Vitamin A is a general term that refers to a group of fat-soluble compounds that play an essential role in supporting one’s health. Particularly, there is a strong association with Vitamin A and eye health – especially in children.
Vitamin A is crucial in maintaining one’s growth, vision, immune function and cell recognition. It also assists in maintaining the proper function of several organs in the body including the heart, lungs and kidneys.
While Vitamin A is an extremely common vitamin found in many foods, those not consuming fatty/oily fish or dairy products may not be getting a lot of Vitamin A in its Retinol form. A high percentage of adults are actually found to not be meeting their daily intake needs of Vitamin A. Those that are vegan or vegetarian would likely be having a higher intake of vegetables, which will provide Vitamin A in its Beta Carotene form, then convert to Retinol in the body. Beta-Carotene is typically highest in more brightly colored vegetables like carrots, sweet potatoes, leafy greens and fruit like papaya. Unfortunately, many people do not have a high intake of vegetables or oily and fatty fish, etc.
To further elaborate: two different forms of vitamin A are preformed vitamin A, which is found in animal-based products and provitamin A, which is found in plant-based products. Preformed vitamin A is an ‘active’ form of vitamin A and is most often found in meat, dairy and oily fish products. This form of vitamin A is ready to be used by the body and often includes retinol, retinal and retinoic acid. Provitamin A is the ‘inactive’ form of vitamin A that our body must convert into the active form for use. The inactive form of vitamin A is usually in the form of beta-carotene, alpha-carotene, and beta-cryptoxanthin and is found in plants – through the diet this would be found in the aforementioned brightly colored fruits and vegetables.
The Recommended Dietary Allowance (RDA) of vitamin A per day for healthy adults aged 19 and older is 900 mcg for men and 700 mcg for women. However, the Upper Intake Level (UL), which is the highest intake level one can consume without experiencing negative health affects is 3,000 mcg per day.
The highest dosages of preformed vitamin A are found in liver meats and fish oils – which many people do not consume in their diet in the western world. Foods such as milk and eggs are also quite high in preformed vitamin A, while containing low levels of provitamin A.
Vitamin A can also be easily obtained through supplements, especially for those concerned with eye health or skin health. Dosages in these supplements range from 750 to 3,000 mcg. Some supplements contain only preformed vitamin A or beta-carotene (provitamin A), while others contain a mixture of both. The details of the nutritional breakdown can easily be found on the label or ingredients list for these products.
Certain groups of people may be more susceptible to a deficiency. These groups include premature infants, individuals with cystic fibrosis, infants and young children – as well as pregnant and lactating women.
Deficiencies are also common in individuals in developing countries as there is a limited access to animal-based food products and poverty limits the availability of foods containing provitamin A. Infants are more likely to suffer from a Vitamin A deficiency as adequate storage of Vitamin A in the liver is not available like it is in adults, resulting in low levels of Vitamin A to remain for the first year of the infant’s life.
Furthermore, individuals with cystic fibrosis are more at risk of developing a vitamin A deficiency because their pancreatic insufficiency results in a difficulty absorbing fat – this can result in issues with fat-soluble vitamins like Vitamin A and Vitamin D.
Studies show that anywhere from 15 to 40 percent of individuals with cystic fibrosis are likely to have a Vitamin A deficiency. However, pancreatic replacement treatments, better nutrition and supplementation have all been proven adequate in restoring sufficient levels of Vitamin A within these individuals.
As Vitamin A plays a pivotal role in the creation and repair of healthy skin cells, a deficiency can result in dry skin and sometimes the development of eczema. The most common risk associated with Vitamin A deficiency is problems with the eyes and with vision health.
Low levels of Vitamin A in the body can result in dry eyes. In severe cases, some individuals may suffer from blindness or dying corneas. A much more common symptom of Vitamin A deficiency is night blindness. A study has shown that women who were given Vitamin A in their diet or through supplementation found that their ability to adapt their vision in the dark increased by 50 percent.
Vitamin A is also extremely important in the reproduction process for men and women. Therefore, a Vitamin A deficiency may lead to fertility issues in men as well as women. Moreover, Vitamin A is also essential in growth. Studies have shown that individuals with Vitamin A deficiencies were more likely to have stunted growth as the lack of Vitamin A has not allowed their body to properly develop.
Vitamin A is very important for preserving one’s vision. The eyes use Vitamin A to convert the light that hits it into an electrical signal that is sent to the brain. As previously mentioned, one of the first symptoms of a Vitamin A deficiency is night blindness.
This occurs in individuals with Vitamin A deficiencies because the lack of Vitamin A results in a reduced amount of rhodopsin on the retina. Rhodopsin is a pigment that is sensitive to light and one of its major components is Vitamin A. Therefore, a reduction in the amount of Vitamin A in the body results in a reduction of the amount of rhodopsin produced which in turn leads to a reduction of one’s ability to see in darker settings leading to night blindness.
Additionally, beta-carotene plays an essential role in reducing the decline in eye sight caused by old age, which is also known as age-related macular degeneration (AMD). The Age-Related Eye Disease Study found that individuals over 50 who were given a Vitamin A supplement containing beta-carotene reduced their risk of developing AMD by 25 percent.
Some research has shown that adequate levels of Vitamin A can reduce one’s risk of cancer. As cancer is caused by an uncontrollable growth or division of cells and vitamin A is essential in ensuring cells are growing and developing adequately, plenty of research has been done on the link between Vitamin A and cancer.
Several studies have shown that consuming vitamin A in the form of beta-carotene in the diet has been linked to reducing one’s risk of developing several different types of cancers including cervical, lung and bladder cancer. Although, Vitamin A obtained from animal products have not been proven to have the same link.
The data on whether Vitamin A is distinctly beneficial in preventing cancer is unclear. However, some evidence shows that obtaining satisfactory amounts of Vitamin A from plant-based food sources (or supplemented as ‘Beta-Carotene’) promotes healthy cell division and may reduce one’s risk of some types of cancer.
Additionally, Vitamin A is essential in maintain proper immune function. Vitamin A is used to improve the efficacy of mucous barriers in one’s eyes, lungs, gut, etc. It is also a very important part of the production of white blood cells which are used to rid the body of bacteria and other pathogens which may be found in the bloodstream.
Therefore, a deficiency in Vitamin A may make an individual more susceptible to some diseases as their mucous barrier and white blood cell count may not be adequate, in turn allowing the body to be more vulnerable to diseases and infections and causing recovery times to be lengthier. Furthermore, some countries which have been affected by measles and malaria have found that Vitamin A supplementation in children has reduced their risk of death from these diseases.
Vitamin A also plays a vital role in ensuring normal growth and development of organs and structures in the fetus. Some of these organs and structures include the nervous system, heart, kidneys, eyes, lungs and pancreas.
However, overconsumption of Vitamin A during pregnancy may also cause some adverse health affects for the unborn baby – this is why it is essential to consult with your doctor regarding supplementation during pregnancy (while trying to conceive extra Vitamin A supplementation may provide benefit). As a result of this, it is recommended that pregnant women avoid Vitamin A rich foods such as liver during pregnancy, as well as Vitamin A supplements.
It has been proven that Vitamin A is an essential nutrient in humans. It is also quite clear it is extremely important to proper immune function, reproductive function, and vision function. Although Vitamin A deficiencies are not common, certain people such as individuals with cystic fibrosis or infants are more likely to exhibit symptoms of a deficiency. Additionally, those suffering from myopia, other vision problems, those trying to conceive, or those with acne prone skin may find benefit of supplementing Vitamin A.