Vitamin A

Our bodies need a variety of vitamins and minerals to work properly and keep us healthy. One of those vitamins is Vitamin A, also known as Retinol. It is an important vitamin that is not often talked about.

WHAT IS VITAMIN A?

Vitamin AVitamin A is considered to be a fat-soluable vitamin, meaning that it dissolves in and is absorbed with fat.  The liver, a fatty organ, stores about 80-90% of vitamin A so that it is available for use in the body. When vitamin A is needed, it is released from the liver into the blood stream and attaches itself to either a liver made protein called pre-albumin or to the provitamin Beta-carotene.  Vitamin A has several important jobs in the body.

  • It is involved in the process of cell production by helping the cell to differentiate or develop into the needed specialized cell.
  • It is an important part being able to have good vision.
  • It is involved in the development of embryos and unborn children.
  • It also helps keep the skin and mucous membranes inside the mouth, nose and sinuses healthy.
  • It helps the body’s immune system work properly.
  • It is also involved in growth, the formation of bones, the reproduction process, and wound healing.

WHERE DO WE GET VITAMIN A?

Vitamin A is found in two forms, retinoids and carotenoids. Retinoid forms of vitamin A, including retinol, come from an animal source. It is the most active form of vitamin A and can be referred to as the active form of it. Carotenoids come from plant sources and includes beta-carotene, the substance that is converted to vitamin A. Beta-carotene is known as provitamin A the precursor to vitamin A and makes up 2/3rds of the vitamin A present in humans. The body gets the needed vitamin A from the food we eat as well from supplements if we are not taking in enough from food. Both meat and plant sources provide vitamin A.

Meat Sources

  • Liver from beef, chicken and calf sources
  • Kidney
  • Milk and milk products including whole milk yogurt, whole milk cottage cheese, butter and other cheese.
  • Fish Oil especially fish liver oils
  • Eggs

Plant Sources

  • Dark green leafy vegetables such as romaine and arugula
  • Kale, mustard greens, collard greens, and broccoli
  • Swiss chard and Spinach
  • Deep yellow/orange fruits and vegetables
  • Carrots
  • Sweet potatoes
  • Pumpkin
  • Cantaloupe
  • Apricots
  • Peaches
  • Mangos

All of these plant sources are rich in many vitamins and minerals in addition to vitamin A. By combining them together, you can get a flavorful, healthy, filling meal.

Supplements

  • Retinol or retinyl palmitate
  • Come in a variety of doses from 10,000 to 50,000 International Units (IU).
  • Fish Liver oils contain more than 180,000 IU/Gram

CAN WE TAKE IN TOO MUCH VITAMIN A AND WHAT HAPPENS IF WE DO?

Because vitamin A is a fat-soluble vitamin, it can easily accumulate in the body and cause a person to develop vitamin A toxicity. Getting your Vitamin A from food sources is safe and should not cause problems, however the use of supplements may cause an accumulation.  According to Medscape emedicine, supplementeddoses greater than 25, 000 units per day are to be used with caution and for a limited time only.

Vitamin A toxicity happens when too much vitamin is taken in. It can happen suddenly, usually because someone has taken too much at one time or it can happen from a slow accumulation over a long period of time. It is important to know the signs of toxicity and how to treat it.

Signs of Toxicity:

  • Headache that keeps getting worse or won’t go away.
  • Rash
  • Feeling sleepy or drowsy
  • Abdominal or belly pain
  • Nausea and vomiting
  • Diarrhea

Signs of long term toxicity include the above symptoms, plus:

  • Hair loss especially on the eyebrows
  • Skin that is dry and rough
  • Yellowing of skin especially on the hands
  • Dry cracked lips
  • Itching
  • Increasing intracranial pressure or swelling on the brain
  • Bone and muscle aches
  • Swelling of face, hands, arms, feet and legs
  • Trouble sleeping

WHAT SHOULD I DO IF I THINK I, OR SOMEONE I KNOW, MIGHT HAVE VITAMIN A TOXICITY?

If you think you or someone you know has too much vitamin A in their body, call a healthcare professional and stop taking any vitamin A supplements including retinol and beta-carotene. If it is a child, call the local poison control center or go to the Emergency Room. The healthcare professional will do a thorough history and physical and may order blood tests to look at the fasting serum retinol levels. Depending on the type and severity of the symptoms additional tests such as X-rays and CT-Scans may be performed to make sure there are no other diseases causing the symptoms. You will be instructed to stop taking any vitamin A supplements and symptoms such as headache, nausea and vomiting will be treated with appropriate medications. The good news is once you stop the vitamin A, the symptoms will go away in 1 to 4 weeks.

HOW CAN I PREVENT TOXICITY?

  • Take Vitamin A while under the supervision and direction of medical professional.
  • Only take Vitamin A for the medical professional recommended amount of time.
  • Keep the Vitamin A supplements out of the reach of children. Use child-proof caps and place in a medicine cabinet or place that a child cannot access them.
  • Inform all Healthcare professionals that you are taking vitamin A and the dose you take so that they can make sure there will not be an interaction with any other medications you take.
  • Contact your healthcare provider if you notice any unusual symptoms such as changes in vision, skin or just don’t feel well.

IS IT POSSIBLE TO HAVE TOO LITTLE VITAMIN A IN YOUR BODY?

Yes, although it is very rare in countries that are well developed such as the United States. Vitamin A deficiency is found most often in people who are malnourished, the elderly and people who have a chronic illness such as cancer. It can also happen to people who have Irritable Bowel Syndrome, difficulties absorbing fat from their diet, undergone small bowel bypass, some vegetarians, and alcoholics. In underdeveloped countries it is estimated that 250 million children are at risk for vitamin deficiencies.

WHAT ARE THE SYMPTOMS OF VITAMIN A DEFICIENCY?

  • Night Blindness or difficulty with eyes adapting to darkness is an early symptom.
  • Drying of the eyes and Cornea causing hazy vision.
  • Blindness caused by an injury to the retina, not allowing the proper amount of light to enter the eye.
  • Dry and scaling skin
  • Itching
  • Fingernails that are broken or break easily.
  • Anemia
  • Drying of the mucous membranes in the respiratory tract and Gastro-intestinal tract
  • Frequent Respiratory infections
  • Retardation or slowing of growth can occur in children.
  • Bone Disease

HOW CAN VITAMIN A DEFICIENCY BE DIAGNOSED?

If any of the above symptoms are noticed, a visit to a healthcare professional needs to be scheduled.  A thorough medical history and physical exam is needed. The health care professional will pay close attention to the eyes as this is often the easiest way to detect Vitamin A deficiency. If the person is having trouble adapting to darkness or has night blindness on the eye exam, tests may be done to rule out other causes such as diabetic retinopathy, a deficiency of the mineral zinc, or cataracts. If there is no evidence of other diseases that may affect the eye, then a very expensive blood test to check a blood retinol level may be done. Other blood tests may include a zinc level, iron studies, albumin level and a complete blood count. Blood electrolytes and a liver enzyme test may also be done to check for nutrition status and make sure that you are not dehydrated. Some healthcare professionals will have the patient take a trial dose of Vitamin A supplements to see if the symptoms get better.

HOW CAN VITAMIN A DEFICIENCY BE TREATED?

The first step in treating Vitamin A deficiency is to make sure that good food choices of Vitamin A are a part of your diet every day.

  • Eat a minimum of 5 servings of fruits and vegetables each day.
  • Include a variety of foods in your diet each day such as breakfast cereals, pastries, breads, crackers as these are often fortified with vitamin A.
  • Liver, beef, chicken and eggs are good protein choices to add vitamin A into your diet
  • Drink whole milk or fortified milk
  • Orange vegetables like carrots and sweet potatoes
  • Green vegetables such as spinach, kale, and broccoli
  • Orange fruits

Some people may have medical conditions or special needs that keep them from getting the recommended dietary allowances from food. These people may need to take Vitamin A supplements to make sure they have enough in their system. They currently use Vitamin A Palmitate in oil as the supplement of choice with the following recommended doses of Vitamin A:

  • Children age 3 and younger: 600 mcg (micrograms) or 2000 IU (International Units)
  • Children 4 – 8 years of age: 900 mcg or 3000 IU.
  • Children 9 – 13 years of age: 1700 mcg or 5665 IU
  • Children 14 -18 years of age: 2800 mcg or 9335 IU
  • Adults : 3000 mcg or 10,000 IU

If severe Vitamin A deficiency is present, especially in children, the dose is 60,000 mcg or 200,000 IU according to studies that showed this dose decreases mortality rates in children by 35 to 70%.

Vitamin A supplements may start out at 60,000 IU by mouth for 2 days and followed up with 4500 units by mouth once a day. Remember that Vitamin A is absorbed best when taken with fat, so it is best to take with food at the same time every day.

Vitamin A can be affected by sunlight, sources of ultraviolet light and temperature and should be stored in opaque containers. Many times aluminum containers are used so that no light reaches the capsules. An unopened, opaque container can be stored for two years. A container that has been opened should be used within 6-8 weeks, as the potency of the supplement declines over time when it is exposed to light.

IS THERE ANYTHING ELSE I NEED TO KNOW ABOUT VITAMIN A SUPPLEMENTS?

It is important to take Vitamin A supplements only under the direction and supervision of a health care professional so you can be monitored for any signs of toxicity.

  • Tell all your physicians and healthcare providers including pharmacists that you are taking Vitamin A supplements. There are medications that can interact with Vitamin A.
  • Tell your healthcare provider if you are pregnant or about to become pregnant. Taking too much Vitamin A can serious birth defects in the unborn baby and how much you are taking may need to be changed frequently.
  • Do not take the synthetic form of Vitamin A if you are pregnant, it can cause birth defects. Your healthcare provider can change you to a natural supplement.

WHAT MEDICATIONS MIGHT HAVE ADVERSE INTERACTIONS WITH VITAMIN A SUPPLEMENTS?

  • Antibiotics containing Tetracycline. This class of antibiotics when taken at the same time as Vitamin A can cause increased pressure in the brain.
  • Some studies have shown that taking a Vitamin A supplement along with antacids, may help ulcers to heal faster.
  • Blood Thinners or anticoagulants such as Coumadin. When taken with high dose or long term use of Vitamin A there is an increased risk of the blood becoming too thin and causing bleeding.
  • Cholesterol lowering medications. The statins, such as Zocor, can raise blood levels of vitamin A.
  • Medication used to treat cancer.
  • Medications that are removed or processed by the liver may cause liver damage or even liver failure when taken with high doses of Vitamin A.
  • Orlistat and Olestra, medications used for weight loss, prevent the body from absorbing fat and may also prevent the absorption of Vitamin A. The Food and Drug Administration requires that any food that contains Olestra requires that Vitamin A and other fat soluble vitamins be added to the food to reach the recommended daily allowances.

It is always best if vitamins and other vital nutrients come from food sources as opposed to taking supplements and having to monitor for signs of toxicity. A healthy well balanced diet that includes at least 5 servings of a variety of fruits and vegetables, lean protein sources, whole grains and low fat milk and milk products should supply all the Vitamin A you need.

REFERENCES

  1. Johnson, LE, MD PHD. (2014, October). Vitamin A. Merck Manual Professional Edition. Retrieved from URL:http://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency-dependency-and-toxicity/vitamin-a
  2. Myhre, A. Carlsen, MH. Bohn, SK. Wold, HL. Laake, P. Blumhoff, R. (2003, December). Water-miscible, emulsified, and solid forms of retinol supplements are more toxic than oil-based preparations. Am J Clin NutrDecember 2003vol. 78 no. 6 1152-1159
  3. Preedy, V. Vitamin A and Carotenoids: Chemistry, Analysis, Function and Effects.RSC Publishing. Pages 381-413. Retrieved from URL:https://books.google.com/books?id=ojNqPbqgepsC&printsec=frontcover&dq=vitamin+a&hl=en&sa=X&ved=0CCoQ6AEwAmoVChMItvbu1JinxwIVDG4-Ch1MBAsf#v=onepage&q=vitamin%20a&f=false
  4. International Vitamin A Consultative Group, UNICEF. Vitamin A Supplements: A Guide to Their Use in the Treatment and Prevention of Vitamin A Deficiency and Xerophthalmia. World Health Organization. 1997.Pages 9-13. Retrieved from URL:https://books.google.com/books?id=S-S1m_RJyYUC&printsec=frontcover&dq=vitamin+a&hl=en&sa=X&ved=0CFIQ6AEwCWoVChMItvbu1JinxwIVDG4-Ch1MBAsf#v=onepage&q=vitamin%20a&f=false
  5. Sommer, Alfred. (2008). Vitamin A Deficiency and Clinical Disease: An Historical Overview.J. Nutr.October 2008vol. 138 no. 10 1835-1839.
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