Corn Oil vs. Soybean Oil — Health Impact and Nutrition Comparison

Introduction

Corn and soybean oils are classified as vegetable oils, meaning they are derived from plant-based sources. 

Soybean or soyabean oil is the second most consumed vegetable oil in the world, after palm oil. Corn oil may also be considered one of the most commonly consumed vegetable oils. 

In this article, we will focus on each oil's smoking points, nutritional values, and health effects to find out their differences.

Types & Flavor

The oils can be used in food processing, salad dressings, margarine, mayonnaise, shortening, and as cooking oils (frying, cooking, and baking).

Soybean oil is extracted from soybean (Glycine max) seeds, whereas corn oil is extracted from the germ of corn (maize, Zea mays).

Corn oil can be crude or unrefined and refined. One of the classifications of soybean oil is crude, once-refined, and highly refined soybean oil.

Refined soybean oil has a mild neutral flavor, which helps it smoothly blend into the dish. Similarly, corn oil mostly has a neutral taste and smell.

Smoke Point & Deep Frying

An oil’s smoke point shows the oil's resistance to heat or the temperature at which it starts burning and smoking, indicating the breakdown of fats into glycerol and free fatty acids. Higher smoke points are recommended for high-heat cooking due to better thermal stability, whereas oils with low smoke points are better suited for salad dressings.

According to the Food Safety and Inspection Service (FSIS USDA), the smoke point of soybean oil is approximately 450°F (232°C), whereas the smoke point of corn oil is 410°F (210°C). Soybean and corn oils are safe for high-heat cooking, such as deep frying, stir-frying, and sautéing (1).

Various factors are responsible for the smoking point of oils, and studies may demonstrate different smoke point values. For example, according to several studies, corn oil and soybean oil have smoking points of 495.5°F (257.50°C) and 482°F (250°C), respectively (2, 3).

Other oils with high smoke points include olive oil, peanut oil, canola oil, grapeseed oil, safflower oil, sunflower oil, and vegetable oil (1).

Nutrition

The nutritional values in this article are presented for corn oil and partially hydrogenated soybean oil. 

Partially hydrogenated oils are processed oils; hydrogen is added to a liquid fat, making it solid at room temperature and increasing its shelf-life.

The nutritional infographics below are presented for 100g of each oil; however, they are commonly used in small amounts. The average serving size of oils per person is 1 tbsp (13.6-14g).

Macronutrients & Calories

Fats & Calories

Like most cooking oils, corn and soybean oils contain 100% fats and provide 900 and 884 calories 100g serving size, respectively. Over 80% of fats in either oil are unsaturated or “healthy” fats.

One serving or 1 tbsp of corn oil provides 122 calories, whereas soybean oil provides 120, making them nearly equal in calories. Corn oil is higher in polyunsaturated fatty acids, while partially hydrogenated soybean oil is higher in monounsaturated and saturated fatty acids.

Precisely, corn oil contains 1.45 times more polyunsaturated fats, whereas soybean oil contains 1.56 times more monounsaturated and 1.15 times more saturated fats. 

Fat Type Comparison

Fat type breakdown side-by-side comparison

Soybean oil

1

Saturated Fat: Sat. Fat 14.9 g

Monounsaturated Fat: Mono. Fat 43 g

Polyunsaturated fat: Poly. Fat 37.6 g

Corn oil

2

Saturated Fat: Sat. Fat 12.948 g

Monounsaturated Fat: Mono. Fat 27.576 g

Polyunsaturated fat: Poly. Fat 54.677 g

Contains more Mono. FatMonounsaturated Fat

+55.9%

Contains less Sat. FatSaturated Fat	-13.1%
Contains more Poly. FatPolyunsaturated fat	+45.4%

Non-hydrogenated soybean oil has a similar fat distribution profile to corn oil; it is only slightly higher in saturated and polyunsaturated fatty acids.

Over 90% of saturated fats in corn and soybean oils are palmitic acid (16:0), monounsaturated fatty acids are oleic acid (18:1), and polyunsaturated fatty acids are linoleic acid (18:2).

Fats are major energy sources and cell membrane constituents; they are also required for the metabolism, regulation, and function of membranes, intracellular signaling pathways, gene expression, and more (4).

Protein & Carbohydrates

Corn oil and soybean oil are absent in proteins and carbs.

Vitamins

Corn and soybean oils contain the fat-soluble vitamins E and K and are absent in other vitamins. 

Corn oil is 1.8 times richer in vitamin E than soybean oil: 100g of corn oil contains 14.3g of vitamin E (1.94mg in 1 tbsp), whereas soybean oil contains 8.1mg of vitamin E (1.1mg in 1 tbsp). 

Soybean oil contains 13 times more vitamin K. 100g of soybean oil contains 24.7mcg of vitamin K (3.36mcg in 1 tbsp), whereas corn oil contains 1.9mcg of vitamin K (0.258mcg in 1 tbsp).

Both oils contain negligible amounts of choline.

Vitamin Comparison

Vitamin comparison score is based on the number of vitamins by which one or the other food is richer. The "coverage" charts below show how much of the daily needs can be covered by 300 grams of the food.

Soybean oil

1

Corn oil

1

Contains more Vitamin KVitamin K

+1200%

Contains more Vitamin EVitamin E

+76.5%

~equal in Vitamin C ~0mg

~equal in Vitamin A ~0IU

~equal in Vitamin D ~0µg

~equal in Vitamin B1 ~0mg

~equal in Vitamin B2 ~0mg

~equal in Vitamin B3 ~0mg

~equal in Vitamin B5 ~0mg

~equal in Vitamin B6 ~0mg

~equal in Vitamin B12 ~0µg

~equal in Folate ~0µg

~equal in Choline ~0.2mg

According to the 2020-2025 Dietary Guidelines for Americans, the recommended daily allowance (RDA) of vitamin E is 15mg for adults. Thus, one serving or 1 tablespoon of corn oil covers the RDA of vitamin E by 13%, whereas soybean oil covers the RDA of vitamin E by 7% (5).

Vitamin E has strong antioxidant activities in the body by protecting our cells and tissues against harmful free radicals. 

Health Impact

Due to their similar fat profiles, soybean oil and corn oil affect health similarly. 

Cardiovascular Health

Replacing saturated fatty acids with unsaturated fats is recommended to reduce the risk of developing cardiovascular disease, such as coronary heart disease. 

A reviewed clinical and epidemiologic literature on soybean oil intake and cholesterol levels, inflammation, and oxidative stress suggests that soybean oil intake does not increase inflammatory markers or promote oxidative stress. Additionally, replacing dietary saturated fats with soybean oil has been shown to decrease blood cholesterol levels, potentially positively affecting overall health and reducing the risk of coronary heart disease (6).

A study compared the health effects of different types of soybean oils. It noted that most varieties of soybean oils (soybean oil (SO), low saturated fatty acid SO, high-oleic acid SO, and low α-linolenic acid SO) resulted in more favorable changes in lipid profile compared to the partially hydrogenated soybean oil (7).

Corn oil has a high concentration of ω-6 linoleic acid and is one of the main dietary sources of phytosterols and tocopherols. According to several studies, corn oil may improve plasma lipids by decreasing total and LDL cholesterol and triglyceride levels, therefore reducing the risk of cardiovascular disease. Tocopherol may help protect against DNA damage, high blood pressure, and diabetes (8, 9).

Diabetes

Corn oil and soybean oil are absent in carbs and, thus, do not raise blood sugar levels after consumption.

Due to high ω-6 polyunsaturated fats, soybean oil has been associated with increased weight gain, liver fat accumulation and inflammation, mitochondrial dysfunction, diabetes, glucose intolerance, and insulin resistance. Polyunsaturated fat and γ-tocopherol accumulation in the liver and dysregulation of Cyp P450 genes have also been reported (10, 11, 12, 13).

The relationship between corn oil and diabetes is yet to be properly studied. However, corn oil may also increase the risk of diabetes (11, 13). An animal study has shown that although lean mass and energy expenditure haven’t changed significantly, corn oil-fed mice demonstrated reduced physical activity, increased blood insulin, and impaired glucose metabolism (14).

To avoid the negative health effects of these oils, consuming them in moderation in a balanced diet and avoiding deep frying is recommended.

Author name: Arpi Gasparyan

Education: General Medicine at YSMU

Last updated: November 04, 2024

Medically reviewed by Elen Khachatrian