(Adapted from a two part series from Journal of American Academy of Dermatology—J Am Acad Dermatol 2014;71:1039.e1-12 and J Am Acad Dermatol 2014;71:1053.e1-16.)
As Dermatologists, we often get asked about how diet can impact the skin. Unfortunately, there is a lack of high-quality studies and studies on diet per se is difficult as it requires a very long follow up and strict adherence to dietary intervention. Therefore, most studies are small and recommendations are weak. However, below is the most recent evidence to date that we have:
Atopic Dermatitis/ Eczema:
- There is no evidence that Vitamin D and primrose oil/ borage oil (sunflower oil, sea buckthorn seed oil, hempseed oil, fish oil) improves or worsens eczema.
- There is some evidence that supplementing pro-biotics in the mother during pregnancy can reduce the risk of atopic dermatitis in the baby.
- Whilst food is commonly blamed for worsening eczema, the contribution of these food to the cause of eczema is questionable. A small percentage of eczema patients have clear food allergy: this is defined as a rash, swelling of the throat/lips or difficulty breathing. In these patients, an elimination diet is useful. For all other patients, an elimination diet is not useful.
- Avoidance of allergen diets in the mother during pregnancy or breast feeding has no impact on the child’s eczema
- Exclusive breast feeding for up to 4 months and supplementation with hydrolysed formula is protective for infants at risk of eczema.
Acne
- There is evidence that high dairy consumption and high sugar/ processed food consumption can worsen acne. More details are on Skin Blog 7 – SEE LINK BELOW.
Non-Melanoma skin cancer
- Fat consumption: there no evidence between dietary fat and non-melanoma skin cancer
- Vitamin A: There are conflicting results. Some studies have shown that retinol can decrease squamous cell cancer risk in individuals with moderate risk. Isotretinoin can reduce the risk for squamous cell carcinoma but not basal cell carcinoma.
- Vitamin C, E and D: Insufficient evidence.
- Selenium: There is some evidence of an increased risk of squamous cell carcinoma and total non-melanoma skin cancer so selenium supplementation cannot be recommended at this stage.
Melanoma
- Polyunsaturated fatty acids have anti-inflammatory effect but data are conflicting. Some studies show an increased risk of melanoma where as others show a reduced risk. At the moment, there is insufficient evidence to recommend supplementation.
- A reduced alcohol consumption may reduce melanoma risk.
- Vitamin D: The data is conflicting but supplementation with Vitamin D may reduce the risk of melanoma.
- There is insufficient evidence for Vitamin E, selenium, green tea, resveratrol and lycopene to prevent the development or progression of melanoma in the general population.
Chronic urticaria (hives)
- Pseudo-allergens and artificial preservatives, dyes and aromatic compounds in processed and natural foods are thought to induce hypersensitivity reactions. They are different from true allergens in that skin prick testing is often negative. However, there is some evidence of benefit for a pseudo allergen-free diet.
- Gluten free diet: This diet may improve symptoms of chronic urticaria in individuals who already have coeliac disease but there is no evidence of benefit in those who do not have coeliac disease.
- Vitamin D at doses of > 2,000IU – 4,000 IU per day may improve chronic urticaria irrespective of baseline vitamin D status.
Psoriasis
- Weight loss by either diet, exercise or bariatric surgery improves psoriasis and reduces the need for psoriasis medications.
- Decreased alcohol consumption improves psoriasis.
- Dietary supplementation with polyunsaturated fatty acids, folic acid and Vitamin D can be considered but there is a lack of high-quality studies.
- Gluten free diet may improve symptoms of psoriasis in patients with coeliac disease
- There is lack of evidence for selenium, vitamin E, beta-carotene or coenzyme Q10 supplementation.
