Vitamin A: The ‘Night-Vision’ Vitamin
6-minute read•July 11th, 2018
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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Types: Vitamin A, retinol, beta-carotene
Best known for: Promoting normal cell growth; keeping eyes, skin and immune system healthy.
Good sources: Liver, fish oils, leafy green vegetables, tomato products and some fruits.
Recommended dietary allowance (RDA): 750 mcg/day (for men); 650 mcg/day (for women). The maximum intake unlikely to cause adverse effects is 3 mg/day.
Good to know: Overconsumption of vitamin A in the form of retinol can be harmful or even fatal. There are no major health consequences associated with overconsumption of vitamin A in the form of beta-carotene.
Vitamin A in Jake:
Jake Light and Original: 33% of RDA
Jake Sports: 25% of RDA
Vitaminbars: 25% of RDA
What is vitamin A?
Vitamin A is a fat-soluble vitamin Vitamins can be fat-soluble and water-soluble. Vitamin A is fat-soluble. This means that it is absorbed with the help of lipids (fats) and can be stored in the body. 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 Beta-carotene is the most important type of provitamin A but is not the only one. Other types of provitamin A are alpha-carotene and beta-cryptoxanthin, which can also be converted to retinol.. 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 T-cell is a type of white blood cell at the core of the body’s ability to respond to bacteria, viruses or other disease-causing microorganisms. proliferate and convert into regulatory T cells Regulatory T-cells are T-cells which regulate and suppress other cells in the immune system. Their normal function is crucial for preventing autoimmune diseases.. 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.These amounts reflect the recommended dietary allowance (RDA) set by the European Food Safety Authority (EFSA). An RDA is the average daily intake sufficient to meet the nutritional requirements of 97%-98% of healthy individuals. 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:
|Food||RDA (%)*||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.This is the tolerable upper intake level (UL) set by the European Food Safety Authority (EFSA). Consumption at this level is unlikely to have any negative health effects.
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.
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.