Introduction
Diet is quite often a question the patient asks when seeing a skin doctor and it is important to acknowledge that frequently “natural” solutions are sought before any medical ones.
Acne has been the classical target of this quest for simplicity and the results of studies over half a century have been contradicting and are still a matter of debate nowadays.
This article is about evidence of influence of foods in skin conditions. The source is a presentation by the author of an article published in the Journal of the American Academy of Dermatology (JAAD) in 2014 (see Bibliography). The author does a review of the literature by classifying studies: from strong ones (Randomized-Control-Trial-RCT=level of evidence IA) to weaker ones (expert opinions=level of evidence IV).
Summary of Findings
I. Acne (Acne Vulgaris)
I.a. Sugar intake and “heavy meals”
-Basis: hyperinsulinemia leads to production Insulin Growth Factor IGF1 (IGF1) which acts on the epidermis.
-Evidence suggests that a high glycemic index and load (IB) can play a role.
-Recommendation: low sugar diets and reduced load for acne patients.
I.b. Milk
-Only level III evidence is available. Randomized-Control Trials (RCT’s) are still required.
-Recommendation: evidence not good enough. [Perhaps the use of skimmed milk can be recommended.]
[More facts on influence of the Diet in Acne: click HERE.]
II. Chronic urticaria (hives)
–pseudoallergens could be involved (IB). [definition of pseudoallergen: see Table II: link]
–Gluten (III): only recommended to have a Gluten-free diet if celiac disease present.
–Vitamin D supplementation is recommended. (IB)
III. Psoriasis
–Weight loss (IB): recommend weight loss via diet and exercise.
-role for Alcohol ? (III): insufficient data.
–PUFA supplementation (e.g. fish oil) (IB): not recommended. (PUFA: polyunsaturated fish acids)
-Gluten (IB): only recommended to have a Gluten-free diet if celiac disease present.
–Folic Acid (IB): only recommended when taking Methotrexate. (systemic MTX)
–Vitamin D supplementation: not recommended.
–Selenium supplementation: not recommended.
–Antioxidants: Beta-Carotene may be beneficial.
IV. Atopic Dermatitis
-Overall there are 11 RCT’s including 596 patients: poor evidence.
–Vitamin D supplementation (IB): insufficient data.
–Primerose and Borage (IB): not recommended.
–Prebiotics (IA): recommended in infants.
–Diet exclusion and food allergies (IA): Helpful if allergy proven but if the patient says that he is allergic and that there is no proof, it is not beneficial.
–Maternal diet (IA): maternal diet avoidance not recommended.
–Breastfeeding or hydrolyzed formula (IA): it is recommended in infants exclusively if an allergy is present.
[More facts on Atopic Dermatitis Prevention through Diet: click HERE.]
V. Non-Melanoma Skin Cancer (NMSC=keratinocytic carcinoma)
–Fat (IB): low fat diet not recommended.
–Vitamin A (IB): Beta-carotene not recommended. Retinol can be moderately effective in preventing Squamous Cell Carcinoma (SCC). Isotretinoin and Acitretin are recommended in Xeroderma Pigmentosum (XP).
–Vitamins C, D and E supplementation (III): no evidence. (insufficient Data)
–Selenium supplementation (IB): good to AVOID as can increase the risk of SCC and NMSC.
VI. Melanoma
–PUFA supplementation: not enough evidence.
–Vitamins D and E: not recommended.
–Selenium, Lycopene, Resveratrol and Green tea (III): no evidence. (no good studies)
Conclusion
Food probably has a significant influence on skin health. However apart from a few good RCT’s, scientific evidence still lags behind when it comes to answering questions that patients consider basic.
Further reading: Publications in the JAAD listed below. (Bibliography)
Bibliography
- Presentation by Rao B., MD. Diet in Dermatology. Dubaiderma 2017
- Diet in dermatology: Part I. Atopic dermatitis, acne, and nonmelanoma skin cancer. Bronsnick T, Murzaku EC, Rao BK. J Am Acad Dermatol. 2014 Dec;71(6):1039.e1-1039.e12. doi: 10.1016/j.jaad.2014.06.015. Epub 2014 Nov 15. Review. http://eblue.org/article/S0190-9622(14)01577-1/fulltext
- Diet in dermatology: Part II. Melanoma, chronic urticaria, and psoriasis. Murzaku EC, Bronsnick T, Rao BK. J Am Acad Dermatol. 2014 Dec;71(6):1053.e1-1053.e16. doi: 10.1016/j.jaad.2014.06.016. Epub 2014 Nov 15. Review. http://eblue.org/article/S0190-9622(14)01577-1/fulltext
- Corrections to the two aforementioned articles in Vol. 73, Issue 2, p353
- Diet and acne. Bowe WP, Joshi SS, Shalita AR. J Am Acad Dermatol. 2010 Jul;63(1):124-41.
- Prevention of Atopic Dermatitis – an Evidence-Based Review. Presentation by Lai D., MD. Atopic Dermatitis Symposium – Oct 2016 – Hong Kong