Beta-carotene Benefits & Negatives + High & Low Levels

Vitamin A: Benefits, Deficiency, Toxicity and More

Beta-carotene Benefits & Negatives + High & Low Levels
Written by Jillian Kubala, MS, RD on October 4, 2018

  • What It Is
  • Functions
  • Benefits
  • Deficiency
  • Sources
  • Toxicity & Dosage
  • Bottom Line

Vitamin A is a fat-soluble nutrient that plays a vital role in your body.

It exists naturally in the foods you eat and can also be consumed through supplements.

This article discusses vitamin A, including its benefits, food sources, as well as effects of deficiency and toxicity.

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Though vitamin A is often considered a singular nutrient, it’s really the name for a group of fat-soluble compounds, including retinol, retinal and retinyl esters (1).

There are two forms of vitamin A found in food.

Preformed vitamin A — retinol and retinyl esters — occurs exclusively in animal products, such as dairy, liver and fish, while provitamin A carotenoids are abundant in plant foods fruits, vegetables and oils (2).

To use them, your body must convert both forms of vitamin A to retinal and retinoic acid, the active forms of the vitamin.

Because vitamin A is fat soluble, it’s stored in body tissue for later use.

Most of the vitamin A in your body is kept in your liver in the form of retinyl esters (3).

These esters are then broken down into all-trans-retinol, which binds to retinol binding protein (RBP). It then enters your bloodstream, at which point your body can use it (4).

Summary Vitamin A is the generic term for a group of fat-soluble compounds found in both animal and plant foods.

Vitamin A is essential for your health, supporting cell growth, immune function, fetal development and vision.

Perhaps one of the best-known functions of vitamin A is its role in vision and eye health.

Retinal, the active form of vitamin A, combines with the protein opsin to form rhodopsin, a molecule necessary for color vision and low-light vision (5).

It also helps protect and maintain the cornea — the outermost layer of your eye — and the conjunctiva — a thin membrane that covers the surface of your eye and inside of your eyelids (6).

Additionally, vitamin A helps maintain surface tissues such as your skin, intestines, lungs, bladder and inner ear.

It supports immune function by supporting the growth and distribution of T-cells, a type of white blood cell that protects your body from infection (7).

What’s more, vitamin A supports healthy skin cells, male and female reproduction and fetal development (8).

Summary Vitamin A is needed for eye health, vision, immune function, cell growth, reproduction and fetal development.

Vitamin A is an important nutrient that benefits health in many ways.

Potent Antioxidant

Provitamin A carotenoids such as beta-carotene, alpha-carotene and beta-cryptoxanthin are precursors of vitamin A and have antioxidant properties.

Carotenoids fight free radicals — highly reactive molecules that can harm your body by creating oxidative stress (9).

Oxidative stress has been linked to various chronic illnesses diabetes, cancer, heart disease and cognitive decline (10).

Diets high in carotenoids are associated with a lower risk of many of these conditions, such as heart disease, lung cancer and diabetes (11, 12, 13).

Essential for Eye Health and Prevents Macular Degeneration

As mentioned above, vitamin A is essential to vision and eye health.

Adequate dietary intake of vitamin A helps protect against certain eye diseases, such as age-related macular degeneration (AMD).

Studies show that higher blood levels of beta-carotene, alpha-carotene and beta-cryptoxanthin may reduce your risk of AMD by up to 25% (14).

This risk reduction is linked to carotenoid nutrients’ protection of macular tissue by lowering levels of oxidative stress.

May Protect Against Certain Cancers

Due to their antioxidant properties, carotenoid-rich fruits and vegetables may protect against certain types of cancer.

For example, a study in over 10,000 adults determined that smokers with the highest blood levels of alpha-carotene and beta-cryptoxanthin had a 46% and 61% lower risk of dying from lung cancer, respectively, than non-smokers with the lowest intake of these nutrients (15).

What’s more, test-tube studies demonstrate that retinoids may inhibit the growth of certain cancer cells, such as bladder, breast and ovarian cancer (16).

Vital for Fertility and Fetal Development

Vitamin A is essential for both male and female reproduction because it plays a role in sperm and egg development.

It’s also critical for placental health, fetal tissue development and maintenance, as well as fetal growth (8).

Therefore, vitamin A is integral to maternal and fetal health and to those trying to conceive.

Boosts Your Immune System

Vitamin A impacts immune health by stimulating responses that protect your body from illnesses and infections.

Vitamin A is involved in the creation of certain cells, including B- and T-cells, which play central roles in immune responses that guard against disease.

A deficiency in this nutrient leads to increased levels of pro-inflammatory molecules that diminish immune system response and function (17).

Summary Vitamin A positively impacts health by keeping oxidative stress in check, boosting your immune system and protecting against certain diseases.

Though vitamin A deficiency is rare in developed countries the US, it’s common in developing countries, as these populations may have limited access to food sources of preformed vitamin A and provitamin A carotenoids.

Vitamin A deficiency can lead to severe health complications.

According to the WHO, vitamin A deficiency is the leading cause of preventable blindness in children worldwide.

Vitamin A deficiency also increases the severity and risk of dying from infections measles and diarrhea (18, 19).

Additionally, vitamin A deficiency raises the risk of anemia and death in pregnant women and negatively impacts the fetus by slowing growth and development (20).

Less severe symptoms of vitamin A deficiency include skin issues hyperkeratosis and acne (21, 22).

Certain groups such as premature infants, people with cystic fibrosis and pregnant or breastfeeding women in developing countries are more at risk of vitamin A deficiency (23).

Summary Vitamin A deficiency can lead to blindness, increased infection risk, pregnancy complications and skin issues.

There are many dietary sources of both preformed vitamin A and provitamin A carotenoids.

Preformed vitamin A is more readily absorbed and utilized by your body than plant-based sources of provitamin A carotenoids.

Your body’s ability to effectively convert carotenoids, such as beta-carotene, into active vitamin A depends on many factors — including genetics, diet, overall health and medications (24).

For this reason, those who follow plant-based diets — especially vegans — should be vigilant about getting enough carotenoid-rich foods.

Foods highest in preformed vitamin A are:

  • Egg yolks
  • Beef liver
  • Liverwurst
  • Butter
  • Cod liver oil
  • Chicken liver
  • Salmon
  • Cheddar cheese
  • Liver sausage
  • King mackerel
  • Trout

Foods high in provitamin A carotenoids beta-carotene include (25, 26):

  • Sweet potatoes
  • Pumpkin
  • Carrots
  • Kale
  • Spinach
  • Dandelion greens
  • Cabbage
  • Swiss chard
  • Red peppers
  • Collard greens
  • Parsely
  • Butternut squash

Summary Preformed vitamin A exists in animal foods liver, salmon and egg yolks, while provitamin A carotenoids are found in plant foods, including sweet potatoes, kale and cabbage.

Just as vitamin A deficiency can negatively impact health, getting too much can also be dangerous.

The recommended daily allowance (RDA) for vitamin A is 900 mcg and 700 mcg per day for men and women, respectively — which can be easily reached by following a whole-foods diet (27).

However, it's important not to exceed the tolerable upper limit (UL) of 10,000 IU (3,000 mcg) for adults to prevent toxicity (27).

Though it’s possible to consume excessive preformed vitamin A through animal-based sources liver, toxicity is most commonly linked to excessive supplement intake and treatment with certain medications, such as Isotretinoin (28, 29).

Since vitamin A is fat-soluble, it’s stored in your body and can reach unhealthy levels over time.

Taking too much vitamin A can lead to serious side effects and can even be fatal if ingested at extremely high doses.

Acute vitamin A toxicity occurs over a short time period when a single, excessively high dose of vitamin A is consumed, while chronic toxicity occurs when doses more than 10 times the RDA are ingested over a longer time span (30).

The most common side effects of chronic vitamin A toxicity — often referred to as hypervitaminosis A — include:

  • Vision disturbances
  • Joint and bone pain
  • Poor appetite
  • Nausea and vomiting
  • Sunlight sensitivity
  • Hair loss
  • Headache
  • Dry skin
  • Liver damage
  • Jaundice
  • Delayed growth
  • Decreased appetite
  • Confusion
  • Itchy skin

Though less common than chronic vitamin A toxicity, acute vitamin A toxicity is associated with more severe symptoms, including liver damage, increased cranial pressure and even death (31).

What’s more, vitamin A toxicity can negatively impact maternal and fetal health and may lead to birth defects (32).

To avoid toxicity, steer clear of high-dose vitamin A supplements.

The UL for vitamin A applies to animal-based food sources of vitamin A, as well as vitamin A supplements.

High intake of dietary carotenoids is not associated with toxicity, though studies link beta-carotene supplements with an increased risk of lung cancer and heart disease in smokers (33).

Since too much vitamin A can be harmful, consult with your doctor before taking vitamin A supplements.

Summary Vitamin A toxicity may cause symptoms, such as liver damage, vision disturbances, nausea and even death. High-dose vitamin A supplements should be avoided unless prescribed by your doctor.

Vitamin A is a fat-soluble nutrient vital to immune function, eye health, reproduction and fetal development.

Both deficiency and surplus intake may cause severe side effects, so while it’s crucial to meet the RDA of 700–900 mcg daily for adults, don’t exceed the upper daily limit of 3,000 mcg.

A healthy, well-balanced diet is a great way to provide your body with a safe amount of this essential nutrient.

Источник: https://www.healthline.com/nutrition/vitamin-a

Researchers reveal ‘dark side’ to high beta-carotene intake

Beta-carotene Benefits & Negatives + High & Low Levels

Writing in the Journal of Biological Chemistry​ researchers from the Ohio State University, USA, revealed that the natural pigment beta-carotene – perhaps best known as a precursor of vitamin A – could also have a ‘dark side’.

But now a team of scientists led by Professor Earl Harrison have found that certain molecules derived from beta-carotene have an opposite effect in the body – by blocking certain actions of vitamin A, which is critical to human vision, bone and skin health, metabolism and immune function.

“We determined that these compounds are in foods, they're present under normal circumstances, and they're pretty routinely found in blood in humans, and therefore they may represent a dark side of beta-carotene,”​ said Harrison.

“These materials definitely have anti-vitamin-A properties, and they could basically disrupt or at least affect the whole body metabolism and action of vitamin A.”​

Because the anti-vitamin-A compounds are derived from beta-carotene at the same time as vitamin A, Harrison predicts that higher intakes of the antioxidant will inevitably lead to a larger amount of the potentially harmful molecules as well.

However he said that more work is needed, adding: “We have to study them further to know for sure.”​

Implications

Harrison explained that because vitamin A provides its health benefits by activating hundreds of genes: “This means that if compounds contained in a typical source of the vitamin are actually lowering its activity instead of promoting its benefits, too much beta-carotene could paradoxically result in too little vitamin A.”​

Hesaid the findings also might explain why previous clinical trials have found that people who were heavily supplemented with beta-carotene had a higher incidence of lung cancer than participants who took no beta-carotene at all.

“Those trials are still sending shockwaves 20 years later to the scientific community,”​ said Harrison. “What we found provides a plausible explanation of why larger amounts of beta-carotene might have led to unexpected effects in these trials.”​

However, the authors were keen to stress that they are not recommending against eating foods high in beta-carotene.

Study details

The US based research team manufactured a series of beta-carotene-derived molecules in the lab that match those that exist in nature. They then exposed the molecules to conditions mimicking their metabolism and action in the body.

Of the 11 synthetic molecules produced, five appeared to function as inhibitors of vitamin A action how they interacted with receptors that would normally launch the function of vitamin A molecules.

“The original idea was that maybe these compounds work the way vitamin A works, by activating what are called retinoic acid receptors,”​ said Robert Curley, who co-authored the study.

“What we found was they don't activate those receptors. Instead, they inhibit activation of the receptor by retinoic acid,”​ he explained.

Once that role was defined, the researchers sought to determine how prevalent these molecular components might be in the human body. By analyzing blood samples obtained from six healthy human volunteers, the scientists in the lab found that some of these anti-vitamin-A molecules were present in every sample studied – suggesting that they are a common product of beta-carotene metabolism.

The researchers are continuing to study these compounds, including whether food processing or specific biological processes affect their prevalence.

Engineered vitamins

The research also has implications for industry efforts to bio-engineer staple crops that contain excess beta-carotene, which is considered a sustainable way to provide these populations with pro-vitamin A in developing countries.

“A concern is that if you engineer these crops to have unusually high levels of beta-carotene, they might also have high levels of these compounds,”​ Harrison said.

Source: Journal of Biological Chemistry​Published online ahead of print, doi: 10.1074/jbc.M111.325142jbc.M111.325142.

“Naturally-occurring eccentric cleavage products of provitamin A beta-carotene function as antagonists of retinoic acid receptors”​

Authors: A. Eroglu, D.P. Hruszkewycz, C. dela Sena, S. Narayanasamy, et al ​

Источник: https://www.nutraingredients.com/Article/2012/05/03/Researchers-reveal-dark-side-to-high-beta-carotene-intake

What is beta carotene? What are the benefits?

Beta-carotene Benefits & Negatives + High & Low Levels

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Beta carotene is a red-orange pigment found in plants and fruits, especially carrots and colorful vegetables.

The name beta carotene comes from the Greek “beta” and Latin “carota” (carrot). It is the yellow/orange pigment that gives vegetables and fruits their rich colors. H. Wachenroder crystallized beta carotene from carrot roots in 1831, and came up with the name “carotene”.

In this article, we explain all about beta carotene, what it does in the body, and what foods it is found in. We will also cover any associated risks.

Here are some key points about beta carotene. More detail and supporting information is in the main article.

  • Beta carotene is a red/orange pigment found in many fresh fruits and vegetables
  • Beta carotene is converted into vitamin A, an essential vitamin
  • Vitamin A is toxic at high levels
  • Beta carotene is a carotenoid and an antioxidant
  • Foods rich in vitamin A include onions, carrots, peas, spinach and squash
  • One study showed that smokers with high beta carotene intake might have an increased risk of lung cancer
  • Some evidence suggests that beta carotene might slow cognitive decline
  • Beta carotene supplements interact with certain drugs, including statins and mineral oil
  • Beta carotene might help older people retain their lung strength as they age.

Share on PinterestCarrots are an excellent source of beta carotene.

The human body converts beta carotene into vitamin A (retinol) – beta carotene is a precursor of vitamin A. We need vitamin A for healthy skin and mucus membranes, our immune system, and good eye health and vision.

Beta carotene in itself is not an essential nutrient, but vitamin A is. Beta carotene’s chemical formula – C40H56 – was discovered in 1907

Vitamin A can be sourced from the food we eat, through beta carotene, for example, or in supplement form. The advantage of dietary beta carotene is that the body only converts as much as it needs.

Excess vitamin A is toxic. Toxic vitamin A levels can occur if you consume too many supplements.

There are a number of ways that beta carotene can benefit human health. Below, we give some examples:

Beta carotene is an antioxidant

Beta carotene, all carotenoids, is an antioxidant. An antioxidant is a substance that inhibits the oxidation of other molecules; it protects the body from free radicals.

Free radicals damage cells through oxidation. Eventually, the damage caused by free radicals can cause several chronic illnesses.

Several studies have shown that antioxidants through diet help people’s immune systems, protect against free radicals, and lower the risk of developing cancer and heart disease.

Some studies have suggested that those who consume at least four daily servings of beta carotene rich fruits and/or vegetables have a lower risk of developing cancer or heart disease.

Beta carotene may slow down cognitive decline

Men who have been taking beta carotene supplements for 15 or more years are considerably less ly to experience cognitive decline than other males, researchers from Harvard Medical School reported in Archives of Internal Medicine (November 2007 issue).

Oxidative stress is thought to be a key factor in cognitive decline, the researchers explained. Studies have shown that antioxidant supplements may help prevent the deterioration of cognition.

Their study, involving 4,052 men, compared those on beta carotene supplements for an average of 18 years to others who were given placebo. Over the short-term, they found no difference in cognitive decline risk between the two groups of men, but in the long-term it was clear that beta carotene supplements made a significant difference.

The researchers emphasized that there may have been other factors which contributed to the slower decline in cognitive abilities among the men in the beta carotene group.

Beta carotene keeps lungs healthy as people age

The BMJ published a report in March 2006 which showed that high blood beta carotene levels compensate for some of the damage to the lungs caused by oxygen free radicals.

They measured the FEV1 of 535 participants and measured their beta carotene blood levels. FEV1 measures how much air you can breathe out in one go. They found that those with high beta carotene levels had much slower decline in FEV1 measures.

Share on PinterestA healthful and varied diet can provide a person’s beta carotene requirements.

The following foods are rich in beta carotene:

  • Apricots
  • Asparagus
  • Broccoli
  • Carrots
  • Chinese cabbage
  • Chives
  • Dandelion leaves
  • Grapefruit
  • Herbs and spices – chilli powder, oregano, paprika, parsley
  • Kale
  • Ketchup
  • Many margarines
  • Onions
  • Peas
  • Peppers
  • Plums
  • Pumpkin
  • Spinach
  • Squash
  • Sweet potatoes.

If you follow a healthy diet rich in beta carotene you do not need supplements. As mentioned above, supplements can lead to undesirable excesses in beta carotene levels – this cannot occur if your source is from the food you eat.

A French study involving adult females published in the Journal of the National Cancer Institute (September 2005 issue) found that smokers with high beta carotene levels had a higher risk of lung cancer and other smoking-related cancers than other smokers. They also found that non-smokers with high beta carotene intake had a lower risk of lung cancer.

They found that the risk of lung cancer over a ten-year period was:

  • 181.8 per 10,000 women for non-smokers with low beta carotene intake
  • 81.7 per 10,000 women for non-smokers with high beta carotene intake
  • 174 per 10,000 women for smokers with low beta carotene intake
  • 368.3 per 10,000 women for smokers with high beta carotene intake.

Further research has suggested that the high intake among smokers is nearly always due to supplements, and not food intake.

Beta carotene drug interactions

Drug interaction refers to a substance interfering in how a medication works, by either making it less effective, increasing its potency, or changing what it is supposed to do.

The following drugs may be affected by beta carotene supplements:

  • Statins – the effectiveness of simvastatin (Zocor) and niacin may be decreased if the patient is taking beta carotene with selenium and vitamins E and C.
  • Some cholesterol-lowering drugs – cholestyramine and colestipol can reduce blood levels of dietary beta carotene by thirty to forty per cent.
  • Orlistat (Xenical, Alli) – this is a weight control medication. It can undermine the absorption of beta carotene by up to 30 percent, resulting in lower blood beta carotene levels. Those choosing to take a multivitamin while on orlistat should take them at least two hours before having their medication.
  • Mineral oil – used for the treatment of constipation can lower blood levels of beta carotene.

Long-term alcohol consumption can interact with beta carotene, raising the chances of developing liver problems.

Beta carotene supplements are available for purchase online. Speak to a doctor before taking new supplements.

Источник: https://www.medicalnewstoday.com/articles/252758

6 Health Benefits of Vitamin A, Backed by Science

Beta-carotene Benefits & Negatives + High & Low Levels

Vitamin A is the generic term for a group of fat-soluble compounds highly important for human health.

They’re essential for many processes in your body, including maintaining healthy vision, ensuring the normal function of your immune system and organs and aiding the proper growth and development of babies in the womb.

It’s recommended that men get 900 mcg, women 700 mcg and children and adolescents 300–600 mcg of vitamin A per day (1).

Vitamin A compounds are found in both animal and plant foods and come in two different forms: preformed vitamin A and provitamin A.

Preformed vitamin A is known as the active form of the vitamin, which your body can use just as it is. It’s found in animal products including meat, chicken, fish and dairy and includes the compounds retinol, retinal and retinoic acid.

Provitamin A carotenoids — alpha-carotene, beta-carotene and beta-cryptoxanthin — are the inactive form of the vitamin found in plants.

These compounds are converted to the active form in your body. For example, beta-carotene is converted to retinol (an active form of vitamin A) in your small intestine (2).

Here are 6 important health benefits of vitamin A.

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Vitamin A is essential for preserving your eyesight.

The vitamin is needed to convert light that hits your eye into an electrical signal that can be sent to your brain.

In fact, one of the first symptoms of vitamin A deficiency can be night blindness, known as nyctalopia (3).

Night blindness occurs in people with vitamin A deficiency, as the vitamin is a major component of the pigment rhodopsin.

Rhodopsin is found in the retina of your eye and extremely sensitive to light.

People with this condition can still see normally during the day, but have reduced vision in darkness as their eyes struggle to pick up light at lower levels.

In addition to preventing night blindness, eating adequate amounts of beta-carotene may help slow the decline in eyesight that some people experience as they age (4).

Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world. Though its exact cause is unknown, it’s thought to be the result of cellular damage to the retina, attributable to oxidative stress (5).

The Age-Related Eye Disease Study found that giving people over the age of 50 with some eyesight degeneration an antioxidant supplement (including beta-carotene) reduced their risk of developing advanced macular degeneration by 25% (6).

However, a recent Cochrane review found that beta-carotene supplements alone won’t prevent or delay the decline in eyesight caused by AMD (7).

Summary Eating adequate amounts of vitamin A prevents the development of night blindness and may help slow the age-related decline of your eyesight.

Cancer occurs when abnormal cells begin to grow or divide in an uncontrolled way.

As vitamin A plays an important role in the growth and development of your cells, its influence on cancer risk and role in cancer prevention is of interest to scientists (8, 9).

In observational studies, eating higher amounts of vitamin A in the form of beta-carotene has been linked to a decreased risk of certain types of cancer, including Hodgkin's lymphoma, as well as cervical, lung and bladder cancer (10, 11, 12, 13).

Yet, though high intakes of vitamin A from plant foods have been associated with a reduced risk of cancer, animal foods which contain active forms of vitamin A aren’t linked in the same way (14, 15).

Similarly, vitamin A supplements haven’t shown the same beneficial effects (16).

In fact, in some studies, smokers taking beta-carotene supplements experienced an increased risk of lung cancer (17, 18, 19).

At the moment, the relationship between vitamin A levels in your body and cancer risk is still not fully understood.

Still, current evidence suggests that getting adequate vitamin A, especially from plants, is important for healthy cell division and may reduce your risk of some types of cancer (20).

Summary Adequate vitamin A intake from whole plant foods may reduce your risk of certain cancers, including Hodgkin's lymphoma, as well as cervical, lung and bladder cancer. However, the relationship between vitamin A and cancer is not fully understood.

Vitamin A plays a vital role in maintaining your body’s natural defenses.

This includes the mucous barriers in your eyes, lungs, gut and genitals which help trap bacteria and other infectious agents.

It’s also involved in the production and function of white blood cells, which help capture and clear bacteria and other pathogens from your bloodstream.

This means that a deficiency in vitamin A can increase your susceptibility to infections and delay your recovery when you get sick (21, 22).

In fact, in countries where infections measles and malaria are common, correcting vitamin A deficiency in children has been shown to decrease the risk of dying from these diseases (23).

Summary Having enough vitamin A in your diet helps keep your immune system healthy and function at its best.

Acne is a chronic, inflammatory skin disorder.

People with this condition develop painful spots and blackheads, most commonly on the face, back and chest.

These spots occur when the sebaceous glands get clogged up with dead skin and oils. These glands are found in the hair follicles on your skin and produce sebum, an oily, waxy substance that keeps your skin lubricated and waterproof.

Though the spots are physically harmless, acne may have a serious effect on people's mental health and lead to low self-esteem, anxiety and depression (24).

The exact role that vitamin A plays in the development and treatment of acne remains unclear (25).

It has been suggested that vitamin A deficiency may increase your risk of developing acne, as it causes an overproduction of the protein keratin in your hair follicles (26, 27).

This would increase your risk of acne by making it more difficult for dead skin cells to be removed from hair follicles, leading to blockages.

Some vitamin-A-based medications for acne are now available with a prescription.

Isotretinoin is one example of an oral retinoid that is effective in treating severe acne. However, this medication can have serious side effects and must only be taken under medical supervision (28, 29).

Summary The exact role of vitamin A in the prevention and treatment of acne is unclear. Yet, vitamin-A-based medications are often used to treat severe acne.

The key nutrients needed for maintaining healthy bones as you age are protein, calcium and vitamin D.

However, eating enough vitamin A is also necessary for proper bone growth and development, and a deficiency in this vitamin has been linked to poor bone health.

In fact, people with lower blood levels of vitamin A are at a higher risk of bone fractures than people with healthy levels (30).

Additionally, a recent meta-analysis of observational studies found that people with the highest amounts of total vitamin A in their diet had a 6% decreased risk of fractures (30).

Yet, low levels of vitamin A may not be the only problem when it comes to bone health. Some studies have found that people with high intakes of vitamin A have a higher risk of fractures as well (31).

Even so, these findings are all observational studies, which cannot determine cause and effect.

This means that currently, the link between vitamin A and bone health is not fully understood, and more controlled trials are needed to confirm what has been seen in observational studies.

Bear in mind that vitamin A status alone does not determine your risk of fractures, and the impact of the availability of other key nutrients, vitamin D, also plays a role (32).

Summary Eating the recommended amount of vitamin A may help protect your bones and reduce your risk of fractures, though the connection between this vitamin and bone health is not fully understood.

Vitamin A is essential for maintaining a healthy reproductive system in both men and women, as well as ensuring the normal growth and development of embryos during pregnancy.

Rat studies examining the importance of vitamin A in male reproduction have shown that a deficiency blocks the development of sperm cells, causing infertility (33, 34).

wise, animal studies have suggested that vitamin A deficiency in females can impact reproduction by reducing egg quality and affecting egg implantation in the womb (33).

In pregnant women, vitamin A is also involved in the growth and development of many major organs and structures of the unborn child, including the skeleton, nervous system, heart, kidneys, eyes, lungs and pancreas.

Yet, though much less common than vitamin A deficiency, too much vitamin A during pregnancy can be harmful to the growing baby as well and may lead to birth defects (35, 36).

Therefore, many health authorities recommended that women avoid foods that contain concentrated amounts of vitamin A, such as pâté and liver, as well as supplements containing vitamin A during pregnancy.

Summary Adequate amounts of vitamin A in the diet are essential for reproductive health and the healthy development of babies during pregnancy.

Vitamin A is a fat-soluble vitamin, which is stored in your body. This means that excess consumption can lead to toxic levels.

Hypervitaminosis A is caused by consuming too much preformed vitamin A through your diet or supplements containing the vitamin.

Symptoms can include nausea, dizziness, headaches, pain and even death.

Though it can be caused by excessive intake from the diet, this is rare compared to overconsumption from supplements and medications.

Additionally, eating a lot of provitamin A in its plant form doesn’t carry the same risks, as its conversion to the active form in your body is regulated (37).

Summary Eating high amounts of the active form of vitamin A from animal foods, medications or supplements can be toxic. Excessive consumption of provitamin A from plant foods is unly.

Vitamin A is vital for many important processes in your body.

It’s used to maintain healthy vision, ensure the normal functioning of your organs and immune system, as well as establishing normal growth and development of babies in the womb.

Both too little and too much vitamin A could have negative effects on your health.

The best way to ensure you get the balance right is to consume vitamin-A-rich foods as part of your normal diet and avoid supplementing with excessive amounts.

Источник: https://www.healthline.com/nutrition/vitamin-a-benefits

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