Where do vegans get vitamin A? Vitamin A is generally easy to find, but there are some big health differences between animal sources and vegan sources.
Vitamin A is best known for its key role in eye health, vision, and fetal eye development.(1)
Less famously, vitamin A is involved in regulating the growth and differentiation of all cells in the body from conception into adulthood. Vitamin A also helps with cellular communication; it takes part in remodeling bone; and it helps maintain normal immune function by stimulating the production and activity of white blood cells.
Vitamin A deficiency in Western countries is most often limited to people with conditions that interfere with normal digestion. Adults and kids who eat a very limited diet because of poverty or self-restriction are also at risk.
Symptoms of vitamin A deficiency include reduced immune function, fatigue, infertility, irregular patches on the whites of the eyes, dry skin or hair, thyroid disorders, and blindness.
Retinoids vs. Carotenoids
Vitamin A is the name of a group of fat-soluble retinoids, including retinol, retinal, and retinyl esters.
The two main forms of vitamin A are called preformed vitamin A (retinol) and provitamin A carotenoids.
Your body converts both preformed vitamin A and provitamin A carotenoids into the active forms of vitamin A.
Active forms of vitamin A are:
- retinal
- retinoid acid
Preformed Vitamin A (Retinol)
Preformed vitamin A is found naturally in animal products and is also often found in fortified foods and vitamin supplements, though synthetic (vegan) forms are also available.
It’s called “preformed” because your body can use it directly and doesn’t need to be converted.
Preformed vitamin A is:
- retinol
- retinal esters
Provitamin A Carotenoids
Carotenoids are natural plant pigments that make certain foods the colors red, orange, and yellow. They’re only naturally found in plants and are totally vegan.
Your body can use certain types of these pigments to make vitamin A. These are called provitamin A carotenoids.
They’re called “provitamin” because your body uses them to make vitamin A as opposed to being able to use it directly, as with preformed vitamin A.
Provitamin A carotenoids are:
- alpha-carotene
- beta-carotene
- beta-cryptoxanthin
Not all carotenoids are able to be converted to vitamin A by your body. While other carotenoids can’t be used to synthesize vitamin A, they can still be used for other important functions in your body.
Other carotenoids (with no vitamin A activity) are:
- lycopene
- lutein
- zeaxanthin
Daily Recommendations
Nutritional recommendations for vitamin A and other nutrients are developed by the National Academy of Medicine (formerly the Institute of Medicine) to plan and assess the nutrient intakes of healthy people.
Recommendations for vitamin A are given as retinol activity equivalents (RAE) to account for the different absorption rates of preformed vitamin A (retinol) and provitamin A carotenoids.
1 mcg RAE equals:
- 1 mcg retinol
- 2 mcg supplemental beta-carotene
- 12 mcg dietary beta-carotene
- 24 mcg dietary alpha-carotene
- 24 mcg beta-cryptoxanthin
Recommended Daily Allowance (RDA) for Vitamin A:
| Age | Male | Female | Pregnancy | Lactation |
|---|---|---|---|---|
| 0–6 months* | 400 mcg RAE | 400 mcg RAE | ||
| 7–12 months* | 500 mcg RAE | 500 mcg RAE | ||
| 1–3 years | 300 mcg RAE | 300 mcg RAE | ||
| 4–8 years | 400 mcg RAE | 400 mcg RAE | ||
| 9–13 years | 600 mcg RAE | 600 mcg RAE | ||
| 14–18 years | 900 mcg RAE | 700 mcg RAE | 750 mcg RAE | 1,200 mcg RAE |
| 19–50 years | 900 mcg RAE | 700 mcg RAE | 770 mcg RAE | 1,300 mcg RAE |
| 51+ years | 900 mcg RAE | 700 mcg RAE |
Recommended Dietary Allowance (RDA): average daily intake of a nutrient that’s sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy people.
Adequate Intake (AI): approximate intake assumed to be nutritionally adequate based on limited research, though still not enough evidence to develop an RDA.
Tolerable Upper Intake Level (UL): maximum daily intake that’s unlikely to cause adverse health effects.
The upper limit for vitamin A is 3,000 RAE for adults. This only applies to the preformed retinol form (found in animal products, fortified foods, and both synthetic and naturally-sourced supplements) and doesn’t apply to vitamin A from carotenoids (found in plants and plant-sourced supplements).
Retinol Toxicity
Vitamin A is fat-soluble, which means any amount your body doesn’t immediately use is stored in your fat tissue and your liver. If too much is stored, it can become toxic.
Even moderately excessive intakes of vitamin A can increase your risk of bone loss and can get in the way of the beneficial actions of vitamin D. If you’re pregnant, vitamin A toxicity can increase the risk of some birth defects.
Carotenoid Toxicity
In contrast to preformed vitamin A, provitamin A carotenoids aren’t toxic even when ingested over long periods at high levels, except for in people with certain health conditions (such as hypothyroidism) which prevent them from converting carotenoids like beta-carotene into retinol.
Carotenoids are antioxidants; the carotenoids your body doesn’t use right away circulate through your body, keeping your cells safe from oxidative stress and damage.
Extremely high levels of beta-carotene from food or supplemental sources can cause a rare and harmless condition called carotenodermia, which turns skin a yellow-orange color. It’s completely reversible by substantially reducing beta-carotene intakes.
How to Absorb More Vitamin A on a Vegan Diet
There’s a lot of variation in different people’s ability to both absorb and convert vitamin A.
Factors contributing to these differences include body composition, age, smoking, medications, alcohol consumption, food processing, and genetic variation. Because a lot of this is difficult to determine, you’re better off eating a diet high in provitamin A carotenoids just to be safe.
You can increase your body’s absorption and synthesis of vitamin A by pairing foods containing provitamin A carotenoids like beta-carotene with foods containing fat, like oil or avocados.
Chopping, blending, and cooking help separate carotenoids from the plant proteins they’re associated with, making them easier to absorb.
Best Vegan Sources of Vitamin A
There are many vegan dietary sources of provitamin A carotenoids.
Top vegan sources of vitamin A are:
- Sweet potato
- Carrots
- Spinach
- Cantaloupe
- Red bell pepper
- Squash
Vegans & Vitamin A Supplements
Most people in Western countries are actually at greater risk of getting too much vitamin A than they are of getting too little. This is because many people eat animal products or take high doses of supplements containing preformed vitamin A when they already get enough from their diet.
People who may need to supplement vitamin A are people with conditions that interfere with normal digestion, causing malabsorption of vitamin A. Some of these conditions are celiac disease, Crohn’s disease, cirrhosis, cystic fibrosis, and alcoholism.
If taking a vitamin A supplement, it’s often best to take the provitamin A carotenoid form rather than preformed vitamin A, since excesses of the provitamin form don’t contribute to toxic levels of vitamin A accumulating your body.
Smokers should steer clear of high-dose beta-carotene supplements as these have been shown to increase risk of lung cancer.
Disclaimer: The contents of this website are for educational purposes and are not intended to offer personal medical advice. To make sure your diet is providing you with the correct amount of nutrients your body needs, be sure to consult a nutrition specialist (ie: registered dietitian) with expertise in vegan diets.