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Vitamin A is anti-inflammatory and involved in restoring healthy epithelial cells to damaged mucosal surfaces.
Vitamin A promotes and regulates the innate immune system and adaptive immunity, thus enhancing immune function against infections.1,2 These include urinary tract and vulvovaginal infections.
Vitamin A is what’s known as a micronutrient, critical in the human body for vision, growth and development, and protecting the epithelium and mucosal surfaces. Our digestive tract, urinary tract, reproductive tract and respiratory tract are all mucosal surfaces.
Vitamin A is a fat-soluble vitamin that comes in three forms: retinol, retinal and retinoic acid.
How vitamin A supports vaginal health and the urinary tract
Epithelial cells line the outer and innermost surfaces of the body and are the first line of defence against invading pathogens. Vitamin A plays an important role at every stage of the epithelium: the formation, keratinisation, stratification, differentiation and maturation of epithelial cells. That is, every part of the life cycle of a skin cell.1
Vitamin A also promotes mucin secretion. Mucin is essentially mucus laden with special protective proteins, and it has a protective effect on the tissue underneath.
MUC5B is the main gel-forming mucin in saliva, and in the vagina it works alongside MUC5AC as one of the two major protective mucins.3,4 These mucins significantly reduce the attachment of pathogens such as streptococci,3 Candida albicans,5 Helicobacter pylori and HIV,6 while also making it harder for them to form biofilms on epithelial cells. They don’t kill bacteria, but keep them in their free-floating (planktonic) form, which adds to the diversity of the flora and helps keep things ‘normal’.3
In our clinic, we use vitamin A to help rebuild the mucin layer of mucosal surfaces, helping to protect those surfaces from reinfection and damage.
In the urinary tract, vitamin A maintains the structure, form and number of the lining epithelial cells. That is, it keeps urinary tract cells healthy and in sufficient numbers to protect the tissue underneath.
When epithelial cells are deprived of vitamin A, they are replaced by stratified squamous keratinising epithelium – hard, dead cells. The cells shrink and keratinise, filling with keratin protein filaments and dying to form a tough structure – think of the dry, tough skin on your heels, or your nails.1
This change to keratinised cells reduces resistance to pathogens, because the healthy epithelial barrier is no longer intact. The innate immunity of the underlying tissue drops, and infections are more easily established.
Immune organs also need a constant supply of vitamin A. Retinoic acid helps regulate the differentiation, maturation and function of innate immune cells such as macrophages and neutrophils, the immediate responders to invasion, which clear pathogens by phagocytosis (engulfing the invader) and by activating natural killer T cells.2
How we use vitamin A in the clinic
We use oral vitamin A as a short-term supportive treatment to build someone back up, when the mucin barrier on their mucosal surfaces is likely to be thinning, leaving them prone to reinfection. It gives the tissue the raw material it needs to rebuild a healthy mucin layer and epithelial barrier.
We never use it long term. Vitamin A is fat-soluble, so the body stores the excess rather than flushing it out, and it can accumulate over time.
We also always check what else you are taking first. Vitamin A is added to a lot of multivitamins, cod liver oil and skin supplements, and it all adds up, so any dose has to account for your whole supplement picture.
Vitamin A, recurrent infections and dryness
Because vitamin A keeps the epithelial barrier and mucin layer intact, it is worth considering when infections keep coming back.
In one randomised, placebo-controlled trial, vitamin A supplementation improved the symptoms of urinary tract infections and reduced kidney scarring in girls with acute pyelonephritis.7
A strong mucin layer also makes it harder for Candida and other pathogens to attach and take hold, which matters for recurrent thrush.5
Low oestrogen thins and dries the vaginal lining, so vitamin A is one of the tissue-supporting nutrients worth looking at alongside vaginal dryness, particularly after menopause.
How to get vitamin A
Vitamin A comes in two forms in food. Preformed vitamin A (retinol) is found in animal foods – liver, cod liver oil, egg yolk, butter and full-fat dairy. Provitamin A carotenoids, such as beta-carotene, are found in orange, yellow and dark-green vegetables like carrots, sweet potato and spinach, and the body converts them into active vitamin A.8
Because it is fat-soluble, vitamin A needs some dietary fat to be absorbed, and the conversion of beta-carotene into active vitamin A is variable and often inefficient. A very low-fat or very low-animal-food diet can leave you short even when you think you are getting enough.8
Who runs low on vitamin A
You are more likely to be low in vitamin A if you eat a very low-fat diet, eat few animal foods, or have trouble absorbing fat.
Because vitamin A is fat-soluble, anything that affects fat digestion can reduce how much you absorb – gut problems, coeliac disease, and bile or gallbladder issues (bile is what emulsifies fat so it can be absorbed).8
Early signs of low vitamin A include poor night vision and dry eyes, dry or rough skin, and more frequent infections.
Vitamin A safety – why we are careful with it
Because vitamin A is fat-soluble, it accumulates in the liver rather than being flushed out, so too much over time can cause toxicity (hypervitaminosis A) – headaches, dry skin, hair loss, liver problems and, over the long term, weaker bones.8
The most important warning is in pregnancy. High-dose preformed vitamin A (retinol) is teratogenic, meaning it can cause birth defects. A landmark study found that high vitamin A intake in early pregnancy significantly increased the risk of birth defects in the baby.9
If you are pregnant or trying to conceive, do not take high-dose vitamin A or cod liver oil without specialist supervision, and go easy on liver, which is so rich in preformed retinol that it is usually limited in pregnancy. It is the high-dose retinol in supplements and liver that is the concern; the beta-carotene in vegetables does not carry this risk.
This is also why we would not suggest starting a vitamin A supplement on your own. Outside pregnancy you can eat vitamin A-rich foods freely, but if a supplement is on the cards, it needs a practitioner’s eye on the dose and on the rest of your supplements.
Frequently asked questions
Can vitamin A help with recurrent UTIs or thrush?
It is worth considering when infections keep coming back. In a placebo-controlled trial, vitamin A eased urinary tract infection symptoms and reduced kidney scarring in girls with acute pyelonephritis, and a strong mucin layer makes it harder for Candida to attach and take hold. It works best as part of a bigger picture, not as a standalone cure.
Is vitamin A safe in pregnancy?
High-dose preformed vitamin A (retinol) can cause birth defects, so if you are pregnant or trying to conceive, do not take high-dose vitamin A or cod liver oil without specialist supervision, and go easy on liver, which is very high in preformed retinol. The beta-carotene in vegetables does not carry this risk.
What foods are high in vitamin A?
Preformed vitamin A (retinol) is in animal foods like liver, cod liver oil, egg yolk, butter and full-fat dairy. Provitamin A carotenoids such as beta-carotene are in orange, yellow and dark-green vegetables like carrots, sweet potato and spinach.
Can I take a vitamin A supplement on my own?
We would not suggest starting one yourself. Outside pregnancy you can eat vitamin A-rich foods freely, but because it is fat-soluble and builds up in the body, any supplement needs a practitioner’s eye on the dose and on the rest of your supplements.
This article is general information and not a substitute for personalised medical advice. If you are concerned about recurrent urinary or vaginal infections, please see an experienced practitioner.
- Stephensen CB. Vitamin A, infection, and immune function. Annual Review of Nutrition. 2001;21:167–192.
- Huang Z, Liu Y, Qi G, Brand D, Zheng SG. Role of vitamin A in the immune system. Journal of Clinical Medicine. 2018;7(9):258.
- Frenkel ES, Ribbeck K. Salivary mucins protect surfaces from colonization by cariogenic bacteria. Applied and Environmental Microbiology. 2015;81(1):332–338.
- Lacroix G, Gouyer V, Gottrand F, Desseyn JL. The cervicovaginal mucus barrier. International Journal of Molecular Sciences. 2020;21(21):8266.
- Kavanaugh NL, Zhang AQ, Nobile CJ, Johnson AD, Ribbeck K. Mucins suppress virulence traits of Candida albicans. mBio. 2014;5(6):e01911-14.
- Wagner CE, Wheeler KM, Ribbeck K. Mucins and their role in shaping the functions of mucus barriers. Annual Review of Cell and Developmental Biology. 2018;34:189–215.
- Kahbazi M, Sharafkhah M, Yousefichaijan P, et al. Vitamin A supplementation is effective for improving the clinical symptoms of urinary tract infections and reducing renal scarring in girls with acute pyelonephritis: a randomized, double-blind placebo-controlled clinical trial. Complementary Therapies in Medicine. 2019;42:429–437.
- National Institutes of Health, Office of Dietary Supplements. Vitamin A and carotenoids: fact sheet for health professionals.
- Rothman KJ, Moore LL, Singer MR, Nguyen US, Mannino S, Milunsky A. Teratogenicity of high vitamin A intake. New England Journal of Medicine. 1995;333(21):1369–1373.
