Did your mom tell you to eat carrots when you were younger because they're good for your eyes? Well, go ahead and tell her she was right. That's the simplified version of the wonders of vitamin A, and it can do so much more for your body than just help you see better at night.
Vitamin A is often taken for granted because most people are rarely deficient, according to the Office of Dietary Supplements (ODS). It helps with immune health, reproduction, vision and growth. The best part? You can get all of the vitamin A you need from your diet, although you will find it available in supplement form, too.
What Is Vitamin A?
Vitamin A is in a class of vitamins called fat-soluble vitamins. This means two things: You can only store small amounts of vitamin A in your body and you need fat to absorb it, according to the Centers for Disease Control and Prevention (CDC). While daily vitamin A is important, it sticks around longer than a water-soluble vitamin such as vitamin C (which isn't stored in the body).
Vitamin A is indeed good for your vision, but more specifically, your night vision, according to Harvard Health Publishing. Vitamin A is also especially important in bone growth during childhood, reproduction and maintaining a healthy immune system.
Where to Find It in Foods
Vitamin A comes in several forms in our food, including preformed vitamin A and carotenoids. Preformed vitamin A is what you might call pure vitamin A. It's naturally found in high-fat animal foods, such as whole milk, eggs, butter and fatty fish.
Carotenoids, however, are converted to vitamin A inside the body. The most well-known carotenoid is beta carotene, which you'll typically find in orange and dark green produce, such as carrots, sweet potatoes, bell peppers, cantaloupe, broccoli and spinach. There are other carotenoids, such as lutein and lycopene, that are not converted to vitamin A, but they are still nutritional powerhouses.
One of the biggest reasons Americans aren't usually deficient in vitamin A is because we fortify our food supply. Vitamin A is widely added to fat-free and low-fat dairy milks, non-dairy milks and some cereals. Eating vitamin A-fortified foods helps improve vitamin A levels, according to the World Health Organization.
Figuring out how much vitamin A you're getting can be a little tricky. On nutrition labels, you'll see vitamin A listed in international units (IU). A single IU of beta carotene that you get in your favorite healthy foods is equal to 0.05 micrograms of retinol activity equivalents or mcg RAE. Adults need between 700 and 900 mcg RAE per day, according to the ODS.
What the Research Says
Foods containing beta carotene or vitamin A have long been thought of as a natural sunscreen of sorts, providing protection from the inside out. While you shouldn't throw out your sunscreen just yet, higher vitamin A intake was linked with a lower risk for squamous cell carcinoma — a common form of skin cancer for those with fair skin — in a July 2019 study published in the Journal of the American Medical Association Dermatology. The research did not find the same association when looking at vitamin A supplements, which means that now is as good of a time as ever to hit the farmer's market.
Then, there's the promising research about vitamin A and weight. An April 2019 review published in Nutrients suggests that in animal and cell studies, beta carotene may affect fat cells in ways that could help in the prevention of obesity.
The way that vitamin A and carotenoids help boost the immune system are still a bit of a mystery. Vitamin A has been studied for its effects on preventing measles, treating tuberculosis and strengthening the immune response in general. A September 2018 review published in Journal of Clinical Medicine reports that vitamin A may play a role in the treatment of respiratory and digestive diseases in children, especially.
What Happens if You Don't Get Enough?
Vitamin A deficiency is the leading cause of preventable blindness in children in developing countries, according to the World Health Organization. We don't typically see this in the United States, mainly because of fortification.
One of the earliest signs of vitamin A deficiency is night blindness, according to the ODS. Diarrhea or anemia — being low in iron — can both be triggered by vitamin A deficiency or result in low levels, so it's important to seek medical attention if you're experiencing either.
If you have a condition where you can't properly absorb fat, like cystic fibrosis or Crohn's disease, you are also at risk for vitamin A deficiency. The right physician can help verify your vitamin A status and get you on the road to a diet and supplement regimen that's right for you and your body.
What Happens if You Get Too Much?
It's rare that you'll be exposed to too much beta carotene from foods. However, an excess of beta carotene can give your skin an orange glow, which goes away after you stop eating excessive amounts of beta carotene-containing foods.
Synthetic vitamin A, however, is one of those supplements you don't want to experiment with. Unlike water soluble vitamins, fat soluble vitamins like A are easily stored in the body, and more doesn't mean better: Taking 4,000 IU daily for six months could cause fevers, fatigue, anemia, swelling, joint pain and hair loss, according to a StatPearls review published in July 2019.
The safe upper limit for vitamin A in supplement form for adults is 10,000 IU. A single dose over 25,000 IU could cause nausea, vomiting, diarrhea, dizziness, increased pressure on the brain and skin issues. Before reaching for any supplement or upping the vitamin A in your regular diet, make sure to chat with a physician.
- National Institutes of Health: "Vitamin A Fact Sheet"
- Journal of the American Medical Association of Dermatology: "Association of Vitamin A Intake With Cutaneous Squamous Cell Carcinoma Risk in the United States"
- World Health Organization:"Micronutrient Deficiencies"
- Nutrients: "β-carotene in Obesity Research: Technical Considerations and Current Status of the Field"
- Journal of Clinical Medicine: "Role of Vitamin A in the Immune System"
- World Health Organization: "Vitamin A Fortification of Staple Foods"
- Centers for Disease Control: "Fat-Soluble Vitamins & Micronutrients: Vitamins A and E and Carotenoids"
- Harvard Health Publishing: "Blinded by the night"
- StatPearls: "Vitamin A"