There are many vitamin A health benefits
Vitamin A health benefits are wide ranging, and include improved vision, skin, immune system functioning, wound healing, and cell reproduction.
Vitamin A is a general term that categorizes many related compounds defined by the derivative dietary sources.
Retinol, the fat-soluble type of vitamin A, is in fish and other animal-based foods, while plant-based carotenoids, including beta-carotene, are principally in yellow and orange fruits and vegetables. The body more easily assimilates retinol because of its advanced form compared with carotenoids, which the body must convert.
The overarching function of vitamin A is to support the epithelial cells and tissues that line the body cavities and surfaces.
Some vitamin A health benefits include stimulating skin cell renewal and supporting healing, appearance and quality of the skin – a concern for most people as they age.
A study of adults 80 years and older found that topical vitamin A application for seven days increased collagen synthesis, and as a skin cell renewal facilitator, it may play a role in preventing skin cancer. Vitamin A also absorbs ultraviolet light to help protect delicate skin areas.
Vitamin A and aging
There are many causes of the increased susceptibility to disease and illness that accompanies aging. One is that over time the body experiences a reduction in nutrient levels and an increased resistance to vaccinations.
Immune system
Vitamin A health benefits include improving the immune system by maintaining mucous secretions and cellular integrity that when diminished, cannot effectively resist the invasion by pathogenic organisms.
While clinically diagnosable vitamin A deficiency in developed nations is rare, sub-optimal levels can have a low-grade impact on immune system health that over time may contribute to a significant deterioration in health.
Macular degeneration
Age-related macular degeneration is an eye disease affecting approximately 25 million people worldwide. It is the principal cause of blindness in the Western world.
The initial stage involves deterioration of the detail-oriented visual focus capacity of the retina used for reading and facial recognition, and can eventually lead to complete vision loss.
The disease can be hereditary and those with genetic markers may be able to reduce the likelihood of developing macular degeneration by eating more vitamin A-rich foods.
Additionally, a large population study found that having a high vitamin A intake reduced cataract risk. Vitamin A supplements may also help slow the damage from retinitis pigmentosa, which causes poor night vision.
Membrane integrity
Nutrients like vitamin A that preserve membrane integrity, protect DNA, and help slow cancer development or progression, also support the immune system.
Vitamin A health benefits also include supporting the regeneration of tissue surfaces and mucous membranes throughout the body. This helps protect the internal cavities with anti-microbial components.
Without an adequate vitamin A level, resistance to potentially pathogenic organisms that can enter the body through cell and tissue membranes is reduced.
This effect expands to other areas, such as the eye’s surface. This normally sloughs dead cells and manages the hydration balance, but without enough vitamin A, the surface begins to age and deteriorate because the membrane integrity is compromised.
Increasing dietary intake of retinol vitamin A or beta carotene can improve the body’s capacity to support membrane health.
Chronic inflammation
Chronic inflammation, if left untreated, can lead to arthritis, diabetes, cancer or cardiovascular disease.
In a healthy scenario, inflammation develops at an injury site to signal, protect and heal the wound. But when an accumulation of harmful compounds occurs, resulting from stress, environmental pollution and the overpowering of the body’s natural maintenance processes, it causes a low-grade, nearly undetectable level of inflammation. This can persist for years and develop into disease unbeknownst to the sufferer.
Do I have a vitamin A deficiency?
As well as poor nutrition contributing to lower vitamin A levels, the body itself may have difficulties effectively converting beta-carotene to the active vitamin A form, or difficulty in digesting fat-soluble vitamin A, due to an impaired digestive system. A doctor can diagnose these conditions.
People with digestive system inflammation such as from ulcerative colitis or Crohn’s disease are also susceptible to vitamin A deficiency.
How can I add vitamin A to my diet?
Preformed vitamin A is in foods such as meat, fish, milk and other dairy products, eggs, and fortified cereals. High concentrations of dietary beta-carotene are available in fruits, leafy green vegetables, broccoli, carrots, tomatoes, and some vegetable oils.
How much vitamin A should I take?
Vitamin A is available as a dietary supplement, usually as retinol acetate, retinol palmitate or beta-carotene.
These may be available individually or in combination. For those with a vitamin A deficiency, doctors often recommend additional dietary sources and a multivitamin that includes the retinol form.
The standard adult recommended daily vitamin A dietary supplement dose is:
- 700 mcg for women
- 900 mcg for men
Taking a fat-soluble retinol form of vitamin A with fat- or oil-based food is recommended to aid absorption because otherwise the digestive system may not assimilate it efficiently. Dividing the daily value into two or three doses also maximizes uptake.
You will know you’re taking the correct level if you have limited the dosage to fewer than 700 mcg for women and 900 mcg for men, and after consistent use have no side effects and relief from deficiency symptoms. It is, however, always best to follow your doctor’s advice to be certain.
During pregnancy, it is important to seek medical guidance about appropriate vitamin A dosage. Women require more vitamin A during pregnancy and while breastfeeding, but large doses of retinol supplements can be toxic. Beta-carotene on the other hand is non-toxic during pregnancy.
Side effects of vitamin A
Because vitamin A is fat soluble, the body stores a surplus amount in the liver, and this level can accumulate and cause vitamin A hypervitaminosis.
A group of arctic explorers, for example, were forced to eat polar bear liver and experienced this condition. Although it would be difficult to acquire with a standard diet and recommended supplementation levels.
Conversely, beta-carotene is water-soluble and does not accumulate in the body, meaning it can contribute to an overabundance.
It manifests with side effects such as skin discoloration, dizziness, increased intracranial pressure, headaches, nausea, skin irritation, and joint pain. Liver damage and coma are the very serious side effects of overdosing.
Contraindications
Vitamin A may contraindicate with the function, absorption, effectiveness or potency of the following prescription medications:
- Antacids
- Antibiotics such as tetracycline antibiotics and neomycin (Mycifradin)
- Anticoagulants such as warfarin (Coumadin)
- Cholesterol-reducing medications (bile acid sequestrants) such as colestipol (Colestid)
- Doxorubicin (Doxil)
- Medications processed by the liver, such as carbamazepine (Tegretol) and methotrexate
- Omeprazole (Prilosec)
- Synthetic vitamin A or retinoids such as bexarotene (Targretin) and tretinoin (Retin-A)
- Anti-obesity drugs such as orlistat (Alli)
- Fat substitutes such as olestra (Olean)
References
- University of Maryland Medical Center. “Vitamin A (Retinol).” June 21, 2011. http://www.umm.edu/altmed/articles/vitamin-a-000331.htm
- Linus Pauling Institute Micronutrient Information Center. “Vitamin A.” November 2007. http://lpi.oregonstate.edu/info
- National Institutes of Health Office of Dietary Supplements. “Vitamin A.” http://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/center/vitamins/vitaminA/
- United Nations Food and Agriculture Organization. “Vitamin A.” http://www.fao.org/docrep/004/Y2809E/y2809e0d.htm
Last reviewed 3/Mar/2017
Ann-Mary Amber
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