Vitamin A, which is also known as retinol or retinoic acid, is a fat-soluble vitamin that can be naturally found in many food sources. Vitamin A is considered to be an essential nutrient for human health, since your body can’t produce it on its own.
There are different forms of vitamin A, and your body utilizes each type differently. The main types of vitamin A are:
Preformed vitamin A: this type of vitamin A is ready to be used for different processes in your body. Preformed vitamin A is commonly found in animal food sources.
Carotenoids: these substances, which include beta carotene, are precursors to vitamin A. Your body has to turn carotenoids into vitamin A to be able to use them properly. Carotenoids are typically present in fruits and vegetables.
Functions of vitamin A
According to the Harvard T.H. Chan School of Public Health, vitamin A is a key nutrient to protect your eye health. It helps your eyes adjust to dim light conditions, and it also plays a role in color perception.
Although its role in vision is perhaps the most commonly known, vitamin A has other functions in human health. It also stimulates the production and functioning of your white blood cells, which are an important component of your immune system.
Vitamin A is also involved in cell growth and development, and it helps regulate bone remodeling. Additionally, it helps keep your endothelial cells healthy; these are the cells that line the interior surfaces of your body. Vitamin A also acts as an antioxidant, which means that it can reduce or neutralize the effects of harmful free radicals in your body.
Vitamin A deficiency causes
A lack of vitamin A is rare in developed countries, since most people who eat a balanced diet will get enough vitamin A from the foods they eat everyday. However, some people have a higher risk of developing vitamin A deficiency, such as those with malabsorption disorders. Risk factors for low vitamin A include:
Preterm infants
Infants, children, and pregnant or breastfeeding people in developing countries
Crohn's disease
Cystic fibrosis
Celiac disease
Symptoms of vitamin A deficiency
According to the Cleveland Clinic, vitamin A deficiency symptoms can include:
Vision problems: lack of vitamin A can lead to xerophthalmia, which is an inability to see correctly in dim lighting. Xerophthalmia can lead to blindness if it’s left untreated.
Skin issues: vitamin A deficiency rash, skin dryness, and itching are common symptoms.
Fertility problems
Delayed growth and development in children
Frequent respiratory tract infections
Vitamin A deficiency health risks
Seek medical assistance if you think you’re suffering from signs of vitamin A deficiency. Your physician may order different tests to determine your vitamin A levels — fortunately, you can also get numerous at-home test kits to monitor your vitamin A levels. Depending on your results, your doctor could recommend dietary changes or taking a supplement.
Vitamin A supplements can interact with different medications, so it’s important to seek guidance from a healthcare professional before starting any new supplements or treatments.
Vitamin A food sources
The good news is that there are many dietary sources of vitamin A. According to the NHS, sources of vitamin A include:
Cheese
Eggs
Yogurt
Milk
Liver
Fortified spreads
Spinach
Carrots
Red bell peppers
Sweet potatoes
Mangoes
Apricots
Papaya
Topical vitamin A or retinol is also frequently used as a skincare ingredient. Retinol can help prevent premature aging, wrinkles, fine lines, roughness, and acne. However, it should always be used in combination with sunscreen to prevent skin redness and inflammation.
Vitamin A upper limit intake
There are different ways to measure your vitamin A intake. It can be measured in international units (IU); however, you may also see vitamin A amounts measured in micrograms (mcg) of retinol activity equivalents (RAE). This accounts for the different absorption rates of the different types of vitamin A, including carotenoids.
According to the FDA, male adults over the age of 19 need 900mcg RAE or 3,000 IU per day. Adult women, on the other hand, need around 700mcg RAE or 2,333 IU each day.
Too much vitamin A can also be bad for you. The tolerable upper intake level for vitamin A is approximately 3,000 micrograms of preformed vitamin A per day. However, research shows that taking 1,500 mcg of vitamin A everyday over a long period of time could also lead to future health problems.
Side effects of vitamin A excess
Even a single, large dose of vitamin A can lead to uncomfortable gastrointestinal symptoms, vertigo, and blurry vision. And according to the Mayo Clinic, taking excess amounts of vitamin A for a long time can lead to:
Bone thinning
Liver damage
Headache
Skin irritation
Diarrhea
Joint pain
Congenital defects
Sources
Vitamin A - hsph.harvard.edu
Vitamin A Deficiency - my.clevelandclinic.org
Daily Value on the New Nutrition and Supplement Facts Labels - fda.gov
Vitamin A - mayoclinic.org
