Vitamin A For Night Vision

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Night vision is a pretty crazy concept. It’s like, “Oh, I can see in the dark?” But it doesn’t always work out that way. Sometimes your eyes just get tired and you need something to help them out.

That’s where vitamin A comes in! Vitamin A is an essential nutrient for maintaining healthy vision. It supports the growth of epithelial tissues in the eye and helps maintain healthy corneas. You’ve heard about its antioxidant properties, but did you know that it also helps you see better at night?

Vitamin A is responsible for producing rhodopsin, an important protein found in the rod cells of your eyes. This protein is responsible for converting light into electrical impulses so that we can see it—and when there isn’t enough vitamin A around, your ability to see well at night will suffer.

Vitamin A For Night Vision

You’ve probably heard it at least once in your life: carrots are good for your eyes! In case you haven’t revealed their secret weapon by now, here it goes – vitamin A is responsible. And yes, it’s true. That and multiple other functions, from cell division to making sure your immune system doesn’t turn on itself. Vitamin A is a true multitasking specialist. Let’s take a look.

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What is vitamin A?

Vitamin A is a fat-soluble vitamin and as such it can be stored in your body, primarily in your liver. In food, vitamin A is found either as preformed vitamin A: retinol, or as provitamin A: e.g. as beta-carotene . Retinol can be used directly by your body or converted to another active form of vitamin A, either retinal or retinoic acid. Provitamin A is always converted into retinol first.

Health benefits of vitamin A

The key functions of vitamin A in your body are:

  • Ensuring normal vision: Vitamin A is an important component of rhodopsin, a light-absorbing protein in the retina. Rhodopsin helps you see in the dark, which is why one of the first symptoms of a vitamin A deficiency is night blindness.
  • Promoting the functioning of your immune system: Vitamin A helps T-cells proliferate and convert into regulatory T cells . This process is important to avoid an autoimmune response.
  • Supporting cell growth and the normal functioning of vital organs like the heart, lungs and kidneys.
  • Keeping your skin healthy: Vitamin A can increase the synthesis of collagen and inhibit the enzymes responsible for its degradation.
  • Promoting the reproductive function: Vitamin A, in the form of tretinoin, plays an important role in the normal functioning of male and female reproductive systems.Source: Nutrients Journal

Some studies find an association between large doses of beta-carotene and an increased risk of lung cancer among current and former smokers.Source: Carotene and Retinol Efficacy Trial However, it is currently unclear whether and how these findings translate to the general population, as well as whether modest intake of beta-carotene can demonstrate similar effects.

How much vitamin A do you need?

Healthy adult men require 750 mcg of vitamin A daily. Women need 650 mcg per day. During pregnancy, dietary needs for vitamin A are increased, partially due to accumulation of vitamin A in the foetus. As a result, the recommended intake of vitamin A during pregnancy is 700 mcg per day. That’s practically three small carrots.

Vitamin A in foods

Vitamin A is present in a variety of foods. Preformed vitamin A, or retinol, is primarily found in animal products, such as liver, fish oils, milk and eggs. Provitamin A is most abundant in leafy green vegetables, tomato products, fruits and certain vegetable oils.

Here are the best sources of vitamin A:

FoodRDA (%)*Vitamin A (mcg)
Beef liver, cooked (85 g)877%6582
Carrots, raw (25 g)61%459
Spinach, raw (112 g)76%573
Red peppers, raw (85 g)16%117
Mango, raw (100 g)31%230

* Based on the recommended dietary allowance (RDA) established by EFSA for healthy adult men (750 mcg/day)

At some point of your life, you’ve probably heard that carrots can help you see better in the dark. Although they help keep your eyes healthy thanks to their vitamin A content, carrots can’t do miracles in improving your night vision. So, how did they get this exaggerated fame? Well, propaganda.
In 1940, the German army started bombing the Brits at night. Thanks to a new radar system, the Brits were very successful with their defense. But to keep the radar secret, they spread the news that troops owed their success to a high intake of carrots, which improved their vision in the dark.

What if you’re not getting enough vitamin A?

Not enough vitamin A in your diet can have serious health consequences. A first sign of vitamin A deficiency is the so-called ‘night blindness’. Left untreated, it can lead to permanent blindness.

Nowadays, severe vitamin A deficiency is uncommon in developed countries. However, it still remains one of the top causes of preventable blindness among children in developing countries. An underlying cause of this is often poverty, which can limit access to vitamin A-rich foods.

Groups at a higher risk of vitamin A deficiency are:

  • Premature babies: Infants born early don’t have an adequate storage of vitamin A in their livers, which increases their risk of eye, lung and gastrointestinal diseases.
  • Pregnant and lactating women in developing countries: Pregnant women have increased needs for vitamin A for their own metabolism, as well as for normal foetal growth. Vitamin A deficiency during pregnancy and lactation can increase the risk of maternal and infant mortality, as well as slow the baby’s development.
  • People with malabsorption disorders: Any condition that affects fat absorption consequently affects the absorption of fat-soluble vitamins like vitamin A.

How much vitamin A is too much?

As a fat-soluble vitamin, vitamin A can be stored in your liver. This means that if you consume too much, it can accumulate and reach toxic levels in your body, known as hypervitaminosis A. Hypervitaminosis A can occur as a result of chronic overconsumption of vitamin A, but it can also happen after a single excessive intake.

Animals also store vitamin A in their livers. No wonder beef liver tops the list of vitamin A sources. Not only liver but also its related products, such as pâté, have a very high vitamin A content and should be consumed in moderation to avoid hypervitaminosis A.

The consequences of hypervitaminosis A can range from dizziness and skin irritation to coma and, in some cases, death. Even after discontinuing the excessive intake of vitamin A, it takes time for vitamin A levels in the body to return to normal. Liver damage incurred in the meantime can be irreversible.

The negative effects of hypervitaminosis A are only associated with high intakes of preformed vitamin A, retinol. There is no evidence that overconsumption of beta-carotene and other provitamin A types is harmful. However, some findings indicate that consuming more than 20 mg of beta-carotene per day might be associated with an increased risk of lung cancer in current and former smokers.

To avoid any negative consequences for your health, you should limit your vitamin A consumption to 3 mg/ day.

If you were offered polar bear liver for dinner, what would you say? First of all, we hope you’re never in that situation. But if you are, the only answer you should be considering is a version of ‘no’. Polar bear liver can contain up to 9 mg of vitamin A per gram – that’s more than 10 times the RDA! Even a few bites of that could kill you.

Take-aways

These are the top three things to remember about vitamin A:

  • Both too little and too much vitamin A can harm you. A vitamin A deficiency affects your eyes and can cause blindness if untreated. Excessive vitamin A intake could lead to permanent liver damage and can even be fatal in some cases.
  • You need vitamin A for multiple functions in your body – from ensuring that your cells are growing properly to keeping your immune system, skin and eyes healthy.
  • Vitamin A is found in a variety of foods, including liver, fish oils, green leafy vegetables and some fruits.

Afraid to miss out on essential nutrients your body needs? You can always take our Jake meal replacement shakes or one of our delicious meal replacement bars.

best form of vitamin a for eyes

Eye benefits of vitamin A and beta-carotene

By Gary Heiting, OD

sweet potato for eye health

Does vitamin A do anything to help eyes and vision? Can a vitamin A deficiency cause blindness? Is it dangerous to consume too much vitamin A?

Read on for answers to these questions and other useful facts about this important antioxidant vitamin, including information about eye benefits of vitamin A and beta-carotene, top vitamin A foods, and possible benefits of vitamin A eye drops.

What Is Vitamin A?

Vitamin A actually is a group of antioxidant compounds that play an important role in vision, bone growth and health of the immune system. Vitamin A also helps the surface of the eye, mucous membranes and skin be effective barriers to bacteria and viruses, reducing the risk of eye infections, respiratory problems and other infectious diseases.

In general, there are two types of vitamin A, depending on the type of food source it comes from:

Sweet potatoes and carrots are excellent sources of provitamin A carotenoids that are good for your eyes.

  1. Vitamin A from animal-derived foods is called retinol. This “pre-formed” vitamin A can be used directly by the body. Good food sources of retinol vitamin A include beef and chicken liver, whole milk and cheese.
  2. Vitamin A obtained from colorful fruits and vegetables is in the form of “provitamin A” carotenoids, which are converted to retinol by the body after the food is ingested. Good food sources of provitamin A carotenoids include carrots, sweet potatoes, spinach, kale and cantaloupes.

Beta-carotene is one of the most prevalent and effective provitamin A carotenoids.

Eye Benefits Of Vitamin A And Beta-Carotene

Because vitamin A helps protect the surface of the eye (cornea), it is essential for good vision.

Studies show vitamin A eye drops are effective for the treatment of dry eyes. In fact, one study found that over-the-counter lubricating eye drops containing vitamin A were as effective for the treatment of dry eye syndrome as more expensive prescription eye drops formulated for dry eye relief.

Vitamin A eye drops also have been shown effective for the treatment of a specific type of eye inflammation called superior limbic keratoconjunctivitis.

Vitamin A, at least when in combination with other antioxidant vitamins, also appears to play a role in decreasing the risk of vision loss from macular degeneration (AMD). In the landmark Age-Related Eye Disease Study (AREDS) sponsored by the National Eye Institute, people with mild or moderate AMD who took a daily multivitamin that included vitamin A (as beta-carotene), vitamin C, vitamin E, zinc and copper had a 25 percent reduced risk of advanced AMD during a six-year period.

It also appears that a combination of vitamin A and lutein may prolong vision in people suffering from retinitis pigmentosa (RP). A four-year study conducted by researchers from Harvard Medical School and other prominent universities found that individuals with retinitis pigmentosa who took daily supplements of vitamin A (15,000 IU) and lutein (12 mg) had a slower loss of peripheral vision than those who did not take the combined supplements.

Because beta-carotene is converted into vitamin A in the body, it’s likely this provitamin A offers similar eye benefits as the pre-formed retinol type of vitamin A, though more research is needed to confirm this.

And researchers at Columbia University Medical Center found that a synthetic, altered form of vitamin A might be able to slow the progression of Stargardt’s disease, an inherited eye disease that causes severe vision loss in young people.

When given to mice with the same genetic defect as humans with Stargardt’s disease (also called juvenile macular degeneration), the modified vitamin A inhibited the growth of clump-like deposits in the retina called “vitamin A dimers” that are associated with degenerative changes and vision loss.

The National Eye Institute has awarded the researchers a $1.25 million grant to further investigate the link between vitamin A dimers and various retinal degenerations, which could lead to new approaches to treat these diseases.

Vitamin A Deficiency

Vitamin A deficiency is rare in the United States, but it is common among the poor in developing countries. It’s estimated that approximately 250,000 to 500,000 malnourished children worldwide become blind each year due to vitamin A deficiency that could have been prevented with a proper diet.

One of the first signs of vitamin A deficiency is night blindness. In ancient Egypt, it was discovered that night blindness could be cured by eating liver, which later was found to be a rich source of vitamin A.

A lack of vitamin A causes the cornea to become very dry, leading to clouding of the front of the eye, corneal ulcers and vision loss. Vitamin A deficiency also causes damage to the retina, which also contributes to blindness.

Because vitamin A also is important for resistance to infection and a healthy immune system, vitamin A deficiency can lead to death from respiratory and other infections.

Vitamin A – Daily Value

In most cases, it’s best to obtain vitamins and minerals from a healthy, balanced diet.

The concept of the Daily Value (DV) was developed to help consumers determine if a food contains a lot or a little of a nutrient, based on its Recommended Dietary Allowance. The DV for vitamin A is 5,000 IU.

The following tables provide DV percentages for some of the best vitamin A foods:

FoodVitamin A (IU)%DV
Beef liver (3 ounces, cooked)22,175443.5
Braunschweiger (pork liver sausage, 2 slices)7,967159.3
Chicken liver (1 liver, cooked)2,61252.2
Milk shake (16 fluid ounces)1,01220.2
Ricotta cheese (1 cup)94518.9
Whole milk3957.9
Butter (1 tablespoon)3557.1
Source: USDA National Nutrient Database for Standard Reference, Release 22 (2009)
FoodVitamin A (IU)%DV
Carrot juice (canned, 1 cup)45,133902.6
Pumpkin (canned, 1 cup)38,129762.6
Sweet potato (baked, 1 potato)28,058561.2
Carrots (cooked, 1 cup)26,571531.4
Carrots (raw, 1 carrot)12,028240.6
Spinach (raw, 1 cup)2,81356.3
Cantaloupe (raw, 1/8 melon)2,33446.7
Source: USDA National Nutrient Database for Standard Reference, Release 22 (2009)

[Try these easy recipes — all contain beta-carotene: deli-style kale salad, orange pepper frittata, pumpkin mousse.]

Vitamin A Toxicity

Vitamin A that comes from animal food sources is not water-soluble and therefore is not readily excreted from the body. Instead, it is stored in body fat and, if ingested in excess amounts, can build up in the body and become toxic.

Beta-carotene and other provitamin A carotenoids found in fruits and vegetables don’t pose the same vitamin A toxicity risk. These compounds are water-soluble and are easily eliminated from the body, so vitamin A toxicity from vegetarian food sources is rare.

Beta-carotene supplements, however, may have serious risks for smokers. Two studies have found that smokers taking daily supplements containing 20 to 30 mg of beta-carotene had an increased risk of lung cancer compared with smokers who did not take the eye supplements. (These studies are controversial, however, and a large study of more than 22,000 male physicians found no adverse health effects when these doctors took beta-carotene supplements of 50 mg every other day.)

The Institute of Medicine has established the following upper intake levels for the animal-based, retinol form of vitamin A to reduce the risk of vitamin A toxicity:

  • Children (ages 4 to 8): 3,000 IU
  • Children (ages 9 to 13): 5,610 IU
  • Teenagers (ages 14 to 18): 9,240 IU
  • Adults (age 19 and older): 10,000 IU

Possible toxicity reactions from long-term daily consumption of vitamin A above these levels include birth defects, liver abnormalities, reduced bone mineral density that can lead to osteoporosis, and central nervous system disorders.

Eye Nutrition News

Breeding Sweet Potatoes In Africa To Fight Blindness

August 2015 — Sweet potatoes are a promising way to help vitamin A-deficient children in South Africa, according to a June report in the journal Crop Science. Vitamin A deficiency is the leading cause of preventable blindness in children around the world. Sweet potatoes have naturally high amounts of beta-carotene (which our bodies convert to vitamin A) and are already a well-accepted food in South Africa.

“We realized it would be great if we could develop a local variety which has good yield, high dry mass, and desirable taste attributes, and promote it to combat vitamin A deficiency,” says Sunette Laurie, a senior researcher with the Agricultural Research Council in Pretoria, South Africa.

Laurie and others tested 12 varieties of sweet potatoes in humid subtropical, drier subtropical and temperate climates. Impilo and Purple Sunset are two varieties that have shown the best results. In a 4.4 ounce serving, Impilo provides 113 percent of the daily vitamin A requirement of a child 4 to 8 years old; Purple Sunset provides 261 percent. Another variety called Bophelo has more beta-carotene than Impilo and tastes better.

Laurie’s team is working on more varieties with an eye toward pest-resistance, and she is working toward the building of more agro-processing units that would make flour, bread, muffins and other foods from sweet potatoes.

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