Vitamin A, Retinol and Carotenoids: What You'll Need to Know (2022)
You may be surprised to learn that retinol is simply a preformed type of vitamin A.2 It's sometimes called the "true" vitamin A because it's the bioavailable form of this nutrient.3
Vitamin A refers to different kinds of nutrients that can be divided into two major categories: retinoids and carotenoids. Natural retinoids are the fat-soluble, biologically active form of vitamin A that's obtained from animal-based foods, whereas carotenoids are the previtamin A found in plant-based food sources.
Retinol belongs to the family of endogenous natural retinoids. It acts as a precursor for the synthesis of retinal, a substance that's essential for visual health.4 Retinal may also be further broken down and converted into retinoic acid, which is the actual compound that affects the chemistry of the skin cells.5 Retinol and its natural derivatives are also necessary for various biological processes, including:6
- Bone growth
- Cell morphogenesis, proliferation, differentiation and apoptosis7
Retinol undergoes two metabolic steps before it's converted into a form that's useful for the skin, so its effect is milder, slower and less irritating than other forms of retinoid.8
Its function and efficiency are usually compared to that of alpha hydroxy acid (AHA), a substance that's commonly used in skincare products. While both of these compounds may help promote healthier skin, retinol is more potent versus AHA.9
Be careful not to use products that contain synthetic versions of retinol. Some popular examples include tazarotene, adapalene, etretinate and acitretin.10 You should also keep in mind that the risk of vitamin A toxicity is higher if you take retinol supplements, since it's fat-soluble. If you want to increase your body's levels of this nutrient, it's advised that you obtain it from your diet instead.
What are carotenoids?Carotenoids are pigments in plants, algae, and photosynthetic bacteria. These pigments produce the bright yellow, red, and orange colors in plants, vegetables, and fruits.
Carotenoids act as a type of antioxidant for humans.
There are more than 600 different types of carotenoids. Some can be converted into vitamin A when released into the body. A few of the most common carotenoids include:
- alpha carotene
- beta carotene
- beta cryptoxanthin
- bell peppers
How do carotenoids work?Carotenoids are fat-soluble compounds, meaning they are best absorbed with fat. Unlike some protein-rich foods and vegetables, cooking and chopping carotenoid-rich foods increase the strength of the nutrients when they enter the bloodstream.
Carotenoids are classified into two main groups: xanthophylls and carotenes.
Both types of carotenoids have antioxidant properties. In addition, some carotenoids can be converted into vitamin A, an essential component for human health and growth.
These provitamin A carotenoids include alpha carotene, beta carotene, and beta cryptoxanthin. Non-provitamin A carotenoids include lutein, zeaxanthin, and lycopene.
Add These Sources of Retinol Into Your Diet
- Grass fed beef liver — 68-gram serving of braised beef liver contains 6,411 micrograms (mcg) of retinol.11
- Turkey liver — A 53-gram serving of simmered turkey liver provides 5,698 mcg of retinol.12
- Pasture-raised chicken giblets — A cup of simmered chicken giblets contains 5,777 mcg of retinol.13
- Grass fed butter — You can get 95 mcg of retinol from a tablespoon of butter.14
- Cheddar cheese — A slice of cheddar cheese provides 92 mcg of retinol.15
- Organic, pastured eggs — One large hard boiled egg contains 74 mcg of retinol.16
Benefits of Vitamin A
Retinol soared to popularity because of its ability to retain and promote the production of collagen, helping maintain the skin's structure, firmness and elasticity. It may also assist to speed up cell turnover, which helps smoothen the skin surface and even out discolorations.17
The merits of retinol go beyond reducing the visible signs of aging; it may also help provide the benefits associated with vitamin A, which include:
Helps patients with COVID-19 - summary results of 6 vitamin A and COVID-19 studies are
available on this dedicated webpage:
c19early.com/va. The authors from a study published in the
Systematic Reviews in Pharmacy
concluded that there is a great benefit of the use of
vitamin A in patients with COVID-19 and to close contacts. Adding
vitamin A to the management protocol of COVID-19 is recommended.
- Helps with COVID-19 Loss of Smell (Anosmia) - Scientists are investigating if taking vitamin A could aid patients who have lost their sense of smell due to COVID-19. The 12-week 'Apollo study' would use nasal drops containing the vitamin to treat individuals who have lost or changed their sense of smell.
- Helps improve visual health — Consuming adequate amounts of retinol may help prevent eye problems such as night blindness, cataracts and macular degeneration.18
- Helps strengthen the immune system — he retinoic acid synthesized from retinol helps promote healthy immune system by modulating the response of macrophages, which in turn inhibits the production of pro-inflammatory cytokines.19
- Helps prevent oxidative damage — Retinol is a lipid-soluble antioxidant that may help fight the damaging effects of free radicals on your cells.20
- Helps support proper bone development — Adequate consumption of retinol may help support proper bone formation, as it works together with vitamin D and K2 to mineralize bones and teeth.
- Helps reduce the risk of cancer — Retinol may help inhibit the growth and development of certain types of cancers, including skin, breast, oral cavity, lung, gastrointestinal, prostatic, hepatic and bladder cancers.21
- Helps alleviate certain skin conditions — The antioxidant properties of retinol, along with its ability to help maintain high levels of collagen and promote cell turnover, may help ease or prevent skin problems like acne, dryness and psoriasis.22,23,24
Too Much Vitamin A May Be Bad for Your Bones
Several studies have shown that excessive vitamin A intake negatively impacts skeletal health by triggering an increase in osteoclast,25,26,27 a type of cell that's responsible for breaking down bone tissues.28 High levels of vitamin A may also interfere with the function of vitamin D,29 which helps improve bone strength by regulating the amount of calcium and phosphate in the body.
According to the National Institutes of Health (NIH) Osteoporosis and Related Bone Diseases, retinol is the form of vitamin A that poses a risk for poor bone health. You can easily get too much vitamin A by using synthetic retinoid preparations, taking supplements and consuming foods that have been fortified with retinol.30It's advised that you get retinol from whole, organic foods instead of through synthetic means. Healthy individuals who eat a balanced diet don't need to take supplements containing vitamin A in the form of retinol.
Can You Take Too Much Vitamin A?
The established upper limit for retinol is 10,000 IU (3,000 mcg) for adults. Be careful not to exceed this limit, as high intakes of this nutrient can be harmful for your health. Some of the side effects associated with excessive retinol intake include:31,32
- Bone and joint pain
- Skin irritation
- Increased intracranial pressure
Getting Retinol From Your Diet Is the Best Option for Your Health
However, if you're still interested in adding retinol supplement into your routine, make sure that you consult your physician to check if this supplement really fits your needs, and to determine the right dosage for your age and health condition.
Frequently Asked Questions (FAQs) About Vitamin A
Q: What does retinol do?
A. Retinol works by acting as a precursor to the synthesis of retinal, which is essential for maintaining good eye health,34 and retinoic acid, which is necessary for regulating the genes involved in cell differentiation, proliferation and morphogenesis.35 It also plays a role in embryogenesis, reproduction, bone growth and inflammation, among others.36
Q: What is retinol used for?
A. Retinol is commonly used for enhancing skin health, since it helps maintain high collagen levels and promote cell turnover.3738, It may also be used for maintaining good eye health,39 fighting off free radicals,40 supporting bone growth and strengthening the immune system.41
Q: Are retinol supplements safe?
A. Retinol can be harmful for your health if obtained as a supplement, since it puts you at a higher risk of vitamin A toxicity. Synthetic versions of this nutrient should also be avoided, since they may cause adverse side effects. If you want to optimize your retinol levels, you can safely obtain adequate amounts of it from animal-based foods.
- 1 Br J Dermatol. 2009 Aug; 161(2): 419–426.
- 2, 32, 33 NIH Office of Dietary Supplements, Vitamin A Fact Sheet for Health Professionals
- 3, 29, 30 NIH Osteoporosis and Related Bone Diseases, Vitamin A and Bone Health
- 4, 5, 6, 34, 36 Clin Interv Aging. 2006 Dec; 1(4): 327–348.
- 7 Curr Pharm Des. 2000 Feb;6(3): 311-25.
- 8 Skinacea, Types of Retinoids
- 9 J Clin Aesthet Dermatol. 2015 Oct; 8(10): 21–26.
- 10 European Handbook of Dermatological Treatments, Retinoids
- 11 USDA National Nutrient Database, Braised Beef Liver
- 12 USDA National Nutrient Database, Simmered Turkey Liver
- 13 USDA National Nutrient Database, Simmered Chicken Giblets
- 14 USDA National Nutrient Database, Butter Without Salt
- 15 USDA National Nutrient Database, Cheddar Cheese
- 16 USDA National Nutrient Database, Whole Hard-Boiled Egg
- 17, 22, 38 Dermatoendocrinol. 2012 Jul 1; 4(3): 308–319.
- 18 Arch Ophthalmol. 2004;122(4): 628-635.
- 19, 41 Ann N Y Acad Sci. 2008 Nov; 1143: 10.1196/annals.1443.017.
- 20, 40 Methods in Enzymology. 1990; Volume 190: Pages 273-280
- 21 Biomed Res Int. 2015; 2015: 624627.
- 23, 37 J Am Acad Dermatol. 1986 Oct;15(4 Pt 2):797-809.
- 24 Drugs. 1997 Mar;53(3):358-88.
- 25 Osteoporos Int (2004) 15: 552.
- 26 PLoS One. 2010; 5(10): e13305.
- 27 J Bone Miner Res. 1988 Apr;3(2):203-10.
- 28 Britannica, Osteoclast
- 31 NIH Office of Dietary Supplements, Vitamin A Fact Sheet for Consumers
- 35 Cell Death & Disease. 2013 October; Volume 4: Page E898
- 39 Arch Ophthalmol. 2004;122(4):628-635.