Vitamin A

Vitamin A is a very important substance in the field of dermatology. The vitamin A derivative called ‘retinoid’ is used in treatment of various skin conditions such as psoriasis and acne. Vitamin A deficiency is known to make the skin rough and dry. Claims that vitamin A is beneficial in keratosis pilaris, acne, eczema, and psoriasis, etc. can be easily found on the internet. The below study also discusses the effect of vitamin A.  

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Figure 1. A published study on the effects of vitamin A.

Studies on the effect of zinc and vitamin A ingestion on acne were conducted before the introduction of oral retinoid supplements. It can be summarized that the effect of zinc has clear benefit, however, there is inconclusive evidence for the benefit of vitamin A on acne. There were more studies on the effects of vitamin A on diseases of the oral mucosa. Majority of these studies discussed the positive effect of vitamin A on oral lichen planus.

Conclusion. Ingestion of vitamin A that is not synthetic retinoid through food or health supplements has little effect on improving acne or psoriasis.

Zinc

The effect of zinc ingestion or injection on acne has been consistently studied since the 1970s. However, many doctors, including myself, do not prescribe zinc in acne treatment. Zinc is a mineral that plays a key role in immunomodulation, wound healing, and anti-inflammatory action, etc. and is associated with expression of vitamin A, and retinol binding protein (RBP). A daily dose of 50mg of elemental zinc or a daily dose of 200mg of zinc sulfate is used in treatment. I believe zinc therapy has potential benefits due to its low cost and low risk of side effects.

Figure 2. Study on the effect of zinc ingestion.