Soybean oil lowers circulating cholesterol levels and coronary heart disease risk, and has no effect on markers of inflammation and oxidation

Abstract

To reduce risk of coronary heart disease, replacement of saturated fats (SFAs) with polyunsaturated fats (PUFA) is recommended. Strong and concordant evidence supports this recommendation, but controversy remains. Some observational studies have reported no association between SFAs and coronary heart disease, likely because of failure to account for the macronutrient replacing SFAs, which determines the direction and strength of the observed associations. Controversy also persists about whether ω-6 (nω-6) PUFA or a high dietary ratio of nω-6 to ω-3 (nω-3) fatty acids leads to proinflammatory and pro-oxidative states. These issues are relevant to soybean oil, which is the leading edible oil consumed globally and in the United States. Soybean oil accounts for over 40% of the US intake of both essential fatty acids. We reviewed clinical and epidemiologic literature to determine the effects of soybean oil on cholesterol levels, inflammation, and oxidation. Clinical evidence indicates that soybean oil does not affect inflammatory biomarkers, nor does it increase oxidative stress. On the other hand, it has been demonstrated that when dietary SFAs are replaced with soybean oil, blood cholesterol levels are lowered. Regarding the nω-6:nω-3 dietary ratio, health agencies have consistently rejected the importance of this ratio, instead emphasizing the importance of consuming sufficient amounts of each type of fat. Thus, several lines of evidence indicate that soybean oil can positively contribute to overall health and reduction of risk of coronary heart disease.