Why Vitamin A is Essential for Women Trying To Conceive
Although most known for its importance in vision, vitamin A is critical for reproduction where it helps to support cell growth and differentiation.
A healthy diet is an essential base when trying to conceive. But what exactly does that mean? The answer may be different for you than for your friend or family member.
Your genes make you unique – from hair color to blood type to the right diet for you. And genetics plays a big role in finding the best source of vitamin A for your body.
What is vitamin A?
Vitamin A is a group of fat-soluble substances called retinoids that include retinol, retinal, retinoic acid, and retinyl esters.
The form of vitamin A that your body uses is the retinol form and can only be obtained from eating animal products such as meat (especially liver), eggs, fish, and dairy products.
Beta-carotene is a precursor to vitamin A that is found in plant foods. Its orange pigment gives carrots, sweet potatoes, butternut squash, cantaloupe, and apricots their vibrant color. Your body must convert the carotenoids into the retinol form of vitamin A so that it can be used.
This is where genetics comes into play – some people are good at converting beta-carotene to retinol, but many people carry genetic variants that make the conversion more difficult.
What does vitamin A do in the body?
Your body uses retinol in quite a few different ways.
At a cellular level, retinol binds to receptors in the cell nucleus and controls gene expression. For example, in skin cells, retinoids binding to receptors control the production of keratin, one of the proteins that make up skin and hair. In the eyes, retinol is a part of your photoreceptors, the rods, that let you see in low light. Retinol is also important in the immune system, the inflammatory responses, and in the liver’s ability to detoxify foreign substances. (study)
Your sleep and circadian rhythm also depend on vitamin A. Your circadian rhythm, which plays a big role in sleep, depends on vitamin A for regulating several important circadian genes. Studies show that vitamin A deficiency can directly affect circadian rhythm. (study) (study)
Vitamin A and fertility
Vitamin A is also essential for the development of the oocyte and essential for the growth of the baby.
Just over 100 years ago, researchers discovered vitamin A, an essential nutrient. By the late 1920s, research showed that vitamin A is necessary in animals for fertility. Researchers continue to study the effects of vitamin A deficiency on reproduction.
In a nutshell: you need the right amount of vitamin A and at the right time for a successful pregnancy. Vitamin A deficiency can impact the quality of the egg, the ability of the egg to implant, and the ability of the embryo to develop. (study)
A lack of vitamin A can reduce luteinizing hormone, which is important in ovulation. (study)
An analysis of embryos from women undergoing IVF found that the higher quality embryos all had higher levels of all-trans retinoic acid. (study)
What are the symptoms of vitamin A deficiency?
Being low in vitamin A can cause night blindness, dry eyes, increased risk of infections, thyroid dysfunction, and keratosis pillaris (bumpy skin on the back of your arms and legs.
As an indication of how important vitamin A is...in developing countries, where children often face hunger and malnutrition, severe vitamin A deficiency often leads to blindness.
How much vitamin A do you need?
The US RDA for pregnant women is 750 μg of Retinol Activity Equivalents (RAE)/day.
The RDA is defined in Retinol Activity Equivalents because of the two different forms of vitamin A – retinol and carotenoids.
If you get your vitamin A from retinol (animal forms), that is the same as an RAE.
But if you get your vitamin A from beta-carotene, the estimated conversion is a 12:1 ratio of beta -carotene to retinol. Thus, the RDA is set so that it includes that conversion factor.
The recommended upper limit (US) per day is 3,000 μg RAE. In supplemental form, vitamin A is often listed on the label in IU (international units). 3,000 μg RAE is equal to 10,000 IU. (article)
What happens if you get too much vitamin A?
Vitamin A is a fat-soluble vitamin which is stored in the liver. If you take excess supplemental vitamin A, it is possible to get too much. Symptoms of too much vitamin A include nausea, headache, fatigue, dry skin, and swelling of the brain.
According to the Linus Pauling Institute at Oregon State University, the long term consumption of vitamin A at ten times the RDA may cause these symptoms.
While very rare, it is also possible to have vitamin A toxicity from eating too much vitamin A in foods. There are case reports of hypervitaminosis A from eating too much fish liver and from “long-term frequent ingestion of beef liver”. (study)(study)
While caution is warranted, most people don’t overeat fish liver or beef liver on a daily basis!
You may have read that women who are pregnant should avoid vitamin A. It is true that too much of the vitamin A derivative, retinoic acid, can cause birth defects. This was discovered when women who were taking Accutane (now known as isotretinoin) for acne were found to have a significantly increased rate of birth defects. Women who are prescribed isotretinoin in the US are now required to get a pregnancy test before using this prescription acne medication.
Goldilocks’ vitamin: just the right amount
Your body regulates the amount of retinol in circulation very tightly. You have specific enzymes involved in absorption, proteins that bind to retinols for transport, and ways to store excess vitamin A. (study)
The majority of people get their vitamin A from fortified dairy products, eggs, fruits, and veggies. People who don’t eat a lot of pasture-raised eggs, dairy, or liver tend to rely on getting enough vitamin A from beta-carotene sources. This is where genetics comes into play…
Genetics and Vitamin A:
An enzyme called BCMO1 converts beta-carotene into the retinol form of vitamin A that your body uses. Some people carry variants of this gene that causes a decrease in this enzyme, reducing conversion of beta-carotene to retinol. People who carry two or more variants can have a decrease of almost 70%!
If you have genetic data from a company such as 23andMe or AncestryDNA, you can check to see how well you convert beta-carotene to retinol.
Check your genetic data for rs7501331:
- C/C: normal
- C/T: decreased beta-carotene conversion
- T/T: decreased beta-carotene conversion
Check your genetic data for rs12934922:
- A/A: normal
- A/T: decreased beta-carotene conversion
- T/T: decreased beta-carotene conversion
If you carry the T allele in both of the rs numbers listed above, you could have a 69% decrease in conversion of beta-carotene to retinol.
Knowing how your genetic variants work can help you to tailor your diet to the right foods for your body. For people who don’t convert beta-carotene to retinol, relying on fruits and vegetable for their vitamin A can lead to lower levels.
If you are a poor converter of beta-carotene to retinol, adding foods such as liver, fermented cod liver oil, pasture-raised eggs, grass-fed butter, and fish to your diet can help to ensure that you are getting enough vitamin A.
Testing vitamin A
The best way to absolutely know your vitamin A (Retinol) status is to get a blood test. This is especially recommended if you are vegetarian or vegan.
You can ask your doctor to order it or you can order it yourself here.