Do You Need a Vitamin A Deficiency Test? Consider This First

• Vitamin A Testing|
• Symptoms|
• Risk Factors|
• Supplementation|
• FAQs|

Vitamin A deficiency is generally uncommon in Western countries like the United States, which is why it can be easy to overlook. The symptoms often seem unrelated at first, and blood levels usually stay within the normal range until the deficiency progresses to more advanced symptoms. This is one reason why people may go years without realizing their levels are low.

If you are experiencing symptoms such as bumps on the backs of your arms, dry eyes, trouble seeing at night, or frequent illness, your serum retinol levels may be worth evaluating.

In this article, we will look at the role vitamin A plays in the human body, the symptoms associated with deficiency, considerations for testing, factors that influence your levels, and when supplementation is appropriate.

Vitamin A Blood Tests

Generally speaking, most healthy adults and children do not need vitamin A testing. Deficiency is rare in most Western countries, and serum levels usually stay normal until liver stores are significantly depleted 1 2. Because the liver holds most of the body’s vitamin A, blood serum levels often remain normal until deficiency is relatively advanced.

Testing becomes more useful when someone has clear symptoms, belongs to a higher-risk group, or when a clinician has a strong reason to suspect a deficiency. In those cases, a serum retinol test is the most practical option. Those with low levels may report symptoms like dry eye and often respond to supplementation 3. Labs may use spectrophotometry or high-performance liquid chromatography, with the latter offering greater accuracy at a relatively low cost.

Other testing methods exist, but are rarely necessary. While a liver biopsy provides the most precise measurement, it is only used in specific clinical situations 2. Dried blood spot testing is another option and has been shown to provide details alongside serum retinol results 3 4.

If you and your clinician agree that it is best to test your levels, these points can help you interpret the results 5:

• Some observational data suggest that serum retinol levels toward the upper end of the reference range (around 58 mcg/dL) may be associated with favorable outcomes.
• Levels below 20 mcg/dL suggest that liver stores are already severely depleted, and supplementation should begin with guidance from a health care provider.

What Are the Signs and Symptoms of Vitamin A Deficiency?

Common signs and symptoms of vitamin A deficiency include 3:

• Dry eye 
• Bumps on the back of the arms
• Recurrent infections and poor immune system function
• Night blindness
• Bitot’s spots (the buildup of protein on the white part of the eye) 

Severe vitamin A deficiency can eventually lead to complete blindness, but this is extremely rare 6.

If you are experiencing symptoms and fall into a higher-risk group, short-term supplementation with a modest dose of vitamin A, along with monitoring for symptom improvement, is often considered safe; however, testing is still preferred when possible. Vitamin A level tests are relatively inexpensive and fairly accurate in cases of severe deficiency. 

Who Is at Risk of Vitamin A Deficiency?

Vitamin A deficiency is rare in Western countries, but some populations have a higher risk, such as: 

• Bariatric (weight loss) surgery patients 7
• Preterm infants 8
• Breastfed infants with vitamin A-deficient mothers 8
• Those with potential gastrointestinal malabsorption, including celiac disease and inflammatory bowel disease 8
• People with cystic fibrosis 8
• People with chronic alcohol use and those with non-alcoholic fatty liver disease 9
• Those consuming a low-fat diet 
• Those with malnutrition or inadequate nutrient intake

Other Deficiencies and Imbalances Can Affect Your Vitamin A Levels

Have you been supplementing with vitamin A and consuming vitamin A-rich foods, yet your serum vitamin A levels remain low? Certain micronutrient deficiencies and health considerations may be at play:

• Zinc deficiency can impair the absorption, transport, and utilization of vitamin A 10.
• Iron deficiency may negatively impact serum retinol concentrations and decrease vitamin A mobilization from the liver 11.
• Low dietary protein intake can falsely lower serum retinol levels 11. 
• Inflammation and infection can temporarily lower serum retinol levels due to reduced retinol-binding protein, even when liver stores are adequate 3.

If you have a low vitamin A level, it’s important to work with your practitioner to uncover and correct potential underlying factors.

When Are Vitamin A Supplements Helpful?

Vitamin A supplements can be helpful in a few situations. The strongest case for a supplement is when someone is low in vitamin A or deficient. Outside of that, it’s more “right tool, right context” rather than a blanket recommendation.

Immune system function

In areas where vitamin A deficiency is a public health concern, high-dose vitamin A supplements can lower the risk of childhood measles in children aged 6 months to 5 years 3.

Post-infectious loss of smell

Some evidence suggests that intranasal (topical, inside the nose) vitamin A may help with post-infectious smell loss when combined with smell training. That said, the strongest study supporting this was retrospective, meaning it looked back at outcomes rather than testing the treatment in a tightly controlled way. On the other hand, a well-designed, double-blind clinical trial found that taking vitamin A by mouth (10,000 IU per day) didn’t work any better than a placebo 12 13.

Dry eye disease

Oral supplementation of 1,500 milligrams (mg) of vitamin A for three consecutive days has been shown to improve tear quality test results in patients with dry eye disease 14.

Skin disorders

Topical and systemic use of vitamin A and its derivatives may be beneficial for acne, psoriasis, keratosis pilaris (tiny bumps and dry rough patches on the skin), skin cancer, and ichthyosis (a genetic disorder causing dry, scaly skin) 15 16.

Hypothyroidism

In children with both iodine and vitamin A deficiencies, vitamin A supplementation along with iodized salt improved thyroid markers and lowered the risk of hypothyroidism 17. 

Parkinson’s disease

In one long-term trial, patients with Parkinson’s disease who took a combination supplement that included vitamin A for 30 months experienced significantly delayed disease progression compared to controls 18.

Multiple sclerosis

In a small clinical trial, patients with multiple sclerosis who received 25,000 IU/day of retinyl palmitate (a fat-soluble form of vitamin A) for six months, followed by 10,000 IU/day retinyl palmitate for another six months, experienced significant reductions in depression and fatigue 19.

Who Should Not Supplement with Vitamin A 

Most people can use vitamin A safely in reasonable amounts, but there are a few situations where extra caution makes sense. Some of the clearest examples come from research on smokers and people who were exposed to asbestos. In those groups, very high doses of vitamin A and beta carotene were associated with a higher risk of lung cancer compared with people who did not supplement 20 21. A few studies have also suggested a possible increase in prostate cancer risk in men with higher circulating levels of carotenoids and retinol 22 23.

Extra care is needed during pregnancy. Vitamin A is important, but more isn’t better. High doses of preformed vitamin A (the retinol form found in some supplements) have been linked with birth defects, so it’s best to avoid high-dose vitamin A supplements in pregnancy unless your clinician specifically recommends them. As a general safety rule, pregnant women should not exceed 10,000 IU (3,000 micrograms) per day 8.

Vitamin A Supplementation Guide and Considerations

Correcting a vitamin A deficiency often starts with food. 

Dietary Forms of Vitamin A and Absorption

Vitamin A comes from food in two main forms. Preformed vitamin A (retinol) is found in animal-based foods such as liver, egg yolks, dairy, and fatty fish. This form is readily absorbed and can be used directly by the body. Provitamin A carotenoids, including beta-carotene, alpha-carotene, and beta-cryptoxanthin, are found in plant foods like carrots, sweet potatoes, pumpkin, spinach, kale, and other dark leafy greens. The body must convert these carotenoids into retinol before they can be used 8.

Because of this extra conversion step, retinol from animal foods is generally more efficiently absorbed and utilized than provitamin A carotenoids from plants. Conversion efficiency varies widely between individuals and can be influenced by genetics, gut health, thyroid function, zinc status, and overall fat intake. While carotenoid-rich foods can meaningfully contribute to vitamin A status, people with absorption issues or higher needs may not convert enough provitamin A to fully meet their requirements 24.

Factors such as the food matrix (how readily accessible vitamins and minerals are in food), cooking, and dietary fat influence how well carotenoids are absorbed and converted. For example, carotenoid absorption and conversion are enhanced when consumed with dietary fat and when plant foods are cooked or processed in ways that release carotenoids from the food matrix 24. 

Eating more vitamin A-rich foods can be enough for many people, although supplemental beta carotene and retinol are also effective. 

Recommended Intake, Upper Limits, and Safety

The recommended dietary allowance (RDA) of vitamin A, in retinol activity equivalent (RAE), is 8:

• 900 micrograms RAE per day for adult men
• 700 micrograms RAE per day for adult women 
• 300-600 micrograms RAE per day for children, with RDA depending on age

You might notice that the RDA for vitamin A is listed in micrograms (mcg) and RAE, but many supplements use international units (IU). Below is the conversion factor for RAE to IU for preformed vitamin A (retinol) and provitamin A (beta-carotene) 8. 

• 1 IU retinol = 0.3 mcg RAE
• 1 IU supplemental beta-carotene = 0.3 mcg RAE
• 1 IU dietary beta-carotene = 0.05 mcg RAE

3,000 micrograms per day of preformed vitamin A from animal sources is the tolerable upper limit for adults, meaning it is not recommended to exceed this amount. 

Taking supplemental vitamin A with other fat-soluble vitamins, such as D, E, and K, is generally considered best practice. Large doses of vitamin A may negatively affect the status of other nutrients. One study found that breastfeeding mothers who received 200,000 IU of retinyl palmitate after the first colostrum collection had decreased vitamin E bioavailability in their breast milk 25.

In certain conditions, higher intakes of these fat-soluble vitamins may be necessary under clinical guidance:

• Exocrine pancreatic insufficiency (a condition in which the pancreas does not produce enough digestive enzymes to properly break down food)
• Cholestasis (a liver disease where the flow of bile is reduced or blocked)
• Those who have undergone weight loss surgery
• Crohn’s disease 
• Celiac disease
• Other malabsorption disorders of the intestine

If your test results indicate you are vitamin A deficient, work with your healthcare provider to determine your specific supplementation needs. 

FAQ’s

What is vitamin A?

Vitamin A is a fat-soluble vitamin that is crucial for immune function, vision, cell growth, and bone development. It comes in two forms: preformed vitamin A (retinol) found in animal foods, and provitamin A carotenoids (like beta-carotene) found in plant foods.

Can I overdose on vitamin A supplements?

Toxicity is uncommon, but as a fat-soluble vitamin, vitamin A can build up in the body with sustained high intakes (10 times the recommended daily amount) of preformed vitamin A over time. 

What are the symptoms of vitamin A toxicity?

Symptoms may include 26:

• Weakened bones, birth defects
• Fatigue, hair loss
• Headache, loss of appetite
• Liver damage, upset stomach
• Dry/itchy skin, brittle nails

How do I know if I have vitamin A toxicity?

Serum retinol tests do not always reflect vitamin A toxicity, since most vitamin A is stored in the liver. As a result, blood levels can appear normal even when liver stores are elevated.

Can vitamin A affect pregnancy?

Yes, excessive vitamin A during pregnancy can cause birth defects. Pregnant women are advised to avoid high doses of vitamin A supplements, especially preformed vitamin A (retinol), and should not exceed the recommended daily amount without consulting a healthcare provider.

How can I improve my vitamin A levels if I’m deficient?

Increase intake of vitamin A-rich foods such as liver, egg yolks, dairy, and dark leafy greens. Modest supplementation is safe and effective if needed, but talk to your provider if your levels remain low.

The Ruscio Institute has developed a range of high-quality formulations to help our clients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you. The information on DrRuscio.com is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment.