Why it’s important, and why we shouldn’t be scaring pregnant women into avoiding it.
Vitamin A is required for healthy gene expression, and is a vital part of embryonic development of spinal cord, vertebrae, ears, eyes, kidneys, lungs and heart. It’s required for healthy immune system function. It’s a vital nutrient for women who are trying to conceive, and for women throughout their pregnancy. But – we scare them away from it.
A safe upper limit for vitamin A (retinol) as set by the Australian government is 3000ug/day. But – many supplements will list retinyl palmitate or retinyl acetate in IU rather than ug – which makes things confusing. So to convert:
1000 IU retinyl palmitate = 549ug
1000 IU retinyl acetate = 345ug
So a safe upper limit would be: 5464IU of retinyl palmitate, or 8695IU of retinyl acetate.
An example of a product that we use in our clinic is Metagenics Thyrobalance. It contains 240ug retinyl palmitate per tablet, which is 436IU vitamin A per tablet. The usual dose we give to women is 4 tablets per day. This gives them 960ug per day of retinyl palmitate of vitamin A which is well within the safe upper limit of 3000ug/day.
However, the TGA sets a labelling requirement for any product containing selenium, all products must list a warning:
“When taken in excess of 3000 μg retinol equivalents, vitamin A can cause birth defects. If you are pregnant, or considering becoming pregnant, do not take vitamin A supplements without consulting your doctor or pharmacist. The recommended daily amount of vitamin A from all sources is 700 μg retinol equivalents for women 900 μg retinol equivalents for men.”
Because vitamin A quantities in this tablet are quoted using 3 different measurements: IU, ug and RE, this confuses women (and practitioners too). It’s also not clear at all from the label what the retinol equivalents are, and that taking 4 tablets per day gives a person 524 ug retinol equivalents – which is within the guidelines stated on the label. The product contains safe levels if taken within the guidelines of 1-4 tablets per day, so a pregnant woman is going to be safely within the limit of getting a therapeutic dose whilst still being away from the toxic upper limit. But the label can leave people feeling very concerned and worried.
And very confused! We get heaps of concerned patients checking with us if they should be taking their Thyrobalance during pregnancy – because it says on the label it can cause birth defects. However by explaining the very convoluted calculations above, and knowing how to properly interpret the information on the label you will assure a woman that she can safely take the product without risking birth defects.
Given the benefits of vitamin A in supporting normal embryological and fetal development, and in supporting the immune system, and thyroid function – it’s usually a really good idea for women to continue to take a vitamin A supplement during their pregnancy if they needed it in order to conceive.
Food sources of vitamin A include butter, ghee and liver. Many thyroid supportive supplements also contain vitamin A as retinyl palmitate (as opposed to beta-carotene). The majority of adverse events associated with vitamin A and teratogenicity are related to synthetic pharmaceutical or supplement related intake in a large dose, rather than with intake from food.
Zinc deficiency can decrease the body’s ability to make use of vitamin A, (and can increase the likelihood of a negative reaction) so always watch out for this.
Promoted as a “safer” option is beta-carotene, which is converted into vitamin A in the liver via a range of processes. A defect in one aspect of the BCO1 gene can impair a person’s ability to convert beta-carotene into retinol – meaning it’s difficult for people to obtain vitamin A from plant based sources like carrots, pumpkin and other carotenoid containing foods. So for these people, taking beta-carotene can land them in an unhelpful scenario where they have a lot of carotenoids in their body but not ability to convert into vitamin A. Excess carotenoids can lead to yellowing of the skin.
Vegans in particular need to watch out for their vitamin A status – it’s not a given that beta-carotene will convert into vitamin A, so any problems with immunity, reproduction, skin etc are worth investigating as a possible vitamin A metabolism issue (this can be genetic as explained above with BCO1 gene mutations). As a separate but related issue, vegans are more vulnerable to zinc deficiency due to the relative dietary ratio of copper to zinc in plant based foods, this can also magnify any vitamin A deficiency. Worth investigating and ruling out if the signs and symptoms suggest it.