Preformed vitamin A comes from animal products, fortified foods, and vitamin supplements. Carotenoids are found naturally in plant foods. There are other types of carotenoids found in food that are not converted to vitamin A but have health-promoting properties; these include lycopene, lutein, and zeaxanthin.

Vitamin A is currently listed on the Nutrition Facts label measured in international units IU. However, the Institute of Medicine lists the Recommended Dietary Allowances RDA of vitamin A in micrograms mcg of retinol activity equivalents RAE to account for different absorption rates of preformed vitamin A and provitamin A carotenoids.

The evidence suggests that eating a variety of foods rich in vitamin A, especially fruits and vegetables , is protective from certain diseases, though the health benefit of vitamin A supplements is less clear. Lung Cancer: Observational studies following nonsmokers and current or former smokers have found that higher intakes of carotenoids from fruits and vegetables are associated with a lower risk of lung cancer.

However, three large clinical trials did not find that supplements of beta-carotene and vitamin A helped to prevent or reduce lung cancer risk.

In fact, two of those three trials actually found a significant increase in lung cancer risk among study participants taking supplements with beta-carotene or retinyl palmitate a form of vitamin A. Additionally, based on current evidence the U. Preventive Services Task Force advises against the use of beta-carotene supplements for the prevention of any cancer, stating that there is potentially greater harm in using these supplements than any suggested benefit.

Prostate Cancer: Lycopene is a carotenoid that gives fruits and vegetables a pink or red hue, as in tomatoes and grapefruit. Observational studies have noted a decreased risk of prostate cancer in men who eat high amounts of fruits and vegetables.

Unfortunately, studies have not provided a clear answer specific to lycopene. Observational studies and clinical trials have shown either a protective effect of lycopene-rich foods specifically tomatoes or supplements, or no effect.

The randomized controlled Mediterranean-DASH Intervention for Neurodegenerative Delay MIND trial examines the effects of the MIND diet to prevent cognitive decline. It found that higher blood levels of alpha-carotene a form of vitamin A that includes lutein and zeaxanthin were associated with better cognition e.

Age-related macular degeneration AMD is a common painless eye condition but a leading cause of vision loss among people age 50 and older. It distorts the sharp, central vision needed to see fine details such as for reading and driving. The exact cause is unclear but oxidative stress is believed to play a role.

Smokers and those with poor diets lacking fruits and vegetables have a higher risk of developing AMD. Lutein and zeaxanthin are two carotenoids with protective antioxidant effects that are found in the retina, the eye tissue that is damaged by AMD.

Studies have looked to see if supplements containing lutein and zeaxanthin, as well as beta-carotene, might be useful for preventing or treating this condition. The NIH-funded Age-Related Eye Disease Studies AREDS, AREDS2 found that daily intakes of high-dose vitamins including vitamins C and E and lutein and zeaxanthin slowed the progression of intermediate and late-stage AMD, particularly in participants who ate the lowest amounts of carotenoids.

Many breakfast cereals, juices, dairy products, and other foods are fortified with retinol preformed vitamin A. Many fruits and vegetables and some supplements contain beta-carotene, lycopene, lutein, or zeaxanthin.

Deficiency Vitamin A deficiency is rare in Western countries but may occur. Also at risk are adults and children who eat a very limited diet due to poverty or self-restriction. Mild vitamin A deficiency may cause fatigue, susceptibility to infections, and infertility.

The following are signs of a more serious deficiency. Toxicity Vitamin A toxicity may be more common in the U. than a deficiency, due to high doses of preformed vitamin A retinol found in some supplements. Vitamin A is also fat-soluble, meaning that any amount not immediately needed by the body is absorbed and stored in fat tissue or the liver.

If too much is stored, it can become toxic. The tolerable upper intake of 3, mcg of preformed vitamin A, more than three times the current recommended daily level, is thought to be safe. However, there is some evidence that this much preformed vitamin A might increase the risk of bone loss, hip fracture [], or some birth defects.

Signs of toxicity include the following. In contrast to preformed vitamin A, beta-carotene is not toxic even at high levels of intake. The body can form vitamin A from beta-carotene as needed, and there is no need to monitor intake levels as with preformed vitamin A. Therefore, it is preferable to choose a multivitamin supplement that has all or the vast majority of its vitamin A in the form of beta-carotene; many multivitamin manufacturers have already reduced the amount of preformed vitamin A in their products.

However, there is no strong reason for most people to take individual high-dose beta-carotene supplements. Smokers in particular should avoid these, since some randomized trials in smokers have linked high-dose supplements with increased lung cancer risk.

The contents of this website are for educational purposes and are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

The Nutrition Source does not recommend or endorse any products. Skip to content The Nutrition Source. The Nutrition Source Menu. Search for:. Home Nutrition News What Should I Eat? Most dietary provitamin A in the U. diet comes from leafy green vegetables, orange and yellow vegetables, tomato products, fruits, and some vegetable oils [ 1 , 5 , 14 ].

Vitamin A is routinely added to some foods, including milk and margarine [ 1 , 2 ]. Some ready-to-eat cereals are also fortified with vitamin A.

Among U. Cooking and heat treatment can increase the bioavailability of beta-carotene from foods [ 19 ]. Table 2 lists a variety of foods and their vitamin A content per serving.

The foods from animal sources in Table 2 contain primarily preformed vitamin A, the plant-based foods have provitamin A, and the foods with a mixture of ingredients from animals and plants contain both preformed vitamin A and provitamin A.

Food and Drug Administration FDA developed DVs to help consumers compare the nutrient contents of foods and dietary supplements within the context of a total diet. FDA does not require food labels to list vitamin A content unless vitamin A has been added to the food. The U.

Vitamin A is available in stand-alone supplements and most multivitamins, often in the form of retinyl acetate, retinyl palmitate, provitamin A beta-carotene, or a combination [ 1 , 21 ]. Average daily intakes of vitamin A from foods and beverages in the United States were mcg RAE for men age 20 and older and mcg RAE for women in —, according to the National Health and Nutrition Examination Survey NHANES [ 23 ].

For children age 2—19, mean daily intakes of vitamin A from foods and beverages ranged from to mcg RAE. population [ 24 ].

The remainder comes from preformed vitamin A, mostly in the form of retinyl esters. population, depending on age, uses supplements containing vitamin A [ 25 ]. Adults age 71 years or older and children younger than 9 are more likely than members of other age groups to take supplements containing vitamin A.

Frank vitamin A deficiency is rare in the United States. However, vitamin A deficiency is still common in many developing countries, often as a result of limited access to foods containing preformed vitamin A from animal-based food sources and to foods containing provitamin A carotenoids because of poverty or traditional diets [ 1 , 26 ].

Limited research suggests that vitamin A deficiency may also be influenced by genetic variability in conversion rates of beta-carotene to vitamin A. Certain polymorphisms in the BCMO1 gene have been found to reduce the activity of the BCMO1 enzyme in humans [ 8 , 9 ], and a study in the Philippines among children and adolescents found an inverse association between vitamin A status and the AV TT variant in the BCMO1 gene [ 7 ].

The first sign is night blindness, or the inability to see in low light or darkness as a result of low rhodopsin levels in the retina [ 1 , 27 , 28 ].

Xerophthalmia also affects the cornea and can eventually lead to permanent blindness; vitamin A deficiency is one of the top causes of preventable blindness in children [ 28 ]. Chronic vitamin A deficiency has also been associated with abnormal lung development, respiratory diseases such as pneumonia , and an increased risk of anemia and death [ 26 , 27 , 29 ].

Another effect of chronic vitamin A deficiency is increased severity and mortality risk of infections particularly measles and infection-associated diarrhea [ 26 ]. In , 94, children in low-income and middle-income countries died of diarrhea and 11, died of measles as a result of vitamin A deficiency [ 27 ].

Preterm infants have low liver stores of vitamin A at birth, and their plasma concentrations of retinol often remain low throughout the first year of life [ 30 , 31 ].

Preterm infants with vitamin A deficiency have a higher risk of eye and chronic lung diseases [ 32 , 33 ]. However, in high-income countries, clinical vitamin A deficiency is rare in infants and occurs only in those with malabsorption disorders [ 34 ].

Pregnant people need extra vitamin A for fetal growth and tissue maintenance and to support their own metabolism [ ]. However, in people with vitamin A deficiency, the vitamin A content of breast milk is not sufficient to maintain adequate vitamin A stores in infants who are exclusively breastfed [ 38 ].

About million preschool-age children one-third of all children in this age group , mostly in Africa and Southeast Asia, have vitamin A deficiency, according to the World Health Organization [ 27 , 39 ]. They have a higher risk of visual impairment and of illness and death from childhood infections, such as measles and infections that cause diarrheal diseases [ 1 , 39 ].

The World Health Organization estimates that 9. As a result, standard care for cystic fibrosis includes lifelong treatment with vitamin A daily amounts of mcg RAE to 3, mcg RAE, depending on age, are recommended in the United States and Australia , other fat-soluble vitamins, and pancreatic enzymes [ 41 , 43 ].

Although some evidence supports the use of vitamin A supplements in people with these disorders [ 46 ], other research has found that supplementation offers no benefit [ 47 ].

Some children and adults with newly diagnosed celiac disease also have vitamin A deficiency; a gluten-free diet can, but does not always, eliminate this deficiency [ ]. This section focuses on three diseases and disorders in which vitamin A or carotenoids might play a role: cancer, age-related macular degeneration AMD , and measles.

Because of its role in regulating cell growth and differentiation, several studies have examined the association between vitamin A and various types of cancer. However, the relationship between serum vitamin A levels or vitamin A supplementation and cancer risk or cancer-related death is unclear.

This fact sheet does not include studies of all-trans retinoic acid, a vitamin A metabolite that is used as a drug in high doses to treat a form of leukemia [ 52 , 53 ]. Several systematic reviews and meta-analyses of observational studies have shown that higher dietary intakes of retinol, carotenoids, fruits and vegetables, or a combination are associated with a lower risk of lung cancer [ 54 ], non-Hodgkin lymphoma [ 55 ], pancreatic cancer [ 56 ], oral cavity cancer [ 57 ], laryngeal cancer [ 57 ], esophageal cancer [ 58 ], ovarian cancer [ 59 , 60 ], glioma [ 61 ], and bladder cancer [ 62 ].

However, other observational studies have found no association between intakes of different forms of vitamin A and risk of liver cancer [ 63 ], non-Hodgkin lymphoma [ 64 ], colorectal cancer [ 65 ], prostate cancer [ 65 ], or all cancers [ 66 ].

Some clinical trial evidence suggests that supplemental vitamin A might reduce the risk of certain cancers but increase the risk of other forms of cancer, cardiovascular disease morbidity and mortality, and all-cause mortality.

Examples are provided below. The Carotene and Retinol Efficacy Trial CARET included 18, male and female current and former smokers with at least a 20 pack-year history [equivalent to smoking 1 pack per day for 20 years or 2 packs per day for 10 years, for example] of cigarette smoking as well as some men occupationally exposed to asbestos who also have a higher risk of lung cancer , all age 45—74 years.

The study randomized participants to take supplements containing 30 mg beta-carotene plus 25, IU 7, mcg RAE retinyl palmitate or a placebo daily for about 6 years to evaluate the potential effects on lung cancer risk [ 67 ].

A subsequent study followed CARET participants for an additional 6 years after they stopped taking the study supplements [ 68 ]. The Alpha-Tocopherol, Beta-Carotene ATBC Cancer Prevention Study also found that beta-carotene supplements increased the risk of lung cancer in smokers [ 70 ].

In this study, 29, male smokers age 50—69 years who smoked an average of A subsequent study followed 25, of these participants for an additional 18 years [ 71 ].

During this period, participants were no longer taking the supplements, but most continued to smoke. The Age-Related Eye Disease Study 2 AREDS2 was a 5-year randomized clinical trial with 4, participants age 50—85 years examining the effects on AMD of a dietary supplement containing several ingredients with or without beta-carotene 15 mg [7, mcg RAE] [ 72 ].

No current smokers received the supplements containing beta-carotene. At the end of the trial, more lung cancers were discovered in the beta-carotene group than in the no beta-carotene group 23 vs.

Three other clinical trials have found no relationship between taking vitamin A or beta-carotene supplements and lung cancer incidence or mortality [ 74 ]. One trial randomized 22, male physicians age 40—84 years to take 50 mg beta carotene on alternate days or a placebo for 12 years [ 75 ].

The results showed no differences between the groups in number of cases of lung cancer or any malignant neoplasms or number of deaths from cancer. Another trial randomized 7, women mean age None of the supplements had any significant effect on total cancer incidence or cancer mortality, including from lung cancer.

A third trial included 29, healthy men and women age 40—69 years who were living in Linxian, China, where micronutrient deficiencies are common [ 77 ]. The study randomized participants to take either a placebo or one of four vitamin and mineral combinations including one providing retinol and zinc and another providing beta carotene, vitamin E, and selenium for 5.

The investigators followed participants for an additional 10 years after they stopped taking the supplements. The nutrient doses in the supplements were equivalent to or twice as high as U. recommended intakes, but the study report did not provide the exact doses. During both the intervention and follow-up periods, lung cancer death rates did not differ among the five groups, even when the investigators further analyzed the results for differences by age, sex, and smoking status.

The CARET and ATBC study results suggest that large supplemental doses of beta-carotene with or without retinyl palmitate have detrimental effects in current or former smokers and workers exposed to asbestos.

However, the other studies described above that used similar vitamin A doses but had smaller proportions of current or former smokers do not raise this concern. Among nonsmokers, beta-carotene and vitamin A supplements do not appear to affect the risk of cancer.

AMD is the leading cause of significant vision loss in older people [ 78 ]. Because of the role of oxidative stress in AMD pathophysiology, supplements containing carotenoids with antioxidant functions, such as beta-carotene, lutein, and zeaxanthin, might be useful for preventing or treating this condition.

Lutein and zeaxanthin which are not precursors of vitamin A , in particular, accumulate in the retina, the tissue in the eye that is damaged by AMD. The AREDS trial found that participants with a high risk of developing advanced AMD i.

The follow-up AREDS2 study confirmed the value of this supplement in reducing the progression of AMD over a median follow-up period of 5 years [ 72 ].

However, this follow-up study showed that adding lutein 10 mg and zeaxanthin 2 mg or omega-3 fatty acids to the formulation produced no additional benefits. Importantly, the follow-up study also revealed that beta-carotene was not a required ingredient; the original AREDS formulation without beta-carotene provided the same protective effect against developing advanced AMD.

A subsequent study monitored dietary intakes of several nutrients in 4, AREDS participants and 3, AREDS2 participants mean age 71 years for a median of

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, like 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.

Men who have been taking beta carotene supplements for 15 or more years are considerably less likely to experience cognitive decline than other males, researchers from Harvard Medical School reported in Archives of Internal Medicine November 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, 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. The BMJ published a report in March 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 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.

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

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.

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.

The RDA includes both preformed vitamin A and provitamin A carotenoids like beta carotene. According to the National Center for Complementary and Integrative Health NCCIH , beta carotene supplements are not linked with major negative effects, even with large supplement doses of —30 mg per day.

Over time, eating extremely high amounts beta carotene can result in a harmless condition called carotenodermia, where the skin turns a yellow-orange color. People who smoke, and possibly those who used to smoke, should avoid beta carotene supplements and multivitamins that provide more than percent of their daily value for vitamin A, either through preformed retinol or beta carotene.

This is because studies have linked high supplement doses of these nutrients with an increased risk of lung cancer in people who smoke. Health experts usually recommend eating a diet rich in fruits and vegetables, which are full of antioxidants as well as other important nutrients over taking beta carotene supplements.

Beta carotene supplements are generally safe, but they may present risks for people who smoke or used to smoke. Dietary sources are generally recommended over supplementation. Beta carotene is an important dietary compound and an important source of vitamin A.

Research has linked beta carotene intake with various health benefits. Eating a diet rich in fruits and vegetables is the best way to increase your beta carotene intake and prevent disease. Talk with your doctor or registered dietitian about specific ways to increase your intake of beta carotene.

Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available. This tasty, although odd-looking, melon is packed with nutrients.

Its health benefits might surprise you. The carrot is a root vegetable that is often claimed to be the perfect health food. It is highly nutritious, and loaded with fiber and antioxidants.

Sweet potatoes and yams are both tuber vegetables, but they're actually quite different. This article explains the key differences between sweet…. Antioxidants are incredibly important, but most people don't really understand what they are.

This article explains it all in human terms. Carotenoids are the bright-colored pigments in some of your favorite fruits and veggies. Learn about how they impact your immune system and health.

MindBodyGreen provides third-party-tested supplements made with high quality ingredients. Our testers and dietitians discuss whether MindBodyGreen…. Vitamins are for athletes to stay healthy. You may get all you need from the food you eat. Some athletes may benefits from vitamin supplements.

Docosahexaenoic acid, or DHA, is a type of omega-3 fat that may improve many aspects of your health, from your brain to your heart. Here are 12…. A Quiz for Teens Are You a Workaholic?

How Well Do You Sleep? Health Conditions Discover Plan Connect. Benefits of Beta Carotene and How to Get It. Medically reviewed by Jillian Kubala, MS, RD , Nutrition — By Natalie Olsen, R. Benefits Foods sources Dosage Risks Bottom line Beta carotene plays an important role in your health and eating lots of fresh fruits and vegetables is the best way to get it into your diet.

Share on Pinterest. Avoiding bias in observational studies: part 8 in a series of articles on evaluation of scientific publications. Deutsches Arzteblatt international , 41 , — Johnson EJ. The role of carotenoids in human health.

Nutr Clin Care. Panche AN, Diwan AD, Chandra SR. Flavonoids: an overview. J Nutr Sci. Published Dec Rein, M. Bioavailability of bioactive food compounds: a challenging journey to bioefficacy. British journal of clinical pharmacology , 75 3 , — Department of Health and Human Services.

Antioxidants: In depth. National Center for Complementary and Integrative Health. About UGA Visit UGA Extended Campuses Campus Map Master Calendar Employment.

Helpful Links MyUGA Athena eLearning Commons UGA Bulletin Academic Calendars.