TABLE 4.
Clinical studies evaluating the dermal effects of vegetable butters and oils. AD—atopic dermatitis, GC—gas chromatography, MC—molluscum contagiosum, SA—Staphylococcus aureus, SC—stratum corneum, SG—striae gravidarum, SLS—sodium lauryl sulphate.
| Clinical study | Population | Aim/type of the study | Application and length of the study | Oil and control | Methods | Results |
|---|---|---|---|---|---|---|
| Non-Affected Adult Skin | ||||||
| 1995 Lodén and Andersson, (1996) | 21 subjects 22–57 years | Irritation Hydration | 50 µL pipetted into aluminium chambers attached to the volar forearm 48 h | Borage oil Sunflower oil Canola oil Shea butter Canola oil unsaponifiables Shea butter unsaponifiables Hydrocortisone Petrolatum Fish oil Control: water | Visual evaluation of irritation Superficial blood flow (laser Doppler flowmeter) TEWL | No significant differences on non-affected skin. Significantly less visible signs of SLS-induced irritation after treatment with canola oil unsaponifiables than after treatment with water. This fraction and hydrocortisone significantly reduced blood flow. Hydrocortisone, canola oil and canola oil unsaponifiables significantly lowered TEWL. |
| 2008 Stamatas et al. (2008) | 9 subjects 30–60 years | Skin penetration Occlusion | 20 µL on an area of 2 × 2 cm on the volar forearm Evaluation before application, and after 30 and 90 min | Paraffin oil Jojoba wax Almond oil Control: petrolatum | In vivo confocal Raman microspectroscopy Skin occlusion was assessed from the amount of SC swelling measured from the water concentration profiles | No statistical difference between paraffin oil and vegetable lipids in the extent of skin penetration and skin occlusion. Vegetable lipids demonstrated modest SC swelling (10–20%) compared to moderate swelling (40–60%) for petrolatum. |
| 7 infants 6–10 months | 20 µL on an area of 2 × 2 cm on the volar forearm Evaluation before application and after 30 min | Paraffin oil Almond oil Control:/ | ||||
| 2011 Patzelt et al. (2012) | 6 subjects 25–50 years | Skin penetration Occlusion | 2 mg/cm2 of a curcumin-labelled lipid to an area of 16 cm2 on the volar forearm Evaluation before application and after 30 min | Jojoba wax Soybean oil Avocado oil Almond oil Paraffin oil Control: petrolatum | Laser scanning microscopy TEWL | Vegetable lipids penetrated into the first upper layers of the SC. TEWL showed that the application of the oils leads to a semi-occlusion of the skin surface; the most effective occlusion was found for petrolatum. |
| 2015 Komane et al. (2015) | 20 females 18–65 years | Irritation Single blind, controlled | On the volar forearm for 96 h | Marula oil Positive control: 1% SLS Negative control: water | Visual evaluation Surface colour determination Evaluation at 0, 24, 48, 72 and 96 h | No irritation. A statistically significant difference was observed with liquid paraffin, vaseline lotion and vaseline petroleum jelly, while marula oil resulted in marginal skin recovery. Marula oil prevented TEWL significantly, while liquid paraffin, vaseline petroleum jelly and vaseline lotion showed significantly better effects than marula oil. The occlusive effect was significant for vaseline petroleum jelly and liquid paraffin, and non-significant for marula oil and vaseline lotion. Marula oil performed better as compared to the untreated skin. |
| Hydration | On the legs (calf area) for 12 days | Marula oil Controls: untreated skin; liquid paraffin, vaseline petroleum jelly, vaseline lotion | Visual evaluation Capacitance TEWL Evaluation on days 1, 2, 3, 4, 5, 8, 10 and 12 | |||
| Occlusion | 0.1 mL to an area 20 mm in a diameter on the volar forearm | Capacitance TEWL Evaluation after 0 and 30 min | ||||
| 2015 Boucetta et al. (2014) | 60 postmenopausal women | Hydration Randomised, open-label | Every night about 240 mg (2 mg/cm2) of argan oil, corresponding to 10 drops, on the left volar forearm for 60 days | Oral: argan oil Oral control: olive oil Both groups dermally: argan oil Control: untreated skin | Capacitance TEWL Evaluation on days 0, 30 and 60 | The consumption of argan oil led to a significant decrease in TEWL and a significant increase in SC water content. The application of argan oil led to a significant decrease in TEWL and a significant increase in SC water content. |
| 2019 Soimee et al. (2020) | 13 females 20–60 years | Hydration Randomised, double-blind, controlled | 0.5 ml on the left or right lower leg, twice a day for 14 days, followed by application discontinuation for 2 days | Sacha inchi oil Control: olive oil | Visual evaluation Capacitance TEWL Evaluation on days 0, 7, 14 and 16 | Visual dryness improved, SC corneum water content improved significantly for both oils, while TEWL decreased but not significantly. The hydration capacity of both oils was equivalent. Improvement in moisture content and skin dryness for sacha inchi oil and olive oil was comparable. |
| Infant Skin | ||||||
| 2004 Darmstadt et al. (2004) | 51 infants <72 h <34 weeks gestational age | Skin condition Rate of nosocomial infections Mortality Randomised, controlled | 3 times daily for the first 14 days, then twice daily until 28 days of life or until discharge from the hospital Dosing: 4 g of oil per kg of body weight per treatment | Sunflower oil Control: standard skin care (i.e. minimum to no use of dermal emollients) | Visual evaluation Diagnosis of nosocomial infection | Skin condition worsened faster in the control group. Incidence of nosocomial infections was significantly reduced (54%) in the treated group. Death due to sepsis beyond the first 2 days of life was not significantly different in both groups. No side effects. |
| 2005 Darmstadt et al. (2005) | 497 infants <72 h <33 weeks gestational age | Rate of nosocomial infections Randomised, controlled | To the entire body surface, except the scalp and face, 3 times daily for the first 14 days, then twice daily until discharge Dosing: 4 g of the lipid per kg of body weight per treatment | Sunflower oil (n = 159) Aquaphor ointment (petrolatum, mineral oil, mineral wax, lanolin alcohol) (n = 157) Control: untreated (n = 181) | Diagnosis of nosocomial infection | Infants treated with sunflower oil were 41% less likely to develop nosocomial infections. The control lipid did not significantly reduce the risk of infections. No side effects. |
| 2005 Solanki et al. (2005) | 120 infants Gestational ages: <34 weeks, 34–37 weeks, >37 weeks | Transdermal absorption Randomised, controlled | 5 ml, massaged on all available surfaces for 10 min 4 times a day, for 5 days | Safflower oil (n = 40) Virgin coconut oil (n = 40) Control: untreated (n = 40) | Visual evaluation Pre and post oil massage samples of blood were analysed for triglycerides and fatty acid profiles using GC. | Infants treated with safflower oil had significantly higher triglyceride and linolenic acid levels, while in the coconut oil group triglyceride and saturated fatty acid levels were significantly higher. No serious adverse events were reported; 3 infants (safflower oil group) developed a transient rash over the abdomen, which then disappeared in spite of continuing the massage. |
| 2014 Kanti et al. (2014) | 22 infants ≤48 h <37 weeks gestational age | Skin barrier development Randomised, controlled | On the whole body surface every 3–4 h during the first 10 days of life, followed by a cessation until day 21 | Refined sunflower oil Control: untreated | TEWL Capacitance pH Sebum levels Microbial colonisation | In the oil group, TEWL remained stable in the forehead, while it increased significantly on the abdomen, leg and buttock skin, where—after cessation of oil application - it decreased to values comparable to the control, or in the case of the abdomen significantly below the control. No significant differences in pH, sebum levels and microbial colonisation were determined. No side effects. |
| 2015 Nangia et al. (2015) | 74 preterm infants 12 ± 6 h | Hydration Randomised, controlled | 4 mL on skin of the trunk below neck, in four strokes without giving a massage, twice a day, for the first 7 days of life | Virgin coconut oil (n = 37) Control: standard care (n = 37) | Visual evaluation TEWL Microbial colonisation | TEWL was significantly lower in the oil group at all measurement points from 12 to 168 h of life. Skin condition and microbial colonisation were significantly better in the oil group. |
| 2016 Cooke et al. (2016) | 115 infants ≤72 h | The impact of dermal use on the development of atopic eczema Randomised, controlled, assessor-blinded | 4 drops to the left forearm, left thigh and abdomen, twice a day for 4 weeks ± 5 days | Olive oil Sunflower oil Control: untreated | ATR-FTIR spectroscopy (structure of the SC lipid lamellae) TEWL Capacitance pH Visual evaluation | Skin condition improved in all infants, while there were no significant differences for skin surface pH and erythema scores. Hydration was significantly higher in the oil groups and the increase in the lipid ordering was significantly lower in the oil groups compared to the control. |
| 2018 Strunk et al. (2018) | 72 infants <30 weeks gestational age | Effectiveness, safety, feasibility Open-label, randomised controlled | 5 mL/kg every 12 h for 21 days, starting within 24 h of birth, to the entire skin, excluding the face, scalp, and sites of catheters/drains, without massage | Virgin coconut oil (n = 36) Control: routine care (n = 36) | Visual evaluation on days 1, 7, 14, and 21 | Twice-daily oil application was highly feasible, without adverse effects. Skin condition was stable in the oil group, but deteriorated in the control group. |
| 2019 Summers et al. (2019) | 995 infants ≤48 h | Skin integrity Randomised controlled | Daily full body massage for 21 days | Sunflower oil (n = 495) Control: mustard oil (n = 500) | Visual evaluation TEWL pH SC cohesion (determined as protein concentration) Evaluation on days 1, 3, 7, 10, 14, 21 and 28 | Skin pH decreased faster in the sunflower oil group in the first week of life. SC cohesion was significantly higher in the sunflower oil group. Erythema, rash and dryness increased over days 1–14, then decreased by day 28, with no significant differences. TEWL increased over time, with no significant differences. |
| 2019 Konar et al. (2020) | 2,294 preterm infants <37 weeks gestational age | Effectiveness for skin maturity, prevention of sepsis, hypothermia, apnea and neurodevelopment, and safety Randomised, controlled | 5 mL 4 times daily, full body massage, excluding face and scalp | Virgin coconut oil (n = 1,146) Control: body massage (n = 1,148) | Visual evaluation on days 7, 14, 21 and 28 Serum vitamin D3 on day 30 Neurodevelopment on months 3, 6 and 12 Sepsis | Significantly better skin and neurodevelopmental condition, higher weight gain and vitamin D3 level, and less hypothermia and apnea in the oil group. No significant difference in the incidence of sepsis. No significant adverse events related to the use of oil. |
| Psoriasis | ||||||
| 2005 Brown et al. (2005) | 24 patients 18–78 years | Effectiveness and safety Randomised, double-blind, controlled, pilot | 3 times daily, to the targeted psoriasis plaque and psoriatic lesions over the entire body, for 12 weeks | Kukui oil (n = 13) Control: mineral oil (n = 11) | Visual evaluation on weeks 0, 2, 4, 6, 8, 10 and 12 | Skin condition in both groups improved, but with no significant differences between the groups. No side effects. |
| Xerosis | ||||||
| 2004 Agero and Verallo-Rowell, (2004) | 34 patients 16–70 years | Effectiveness and safety Randomised, double-blind, controlled | Twice a day, on the legs, for 2 weeks | Virgin coconut oil Control: mineral oil | Visual evaluation Capacitance Sebum levels TEWL pH Evaluation on days 0, 7 and 14 | Skin condition in both groups improved. SC hydration and sebum level improved significantly for both the oil and control groups, while no significant differences were found for TEWL and pH. No irritation of allergenic reaction was observed. |
| UVB-Induced Erythema | ||||||
| 2005 Bonina et al. (2005) | 6 subjects 31 ± 9 years | Protection against UVB-induced erythema | 200 µL immediately after exposure to UVB irradiation, on the ventral forearm | Soybean oil Control: untreated, tocopheryl acetate | Induction of erythema with an irradiation dose of twice the minimum erythema-inducing dose Evaluation after 3 h | Significant protective effect in comparison to the untreaded control and tocopheryl acetate. No side effects. |
| Atopic Dermatitis (AD) | ||||||
| 2008 Verallo-Rowell et al. (2008) | 52 patients 18–40 years | Hydrating effectiveness and anti-Staphylococcus aureus (SA) activity Randomised, double-blind, controlled | 5 mL twice a day, at two non-infected sites, for 4 weeks | Virgin coconut oil (n = 26) Virgin olive oil (n = 26) | Visual evaluation SA cultures | Significant SA antibacterial action for coconut oil. Significant improvement in skin condition for both oils, with greater effects of coconut oil. |
| 2013 Danby et al. (2013) | Cohort 1 7 patients (self-reported AD; no symptoms for 6 months) 46 ± 5.7 years Cohort 2 12 subjects, 6 (37 ± 6.7 years) with no history of AD and 6 (32 ± 5.4 years) with a self-reported AD (no symptoms for 6 months) | Effects on adult skin barrier and implications for neonatal skin care Randomised, observer-blind, controlled | Cohort 1: 6 drops of olive oil, twice daily, on one forearm, for 5 weeks Cohort 2: 6 drops of olive oil to one forearm and 6 drops of sunflower oil to the other, twice daily, for 4 weeks | Olive oil Sunflower oil Control: untreated | pH Capacitance Erythema TEWL SC cohesion (determined as protein concentration) SC thickness | Significant increase in TEWL and decrease in SC thickness for olive oil than untreated control. Significant increase in TEWL, decrease in SC cohesion and erythema for olive oil compared to sunflower oil, in patients with a history of AD. Improved hydration and no erythema with sunflower oil. |
| 2014 Evangelista et al. (2014) | 117 patients 1–13 years | Effectiveness and safety Randomised, double-blind, controlled | 5 mL, twice daily (after bath and at night), to all body surfaces (except diaper/inguinal area and the scalp), for 8 weeks | Virgin coconut oil (n = 59) Control: mineral oil (n = 58) | Visual evaluation TEWL Capacitance Evaluation on weeks 0, 2, 4 and 8 | Skin condition improved in both groups, but was significantly better in coconut oil than in mineral oil group. TEWL decreased in both groups, with a significantly higher result for coconut oil than mineral oil. Skin hydration improved in both groups and was higher for coconut oil, but a significant difference only seen after 8 weeks. No side effects. |
| Molluscum Contagiousum (MC) | ||||||
| 2017 Kwon et al. (2017) | 41 children 2–10 years | Effectiveness and safety Open | Twice daily to all lesions, for 3 months | Evening primrose oil Control:/ | Visual evaluation every month | Complete or partial resolution of lesions observed in 53.7% patients. No serious adverse events related to the use of the oil, but mild inflammation was observed. |
| Tungiasis | ||||||
| 2019 Elson et al. (2019) | 93 children 6–14 years | Effectiveness and safety Randomised, controlled | 1 drop of oil mixture per a feet flea, on days 1 and 3 following community practice. Control: On day 1, the feet were placed up to the ankles in a basin with 2.5 L of 0.05% KMnO4 for 15 min followed by the application of petroleum jelly over the whole foot | 20% virgin neem oil and 80% virgin coconut oil (n = 48) Control: 0.05% KMnO4 foot bath (n = 45) | Evaluation of pain and itching Tunga penetrans viability Evaluation on days 0, 1, 3, 5 and 7 | Significant, but similar flea mortality was observed for both groups. Faster aging of fleas and less pain in the oil group, but with no significance. No side effects. |
| Striae gravidarum (SG), striae and scars | ||||||
| 2011 Taavoni et al. (2011) | 70 pregnant women 20–30 years 18–20 weeks gestational age | Effectiveness in striae gravidarum (SG) Randomised | Twice daily on the abdominal area without massaging, for 8 weeks | Olive oil (n = 35) Control: untreated (n = 35) | Occurrence of SG Weekly evaluation | Among women without previous striae, SG occurred in 54.3% women using olive oil and 37.1% control women. Among women with striae present, SG occurred in 45.7% women using olive oil and 62.9% control women. However, there was no significant difference. |
| 2012 Soltanipour et al. (2012) | 100 pregnant women 20–30 years 18–20 weeks gestational age150 pregnant women | Effectiveness in SG Randomised, controlled | 1 cm3 twice daily on the abdominal skin, without massaging, until delivery | Olive oil (n = 50) Control: untreated (n = 50) | Occurrence of SG Evaluation on 37–40 weeks gestational age | The incidence and severity of SG were lower in the olive oil, but with no significant difference. |
| 2014 Soltanipour et al. (2014) | 20–30 years 18–20 weeks gestational age | Effectiveness in SG Randomised, assessor-blinded, controlled | 1 cm3 twice daily on the abdominal skin, without massaging, until delivery | Olive oil (n = 50) Saj® cream (n = 50) Control: untreated (n = 50) | Occurrence of SG Evaluation on 38–40 weeks gestational age | No significant differences among the three studied groups regarding the incidence and severity of SG. |
| 2017 Bielfeldt et al. (2018) | 80 subjects 35.3 ± 12.0 years | Effectiveness in scars and striae, and safety Randomised, assessor-blinded, controlled | Twice daily, for 8 weeks | Safflower oil (55.9%), olive oil (42%), grapefruit (Citrus grandis) peel essential oil (2%) oil, tocopherol (0.1%) Control: untreated | Visual evaluation on day 57 | Skin condition improved significantly. No side effects. |