How Well Do YOU ConvertBeta-Carotene to Vitamin A-Everyone knows that carrots and sweet potatoes are great sources of vitamin A, right?

Well…  it turns out it isn’t that straightforward for everyone. The beta-carotene in orange fruits and vegetables has to be converted into the form of vitamin A that our bodies can use, and genetics plays a huge role in how well we do that conversion.

Almost half of us have variants in our BCMO1 gene which cause a 30% to 70% decrease in the amount of vitamin A that we get from beta-carotene.

Background information on Vitamin A:
Vitamin A is a general term that covers several different forms of the vitamin. Animal food sources mainly provide retinyl palmitate, which is broken down in the intestines to retinol. In this form, it is stored by the body and then converted to an active form for use.

The plant forms of vitamin A are called carotenes, such as beta-carotene which is found in abundance in carrots and other orange-colored foods. Beta-carotene is broken down by an enzyme in the intestines to also form retinol. Interestingly, most carnivores are poor converters of beta-carotene, and cats cannot create any vitamin A from beta-carotene.[source]

About 80-90% of the retinoids in the body are stored in the liver and used to maintain a steady level in the blood.[study] The body then used the retinoids in a variety of ways including in stem cells, photoreceptors in the eye, epithelial cells, embryonic cells, various immune cells, red blood cells, and much more.


Genetics of Beta-carotene Conversion:
Beta-carotene is converted by the enzyme β-carotene 15,15′-monooxygenase (BCMO1 gene) into retinol. It is then used by the body in the same way as preformed vitamin A from animal products is used or stored.

There are two gene variations in the BCMO1 gene that help determine a person’s ability to convert beta-carotene into the retinol a body uses. A study in 2008 shows that the SNP’s rs12934922 and rs7501331 control a person’s conversion rate of beta-carotene into retinol. People with a T allele on both rs12934922 and rs7501331 have a 69% decreased conversion of beta-carotene to retinol.  For people with only a single T in the rs7501331 SNP, the conversion is decreased by 32%.

Check your 23andMe results for rs7501331 (v.4 and v.5):
CC: normal
CT: decreased beta-carotene conversion
TT: decreased beta-carotene conversion
Check your 23andMe results for rs12934922 (v.4 and v.5):
AA: normal
AT: decreased beta-carotene conversion
TT: decreased beta-carotene conversion

Three other variants that are found near the BCMO1 gene have also been shown in a small study to affect the rate of conversion by about 50%

  • rs11645428 – GG has lower beta-carotene conversion
  • rs6420424 – AA has lower beta-carotene conversion
  • rs6564851 – GG has lower beta-carotene conversion

Lifehacks

If you are a vegan or vegetarian, your main source of Vitamin A is probably beta-carotene. If you don’t process it into retinol very well, you may want to increase your vegetables that are high in beta-carotene or supplement with a retinol form Vitamin A.

If you are supplementing with Vitamin A, check and see if your supplement is in the form of beta-carotene or retinol palmitate. If you have a decreased ability to convert beta-carotene to retinol, you may be getting less vitamin A than you think.

A word of caution: Vitamin A is a fat-soluble vitamin that can build up in the body, so you don’t want to go overboard with it. The upper daily recommended limit of vitamin A is 3000 μg/day (3 mg/day). Most supplements list the amount of vitamin A in IU (international units). One IU is equivalent to 0.3 μg (.0003 mg) for vitamin A. So 8000 IU would equal 2.4 mg retinol.

So how much beta-carotene is in carrot juice? According to the Nutridesk website, one cup of carrot juice contains 22mg of beta-carotene. That site also claims that for an average person, 1/12th of that beta-carotene is converted into retinol thus giving 1.8 mg of retinol per cup of carrot juice. If you are a poor converter of beta-carotene, you could be getting more like 0.5mg from a cup of pure carrot juice.

Carlson’s Vitamin A on Amazon.com is a good source of the retinol form of vitamin A. There are other good brands as well — just be sure to read the labels to know what you are getting.

Beef liver is also an excellent source of vitamin A. A three-ounce serving of liver packs a big punch with about 15,000 IU of vitamin A.

Vitamin D: There are a few studies that show that too much vitamin A without enough vitamin D can be a risk factor for osteoporosis.[ref]  So be sure to get out in the sunshine for vitamin D, and if you are getting your vitamin A levels checked, you may want to also get vitamin D tested at the same time.

Why is vitamin A so darn important?
A deficiency in vitamin A can cause night blindness, worsen infectious diseases, and, when severe, cause blindness. It is used by the body in a variety of different ways. In the immune system, it is involved with both the innate and adaptive immune responses.[study] Vitamin A can also help with skin problems such as some types of acne and hyperkeratosis.[study]

More to Read on Vitamin A:

Other posts you might enjoy:

 


14 Comments

Hazel Amber · March 19, 2018 at 10:11 pm

Can a person be overly efficient at converting carotenes to retinol and so risk vitamin A sub-toxicity by eating a diet very high in carotenes?

    Debbie Moon · March 20, 2018 at 1:03 am

    Good question :-) I don’t know of any genetic variants that cause extremely high rates of conversion. According to the Linus Pauling Institute at Univ. of Oregon, there is no worry of toxicity from eating sources of beta-carotene: http://lpi.oregonstate.edu/mic/vitamins/vitamin-A#toxicity I think the worst you will have from a diet that is very high in carotenes is turning orange – called hypercarotenosis.

Amber · May 23, 2018 at 4:59 pm

Question: I have a TT and a CT on the above, so I have a decreased beta-carotine conversion. My question though is about topical retinol/retin-A. Do these genetic markers affect the way the body absorbs vitamin-a topically? I am asking because the several times I was prescribed tretinoin or retin-a micro, I had an adverse reaction. I stuck through the so called purging and dry/red/flaky period of about 4-6 months but my skin only continued to get worse until I had to stop. The doctor had no explanation for me and basically said everyone takes well to these topicals. I guess I’m an anomaly. Just wondering if these alleles have something to do with this.

    Debbie Moon · May 25, 2018 at 10:41 am

    Hi Amber,
    I don’t think that the decreased beta-carotene conversion would affect topical retin-A. My guess would be that you are somewhat allergic to something in the topical creme?
    I’ve read that you can open up the liquid vitamin A gel caps and put them directly on your skin. That may be a way to see if it is the vitamin A that is irritating your skin vs something else in the cream. You might want to try it on a weekend though –the vitamin A gel cap that I tried on my skin smelled a bit like fish and the odor lingered…
    Have you tried taking a true vitamin A internally? Personally, I had keratosis pilaris (little bumps) on the back of my arms and on my thighs since childhood and didn’t know what caused it. When I found out that I didn’t convert beta-carotene very well, I started taking vitamin A. After a month or so, I noticed that my arms were smooth, but I didn’t really make the connection to the vitamin A until I stopped taking it and the bumps came back. That was a few years ago, and I now kind of use the smoothness of my arms as a way to know if I’m getting enough vitamin A. Like the rest of the fat-soluble vitamins, I don’t want to go overboard on vitamin A.
    Good luck on getting it figured out!

    Teresa Hickey · October 9, 2018 at 4:16 pm

    Hi Amber,
    I also have CT on my BCM01. Are you supplementing Vitamin A? I’m having trouble understanding A. If I need to B. If I have the correct kind. I purchased Vitamin A Retinyl Palmitate 2400 mcg and was hoping to see if anyone knows if that is the correct from/dosage.

shallah · September 8, 2018 at 8:38 pm

are there other genes that make humans and cats need certain forms of vitamins due to poor conversion besides these and MTHFR? I’m asking because I noticed signifigant differences when when taking vitamin A instead of beta carotene supplement and an activated b-complex with methylfolate and methylcobalamin instead of basic folic acid and cyanocobalamin.

    Debbie Moon · September 11, 2018 at 11:29 pm

    Hi Shallah,
    Not sure about cat genes… :-)
    But yes, there are lots of genetic variants that affect our need for vitamins. Check out my articles on MTHFR, vitamin D, vitamin K, vitamin C, iron, and more. There is a whole category of articles on vitamins and minerals.
    Debbie

Teresa · September 9, 2018 at 1:17 am

I believe I am not converting beta carotene because my hands get orange when I eat too many carrots and butternut squash. I don’t have jaundice. Is there anything I can take, supplement wise, to help my liver convert. I am going through a major heavy metal detox and my liver is definitely overburdened due to the fact that I can’t tolerate a lot of liver supplements.

    Debbie Moon · September 11, 2018 at 11:27 pm

    Hi Teresa,
    Thanks for commenting on the Beta-carotene article. From what I’ve read on the topic, turning orange from too much carrot juice, etc is due to your body not breaking down the beta-carotene and storing it instead. I haven’t seen anything to indicate that it is harmful…
    I’m honestly not sure if there are any specific liver supplements that would help you convert more beta-carotene. Did you check your genes to see how well you should be converting beta-carotene?
    Debbie

Teresa Hickey · October 9, 2018 at 3:42 pm

Hi there. I am heterozygous CT on BCM01. Do I need to supplement with Vitamin A and if so, what is the best way to do that. I purchased a supplement that is Vitamin A as Retinyl Palmitate, 2,400 mcg. Is the correct form/dosage?

    Debbie Moon · October 11, 2018 at 6:26 pm

    Hi Teresa,
    As far as whether you need to supplement with Vitamin A… that would depend a lot on your diet. If you are eating liver or other high vitamin A foods, you may not need any more vitamin A. One way to know for sure if you need to supplement with vitamin A would be to get a blood test done.
    Retinyl Palmitate is the active form of vitamin A that should work well for someone who doesn’t convert beta-carotene very well. You might want to talk to your doctor or get a blood test done if you are uncertain about dosages.
    Debbie

BPA: Genetics and Detoxification | Genetic Lifehacks · February 6, 2017 at 12:38 pm

[…] and depending on beta carotene as your source of vitamin A, you may want to check and see if you convert beta carotene to retinol […]

Gör örttinkturer som naturläkemedel & för hudvård + förslag på växter – Mona Rosenberg · June 21, 2018 at 7:33 pm

[…] svårt för våra kroppar att omvandla betakaroten till A! Om A-vitamin/betakarotenmyten HÄR  HÄR. Det betyder alltså att vara observant när det står A-vitamin på ett […]

Make-It-Monday: Fall Is Here – Wild Radish Studio Blog · September 28, 2018 at 8:19 pm

[…] You’ve probably heard of beta carotene, which contributes to the orange/yellow color in many fruits and vegetables.  Pumpkins obviously have plenty! Once ingested, beta carotene gets converted to vitamin A. The other way we can get pre-formed vitamin A is through animal products (liver, fish, dairy products) because their bodies already did the conversion work for us.  This is important to know if, like me, you don’t eat meat very often, or if you are vegetarian or vegan.   Deficiency in this vitamin could impact our immune system, eyesight and our skin among other things.  It’s also noteworthy that not everyone converts beta carotene to vitamin A at the same efficiency.  You can read more about this here. […]

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