Vitamin A

Why is vitamin A important?

Vitamin A is important for eye health, immune function, and cell growth. Vitamin A deficiency can be considered a nutritionally acquired immunodeficiency disease – meaning your immune system will not function properly if you are deficient in vitamin A.

Worldwide, vitamin A deficiency is the leading cause of preventable blindness in children and increases the risk of disease and death from infections. An estimated 250,000 to 500,000 vitamin A deficient children become blind every year, half of them dying within 12 months of losing their sight.[1]

What are signs of deficiency?

The first sign of vitamin A deficiency is difficulty seeing at night. Vitamin A deficiency can also cause dry eyes, bitot’s spots, and can eventually result in blindness. Another possible sign of vitamin A deficiency is bumpy (acne or pimple-like) skin on the back of the arms.

Being a born and raised vegetarian, I had these bumpy spots on my triceps as a child but didn’t know at the time that this was likely due to a vitamin A deficiency (I also had white spots on my fingernails indicative of a zinc deficiency; zinc is necessary for proper vitamin A metabolism).

Vitamin A deficiency often co-exists with iron deficiency and may worsen iron deficiency anemia.[2]

What is vitamin A?

Vitamin A can refer to both pre-formed vitamin A (retinol) and pro-vitamin A (carotenoids that can be converted to retinol in the body, the best known of which is beta-carotene). For simplicity’s sake, I will refer to pre-formed vitamin A as “retinol” and pro-vitamin A as “beta-carotene”.

There are a couple important differences between retinol and beta-carotene. Pre-formed vitamin A (retinol) can be toxic in high amounts, whereas beta-carotene from food is not.

As a child, I regularly drank carrot juice (high in beta-carotene) which made my skin turn a yellowish tinge. This was purely cosmetic and not harmful. Once I stopped drinking carrot juice my skin color returned to normal.

The other important thing to note is that retinol is a much more efficient source of vitamin A. The conversion process of turning carotene into retinol in the body is very inefficient, and it may take 12-24 times the amount of dietary carotene to equal the same amount of retinol.

What is the recommended daily intake?

The Recommended Dietary Allowance (RDA) – the amount needed to meet the nutrient needs of 97% of an age-specific population is as follows:

Vitamin A – recommended daily intake

Adult males: 900 micrograms RAE (3,000 IU)

Adult females: 700 micrograms RAE (2,300 IU)

Pregnancy: 750 micrograms RAE (2,500 IU)

Breast-feeding: 1,200 micrograms RAE (4,000 IU)

The units used to measure vitamin A are as follows:

1 microgram retinol = 1 Retinol Activity Equivalent (RAE) = 3.33 International Units (IU)

*Note: 12 micrograms dietary beta-carotene = 1 RAE

How much vitamin A can I take?

The tolerable upper intake limit (UL) – the highest level of daily intake likely to pose no risk of adverse health effects in almost all individuals of a specified age – is 3,000 micrograms RAE (10,000 IU) per day of vitamin A for adults.

Trivia

Did you know that eating polar bear liver can make you deathly ill? Symptoms described include: drowsiness, sluggishness, irritability, irresistible desire to sleep, severe headache, vomiting, and peeling of the skin – in some cases, from head to toe. This is because the pre-formed vitamin A content of polar bear liver can be so high that it causes vitamin A toxicity (hypervitaminosis A).[3]

Vitamin A in pregnancy

Pregnant women need to be especially careful to get the appropriate amount of vitamin A in their diet as both too little vitamin A and too much pre-formed vitamin A can cause birth defects. If you are pregnant, or plan on getting pregnant, pay close attention to how much pre-formed vitamin A (retinol) you are getting from both food and supplements, and avoid taking daily supplements that contain more than 1,500 micrograms RAE (5,000 IU) of vitamin A.

When pregnant, aim for the RDA of 750 micrograms RAE (2,500 IU) per day, and take care not to exceed the upper limit (UL) of 3,000 micrograms RAE (10,000 IU) per day.

Vitamin A and liver conditions

People with liver problems need to be careful when taking supplements containing pre-formed vitamin A as impaired liver function can lead to symptoms of vitamin A toxicity at lower doses (perhaps even at doses found in some multivitamin supplements). Signs of vitamin A toxicity include: loss of appetite, nausea, vomiting, fatigue, headache, and so on.

When my liver was in very bad shape, multivitamins containing pre-formed vitamin A gave me nausea and lack of appetite.

What is the best food source?

Liver has the highest concentration of pre-formed vitamin A of any food. A single 3-ounce serving of (preferably grass-fed) beef liver can meet, or even exceed, vitamin A requirements for an entire week. If you choose to consume beef liver, limit your intake to one serving per week and do not supplement with additional pre-formed vitamin A. I like to think of liver as “nature’s multivitamin” because it is high in many different nutrients including: vitamin A, vitamin B12, copper, iron, and zinc. Mickey Trescott, a fellow nutritional therapy practitioner, has an excellent liver pâté recipe that can be found here.

Measles and vitamin A

In almost every known infectious disease, vitamin A deficiency is known to result in greater frequency, severity, or mortality… even mild deficiency appears to be associated with an increased risk of pneumonia, diarrhea, and death in childhood. In a randomized, controlled trial of children with severe measles, treatment with high-dose vitamin A supplementation reduced the overall risk of an adverse outcome (death or major complication) by almost 50%.[4]

What vitamin A supplement do you recommend?

My personal preference for meeting vitamin A needs are to eat grass-fed beef liver (once a week) and avoid nutritional supplements that contain vitamin A. If you are unable to eat liver, then dietary supplements can be a viable option.

Almost all multi-vitamin supplements contain vitamin A as either pre-formed retinyl acetate or retinyl palmitate, and/or beta-carotene. If you prefer avoiding synthetic forms of vitamin A, then cod liver oil is probably the best option for obtaining large amounts of naturally occurring pre-formed vitamin A.

That said, despite its history of being used as a medicine and health product[5], there is some recent controversy surrounding cod liver oil – the main concern being that the ratio of vitamin A to vitamin D is skewed too highly in favor of vitamin A.[6] The proper balance between vitamin A, vitamin D, and vitamin K is very important for optimal health.

My favorite cod liver oil supplement is Rosita Extra Virgin Cod Liver Oil (EVCLO). The fish used to make the oil are said to be wild-caught and sustainably harvested. According to the manufacturer, Rosita EVCLO is completely unrefined and no chemicals, heat, or solvents are used in the extraction process.[7] A single teaspoon serving contains an average of 3,900 IU of pre-formed vitamin A and a modest 395 IU of vitamin D. Be sure to get extra vitamin D to maintain a good balance between vitamin A and vitamin D. Rosita Extra Virgin Cod Liver Oil is available through our online supplement dispensary.