Vitamin A and the Beta-Carotene Myth: “A” is for Athletics, Aging and Advanced Health

By April 29, 2015 January 30th, 2017 Exercise, Nutrition

Vitamin A was first discovered in butterfat and cod liver oil in 1913. While these two foods are still great sources of this vital nutrient, fruits and vegetables don’t have any of it. Many are surprised by this, and one reason millions of people don’t get enough vitamin A. The result is reduced human performance, poor aging and potential problems in virtually all areas of the body.

There are three key reasons why so many people don’t get enough vitamin A.

First, vitamin A is only found in animal foods. It’s a myth that plant foods are high in this nutrient. Instead, fruits and vegetables are high in a family of phytonutrients called carotenoids. The body must convert three of these compounds—beta-carotene, alpha-carotene, and beta-cryptoxanthin—to vitamin A. But in humans, this conversion is quite inefficient, with about 10 to 20 molecules of carotenoids needed to make one of vitamin A. In addition, 80 percent or more of natural vitamin A from animal sources is absorbed, but only three percent or less of carotenoids from plant foods are absorbed.

Second is that there are a number of genetic variants, polymorphisms similar to those described for folates in the article, “The Folate Plot,” which can significantly impair the body’s ability to convert the carotenoids to vitamin A. This genetic problem may exist in up to half of the population. Its presence appears to be associated with high blood levels of beta-carotene, alpha-carotene, beta-cryptoxanthin, and low levels of lycopene, lutein and zeaxanthin—three other carotenoids important for health but don’t convert to vitamin A.

Third, in healthy individuals, vitamin A is continuously being used for many functions throughout the body as noted below. Most vitamin A is stored in the liver, and about five percent of it is used up each day, which must be replaced by sufficient dietary sources.

Because of these three important factors, we must get our vitamin A from animal sources to avoid the risk of low levels. The best sources are meats, including liver, beef, chicken and turkey, dairy, especially cheese and butter, and egg yolks. It’s obvious this means finding healthy, organic or otherwise real foods. Likewise, dietary supplements of cod liver oil are the best.

Vitamin A is not a single nutrient but actually a group of compounds called retinoids, of which many forms exist in nature and in the body. Each form of vitamin A performs functions the others cannot. For example, retinol is the major transport and storage form of vitamin A; retinal is essential for vision, and retinoic acid has hormone actions and regulates more than 500 genes.

In addition to the poor conversion of carotenoids to vitamin A, two important factors are also necessary for the body to obtain this vitamin from plant sources. Good gut function, especially stomach, gall bladder, liver and small intestines, is necessary for optimal absorption. While vitamin A is found in foods containing fat, the carotenoids are often not, making the addition of fat in the meal important for their absorption. Conversion of carotenoids takes place in the small intestines (with some in liver and kidney), first to the retinol form of vitamin A. This process requires other nutrients including riboflavin, niacin, iron, zinc, and adequate dietary protein.

Labeling laws continue to allow the myth that beta-carotene is the same as vitamin A. Read any label on a plant-based product and it lists the amount of vitamin A. Likewise for dietary supplements—most don’t have any vitamin A even when labeled as such (except for those containing synthetic A, the most common source used in both fortification and supplementation). What the label really refers to is the vitamin A equivalent under ideal circumstances. For example, to obtain 1 mcg (microgram) of vitamin A as retinol it takes 10 mcg of beta-carotene, and 20 mcg of alpha-carotene or beta-cryptoxanthin. However, for labeling purposes, dietary supplements can claim that, to obtain 1 mcg of vitamin A, 2 mcg of beta-carotene is required—the assumption is that the pill will be taken on an empty stomach with no other food taken with or soon after it, and digestion and absorption will be ideal.

Signs and symptoms and risk factors of vitamin A insufficiency or deficiency are many. Below are 20 common ones. How many do you have?

1. Increased sun exposure
2. Reduced immunity
3. Recurrent infections, especially viral and fungal
4. Chronic intestinal problems
5. Liver dysfunction
6. Poor night vision
7. Female of childbearing age
8. Low fat diet
9. Vegetarian diet
10. Macular degeneration
11. Dry skin
12. Dry hair
13. Dry mucous membranes
14. Weak or ridged fingernails
15. Chronic inflammation
16. Allergies or asthma
17. Weak bones or teeth
18. Difficulty maintaining vitamin D levels
19. Excess body fat
20. History of cancer

In addition to acne, psoriasis and a few conditions, much of the research around vitamin A is related to cancer. Studies show that eating foods rich in vitamin A, not carotenoids, is linked to a lower risk of cancer, while others demonstrate vitamin A can also prevent normal cells from becoming cancer. Others show this nutrient can slow tumor growth, shrink tumors, and make some cancer treatments work better.

The relationship between better brain function and vitamin A is also very important, with many clinicians using this nutrient in adults and children with a wide range of neurological deficits, including those with learning and memory problems.

The recommended daily allowance (RDA) of vitamin A is between 2,310 IU (0.7 milligrams) per day for adult women (more for women who are pregnant or breastfeeding), and 3,000 IU (0.9 milligrams) per day for men, with children needing less. (Vitamin A is still listed on food and supplement labels in international units—IUs—even though scientists rarely use this measure.)

Blood tests for vitamin A as retinol, and even for carotenoid levels, are typically measured in a simple blood test. However, the value of blood tests for assessing true vitamin A status is limited because this nutrient does not decline in the blood until vitamin A levels in the liver are almost depleted.

The best source of vitamin A is cod liver oil. But if you’re taking a high dose of vitamin D due to very low levels (such as 5-10,000 IUs or more) take your dose of A in the morning and D in the evening (or the other way around) as vitamin D can reduce the absorption of vitamin A.

Low intakes of carotenoids are associated with poor health, in particular, chronic disease and disability, so continue eating your ten servings of fruits and vegetables—studies show consuming them is protective against the decline in physical performance, and overall mortality. But think of the carotenoids and vitamin A as two separate groups of nutrients. And don’t rely on beta-carotene or other phytonutrients to provide adequate vitamin A levels. Get this from animal foods, or supplements made from such, including cod liver oil.


  • Annette says:

    Excellent article! Thank you for clearing many things up for me. I can see how important it is not to count on vegetable sources only for vit A. I’m going to make small changes and turn to Cod liver oil since you benefit from both A and D. Although I love my raw eggs in my smoothies and I supplement with a good quality fish oil, I now will switch my standard fish oil to a good quality Cod liver oil.

    Thanks very much!

  • Paul says:

    This is totally incorrect Dale. B12 most definitely IS found in the soil. Bacteria in the soil produce it and it is deposited on plants.
    I am not vegan by the way but I am a physiologist and nutritionist and have been studying evolutionary nutrition for over 25 years now.

  • james says:

    interesting subject. i was wondering what percentage of vitamin A stores are affected by daily alcohol use

  • Dale says:

    Also i want to add that your body can store around 2 years worth of vitamin A in your liver, so if you go vegan symptoms of vitamin A deficiency may take years to show up.

  • Dale says:

    Many comments from people that can’t understand that almost half the population can’t get vitamin A from plants, it’s impossible. I wonder how they test for vitamin A, if they assume beta-carotene in the blood is vitamin A like they do for food labels of plants then many people who show a healthy level of vitamin A on blood test can actually be deficient. It’s like some people are mentally disabled, since they can’t understand these things. Also, some vegans will say people used to get their b12 from the soil and the water, this is false. What is found in the soil and the water is cobalt, this is then converted into b12 by herbivores… humans can’t really make this conversion. The vegans are right about some things though. Factory farming is terrible for the animals and for us and paesturized milk does cause problems that raw milk doesn’t. Commercial agrigulture for growing crops is bad to and it’s negatively impacting our soil. Raising animals on pasture and letting them eat their natural diet would be good for the environment, the top soil and would be good for us as well when we eat these nutritious animal foods rather than the unhealthy factory farmed animal food. Another problem with beta-carotene and other nutritents from plant sources is you only absorb a small fraction of the nutrition, where with animal food you abosorb the vast majority of the nutrition. There’s other problems too i won’t get into.

  • David Sander says:

    About 18 months ago I had an old skin scrape that was not healing completely after twelve months and was still pink. In looking for a solution in improved skin health I came across retinol vitamin A in references. I’m over sixty and still run regularly but at the time could not run more than two miles without also getting a lot of lower back muscle soreness. Despite my love of carrots, I still turned out to be low in vitamin A!

    After reading a number of research and athletics sources, I started on 8000 IU of retinol from cod liver oil pills. This slowly resulted in the improvement of my scraped knee, but in two to three weeks it also resulted in improved strength and reduced muscle soreness in my lower back. Thrilled at the result, I gradually increased the cod liver oil until the muscle soreness was minimized. I now take 25,000 to 30,000 IU daily which seems optimal. I had regular episodes of light tiredness or low motivation from going to 40,000 IU and pulled back after noting the improvement of skipping a day on this condition. I’ve been rewarded with a much stronger immune system and a 75% reduction in colds and viruses.

    I also take 10,000 IU of vitamin D3. Taking vitamin D3 is important to balancing the intake of retinol as the body uses vitamins A and D3 together in some reaction chains as noted in reports by Dr Chris Masterjohn. There is some research that notes this need for balance, usually in the improvement in overdose symptoms of one vitamin by taking its opposing vitamin. Research shows that improvements of the immune system are also maximized by taking both vitamins, while taking vitamin D or A alone is much less effective.

  • Daniel says:

    I tested my Vitamin A levels for the first time and my number was 58 mcg/dL. The reference interval is 24-85 mcg/dL. And I eat zero animal products and have never eaten organ meats or butter my whole life, so all of that 58 mcg is from beta carotene conversion. That is not even close to deficient.

    • That’s fantastic! It means that you have a very varied, well-balanced vegetarian diet.

      • mik says:

        You don’t need a “balanced diet” to do that. My single morning smoothie of 300gr. kale, 4 bananas, 200 gr. berries has about 54000 UI from the kale alone. And that’s just to start the day off. Anyone can do that. Vit. A is not a problem for most of the human population and the Genetic disorder might be fixed with a vater faste and a book or 2 about epigenetics?

        • mik says:

          And just to add:
          Linking to valid sources / studies for claims made in posts etc. shows scientific integrity and should be done here as well.

        • Hello mik,

          Thanks for your continued comments. The takeaway from our article is simple: it is phenomenally easier in terms of meeting your vitamin A requirements to skip a step and take in vitamin A instead of a precursor that is poorly converted on the best of times. (Within the scope of nutrition, we believe that when you can not only meet your nutritional requirements with fewer steps or intermediaries, but the fewer steps allow you to additionally meet your requirements with less food volume, that is phenomenally better than the alternative).

          And because many individuals don’t know whether they are of that chunk of the population who can’t convert vitamin A (many of which aren’t in a position to take blood tests), we believe that the prudent course of action is to be safe instead of sorry—or at the very least, for us to make it abundantly clear that for many individuals, any amount of beta-carotene will not satisfy their vitamin A requirements.

        • valerie says:

          If you are consuming dairy, and that much kale or spinach, etc. every day, it is good to know that many leafy greens contain high amounts of calcium (more calcium than magnesium) and also oxalates which can end up causing kidney stones, calcification of soft tissues, atherosclerosis, bone spurs, arthritis, etc. Multivitamin supplements are also usually higher in calcium. If you, by chance, also take hormone D supplements, those cause more calcium to be absorbed from the intestines into the blood, at the expense of magnesium. Test your serum, ionized calcium level and your magnesium RBC level. Magnesium is needed to properly metabolize calcium, but calcium lowers the absorption of magnesium. Kidney stones are not fun.

    • Genetic testing for vegetarians 23andme raw data says:

      Levels in the blood do not decline until liver stores are almost completely depleted. About half of Americans have genetics that impair plant beta carotene conversion to retinol, these rates can be reduced by 37% or 69%. Rates of beta carotene absorption in plants is very low at about 3%. I implore any vegetarian to get their 23andme done and check raw data through multiple snp analyzers.

  • Ryan Daley says:

    After some genetic testing it was discovered that I do not convert Vitamin A from beta carotene… this has required me to supplement consciously with preformed vitamin through diet and a supplement (very hard to find actual vitamin A and not beta carotene)… with that said nearly every multi vitamin or other supplements are loaded with beta carotene which will do nothing for me… but my question is what happens to the unconverted beta carotene – should I at all be concerned with getting too much of something that will not convert?

  • mike says:

    “One small raw carrot contains 8,353 international units of vitamin A, which includes 4,142 micrograms of beta-carotene. Daily intake guidelines have not been established for beta-carotene, but you’ll get 278 percent of your recommended daily intake of vitamin A. Carrots are one of the best sources of beta-carotene. One cup of carrot juice has more beta-carotene than a cup of any other food. One baked sweet potato and 1 cup of canned pumpkin and cooked spinach are the only foods that supply more beta-carotene than 1 cup of cooked carrots.”

    would it be safe to assume we could leave animals alone if we simply eat 2 carrots a day?

    • Nope. There are other reasons to eat animals than beta carotene. Many fat soluble vitamins and enzymes are only found in force in animal foods.

      One of the most important reasons, (which is the reason we are omnivores in the first place) is that eating animal flesh offers the guarantee that you will have all the aminoacids necessary to build complete proteins. While it’s entirely possible to find all these aminoacids in plants, very few plants (in very few biomes) offer the same guarantee.

      Similarly, very few plants in very few biomes offer other critical vitamins, such as b12. b12 and a few other vitamins are actually the most solid proof that we are omnivores and not herbivores: (a) ancient humans by and large lived in biomes where b12 was not naturally occurring in plants, and (b) protein synthesis in humans cannot occur in the absence of b12.

      While it is entirely possible to eat an animal free diet and be fully healthy, it requires a phenomenal degree of nutritional knowledge and logistical sophistication, such as a globalized food transport network, to maintain health outside of selected biomes with specific soils. In other words, unless you live in specific places in Asia (because of the soil and its bacteria), the completely healthy, local vegan diet does not exist.

      (You can still take that soil to other places, and the same bacteria would be able to live in some of them, but then it becomes a game of access and affluence: the healthiness of vegan diet would covary strongly with the degree of access to those soils).

      In contrast, the nutritional knowledge and logistical sophistication necessary to remain fully healthy while eating a predominantly plant-based diet occasionally supplemented with animal protein (think a 5:1 or 10:1 ratio) pales in comparison.

      • Anon says:

        One molecule of β-carotene can be split by the intestinal enzyme β,β-carotene 15,15′-monooxygenase into two molecules of vitamin A, this means beta- carotene alone is enough to make Vitamin A.

        Source, Biesalski HK, Chichili GR, Frank J, von Lintig J, Nohr D (2007). “Conversion of β-carotene to retinal pigment”. Vitamins and hormones. Vitamins & Hormones. 75: 117–30. ISBN 978-0-12-709875-3. PMID 17368314. doi:10.1016/S0083-6729(06)75005-1.

        “Labeling laws continue to allow the” *”myth that beta-carotene is the same as vitamin A.”, Dr. Phil Maffetone

        “Many fat soluble vitamins and enzymes are only found in” *”force in animal foods.”, “Ivan Rivera”

        The author & your choice of words clearly shows you’re both trying to mislead people.

        • Anon:

          Thanks for your comment.

          Note that one of the main topics of the article is a genetic polymorphism that causes people to not have the very enzyme that splits beta carotene into Vitamin A. In fact, a large chunk of the population with Vitamin A deficiency are deficient precisely because they have the polymorphism, which disallows them to get their vitamin A by converting beta carotene (because they can’t). For this significant chunk of individuals, eating plants with beta carotene (or taking beta carotene supplements) does not solve their Vitamin A deficiency problems. This is, to say the least, unfortunate, as they were ostensibly taking beta carotene supplements (or eating plants rich in the compound) specifically to mitigate their Vitamin A deficiency.

          In light of this, I’m surprised at the source you decided to quote, as it does not address this very issue. Can you explain?

        • sheep says:

          Excellent article! MAF editors, can someone please send me a few links to some studies for this? I love this information and I want to spread it. Thank you

  • Um, yes you can get vitamin A from plants! Don’t know where you’re getting your info!!

    • Kristine:

      Indeed you can! But animal sources are a better guarantee that you’ll get enough, due to the overabundance of Vitamin A in them.

    • Sandi says:

      Some of us can’t convert beta carotene into vitamin A, which is plant sources. I have Hashimoto’s and need to get my vitamin A from egg yolks, liver and ghee butter. It still wasn’t enough so I just started taking only one 10,000 iu of vitamin A once a week. Vision is getting better, joint pain is going away, sinuses are clearing as well as years of tinnitus and clogged ears. I’m feeling so much better now. It’s a shame I didn’t realize I couldn’t convert from fruits and veggies years ago. I’m almost 60 years old now and finally feel healthier again!!!

    • Annette says:

      You should “read” the article! LOL!!!!
      They didn’t say you can’t get it from plants, they stated that it is not “efficient” One has to convert 3 compounds to achieve vitamin A and STILL receive VERY low amounts. Where animal sources is 80 %

  • steve seguin says:

    So we absolutely need animal flesh to get vitamin A?! I think you need to refine your research before saying false claim and misleading people. First of all, humans where not meant to eat animals. If you look at the latest nutritional science (loot at animal products cause inflamation in our body. I mean the first humans were vegetarian and meat became food for survival. We did not evolve to eat meat, without tools and cooking we couldnt eat meat so seriously!!! Monsanto tried to create the “Golden Rice” fortified with vitamine A for African people which are highly defficient in Vit A but that did not work…..what did was sweet potatoes!!!! TWO sweet potatoes a day was all that was needed to prevent vit A defieciency!!! Carnivores get their vit A from eating vegetarians which get their vit A where!?!?Plants!!!!!

    • Steve:

      Thanks for your comment.

      The implication of the article is not that we can’t get Vitamin A from plant sources, but rather that getting them from animal sources helps us avoid the risk of low levels. Since animal products have much more (and much more bioavailable) vitamin A, you need comparably much less to avoid deficiency.

    • Annette says:

      Oh Steve, why say such statements that humans are not meant to eat meat. Fish, chicken, “some” red meat is NOT going to be detrimental to your body. Sure one can survive off of plants and fats (ALA) etc… but we NEED animal fats too, just in moderation, lean, grass fed (organic) 🙂 Don’t have a COW man.

  • Liv-Kristin Eriksen says:

    This is the worst drivel I’ve had the misfortune of reading in a looooong time. It you have excess body fat or are a woman of childbearing age…. that’s a BIG percentage of the population. Well, at least I had a good laugh and was mildly entertained for a while. When you post claims such as this then also post links to research that prove the shit you’re writing.

    • Liv:

      That would include almost all of the population, at least in Western economies. In fact, when you look at a lot of these indicators, you’ll find that a majority of the population has 10 or 12 risk factors for health issues, meaning that what you pointed out (that X is an issue in a big percentage of the population) is often the rule, not the exception.

      Incidentally, these indicators are quite well-known. I imagine that Phil did not cite sources because they have been in the public domain for at least a decade.

    • Annette says:

      Well keep laughing, (at yourself) because when you have high levels of body fat it there where your fat soluble vitamins can be stored and NOT utilized. This is actually a very good article, don’t blame your misfortunes on other people. (or writers)

  • Jennifer says:

    Thank you for this discussion on Vitamine A. I am trying to find more studies regarding the body not converting beta carotene into Vitamine A therefore causing a buildup of beta carotene in the skin with subsequent yellowing of the palms and feet. Also I’ve heard Vit A deficiency can be associated with itchy skin and anemia and poorer night vision. These are all symptoms I have but have yet to find a MD to diagnose a problem and provide a treatment protocol. Any suggestions for testing or how to clear up this problem would be welcome! I love the podcast and follow the Maff nutrition and exercise protocols. They have been game changers for me.

    • Yolene says:

      Dear Jennifer – I am not associated with this site nor am I a doctor – I do however have a severe Vitamin A deficiency. This was found by my gastroenterologist after I had been suffering with stomach problems for three years. He took a blood draw and the results were in a week later. He practically fell off his chair when he saw the results and said that it is extremely rare for anyone in Europe to have this level of deficiency. He gave me high dose supplements. But after I stopped taking these the problem returned. Recently I did a genetic test (actually it was to trace my family line but a health report came with it) .. and it turns out that I have the genetic variants which mean I cannot easily convert carotenoids to vitamin A … and since i am also genetically lactose intolerant and have an allergy to eggs (I was also a vegetarian for ten years) … I had completely depleted my stores. I am practically night blind, have extremely dry skin and hair, have anemia and all sort of problems. But the fix is actually very simple .. I now eat liver once or twice a week .. and it is as if I’ve been reborn — my night vision is mostly back and i feel ten years younger. I still have dry skin and hair but hope this will clear up eventually too. I do not have yellow palms and feet, nor do I have itchy skin (could that all be liver related?). So far I no longer need to supplement. Hope this helps!

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