes share the same order called Solanales. From that point on these vegetables start to diverge.
The flowering plant of sweet potato belongs to the Convolvulaceae family, the Ipomoea genus and the batatas species. The Convolvulaceae family is also often called morning glory, which is mostly used as the term for the ornamental flowers of this family.
The common potato plants, on the other hand, are a part of the Solanaceae family, the Solanum genus and the tuberosum species. The Solanaceae family of flowering plants is commonly referred to as the nightshades, that also includes tomatoes, eggplants, chili and bell peppers.
Sweet potatoes are often called “yams”, however true yams are a separate and distinct species of vegetables.
Sweet potatoes are commonly perceived to have brown skin and an orange or red flesh, however they can also be white skinned and white, gold, purple fleshed.
Common potatoes can also appear in white, yellow, red, purple and other cultivars.
Taste and Use
Sweet potato and white potato taste quite similar. As the name suggests, sweet potatoes are naturally sweeter. However, different varieties of sweet potato have different levels of sweetness. Varieties with pale yellow or white flesh are less sweet and moist than those with red, pink or orange flesh (1).
These two vegetables are also often used in the same ways: boiled, baked, roasted, grilled, fried and so on.
There are hundreds of varieties of both sweet potatoes and potatoes. Different varieties and types of these vegetables have different appearances, tastes and nutritional values.
The most common varieties of sweet potatoes are Beauregard, Jewel, Garnet, Covington, White and Japanese.
Most potato varieties fit into seven types: russet, red, white, yellow, blue or purple, fingerling and petite (2).
Sweet potatoes are often considered to be healthier and more nutritious than white potatoes. In this section, we will look into the specific difference between their nutrients and see how that statement holds up.
Macronutrients and Calories
Sweet potatoes and white potatoes have similar densities. Potato contains a little more water with a percentage of 79, while sweet potatoes contain 77% water.
One average serving size of a potato is half a cup of potatoes, diced, weighing around 75g. A serving size of sweet potatoes is double that amount, equalling one cup of sweet potatoes in cubes that weighs 133g.
Sweet potatoes are a little higher in calories with 86 per 100g, whereas potatoes contain 77 calories in the same amount.
Protein and Fats
White potatoes are richer in both protein and fats.
Both sweet potatoes and potatoes contain some level of all essential amino acids. Sweet potato is a little richer in those essential amino acids, like tryptophan, and threonine.
The predominant fats found in potatoes are polyunsaturated fatty acids and are considered to be healthier. Over half of the fat found in sweet potatoes is saturated.
Sweet potatoes contain 3g more carbohydrates than potatoes per 100g. Sweet potato contains more sugars than fiber, whereas the opposite can be said for potatoes. However a 100g of sweet potatoes still contains more fiber than the same amount of potatoes.
White potatoes contain more starch than sweet potatoes. In fact, starch makes up for the 95 percent of carbohydrates found in white potatoes. Both vegetables also contain low amounts of sucrose, glucose and fructose.
Sweet potato and white potato have quite different vitamin compositions.
Sweet potato is a great source of vitamin A, containing much more of it than potatoes do. One hundred grams of sweet potatoes provide 284% of the daily value of vitamin A needed. Sweet potatoes are also richer in vitamin E, vitamin B2 and vitamin B5.
White potato, on the other hand, is higher in vitamin C, vitamin B3, vitamin B6, the folate form of vitamin B9 and vitamin K.
The two vegetables contain a similar amount of vitamin B1.
Both sweet potato and white potato are completely absent in vitamin D, vitamin B12 and folic acid.
Sweet potatoes contain higher levels of calcium and copper, as well as magnesium, manganese and selenium.
Potatoes, on the other hand, are richer in iron, potassium and phosphorus. They are also much lower in sodium.
Sweet potatoes and white potatoes contain similar amounts of zinc and choline.
Sweet potatoes have a lower glycemic index compared to potatoes. The glycemic index of potatoes and sweet potatoes can range from moderate to high levels.
Based on the mean of nine studies, the glycemic index of a cooked sweet potato is 70±6. However, based on cooking methods and variety of sweet potatoes, the GI can range from 44 to 94.
Baked potatoes can have a glycemic index ranging from 60 to 98. The average GI of four types of baked potatoes is 86±6 (3).
Another study puts the glycemic index of boiled sweet potatoes at 63±6 and the GI of boiled potatoes at 78±4 (4).
The pH value for sweet potatoes falls between 5.3 to 5.6, making it slightly acidic (5).
The acidity of potatoes is similar, also slightly acidic, with a pH that ranges from 5.4 to 5.9 (5).
Another value that shows the acidity of the food is the potential renal acid load. The PRAL shows the capacity of the food to produce bases or acids in the body.
The PRAL of sweet potatoes has been calculated to be -5.6, alkaline, with the PRAL value for potatoes being -6.6, more alkaline.
Sweet potatoes and white potatoes, both contain moderate levels of calories per serving. This can change depending on the cooking methods of these vegetables. For example, a hundred grams of boiled potatoes contain 87 calories, whereas the same amount of French fries contain 312 calories. Leaving the skin on, makes these vegetables more nutritious, providing more fiber.
Meal replacements with white sweet potato may aid individual weight loss (6).
Some studies have found a correlation between the intake of French fries, baked or mashed potatoes and weight gain - an added 1.5 and 0.6 kg (3.4 and 1.3 pounds) respectively for every four years (7).
However, another research suggests that there is no need to exclude potatoes from weight management diets (8).
Overall, these vegetables aren’t ideal for low carb or low calorie diets, however they can be included in all diets, when prepared with the right methods and in moderation.
The Sweet Potato and Potato Diets
Both of these diets are restrictive and promise weight loss if you eat nothing but sweet potatoes or potatoes for multiple days. There are variations to these diets but all require you to eat cooked, not fried or highly processed, sweet potatoes or potatoes for every meal of the day.
Since, these are low calorie diets, they are likely to lead to weight loss. However, there are few problems with these diets. As nutritious as these vegetables are, they do not provide all the essential nutrients for the human body. There is also a likelihood of easily regaining the rapidly lost weight.
We learned that sweet potatoes and potatoes are both very nutritious, but what exact effects do they have on the human organism?
Potatoes being much lower in sodium compared to sweet potatoes, may be a better choice for people with high blood pressure. However, one study has found an association of higher intake of baked, boiled, mashed, or fried potatoes with an increased risk of hypertension (9). This effect may be explained by potatoes’ high glycemic load and gaining weight. Overall, higher consumption of potatoes has been shown to be adversely related with cardiovascular risk factors (10).
In contrast to that, some studies suggest that potatoes may have a positive effect on high blood pressure (11).
There is not enough research to conclude about sweet potato’s effect on cardiovascular health. However, one research found purple sweet potato beverage to have an inclination to lower systolic blood pressure (12).
There is some evidence of association between high glycemic index foods, such as some types of potatoes and sweet potatoes, and diabetes.
Studies about potatoes and diabetes are also inconclusive․ Some studies suggest that potato consumption leads to an increased risk of developing type 2 diabetes (12). However, more research on humans is needed in order to have a final result.
A study has suggested that supplementation of white sweet potato may improve nutritional status and glycemic control in elderly diabetic patients (13). However, there is also insufficient evidence about the use of sweet potato for type 2 diabetes mellitus (14).
There are strong suggestions that purple sweet potatoes can be used as a preventive factor for colorectal cancer, due to their high levels of anthocyanin (15). Anthocyanins are flavonoids that give vegetables, such as purple sweet potatoes, their dark colour.
Studies about the association of potatoes and cancer have been inconclusive and at times contradictory. Some research shows there to be no link between potato consumption and pancreatic cancer, while others associate it with an increased risk. Some studies found potato intake to have correlations with a higher risk of rectal, colon and colorectal cancers (16). At the same time, there has been research showing an inverse association between potato consumption and rectal cancer. More research is needed on this topic.
Downsides and Risks
Vegetables in the nightshade family, that potatoes belong to, produce a toxic compound called solanine, a glycoalkaloid. Naturally potatoes produce such low amounts of this compound that it does not affect human health. However, under certain unfavourable conditions, such as pests, potato plants can increase the production of solanine, especially when kept in sunlight. Solanine gives potatoes a bitter taste and a green colour.
Solanine poisoning may include symptoms, such as diarrhea, vomiting, fever and abdominal pains (18).
As sweet potatoes do not belong to the same family, they do not produce this compound.
Sweet potatoes and potatoes are root vegetables that are only very distantly related to each other. Sweet potatoes are higher in calories and carbs, while potatoes contain more protein and fats. Both are rich in various vitamins and minerals. Sweet potato is higher in vitamin A, vitamin E, vitamins B2 and B5, calcium and copper. Potatoes, on the other hand, contain higher amounts of vitamin C, vitamins B3, B6 and B9, vitamin K, iron, phosphorus and potassium, while also being lower in sodium.
When it comes to the health effects of potatoes, research is overall inconclusive. Sweet potatoes have a lower glycemic index compared to potatoes. White and purple sweet potatoes may have a positive effect on diabetes and cancer.
In summary, both sweet potatoes and potatoes are rich in nutrients, and can be good for your health, as long as they are used in moderation.
Vitamin and Mineral Summary Scores
Comparison summary table
|Lower in Saturated Fat|
|Lower in glycemic index|
|Lower in Sugar|
|Lower in Sodium|
|Lower in Cholesterol||Equal|
|Lower in price||Equal|
|Rich in minerals||Equal|
|Rich in vitamins||Equal|
Which food is preferable for your diet?
|Low Calories diet|
|Low Fats diet|
|Low Carbs diet|
|Low glycemic index diet|
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All nutrients comparison - raw data values