Infant Skincare: Mineral versus Olive Oil – Reviewing the Evidence
Pauline Carpenter and Karen Richards
In this paper, the Community Practitioner Journal’s Education Supplement ‘Infant Skincare’, and the associated research-based evidence that support the document are reviewed, in order to establish whether olive oil should be considered detrimental to the skin and that mineral oil should be deemed as the first choice for baby skin care regimes. It was established that the application of solutions of oleic acid was the main focus of the evidence used to support the articles in the supplement and not olive oil, as is implied. Also many of the statements made about olive oil and mineral oil were unsubstantiated and further investigation failed to support the claims asserted. This review includes information about the chemical components of oils commonly utilised for massage and other skin care regimes, in order to indicate that olive oil cannot be dismissed and that mineral oil should still be used with caution until clear evidence-based research has been found.
The Educational Supplement ‘Infant Skincare’, which accompanied the October 2010 Community Practitioner journal, prompted many parenting practitioners, who teach infant massage to parents, to question both the arguments posed in the supplement and their current practice vis-à-vis the supply of oils and the advice given to parents. The majority of infant massage teacher training providers and subsequently infant massage teachers, throughout the UK, encourage the use of vegetable oils for massage and suggest that mineral oil should be avoided. The Infant Skincare articles [1,2] suggest the opposite! As these are supported by, what appears to be, a good deal of research-based evidence, confusion and uncertainty as to the advice to give parents now exists.
Olive oil and oleic acid
Having reviewed the articles in the supplement and, in particular, the research-based evidence associated with the effect that certain oils1 (mainly olive oil and mineral oil) have on the skin, this review hopes to clarify the situation and alleviate any concerns parenting practitioners may have. The articles in question [1,2] are well referenced, but many statements within them are not. For example, the assertion that : ‘evidence suggests that olive oil can be damaging to the skin barrier’ (page 51) was not referenced. This review has undertaken an extensive search for some form of evidence to support the statement, rather than simply dismissing this claim.
Natural oil evidence
The majority of research referred to1 and used as supporting evidence by the supplement, concerns the application of solutions of oleic acid, which is argued to be a major constituent of olive oil. However, these studies [3,4,5,6] do not give consideration to natural vegetable oils and are not concerned about the on-going health or repair of the skin. Instead, they concentrate on substances that are actually efficient at breaking down the skin barrier in order to aid skin penetration to enhance the absorption of drugs.
To date, only one study has been found that compares the impact of topical oils on skin barrier function. The study included olive oil and its effect when applied to damaged skin; although this was not the main focus of the enquiry. The study  directly investigated the effect of vegetable oils on the recovery of skin barrier function of mice after acute barrier disruption by tape-stripping had been carried out. The results showed that a single application of sunflower oil accelerates recovery of barrier function, mustard oil has the most deleterious effects on barrier function and olive oil delays the skin barrier recovery. This suggests that it is inadvisable to put olive oil on already damaged skin and not that it can damage the skin barrier. It is necessary to point out that compromised or damaged skin is a contraindication to massage, regardless of the oil applied .
In contrast to the claim in the supplement that olive oil has potential for harm, a study looking at the effects of daily treatment with an olive oil and lanolin cream, applied to undamaged skin in preterm infants, found that this lowered the risk of dermatitis and was superior to a commonly used panthenol emollient cream (Bepanthen®).
Oleic and other fatty acids
It is indicated in the educational supplement that the percentage of oleic acid content in olive oil is ‘55% to 83%’ (page 5). Drawing on the results of the above mentioned study , the sunflower oil evaluated had 29.6% oleic acid content, with 58.3% linoleic acid and an undetectable level of erucic acid. (The usual range for a sunflower oil is - 48% -74% Linoleic Acid; 14%–40% Oleic Acid)9. One of the mustard oils tested  was found to have an undetectable level of oleic acid, with 34.1% of linoleic acid content and 41.5% erucic acid. There was no reference to levels of linoleic acid or erucic acid, in the olive oil used in the tests.
This begs the question: could it be the erucic acid in the mustard oil that is the damaging factor? Particularly as the level of oleic acid present in the mustard oil was undetectable, yet the mustard oil still proved to be damaging to the stratum corneum. Furthermore, sunflower oil has the potential to have a comparatively high oleic acid level , and potentially high linoleic acid and low erucic acid . Evidence of the usual levels of linoleic and erucic acid within olive oil were not quoted in the supplement. However, during the search for relevant information for this review, it was found that the usual percentage range of linoleic acid in olive oil is 3.5% - 21%10, while levels of erucic acid could not be established.
Free fatty acids and triglycerols
This information can be explored more deeply, by considering the chemistry behind the above percentages and what they mean in reality. Vegetable oils contain triglycerols, which are fatty acids bound to a glycerol molecule, as well as free fatty acids. The figure often quoted as fatty acids present in an oil is the total percentage of triglycerols and free fatty acids. For example, the main constituents of olive oil and sunflower oil, as quoted above, are the total levels of triglycerols and free fatty acids. In a given quantity of extra virgin olive oil, the free fatty acid present is usually well under 0.8%10. The majority of fatty acids found in olive oil are bound to glycerol, making them chemically less active. Therefore, the measurement of total fatty acid content is not a true measure of the reactivity of an oil. A more accurate measure of an oil’s reactivity would be the amount of free fatty acid present.
In the research papers reviewed [,3,4,5,6] the substance used is not natural olive oil but a fabricated solution of pure oleic acid (1% - 15%) dissolved in ethanol, propylene glycol or Myritol® 318. The oleic acid solutions were applied to mouse, rat or human skin, which was usually tape-stripped before testing commenced to artificially compromise the epidermal barrier. The solutions used in the studies therefore contained free fatty acid concentrations in excess of those found in natural olive oil, and it is difficult to draw direct conclusions about natural olive oil from them.
The suggestion that mineral oil is much safer to use for massage and skincare [1,2] was more difficult to confirm or refute. Although there is extensive research investigating unrefined or partially refined mineral oil, searching for information on refined (or ‘medicinal grade’1) mineral oil proved fruitless. There is a lot of confusion relating to the term ‘mineral oil’. Published articles relating to unrefined mineral oil indicate that it is carcinogenic, but this ought not to be taken to mean that all mineral oils are carcinogenic without taking refining processes into account. It is easy to tar all mineral oil with the same brush, but that would openly invite criticism. The educational supplement, has drawn conclusions from the research about oleic acid, implicating olive oil as an ‘oil to avoid’ vis-à-vis infant skincare. It is important not to have the same knee-jerk reaction to the research relating to mineral oil, but instead, assess the evidence supporting the arguments presented.
Medicinal grade mineral oil
The supplement  indicates that medicinal grade mineral oil should be used for infant skincare and massage because it does not contain oleic acid, is extremely inert and less likely to irritate the skin and, contrary to popular belief, able to penetrate the skin as well as a vegetable oil and therefore not block the pores. These statements, like others in the articles included in the supplement, are unreferenced. There is no indication of any published research to support these claims in the supplement and research for this review also failed to find any concrete evidence.
Furthermore, there is no explanation of precisely what ‘medicinal grade mineral oil’ is. If it is pure, unadulterated mineral oil, then the problem arises that this is not readily available over the counter. It is actually quite difficult to obtain - several unsuccessful attempts to do so were undertaken as part of the process for this review- and it is generally only purchased in large quantities by cosmetics companies.
Commercially available oils
If ‘medicinal grade mineral oil’ refers to the oil that is widely available commercially, then it is mixed with at least a couple of additives, and there is a question over how this can be beneficial for an infant’s skin.
Having investigated the ingredients of three commercially available mineral oils, which are specifically marketed for use with babies, the following chemicals were found: Hexyl laurate, hydrogenated styrene and cyclopentasiloxane, which are all chemical ingredients, commonly used by the cosmetic industry. One product sample included Prunus dulcis, the Latin name for the almond tree. Lavandula angustifolio (found in another) is Lavender, Bisabolol (found in one) is the main active ingredient in Chamomile essential oil, and Chamomilla recutita (found in another) Chamomile. They also all contained ‘Parfum’, which is perfume, though what perfume was used and what it contains was not specified.
The question of whether unnecessary chemicals should be put on a baby’s skin should be asked. Why let them potentially ingest, or absorb ingredients that are of no benefit to them? Furthermore, there is research[1,2] to indicate that essential oils are potential endocrine disruptors and should be avoided for prepubescent children. If a product is being applied regularly, over a sustained period, there is a greater chance of an effect. Particularly in the case of infant massage, parents are encouraged to massage as often as possible (preferably every day), until their infant is at least crawling, but preferably beyond .
Having reviewed the Educational Supplement and the associated research papers, it is difficult to draw a clear conclusion that olive oil per se is harmful to the skin and that mineral oil is beneficial. For infant massage, sunflower, grapeseed and fractionated coconut oils are considered the most suitable , but olive oil is recognised as a safe alternative, particularly when mixed with a lighter oil, such as sunflower . This would have the further effect of reducing the already low levels of free fatty acids present in olive oil. Since contraindications to massage include infectious skin conditions, open, weeping wounds and rashes (i.e. if the skin is damaged in any way), such application should not occur and the infant’s skin health safeguarded.
1 Introduction by Fergie, G. (2010) Infant Skincare: Common Myths about Baby Skincare. Community Practitioner - Educational Supplement. 2: 4-5
2 Introduction by Fergie, G. (2010) Infant Skincare: Implications for Practice. Community Practitioner - Educational Supplement. 2: 10
3 Mélot, M., Pudney, P.D.A., Williamson, AM. & Caspers, P.J. (2009) Studying the effectiveness of penetration enhancers to deliver retinol through the stratum corneum by in vivo confocal Raman spectroscopy. Journal of Controlled Release. 138: 32-39
4 Naik, A., Pechtold, L., Potts, R.O. & Guy, R.H. (1995) Mechanism of oleic acid-induced skin penetration enhancement in vivo in humans. Journal of Controlled Release. 37: 299-306
5 Jiang, S.J. & Zhou, X.J. (2003) Examination of the Mechanism of Oleic Acid-Induced Percutaneous Penetration Enhancement: an Ultrastructural Study. Biol. Pharm. Bull. 26(1): 66-68
6 Larrucea, E., Arellano, A., Santoyo, S. & Ygartua, P. (2001) Combined effect of oleic acid and propylene glycol on the percutaneous penetration of tenoxicam and its retention in the skin. European Journal of Pharmaceutics and Biopharmaceutics. 52: 113-119
7 Darmstadt, G.L., Mao-Qiang, M., Chi, E., Saha, S.K., Ziboh, V.A., Black, R.E., Santosham, M. & Elias, P.M. (2002) Impact of topical Oils on the Skin Barrier: Possible Implications for Neonatal Health in Developing Countries. Acta Paediatr. 91: 546-554
11 Kiechl-Kohlendorfer et al. (2008) The effect of daily treatment with an olive oil/lanolin emollient on skin integrity in preterm infants: a randomized controlled trial. Pediatr Dermatol. 25(2): 174-8
12 Henley, D.V. & Karach (2007) Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils. The New England Journal of Medicine. 356: 479-485
For clear information about the chemical structures of oleic acid see: