8 Incredible Vitamin A Benefits for Skin and How to Use it Correctly

If you are serious about skincare, put vitamin A at the top of your list. Vitamin A can do your skin a world of good. That is, if you use it correctly. Unfortunately, there has been a lot of confusion about vitamin A in the last few years. Many people have been scared off of it for good because of what they have read in the news, or from using it incorrectly themselves. Some forms of vitamin A are stronger than others. The side effects can vary greatly depending on the product and how you take it.

Many patients are not educated on how to use vitamin A. The truth is, it is powerful stuff. This is not the kind of product you can slather on your skin willy nilly. Today, let’s put the confusion about vitamin A to rest once and for all. Read on to learn about vitamin A benefits for skin, how to use it, best products to try, side effects and prevention, and much more.

By the time you finish reading this, you will be a vitamin A skin care expert!

8 Incredible Vitamin A Benefits for Skin and How to Use it Correctly

Vitamin A is a powerhouse of benefits. It does two things very well. That is cell turnover and oil control. By doing these two things, it can correct a variety of complex skin issues. Some common conditions that can be improved with vitamin A are:

  1. Oil production
  2. Acne
  3. Enlarged pores
  4. Uneven skin tone
  5. Aging skin
  6. Poor skin texture
  7. Dryness
  8. Eczema
Specialist Skin Solutions Mother and Daughter

Oil production

Oil production is triggered by testosterone. Both men and women have testosterone, although men produce more of it. This hormone flares up most during puberty, leading to a shiny complexion that is the bane of many teenagers’ existence. Controlling oily skin is not always easy, but vitamin A can help. Retinol and retinyl palmitate are often used for this purpose.(15)

Acne

Vitamin A is excellent for defending against acne. Many factors can cause acne, but oily skin is one of the biggest culprits.(6) Sebum is rather sticky. It mixes with dead skin cells to clog pores, leading to congestion. Congested skin tends to get acne. Dermal nurse Lea Barclay explains that vitamin A is essential for shrinking oil glands and balancing oil production, which in turn reduces pimples and blackheads.

We already know that vitamin A can help with oil, so it is no surprise that it is great for blemished skin. There are many vitamin A products for acne. These include topical forms of vitamin A (both over the counter and prescription) along with oral prescriptions like isotretinoin. We will talk about these vitamin A acne products in more detail later.

Acne Treatment by Dr Beldholm

Enlarged pores and skin texture

Large pores can be hard to treat. Big pores can give the skin a textured appearance that is especially obvious in certain lighting. A cloudy day or fluorescent lighting is not kind to men and women with enlarged pores. Genetics and skin oil are to blame. People with oily skin tend to have significantly larger pores, so again, vitamin A is perfect for that.

Ethnicity is also linked to pore size. For example, this study shows that Indian patients tend to have more obvious facial pores than the other three ethnic groups studied (Caucasian, Japanese, and Chinese). Chinese patients had the most refined pores of all in this particular study.(5) Mediterranean skin is also known to produce more oil, and thus may have larger pores.

VItamin A can prevent large pores from getting worse by reducing sebum production.(4) It also helps keep the pores clear of debris by speeding cell turnover, which can help make pores appear smaller.

Poor skin tone and aging skin

Call vitamin A the youth vitamin. Skin cell turnover tends to slow with age. When the cells don’t turn over as quickly, your complexion looks rather dull. Bright, healthy skin has fresh new cells at the surface all the time. Vitamin A does wonders to revitalize aging skin. Prescription retinoids and over-the-counter retinols may be prescribed to help refresh a tired, lackluster complexion. They work by sloughing off dead skin cells and increasing cell turnover.(11) When dead cell buildup is finally cleared away, the beautiful new skin beneath it glows. Everyone wants an even skin tone, and vitamin A is made for that.

According to Lea, it can even reverse sun damage and boost collagen and elastin to make your skin appear strong and healthy. Vitamin A is one of the best kept secrets to youthful, radiant skin.

Dry skin and eczema

Dry Skin and eczema Treatent by Specialist Skin Solutions

Dehydrated skin can have many causes, of course. However, if you have chronic dry skin, it may be a signal of vitamin A deficiency.(1) Dry skin has a weak protective barrier that gets irritated easily. Sun, wind, low humidity, and drying soaps can make it even worse. That can be a real problem for eczema sufferers. Luckily, certain types of vitamin A can help repair dry skin. In one 12-week study, patients with eczema who used 10–40 mg of alitretinoin each day saw up to a 53 percent reduction in symptoms.(12)

Using vitamin A to prep the skin for other treatments

Prepping the skin with Vitamin A can make facial treatments like peels more effective. You can do a series of vitamin A peels to improve penetration of future peels. This is great for patients who want to get better anti-aging results from enzyme peels, as well as people with sun damage and scarring. It works by removing dead skin cells and revealing fresh, new skin. This allows other topical products and serums to sink into the skin better to maximize results.

However, you want to space the treatments apart by a few weeks to avoid excess irritation since it can make skin sensitive. If you use topical vitamin A products at home, discontinue using them for at least 5 days before and after treatment.

Types of vitamin A

There are many vitamin A products, and they are sold under various names. This is a big reason why there is so much confusion surrounding vitamin A. Retinols and retinoids are two distinct classes of vitamin A. They come from the same family, but they’re not the same. Retinoids are an active form of vitamin A that goes to work right when it comes in contact with your skin. Meanwhile, retinols are a simple form of vitamin A that is not considered an “active” ingredient. The effects of retinols are milder because of this. However, they are still great for improving mild skin concerns.

Retinol

Retinols are a simple form of vitamin A. These can be purchased over the counter. OTC wrinkle creams often contain retinol, but quality varies greatly. You can step into any drugstore or medical spa to buy them without a prescription.

Retinol is ideal for promoting cell turnover, which is great for aging skin and congested pores. Unfortunately, many people experience adverse side effects because they are not advised on how to use them properly since a prescription isn’t needed. They do work, you just have to know how to use them.

Not all OTC retinol products are created equal. An anti-aging wrinkle cream may advertise that it contains retinol, but some manufacturers dilute the formula with fillers. The FDA requires that all cosmetics list what the product contains on the label. If you see that retinol or vitamin A is at the end of the ingredient list, you can bet it is just a marketing gimmick.

Retinoids

Retinoids are mostly prescription-strength form of vitamin A. (One exception is Differin Gel, aka adapalene, which used to be available by prescription only, but is now sold over the counter.) Retinoids are more powerful than the majority of retinols you find at the drugstore.

Lea explains that many patients want to get their hands on the strongest vitamin A possible, thinking that it will lead to better and faster results. That is not always the case. While they are stronger than retinols, not everyone needs vitamin A of this intensity. Retinoids are more aggressive, and the side effects are more intense. Different retinoids can be prescribed for various skin issues, such as aging skin, poor texture, large pores, oily skin, and acne.

Best vitamin A products for skin

What kind of vitamin A should you use? There are topical creams and vitamin A oil for skin, oral supplements, and prescription pills and gels. There are so many to choose from. Let’s take a look at some of the best vitamin A products for skin.

Topical vitamin A for skin

Non-prescription retinols are effective for correcting many skin issues. Lea recommends Aspect Dr Exfol A, which contains a mild retinol. This anti-aging product is great for early signs of skin aging. It works to reveal a youthful, glowing complexion and brightens your skin. Aspect Dr Exfol A is gentle and well tolerated. If you are interested in trying a high-quality vitamin A product, this is a good place to start.

Exfol A plus by Specialist Skin Solutions

Vitamin A oil for skin is also very popular. Many people say the best vitamin A oil for skin is Skin Doctors Vitamin A ampoules. It has a more creamy texture compared to most oils. The capsules are supposed to boost collagen production, which can help strengthen aging skin. People love it because it has 15 percent retinol, yet it is gentle thanks to the patented slow-release formula. The formula gets bonus points for being free of parabens.

For patients who need something stronger, retinoids may also be used topically. Lea recommends AlphaRet, which contains a retinoid known as ethyl lactyl retinoate. This is the next step up from Aspect Dr Exfol A. It is stronger, so be careful of that if you have sensitive skin. Of course, not everyone needs something stronger. A gentle retinol product is great for daily use for skin that needs a little nudge to get those cells turning over faster.

Other common retinoids include Retin-A (tretinoin) for anti-aging and acne, Differin (adapalene) for acne and oil production, retinyl palmitate for aging skin, alitretinoin for skin sores and eczema, and more. Adapalene is the main one that is FDA approved to treat acne. All these products promote cell turnover. Your doctor or dermal nurse can help advise which one can help you achieve your skin goals.

It usually takes 6-8 weeks to start seeing results from topical vitamin A treatments. Full effects are usually visible by 3-4 months. That is the same for both prescription retinoids and over-the-counter retinols. Patience is key.

Vitamin A peels

These peels can help lift away all the dead skin cells that leave your skin looking dull and uneven. Vitamin A peels deliver a beautiful glow to the skin, while helping to correct sun damage, post-acne dark marks, and age spots. Lea explains that it is a nice alternative for patients who are not ready to try laser. Vitamin A peels can be repeated to maximize effects. The peels are more intensive than the gradual effects you see with daily topicals. This is great news if you want more instant results.

Oral vitamin A supplements

Sure, you can walk into any nutrition store and purchase vitamin A pills. But are they really effective? The research so far says no. At least, not in the normal doses. For example, oral vitamin A (retinol) is largely ineffective for acne in the normal dose of 50,000 to 100,000 IU per day.(9) Effectiveness increased at 400,000 to 500,000 IU, but overall it appears that oral vitamin A supplements are not the best approach to treating skin conditions like acne. According to research in the International Journal of Dermatology,  it takes about three to four months for effects to take place.(9)

Vitamin A supplements are not FDA approved for treating skin conditions. They may offer some benefits, but the results are likely to be minimal. Not to mention, too much vitamin A can be toxic. More on that later!

Oral vitamin A by prescription

Most people have heard the name Accutane (isotretinoin). There is a great deal of controversy around the drug. For some, the name symbolizes hope for the most severe acne-prone skin. For others, Accutane is a scary drug that leads to depression and even suicide. Yet there is no proof that Accutane has mental side effects(10), which suggests that these news stories are anecdotal.

Interestingly, Roche (Accutane’s manufacturer) discontinued the drug in the USA and Australia around 2009. But the reason is not what you may think. Rather than its suggested link to mental health problems, it was discontinued because it increased the risk of inflammatory bowel disease in some patients. Generic isotretinoin is still available by prescription.

Isotretinoin is prescribed for severe cystic acne. It can have some pretty intense side effects such as redness and peeling. Patients with mild to moderate acne are better off using topical vitamin A products, which tend to have milder side effects. Just because you get breakouts, it does not mean you need the most potent medication available.

Vitamin A side effects, safety, and proper use

Vitamin A is powerful. However, many people are afraid of it when they really shouldn’t be. Many forms of it are safe and effective when used properly. Despite this, some myths persist — namely that it is a dangerous product that you should avoid except as a last resort. This couldn’t be further from the truth.

So why the bad rap? Lea explains that many years ago, vitamin A was not regulated as well as it is today. It was often used in its most powerful form, an oral tablet used only for the most severe acne cases. The side effects were comparable to the strength of the pills. There were outrageous news headlines and claims of mental health effects that have yet to be proven.

It is important to clarify that topical and oral medications are very different. Certain types of vitamin A are gentle enough for daily use. The key is using it correctly.

List of common side effects

Vitamin A side effects are common, especially when you first start using it. Once your skin builds a tolerance, you will not have to worry about most of these conditions. It can take 6-8 weeks for skin to get used to a new vitamin A regimen. During that time, you may experience the following:

  • Redness
  • Mild irritation
  • Flaking and peeling
  • Tight skin
  • New breakouts

Peeling is normal

A little redness and flaking is normal in the beginning. This is one of the most common side effects of vitamin A. Mild skin peeling is not a bad thing. In fact, that is part of how vitamin A revitalizes skin. It works by sloughing away dead skin cells and increasing cell turnover. Fresh, healthy skin starts to peek through, giving you a brighter, more youthful skin tone over time.

Vitamin A does take some getting used to. Peeling can be worst in the beginning. That puts some patients off from using it, but if you can push past the first few weeks of minor peeling, you will be rewarded with healthy, glowing skin in as little as 6-8 weeks.

Unfortunately, many people see the initial peeling as an adverse side effect. Lea explains that peeling is a good thing. It does not mean that the peel was too strong or that your dermal therapist did something wrong. Peeling is desirable to get to the new, healthy skin hiding beneath. Try to stick with your regimen. As your skin gets used to it, the peeling will decrease with time. A gentle daily moisturizer can help keep flakes at bay.

Avoiding side effects

Proper use can help keep the side effects of vitamin A under control. It can take your skin 6-8 weeks to get used to vitamin A. This adjustment period can be hard for some people to get through. Stick with the program, and your skin will get past this stage.

Building tolerance

Vitamin A can be strong, even the over-the-counter kind. It is important that your skin builds up a tolerance to it. This can help you avoid adverse reactions, such as excess redness and peeling. By lowering your risk of side effects, you are more likely to stick with your vitamin A regimen for the long haul. That is important since it takes up to two months or longer to see visible results.

Patients who introduce vitamin A too much or too quickly into their skincare routine may stop using it because of the side effects. They think vitamin A caused their skin to get worse. But it is really just the aggressive approach that caused their skin flare up. To prevent this, add vitamin A into your beauty routine gradually.

A great way to do this is to apply a dab of lotion to your face before your vitamin A goes on. The lotion works to create a barrier so that the vitamin A sinks in gradually. It is also a good idea to wait until your skin is fully dry after washing. Damp skin absorbs better — sometimes too well. It can soak up too much vitamin A and lead to irritation. Allow your skin 30 minutes to dry after washing, then apply the vitamin A product with clean hands.(15)

If your skin is still reacting to the vitamin A, you may want to use it every other night at first so that your skin gets a break in between. Then you can work up to using it every night as your skin gets used to it. For ultra sensitive skin, Lea recommends leaving the vitamin A on for five minutes, then washing it off on the first day. The next night, you can leave it on for ten minutes before washing, and so on.

Lea also recommends starting with OTC retinol vitamin A products. They have less side effects because they are gentler than prescription retinoids.

Use sunscreen

Sunscreen by Specialist Skin Solutions

Skin that is being treated with vitamin A can be photosensitive. Precautions should be taken to protect your skin from getting burned. Avoid strong sun during peak daylight hours (12-3 p.m.) when possible. SPF 50+ sunscreen is always a good idea. If your skincare regimen calls for vitamin A once per day, you can use it at night when sun exposure won’t be an issue. It is important to protect that fresh, healthy skin you have worked so hard to achieve!

Stop using before other skin treatments

Lea explains that using retinol or retinoids on your skin makes it more sensitive. If you are planning to have medical-based peels or laser skin treatments, it is a good idea to stop using vitamin A products for 5-7 days before your appointment. Remember that vitamin A brings your freshest, youngest skin to the surface. That means that the peel or laser will go to work too quickly. That can result in extra sensitivity, irritation, or even a burn if you are having laser done.

Vitamin A is not for everyone

Almost anyone can benefit from using retinol, the mildest OTC form of vitamin A. In the mid-20s, skin aging and wrinkles start to be a concern, so that is when most people turn to vitamin A products.

However, vitamin A may not be for everyone. Some skin types simply can’t tolerate it, no matter how gradually they add it to their skincare routine. People with rosacea often have the hardest time getting used to it. Pregnant women are also advised against using vitamin A, along with breastfeeding mothers.

The importance of vitamin A in your diet

Vitamin A is essential to a healthy diet. It is a fat-soluble vitamin that supports many body functions. This includes proper vision, reproduction, skin health, bone formation, and a strong immune system. Vitamin A foods contain antioxidants, which are great for your overall health and wellness.

Eating vitamin A has many benefits for skin

Vitamin A is key for the creation and repair of skin cells. Without it, skin can become dry, develop eczema, or age more quickly. It also combats inflammation, which protect your skin from environmental damage and free radicals.(13) Topical vitamin A products can help skin look better, but you should make sure to eat enough vitamin A as well.

Preformed vitamin A vs. provitamin A

There are two types of vitamin A you can eat. One is preformed vitamin A, and the other is pro-vitamin A. Preformed vitamin A is also known as retinol. It is found in animal sources. You can get preformed vitamin A from eating meat, fish, eggs, and dairy. The reason it is called “preformed” is because it does not need to be converted in your body before it starts working.

On the other hand, provitamin A needs to be converted before your body can start using it. It is abundant in plant sources. Bright-colored vegetables are rich in provitamin A, thanks to the carotenoids these foods contain. Think yellow and orange bell peppers and tomatoes. Carotenoids are a precursor to vitamin A. Your body turns them into active retinoids after you eat them. Your liver is responsible for vitamin A conversion. Once it has been converted, it gets transported to cells throughout your body via the lymphatic system.

Best foods to eat for vitamin A

Kidney, liver, and eggs are all excellent sources of preformed vitamin A. This gives you the most bang for your buck since this type of vitamin A goes to work straight away. Carotenoid-rich foods are good to eat, too, even though your body has to convert them to a usable form of vitamin A first. Bright vegetables are loaded with other skin-enhancing vitamins that support good skin health. Sweet potatoes, carrots, papaya, and cantaloupe are packed with carotenoids.

Signs of vitamin A deficiency

Vitamin A deficiency is uncommon in developing countries, but it is important to make sure you get enough vitamin A in your diet. Pregnant women, breastfeeding mums, and young children are most at risk for vitamin A deficiency.(1) The following symptoms are associated with vitamin A deficiency:

Poor night vision

Bad vision can be caused by vitamin A deficiency. For example, nyctalopia is a reversible form of night blindness that has been linked to a lack of the vitamin.(3) Being able to see at night is very important for driving. It can also help you avoid injury if you are walking around your home in the evening when the lights are dim. Luckily, increasing your vitamin A intake can help correct the problem.(3)

Eczema

Eczema is also known as atopic dermatitis. This pesky condition can make skin look inflamed, red, scaly, and itchy. Vitamin A deficiency can cause eczema.(12) Adding vitamin A to your diet may reduce the condition. It contains plenty of antioxidants that calm and soothe the skin irritation that is the hallmark of eczema. Antioxidants boost skin’s ability to repair itself and fight off free radicals. They are essential for healthy skin.

Acne and keratosis pilaris

Did you know a lack of dietary vitamin A may cause acne?(5) Low levels of vitamin A are common in people with breakouts. This can include closed comedones (whiteheads), open comedones (blackheads), red papules, and painful cystic acne.

The reason this happens is mainly due to follicular hyperkeratosis. That means the skin has too much keratin in the hair follicle. Keratin is abundant in facial pores, as well as the back and chest. It is no surprise that is where acne breakouts tend to occur most.

Even the back of the arms and neck can develop a rough, bumpy texture when there is too much keratin. This condition is known as keratosis pilaris (KP). It is sometimes called “chicken skin” because it looks like the skin has permanent goosebumps.

Reproductive issues

Vitamin A is very important for reproductive health. Without it, both men and women may experience infertility or difficulty conceiving.(2) It can be confusing to couples who are trying to conceive what the problem could be. In women lacking adequate vitamin A, the menstrual cycle can appear completely normal. However, it can reduce the quality of the eggs, making it more difficult to get pregnant. Vitamin A aids sperm production in men.(2)

Miscarriage

Research suggests that women who have had multiple miscarriages tend to share something else in common. You guessed it: vitamin A deficiency.(16) This vitamin is key for embryo development. However, pregnant and lactating women should seek advice from their caregiver about how much vitamin A is safe. Too much vitamin A may cause birth defects. Adequate vitamin A supports the development of nearly every part of the baby’s body.(2) This includes:

  • Lungs
  • Diaphragm
  • Nervous system
  • Spinal cord
  • Eyes
  • Skeleton
  • Heart
  • Kidney
  • Urinary tract
  • Pancreas
  • Limbs

Stunted growth

Height is usually a result of genetics, but nutrition plays an important role. Vitamin A deficiency could be one reason for a short stature.(8) Vitamin A is key for growth, but it does not work alone. Iron, zinc, and vitamin D are also necessary for proper growth.

Can you eat too much vitamin A?

The short answer is yes. If you want to add more vitamin A to your diet, be sure not to eat too much. You can certainly overdo it. Taking too much of any fat-soluble vitamin can lead to a condition called hypervitaminosis. This is when there is a toxic buildup of a vitamin that can wreak havoc on your body.

Your body only needs so much vitamin A to function properly. Any excess gets stored in the liver, which can become toxic. Consuming too much vitamin A can lead to all sorts of problems, such as vision changes, bones problems, dizziness, confusion, mouth sores, and even birth defects in pregnant women. The recommended dose of vitamin A is 900 mcg per day.(14)

Rest assured, the average person is not in danger of overdoing it on the vitamin A from diet alone. However, people who use oral vitamin A supplements should take care not to consume too much since you can get a lot of vitamin A from the foods you eat.

Vitamin A is a healthy body’s best friend

There are countless vitamin A benefits for skin, whether you have acne, oily skin, wrinkles, poor texture, large pores, age spots and pigmentation, eczema, and sun damage. It is also necessary for the health of your body overall. Eating vitamin A is very important, but too much of it can be harmful. The same goes for using topical vitamin A products. When it comes to vitamin A, moderation is key!

Want to improve your skin further? Check out our article on “Why a chemical peel is great for your skin”

References

  1. “8 Signs and Symptoms of Vitamin A Deficiency.” Healthline, Healthline Media, www.healthline.com/nutrition/vitamin-a-deficiency-symptoms#section1.
  2. Clagett-Dame, Margaret, and Danielle Knutson. “Vitamin A in Reproduction and Development.” Nutrients, vol. 3, no. 4, 2011, pp. 385–428., doi:10.3390/nu3040385.
  3. Clifford, Luke J., et al. “Reversible Night Blindness – A Reminder of the Increasing Importance of Vitamin A Deficiency in the Developed World.” Journal of Optometry, vol. 6, no. 3, 2013, pp. 173–174., doi:10.1016/j.optom.2013.01.002.
  4. Dong, J, et al. “Enlarged Facial Pores: an Update on Treatments.” Cutis, vol. 98, July 2016.
  5. El-Akawi, Z., et al. “Does the Plasma Level of Vitamins A and E Affect Acne Condition?” Clinical and Experimental Dermatology, vol. 31, no. 3, 2006, pp. 430–434., doi:10.1111/j.1365-2230.2006.02106.x.
  6. Endly, Dawnielle, and Richard Miller. “Oily Skin: A Review of Treatment Options.” Journal of Clinical and Aesthetic Dermatology, vol. 8, 10 Aug. 2017.
  7. Flament, Frederic, et al. “Facial Skin Pores: a Multiethnic Study.” Clinical, Cosmetic and Investigational Dermatology, 2015, p. 85., doi:10.2147/ccid.s74401.
  8. Hadi, Hamam, et al. “Vitamin A Supplementation Selectively Improves the Linear Growth of Indonesian Preschool Children: Results from a Randomized Controlled Trial.” The American Journal of Clinical Nutrition, vol. 71, no. 2, 2000, pp. 507–513., doi:10.1093/ajcn/71.2.507.
  9. Kilgman, AM, et al. “Oral Vitamin A in Acne Vulgaris. Preliminary Report.” International Journal of Dermatology, vol. 4, no. 278, ser. 285, 20 May 1981. 285.
  10. Magin, Parker, and Dimity Pond. “Isotretinoin, Depression and Suicide: a Review of the Evidence.” British Journal of General Practice, vol. 55, 1 Feb. 2005, pp. 134–138.
  11. Mukherjee, Siddharth, et al. “Retinoids in the Treatment of Skin Aging: an Overview of Clinical Efficacy and Safety.” Clinical Interventions in Aging, vol. 1, no. 4, 2006, pp. 327–348., doi:10.2147/ciia.2006.1.4.327.
  12. Ruzicka, Thomas, et al. “Oral Alitretinoin (9-Cis-Retinoic Acid) Therapy for Chronic Hand Dermatitis in Patients Refractory to Standard Therapy.” Archives of Dermatology, vol. 140, no. 12, 2004, doi:10.1001/archderm.140.12.1453.
  13. Schindler, Mandana, et al. “Immunomodulation in Patients with Chronic Hand Eczema Treated with Oral Alitretinoin.” International Archives of Allergy and Immunology, vol. 165, no. 1, 2014, pp. 18–26., doi:10.1159/000365659.
  14. “Vitamin A.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 27 Oct. 2017, www.mayoclinic.org/drugs-supplements-vitamin-a/art-20365945.
  15. “What Can Treat Large Facial Pores?” What Can Treat Large Facial Pores? | American Academy of Dermatology, www.aad.org/public/skin-hair-nails/skin-care/pores.
  16. Şimşek, M., et al. “Blood Plasma Levels of Lipoperoxides, Glutathione Peroxidase, Beta Carotene, Vitamin A and E in Women with Habitual Abortion.” Cell Biochemistry and Function, vol. 16, no. 4, 1998, pp. 227–231., doi:10.1002/(sici)1099-0844(1998120)16:4<227::aid-cbf787>3.3.co;2-d.