Roasted Sweet Potatoes: Beware of Acrylamide in Overcooked or Burnt Portions, Warns Nutritionist

While sweet potatoes are celebrated as a healthy whole food, a nutritionist is urging caution regarding how they are prepared, particularly when roasted. Lao Gu, a nutritionist, highlighted research indicating that high-temperature, prolonged cooking of starchy foods like sweet potatoes can lead to the formation of acrylamide, a substance of concern due to its potential carcinogenic and genotoxic properties.

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The World Health Organization (WHO) and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) consider acrylamide a genotoxic and carcinogenic compound.

Studies have shown that acrylamide formation is linked to the Maillard reaction, occurring when amino acids, especially asparagine, react with reducing sugars at high temperatures and low moisture. One 2022 study found that sweet potato strips baked at 190°C for 14 minutes contained up to 327 μg/kg of acrylamide. The risk increases significantly with temperatures above 175°C and longer baking times.

Further research in 2025 explored how preparation methods influence acrylamide levels. It was found that air-fried sweet potato slices can contain very high concentrations, sometimes exceeding 10,000 μg/kg. The study also noted that different sweet potato varieties, due to varying levels of reducing sugars, can produce different amounts of acrylamide. Thinly sliced, dry, and burnt sweet potatoes are particularly prone to higher acrylamide formation because their increased surface area and reduced moisture content lead to higher surface temperatures.

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When eating roasted sweet potatoes, many people often pursue fragrance, sweetness, charring, and crispiness, but the drier, browner, and more charred the surface, the higher the chance of acrylamide formation.

Lao Gu advises consumers to prioritize steamed or boiled sweet potatoes for lower acrylamide intake. If roasting, he recommends cooking them only until they are golden, thoroughly cooked, and soft, strictly avoiding any burnt or excessively browned sections. While sweet potato snacks like chips and fries are acceptable occasionally, they should not be considered a staple healthy food. He also emphasizes that sweet potatoes are best consumed as a replacement for a portion of staple carbohydrates rather than an additional item, and a varied diet including vegetables, legumes, and protein is key to a balanced and lower-risk eating pattern.

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Healthy eating is not about eliminating all possible risks; roasted sweet potatoes are not necessarily unhealthy.