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FAQ: Vitamin A

Tuesday 20 October 2015
What is the tolerable upper limit of vitamine A intake?

The tolerable upper limit indicates the amount of vitamin A that someone can ingest without elevating the risk of experiencing adverse health events. The EFSA (European Food Safety Authority) states that the tolerable upper limit of vitamin A intake for anyone up to 17 years of age is between 800 mcg (1-3 years) and 2600 mcg (15-17 years) a day.  For 18 and up the tolerable upper limit is 3000 mcg a day.

 

What is the RDA for vitamin A?

The RDA for vitamine A in the UK is 800 mcg.  In the Netherlands RDA´s are higher or lower depending on age, gender and whether one is pregnant or breastfeeding (please see the table below).

 

Woman

Man

1-10 years* 400-700 mcg 400-700 mcg
11-18 years 800 mcg 1000 mcg
19-50 years 800 mcg 1000 mcg
51-65 years 800 mcg 1000 mcg
65+ years 800 mcg 1000 mcg
Pregnant 1000 mcg  
Breastfeeding 1250 mcg  

* For children between 1-4 years of age the RDA is 400 mcg/day.

* For children between 5-7 years of age the RDA is 500 mcg/day.

* For children between 8-10 years of age the RDA is 700 mcg/day.

 

As you can see, both in the UK and in the Netherlands RDA’s for vitamin A are much lower than the tolerable upper limit established by the EFSA.

 

At which dose does retinol become toxic to the liver?
The lowest dose on record that has caused liver toxicity is chronic use of > 7500 mcg a day during six years.  This is twice the tolerable upper limit. Food supplements containing a maximum of 1200 mcg of retinol per dosage unit are generally safe, yet may cause liver damage in people who already have a damaged liver and, in addition to that, consume very large amounts of liver and liver products. Compared to pure liver itself, which on average contains 13,000-40,000 mcg of retinol per 100 grams, a supplement with 1200 mcg of retinol is very low-dosed. It is therefore also very unlikely that a supplement could cause liver toxicity or cirrhosis of the liver.

 

Does liver toxicity caused by vitamin A occur frequently?
Liver toxicity caused by vitamin A is very rare and occurs only in certain groups within the population (Please read: At which dose does retinol become toxic to the liver). It is sometimes unjustly claimed that more groups are at an increased risk.

 

When does chronic or acute liver toxicity occur?
According to the scientific literature, cumulative toxicity is possible when, over a long period of time,  dosages exceeding 30,000 mcg a day are ingested. Acute toxicity is extremely rare in adults: dosages required for this effect are in the range of 600,000 mcg and more. This is 750 or more times the RDA in the UK.

 

Are children between 0-3 years of age at an increased risk of an overdose?

According to some sources the consumption of retinol from food in 5-33% of children between 0-3 years of age in the Netherlands is already above the tolerable upper limit. One should know that Dutch children frequently consume products containing a large amount of retinol (such as leverpostej, a kind of French pâté). Some sources therefore suggest there is no more room left for retinol intake from nutritional supplements. Children of 4 years and over and all other age groups still have, despite their high retinol intake from food, enough room for supplements. As has been discussed, the tolerable upper limit of vitamin A is not implicated in cirrhosis of the liver.

 

Why is there no vitamin A in Multi Vital Forte Junior? Is this for safety reasons?

Our Multi Vital Forte Junior does not contain vitamin A. It does however contain betacarotene, which is converted into vitamin A in the body when needed. When there is enough vitamin A in the body, vitamin A levels do not rise and betacarotene is left unconverted. Two chewable tablets of Multi Vital Forte Junior offer 1 mg betacarotene, which in the body is converted into a maximum of 83 mcg vitamin A (as needed). This is approximately 21 percent of the RDA for Dutch children between 1-4 years of age. There is thus no need to worry about safety in this regard.

 

Are pregnant and breast feeding women at an increased risk of a vitamin A overdose?

Pregnant women who ingest too much retinol are at an elevated risk of causing developmental problems to their unborn child. Some conservative sources state the risk is already elevated at dosages as low as 3500 mcg.  There are, however, too many conflicting sources to adequately establish what is a safe amount of additional retinol from nutritional supplements in pregnant and breast feeding women. Based on the literature, we suggest dosages of up to 3300 mcg of vitamin A (approximately 4 times the RDA) are completely safe in fully healthy pregnant and breast feeding women.

 

Should my pregnant client avoid vitamin A altogether?

During pregnancy the body needs approximately three times as much vitamin A as usual. When your client tries to avoid any vitamin A, the risk of problems with their pregnancy increases, in particular the risk of a premature birth. It is therefore not advisable to stop intake of vitamine A altogether.

 

Why is there no vitamin A in Multi Natal Forte? Is this for safety reasons?

Indeed, Multi Natal Forte does not contain vitamin A as such, but two tablets do offer 5 mg of betacarotene, which in the body is converted (as needed) into a maximum of 415 mcg vitamin A. This is approximately 46 percent of the Dutch RDA for adults and children of ages 11 and up. There is thus no need to worry about safety in this regard.

 

Literatuur

Combs GF jr., The Vitamins: Fundamental Aspects in Nutrition and Health, Fourth Edition 2012, Academic Press. 

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