Vitamin A: the lesser talked about letter vitamin that you need to know
If you live on planet Earth, you’ve probably been told, “eat your carrots -- they’ll make you see in the dark”...and you may have even repeated this saying to your children. But does this saying hold any truth?
Unfortunately for those of us with superhero aspirations, eating your weight in carrots and other orange fruits and vegetables will not help your body to reach superhuman vision abilities, but it may lead to a condition called carotenemia. Carotenemia is the rare occurrence of orange coloring of their feet, hands and other areas of thicker skin on the body in people who eat too many carotenoid-containing foods regularly, and who may have a genetic variation in how they convert beta-carotene to vitamin A.1 Have no worries if you’re a carrot connoisseur - this condition is not dangerous.
Visions of orange-colored people aside, deficiency and sub-optimal levels of vitamin A is a real concern in the United States. In a survey of over 44,000 people living in the US, 43% of people were consuming inadequate amounts of vitamin A and not meeting the daily recommended intake levels.2
Vitamin A comes in multiple forms, each playing a different role in human health. In one form or another, vitamin A is important for normal vision, skin health, reproductive health, proper immune system function, fetal health, thyroid health, and many other functions.3 Get the details around for whom, when, and why vitamin A should be talked about more...
What is Vitamin A, and Why Should You Care?
Vitamin A is a generic term that refers to fat-soluble compounds found as preformed vitamin A in animal products and as provitamin A carotenoids in fruit and vegetables.
The three most active forms of vitamin A in the body are retinol, retinal, and retinoic acid, and the less active form is beta-carotene.4 Dietary supplements usually contain the active forms, retinyl acetate or retinyl palmitate (preformed vitamin A), beta-carotene (provitamin A), or a combination of preformed and provitamin A.
Vitamin A is crucial for many functions in the body, including vision. Deficiency of vitamin A is most common in children and women of childbearing age, and is the leading cause of preventable blindness in the world.5
While critically low levels of vitamin A are not common in developed countries, subclinically low levels are surprisingly common. Defined as serum retinol concentrations lower than 0.70 μmol/L or 20 μg/dL, subclinical vitamin A levels are often dismissed by traditionally trained doctors and healthcare providers because they are higher than the conventional lab ranges for deficiency.
Optimal vitamin A levels are important for:
- Healthy vision and eye development in developing fetuses and adults, including normal color vision, normal vision in dim lighting, and normal dark adaptation6
- Regulating the growth and differentiation of virtually every cell in the body, from embryos to adults (meaning, deciding which cells become which organs and body systems as the fetus develops)
- Healthy immune response to infectious diseases from fetal development through adulthood
- Normal red blood cell production, including integration of iron and oxygen-carrying capacity within those cells
- Normal iron levels in the blood
- Healthy thyroid function and thyroid stimulating hormone (TSH) levels
- Healthy skin cell turnover and healing
Vitamin A plays a massive role in the health and development of the human body, so it’s important to get clear on the who, what, where, and how of vitamin A and your body.
Provitamin A Does Not Equal Preformed Vitamin (and Why Animal-based Foods Matter)
We know the importance of vitamin A, but how does one ensure that we consume enough of the right kinds for optimal health?
The truth is, the most active forms of vitamin A are found in animal-based foods consumed from healthy animals, raised humanely, eating the foods that are ideal for them. This means that choosing the quality of your food really does matter.
Here are some of the top real foods for consuming the most active forms of vitamin A4:
- Beef liver
- Cod liver oil
- Pastured butter
- Pastured eggs (yolk, please!)
- Whole, organic milk
According to the US Institute for Medicine (IOM), dietary retinol (one of the preformed, “active” forms of vitamin A) is 12-24 times more active than dietary beta-carotene and alpha-carotene, and the bioavailability (availability to actually use the nutrient in the body) varies greatly from food to food, with food combinations, with amount of fat consumed with the meal, gut health environment, and effectiveness of the individual’s enzyme activity for doing the conversion (here’s looking at you, BCMO1 gene!)7.
While carotenoids like beta-carotene are not the most active form of vitamin A, they do convert to active vitamin A in the body in part, and are also utilized in the body for non-provitamin A jobs, like as potent antioxidants.
Here’s a list of plant-based foods that are rich in carotenoids, which convert in varying amounts to the active forms of vitamin A8:
- Sweet potatoes
- Mustard, collard, turnip, and beet greens
- Swiss chard
- Winter squash
How much vitamin A do you really need?
Vitamin A needs vary from person to person based on their genetics, gut health, health conditions, and stage of life. For the average person, vitamin A needs can be generalized based on sex, age and stage of life. Here we’ll take a look at womens’ needs4:
- Adults (19+ years): 700 μg/day (2,331 IU)
- Pregnant (19+ years): 770 μg/day (2,564 IU)
- Breastfeeding (19+ years): 1300 μg/day (4,330 IU)
To break these numbers down further, let’s clarify some often confusing labeling terminology and conversions. Each of the following is equivalent to 1 microgram (μg) of active vitamin A (retinol)4, with daily intake goals listed above:
- 1 μg supplemental vitamin A (retinyl acetate, or retinyl palmitate)
- 2 μg of supplemental β-carotene
- 3.33 IU of retinol
Units of measurement can be confusing when reading labels, and understanding how much active vitamin A you’re consuming is important. One such conversion is getting micrograms converted into a standardized unit that measures the activity level. Retinol activity equivalents are used to measure the vitamin A activity of the type of pre- or pro- vitamin A consumed, and 1 IU of retinol is equivalent to 0.3 μg retinol activity equivalents (RAE).
Harking back to the fact that animal- or supplement-based vitamin A in the form of retinoids are more reliable for absorption, their RAE ratio is 1:1 for what goes in and what can be used when the gut is healthy.
Alternatively, beta-carotene in food has a RAE ratio of 24:1, and in supplements a RAE ratio of 12:1. This means that it takes 12-24 times as much vitamin A from beta-carotene to have the same activity in the body as active vitamin A consumed from animal-based foods.
What does this mean in real life?
If one large egg has 80 μg of preformed vitamin A (retinol), 270 IU (80 μg RAE) is readily used in the body. There is no need to worry about your genes and how well (or unwell) you convert to the active, usable form.
Alternatively, one-half of a baked sweet potato does not contain any ready-to-use retinol, but does have 11,091 beta-carotene (961 μg RAE). In the perfect genetic conversion world, all of this converted vitamin A is readily used in the body, but when you consider vitamin cofactors needed for conversion, genetics, and gut health/digestibility, it’s understood that real life versus theory doesn’t always play out calculated.
Facts versus Fears
They’re out there and they’re everywhere - fear-based statements that are meant to scare the minority of folks into not “overdoing it” with vitamin A.
We have to look at the facts, though. When it comes to supplementing with vitamin A, one common fear is that supplementing with vitamin A is unsafe, especially when planning to conceive or while pregnant/breastfeeding.
The truth is, many women are living, becoming pregnant, and breastfeeding while deficient in vitamin A. This is not optimal for mom or baby’s health. As mentioned earlier, 43% of people are consuming inadequate amounts of vitamin A and not meeting the daily recommended intake levels.2 In fact, a recent study showed that vitamin A plays an important role in healthy embryo development and fertilization.9
In addition to genetic factors affecting conversion of provitamin A to preformed vitamin A, many women live with and experience conditions that reduce absorption or usability of vitamin A, including digestive conditions (Crohn’s, ulcerative colitis, irritable bowel syndrome, diarrhea, etc), thyroid issues, gallbladder issues, fat malabsorption, and more. These women may have higher needs than what the Recommended Daily Values assert.
How to Backstop Your Best Efforts
Nothing can replace a healthy diet, but even our best efforts may not get us all the way to our goals with modern day stressors, chemicals in our environment, and depleted soil.
Supplementing with active vitamin A in safe amounts can be a great way to fill nutrient gaps, improve health, and ensure adequate usability in the body.
If you’re looking to improve your health, prepare for pregnancy, or deliver adequate nutrition to your breastfeeding babe, assess your diet and lifestyle, and speak to a professional who specializes in nutrition, supplements, and women’s health.
Full Circle Prenatal multivitamin is an expert-formulated and recommended supplement including 750 μg (2,500 IU) of vitamin A as active retinyl palmitate. No need to worry about genetic factors, food combining, or other nuances to supplementing your diet to achieve adequate vitamin A stores.
- Al Nasser Y, et al. Carotenemia. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan. 2020 Aug 23.
- Fulgoni VL, et al. Foods, fortificants and supplements: Where do Americans get their nutrients? J. Nutr. 2011, 141, 1847–1854.
- "Vitamin A." National Institutes of Health, Office of Dietary Supplements. 14 Feb. 2020. Web. 10 Nov. 2020. <https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/>.
- Higdon, Jane. Vitamin A. Edited by Libo Tan, 1 Jan. 2020, lpi.oregonstate.edu/mic/vitamins/vitamin-A.
- Underwood BA, Arthur P. The contribution of vitamin A to public health. Faseb J. 1996;10(9):1040-1048.
- Sherwin JC, et al. Epidemiology of vitamin A deficiency and xerophthalmia in at-risk populations. Trans R Soc Trop Med Hyg. 2012;106(4):205-214.
- Weber D, Grune T. The contribution of β-carotene to vitamin A supply of humans. Mol Nutr Food Res. 2012 Feb;56(2):251-8. doi: 10.1002/mnfr.201100230. Epub 2011 Sep 29. PMID: 21957049.
- Vitamin A. www.whfoods.com/genpage.php?tname=nutrient&dbid=106. Accessed 23 Nov 2020.
- Skowrońska P, et al. Follicular fat-soluble vitamins as markers of oocyte competency. Syst Biol Reprod Med. 2020 Apr;66(2):112-121. doi: 10.1080/19396368.2020.1718244. Epub 2020 Feb 14.