health twins

Acne

We know a significant cause acne is environmental since Inuit populations had no acne before the introduction of Western culture. Likewise, acne is much more common among people living in wealthy countries than the same ethnicities living in the rural areas of their poor origin countries Kucharska.

Genes

Twin studies generally find minimal common environment and very large heritability of acne:
Studyh2Year
Mina-Vargas0.852017
Evans0.832005
Bataille0.812002
Sobral Filho0.951997
Friedman0.871984

Recall that twin studies are typically biased against heritability, so it appears that acne is virtually entirely genetically determined. That being said, explaining 90% of variance, would still leave an r~0.32 correlation between environmental factors an acne, so it's worth exploring further.

Diet

From Kucharska and Spencer:

  • Dairy consumption (esp. skim milk) positively correlates with acne (see also Adebamowo).
  • Cocoa does not cause acne, but eating chocolate does - probably because of other ingredients in chocolate.
  • A diet's glycemic index correlates with acne and a trial found switching to a low glycemic load improved skin. Another study found eating high fiber cereal also improved skin.
  • There exist some chemical pathways that suggest eating Omega-3 should reduce acne and a promising correlation has been observed.
  • Studies have found that Vitamin A, Vitamin E, selenium, and zinc intake improved skin condition. Iodine can make it worse.
  • Vitamin D looks like it probably improves acne Lim.

See also Simonart and Fiedler.

Kucharska, A., Szmurło, A., & Sińska, B. (2016). Significance of diet in treated and untreated acne vulgaris. Advances in Dermatology and Allergology/Postȩpy Dermatologii i Alergologii, 33(2), 81. https://dx.doi.org/10.5114%2Fada.2016.59146 Spencer, E. H., Ferdowsian, H. R., & Barnard, N. D. (2009). Diet and acne: a review of the evidence. International journal of dermatology, 48(4), 339-347. https://doi.org/10.1111/j.1365-4632.2009.04002.x Lim, S. K., Ha, J. M., Lee, Y. H., Lee, Y., Seo, Y. J., Kim, C. D., ... & Im, M. (2016). Comparison of vitamin D levels in patients with and without acne: a case-control study combined with a randomized controlled trial. PLoS One, 11(8), e0161162. Adebamowo, C. A., Spiegelman, D., Berkey, C. S., Danby, F. W., Rockett, H. H., Colditz, G. A., ... & Holmes, M. D. (2008). Milk consumption and acne in teenaged boys. Journal of the American Academy of Dermatology, 58(5), 787-793. https://doi.org/10.1016/j.jaad.2007.08.049 Simonart, T. (2012). Acne and whey protein supplementation among bodybuilders. Dermatology, 225(3), 256-258. https://doi.org/10.1159/000345102 Fiedler, F., Stangl, G. I., Fiedler, E., & Taube, K. M. (2017). Acne and nutrition: a systematic review. Acta Dermato-Venereologica, 97(1), 7-9. https://doi.org/10.2340/00015555-2450 Mina-Vargas, A., Colodro-Conde, L., Grasby, K., Zhu, G., Gordon, S., Medland, S. E., & Martin, N. G. (2017). Heritability and GWAS analyses of acne in Australian adolescent twins. Twin Research and Human Genetics, 20(6), 541-549. https://doi.org/10.1017/thg.2017.58 Bataille, V., Snieder, H., MacGregor, A. J., Sasieni, P., & Spector, T. D. (2002). The influence of genetics and environmental factors in the pathogenesis of acne: a twin study of acne in women. Journal of Investigative Dermatology, 119(6), 1317-1322. https://doi.org/10.1046/j.1523-1747.2002.19621.x Friedman, G. D. (1984). Twin studies of disease heritability based on medical records: application to acne vulgaris. Acta geneticae medicae et gemellologiae: twin research, 33(3), 487-495. https://doi.org/10.1017/S0001566000005948 Evans, D. M., Kirk, K. M., Nyholt, D. R., Novac, C., & Martin, N. G. (2005). Teenage acne is influenced by genetic factors. British Journal of Dermatology, 152(3), 579-581. https://doi.org/10.1111/j.1365-2133.2005.06387.x Sobral Filho, J. F., Silva, C. N. A., Rodrigues, J. C., Rodrigues, J. L. T. D., & Azouz, M. A. (1997). Avaliaçäo da herdabilidade e concordância da acne vulgar em gêmeos. An. bras. dermatol, 417-20. https://pesquisa.bvsalud.org/portal/resource/pt/lil-217793