What Cornstarch is (and What it Isn't)
Cornstarch, also known as cornflour in some regions, is a fine, powdery substance derived from the endosperm of the corn kernel [1.4]. The wet milling process used to extract the starch from the kernel strips away most of its nutritional value, leaving behind a pure carbohydrate [1.5]. Because it lacks the fiber, protein, and essential nutrients found in whole corn, it is considered a refined and highly processed food [1.4, 1.5]. While its thickening properties make it a kitchen staple, especially in gluten-free cooking, it offers very little in the way of dietary benefits [1.4].
High Glycemic Index and Blood Sugar Spikes
One of the most significant health concerns associated with cornstarch is its high glycemic index (GI) [1.4]. The GI measures how quickly a food raises blood sugar levels. With a GI rating often between 77 and 88, cornstarch causes a rapid and significant spike in blood glucose [1.4]. Since it contains almost no fiber to slow digestion, the carbohydrates are converted to glucose very quickly [1.4].
For most people using a small amount to thicken a sauce, this effect is minimal. However, for individuals with diabetes, insulin resistance, or those consuming large amounts (such as in many processed foods), this can lead to:
- Unstable Blood Sugar: Frequent spikes and crashes can make blood sugar management difficult [1.4].
- Increased Risk of Complications: Diets rich in high-GI, refined carbs are linked to a higher risk of type 2 diabetes, obesity, and heart disease [1.4].
Potential for Weight Gain and Obesity
Because cornstarch is high in calories and carbohydrates but lacks fiber and protein, it contributes to caloric intake without promoting a feeling of fullness [1.8]. This can easily lead to excessive calorie consumption and, over time, weight gain [1.8]. Regular, heavy intake of highly processed, carb-dense foods is a known contributor to the development of obesity [1.8]. While a small amount in a stir-fry is unlikely to cause issues, consistently eating processed foods where cornstarch is a hidden ingredient can add up [1.6].
Minimal Nutritional Value
Cornstarch offers an insignificant amount of essential nutrients [1.4]. Unlike whole grains that provide fiber, vitamins, and minerals, cornstarch provides little beyond calories and carbohydrates [1.4]. This can become a problem if it frequently replaces more nutrient-dense ingredients in a diet [1.8]. For example, using a cornstarch-based gluten-free baking mix instead of a blend made from whole grains, nuts, or beans means missing out on valuable nutrients like B vitamins, fiber, and protein [1.5].
Digestive Issues and Cornstarch Intolerance
While typically easy to digest when cooked, consuming raw cornstarch can lead to digestive problems [1.4]. Starches are harder for the body to break down in their uncooked state, and fermentation in the gut can cause symptoms like [1.4]:
- Bloating
- Gas
- Abdominal pain
Some individuals may also have a specific cornstarch intolerance or sensitivity, experiencing these symptoms even from cooked preparations [1.4].
Cornstarch and Pica
A persistent, habitual craving to eat raw cornstarch is a symptom of a rare eating disorder called pica [1.4]. Pica is the consumption of non-food items, and in this context, it has been linked to underlying nutritional deficiencies, particularly iron-deficiency anemia or zinc deficiency [1.4]. If you or someone you know experiences this craving, it is important to seek medical advice to diagnose and treat any potential deficiencies [1.4].
Cornstarch vs. Healthier Alternatives
When cooking and baking, numerous healthier options can achieve similar results with added nutritional benefits. Below is a comparison of cornstarch with a few common alternatives.
| Feature | Cornstarch | Arrowroot Powder | Whole Wheat Flour | Tapioca Starch |
|---|---|---|---|---|
| Glycemic Impact | High [1.4] | Lower [1.6] | Lower [1.5] | Moderate [1.9] |
| Nutritional Value | Minimal; mostly carbohydrates [1.5] | Contains some B vitamins, iron, and potassium [1.6] | Contains fiber, B vitamins, and protein [1.5] | Low; mostly carbohydrates [1.9] |
| Thickening Power | Strong [1.6] | Strong, works at lower temps [1.9] | Moderate [1.6] | Moderate-High [1.9] |
| Appearance in Dishes | Translucent/Glossy [1.9] | Translucent/Glossy [1.9] | Opaque/Cloudy [1.9] | Translucent/Glossy [1.9] |
| Cook with Dairy? | Works well | Avoids slimy texture with dairy [1.9] | Works well | May become stringy in high heat [1.9] |
How to Use Cornstarch Safely
For most people, using small amounts of cornstarch for specific culinary purposes is perfectly safe and poses no health risks [1.6]. The key is moderation. Here are some guidelines:
- Use sparingly: A tablespoon or two used to thicken a large pot of stew or sauce is unlikely to be a problem [1.6].
- Choose whole food alternatives: In recipes that call for larger amounts, like gluten-free baking, consider swapping cornstarch for a healthier alternative like almond flour, oat flour, or bean flour [1.4].
- Read ingredient labels: Be aware of hidden cornstarch in processed and packaged foods, which can increase your overall intake without you realizing it [1.6].
- Avoid raw consumption: Never consume raw cornstarch, as it can cause digestive upset and may harbor bacteria [1.4]. Always mix it into a cold liquid first to create a slurry before adding to hot dishes [1.5].
Conclusion
While a common and useful kitchen ingredient, cornstarch is a refined carbohydrate that offers very little nutritional value [1.5]. The primary side effect of cornstarch arises from excessive consumption, which can lead to negative health impacts such as blood sugar spikes, increased risk of heart disease, and weight gain [1.4]. Most of these risks are tied to large quantities, not the small amounts typically used in cooking [1.6]. For better overall nutrition, prioritizing whole-food alternatives and using cornstarch in moderation are the wisest choices. Always consult a healthcare professional or registered dietitian for personalized advice, especially if managing conditions like diabetes or experiencing unusual cravings [1.4, 1.7].
For more information on the health effects of refined carbohydrates, you can consult sources like this guide from the American Diabetes Association.
