Which is Healthier?
Sweet potato fries have a reputation for being healthier than French fries, but you may wonder whether they’re really better for you.
After all, both kinds are usually deep-fried and served in oversized portions.
This article reviews the nutrition of sweet potato and French fries, as well as their potential health effects.
Detailed nutrition information is most readily available for store-bought, frozen fries.
The following nutritional comparison is for a 3-ounce (85-gram) serving — or 10–12 pieces of frozen fries — which can be baked as-is from the freezer (1):
*Fat and sodium content may vary between different brands of either type of fries.
Sweet potato fries are slightly higher in calories and carbs but also more nutrient dense than French fries.
The greatest nutrient difference is that French fries have no vitamin A, while sweet potato fries are high in this nutrient. Vitamin A is important for your vision and immune system (2).
SUMMARY Sweet potato fries are a bit higher in calories and carbs than French fries. However, sweet potato fries are also more nutrient dense and particularly high in vitamin A.
Serving Size and Cooking Methods Matter
The table in the previous chapter shows that a 3-ounce (85-gram) serving of baked French fries has 125 calories, compared to 150 calories for the same serving of baked sweet potato fries.
In contrast, fries at restaurants are typically deep-fried — which nearly doubles the calorie content.
Here’s a comparison of the average calories, fat, and carbs in different size orders of deep-fried fast food fries (1):
A large serving of each kind of fast food fries has as many calories as some people need in an entire meal.
Additionally, the carb and fat content are about doubled if you choose a large rather than a small serving — regardless if they’re French or sweet potato fries.
SUMMARYDeep-frying nearly doubles the calories in both French and sweet potato fries compared to baking. When deep-fried, a large serving of either type of fries contains a full meal’s worth of calories.
Two issues that have made news headlines over the past few decades are trans fat and acrylamide in fries.
Is Trans Fat Still a Problem?
Trans fat in fries and other processed foods became a big concern in the 1990s, as studies linked it to increased heart disease risk (3, 4).
Fortunately, new FDA rules ban the use of partially hydrogenated oil — the primary source of trans fat — in the U.S. food supply as of June 2018, though some may remain in the food supply until January 2020 as inventories are depleted (5).
Therefore, you should no longer see “partially hydrogenated oil” in ingredient lists of fries, nor should you find any trans fat listed in their nutrition information.
However, it’s likely still wise to limit your intake of deep-fried foods, as two studies suggest that small amounts of trans fat may form when oil is repeatedly used in a deep fryer (6, 7).
Acrylamide Forms in Both Types of Fries
Acrylamide is a potentially harmful compound discovered in 2002 in cooked, starchy foods — including fries. In fact, fries are one of the major dietary sources of acrylamide (8, 9, 10).
It’s formed through a reaction between the amino acid asparagine and certain sugars when starchy foods are fried and — to a lesser extent — when they’re baked or roasted (11, 12).
Though most studies on acrylamide levels in fries have tested French fries, this compound also forms in sweet potato fries and is what makes fries brown (13).
Acrylamide is classified as “probably carcinogenic” in humans. However, this is based on studies of animals given high doses of the compound (14).
A review of human observational studies suggests that typical acrylamide intakes are unlikely to be related to the most common causes of cancer — but more research is needed (15, 16, 17, 18).
Additionally, food suppliers may use several strategies to reduce acrylamide levels — such as treating fries with certain additives — though this isn’t required by law (13, 19, 20).
If you’re making fries from scratch, you can reduce acrylamide formation by avoiding refrigerating potatoes, baking instead of frying, soaking potato slices in water for 15–30 minutes before cooking, and heating them just until golden, not brown (12, 13, 21, 22).
SUMMARY New FDA rules have largely eliminated trans fat content in fries. However, acrylamide, a potentially carcinogenic byproduct in fried starchy foods, occurs in fries. Still, a typical intake through a normal diet is unlikely to be problematic.
Regular Consumption May Increase Disease Risk
French fries have come under increasing scrutiny due to new studies suggesting that higher intake may raise your risk of obesity, type 2 diabetes, and high blood pressure.
In observational studies, higher intake of French fries is linked to an increased risk of weight gain and obesity (23, 24).
One study associated an additional daily serving of French fries with gaining 3.35 pounds (1.5 kg) over a four-year period (25).
Studies also suggest that eating French fries at least once or twice a week may double the risk of food addiction in adults and children (26, 27).
These observational studies don’t prove that French fries were what really contributed to weight gain or food addiction, but they do suggest that it may be wise to limit your intake.
Type 2 Diabetes
French fries and sweet potato fries are both rich in carbohydrates, which raise your blood sugar.
The glycemic index (GI) — a measure of a food’s potential blood sugar impact — is 76 for fried sweet potatoes and 70 for fried white potatoes on a 100-point scale (28).
These are moderately-high values and suggest that both types of fries may raise your blood sugar similarly (29).
In an observational study, people who reported eating 3 or more servings of French fries per week had a 19% higher risk of type 2 diabetes, regardless of their body weight (30).
Additionally, a review of eight studies linked each daily 5.4-ounce (150-gram) increase in the consumption of French fries with a 66% higher risk of type 2 diabetes (31).
Though these studies don’t prove that fries increase diabetes risk, it may be wise to cut back on both types if you’re trying to lower your blood sugar.
Some observational studies suggest that a higher intake of fried foods may increase heart disease risk — though studies haven’t been able to pinpoint French fries as a culprit (24, 32, 33, 34).
Still, if you frequently eat fries, you may be more likely to develop heart disease risk factors, such as obesity and high blood pressure (24).
In a large observational study, people who ate 4 or more servings of French fries per week had a 17% higher risk of high blood pressure, compared to people who ate fewer than one serving per month (35).
The reasons behind these findings are uncertain but may be related to weight gain, which may increase high blood pressure risk (36, 37, 38).
SUMMARY Regularly eating French fries may increase your risk of some diseases, including obesity, type 2 diabetes, and high blood pressure. It’s uncertain if regularly eating sweet potato fries would similarly increase disease risk.
Which Type Should You Choose?
To make the best choice, it would be ideal to have studies that directly compare the health effects of sweet potato and French fries when eaten in the same quantities. However, such studies are unavailable.
Still, many people’s diets fall short of meeting the Reference Daily Intake (RDI) for vitamin A. Sweet potato fries boost your vitamin A intake whereas French fries lack this vitamin (39).
While sweet potato fries may be slightly healthier than French fries, neither is healthy if eaten in large amounts.
Sweet potato fries are slightly higher in calories and carbs than French fries but also high in vitamin A — giving them a nutritional edge.
Still, deep-fried fries of any kind served in over-sized portions — as in many restaurants — may increase your risk of weight gain and related health problems.
A better choice is to bake frozen or homemade fries — regardless of what kind they are. This gives you more control over your serving size and helps limit your calorie intake.