Soybean oil or sunflower oil: which one to choose?

Respectively known as Glycine Soja Oil and Helianthus Annuus Seed Oil, soybean oil and sunflower oil are two vegetable oils often compared. Indeed, their colour, extraction method, and use are similar. This similarity extends to the cosmetic field where their skin and hair properties are alike, due to their similar biochemical compositions.

• Moisturising and nourishing vegetable oils.

  Both soybean oil and sunflower oil possess moisturising and nourishing properties, making them highly valued by individuals with dry or atopic-prone skin. These virtues are due to their richness in fatty acids, specifically oleic acid and linoleic acid. Indeed, oleic acid is an omega-9 naturally found in the skin's protective hydrolipidic film, contributing to its proper hydration. Linoleic acid, on the other hand, provides lipids to the epidermis, which helps to strengthen its barrier function.

• Anti-inflammatory plant oils.

  Another shared property of sunflower oil and soybean oil is their anti-inflammatory and soothing action. Redness, irritation, inflammation, itching... these are all discomforts that can be alleviated thanks to these vegetable oils. The mechanisms involved vary slightly depending on the oils, but both are recognised for their soothing virtues.

• Antioxidant plant oils.

  Finally, both soybean and sunflower oils are antioxidants, a property derived from their vitamin E content. This allows them to protect the skin from oxidative stress and counteract the activity of free radicals, which are responsible for the premature ageing of the skin and skin damage (wrinkles, skin sagging, hyperpigmentation).

While soybean oil and sunflower oil share many similarities, there are still some differences between them, allowing one to choose the most suitable for their needs. One can first think of their texture and their comedogenicity index : the sunflower oil is non-comedogenic whereas the soybean oil has an index of 2, making it very slightly comedogenic. Therefore, it is recommended for individuals with oily skin to opt for sunflower oil.

Similarly, it is recommended for pregnant women to apply sunflower oil rather than soybean oil, which is discouraged as a precautionary principle. Furthermore, several studies have focused on the topical use of sunflower oil on babies and concluded that, not only is it safe, but it also has benefits for the barrier function of their skin.

On the other hand, individuals with pigmentation spots or wrinkles they wish to diminish may opt for soybean oil. Indeed, studies have shown that this vegetable oil possesses lightening properties and a protective effect on elastin, a protein essential for skin tone. After 12 weeks of daily application of a cream based on soybean oil, 65 participants in a study saw a significant improvement in their skin texture and complexion.

In summary, the use of sunflower oil is recommended for infants, for women who are pregnant and for individuals with skin that is oily , while it is advised for those wishing to prevent or reduce wrinkles or signs of hyperpigmentation to opt for soybean oil.

• CORK M. J. & al. Effect of Olive and Sunflower Seed Oil on the Adult Skin Barrier: Implications for Neonatal Skin Care. Clinical and Laboratory Investigation (2012).

• MURTAZA G. & al. Dermatological and cosmeceutical benefits of Glycine max (soybean) and its active components. Acta Polonia Pharmaceutica (2015).

• MOREL K. & al. Use of “natural” oils for moisturization: Review of olive, coconut, and sunflower seed oil. Pediatric Dermatology (2018).