Main functions Beta-carotene and vitamin A play a vital part in the reproductive process. Demonstrated uses Beta-carotene and other carotenoids help reduce free radical damage in your body. Reasons for increased need Poor nutrition is a leading cause of beta-carotene and vitamin A deficiency. These problems can keep you from getting enough vitamin A: Lactose intolerance Celiac disease Sprue Cystic fibrosis Women who are pregnant or breastfeeding may need to take supplements.
Claims Beta-carotene may reduce the risk of some types of cancer, such as prostate cancer. Recommended intake There are no Dietary Reference Intakes for beta-carotene. Signs of deficiency Vitamin A deficiency can cause symptoms such as, night blindness, fatigue, skin issues, and a weakened immune system.
Interactions Orlistat, a medicine for weight loss, decreases fat absorption in the body. You should not use vitamin A or beta-carotene supplements if you take any of these medicines, as they contain derivatives of vitamin A: Isotretinoin Acitretin Etretinate. Age years. Children mcg RAE. Males mcg RAE. Females mcg RAE. Pregnancy mcg RAE.
Lactation mcg RAE. Males and Females mcg RAE. Sweet potato, baked in skin, 1 whole. Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes.
Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. Any use of this site constitutes your agreement to the Terms and Conditions and Privacy Policy linked below. This site complies with the HONcode standard for trustworthy health information: verify here. This content does not have an English version.
This content does not have an Arabic version. AMD's etiology is usually unknown, but the cumulative effect of oxidative stress is postulated to play a role. If so, 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, in particular, accumulate in the retina, the tissue in the eye that is damaged by AMD.
A 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 but found that adding lutein 10 mg and zeaxanthin 2 mg or omega-3 fatty acids to the formulation did not confer any additional benefits [ 31 ]. Importantly, the study 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.
Measles is a major cause of morbidity and mortality in children in developing countries. About half of all measles deaths happen in Africa, but the disease is not limited to low-income countries.
Vitamin A deficiency is a known risk factor for severe measles. The World Health Organization recommends high oral doses 60, mcg RAE [, IU] of vitamin A for two days for children over age 1 with measles who live in areas with a high prevalence of vitamin A deficiency [ 32 ].
A Cochrane review of eight randomized controlled trials of treatment with vitamin A for children with measles found that 60, mcg RAE , IU of vitamin A on each of two consecutive days reduced mortality from measles in children younger than 2 and mortality due to pneumonia in children [ 32 ]. Vitamin A also reduced the incidence of croup but not pneumonia or diarrhea, although the mean duration of fever, pneumonia, and diarrhea was shorter in children who received vitamin A supplements.
A meta-analysis of six high-quality randomized controlled trials of measles treatment also found that two doses of 30, mcg RAE , IU in infants and 60, mcg RAE , IU in older children significantly reduced measles mortality [ 33 ]. The vitamin A doses used in these studies are much higher than the UL. The effectiveness of vitamin A supplementation to treat measles in countries, such as the United States, where vitamin A intakes are usually adequate is uncertain.
The body needs vitamin A to maintain the corneas and other epithelial surfaces, so the lower serum concentrations of vitamin A associated with measles, especially in people with protein-calorie malnutrition, can lead to blindness. None of the studies evaluated in a Cochrane review evaluated blindness as a primary outcome [ 34 ]. However, a careful clinical investigation of African children with measles revealed that half of all corneal ulcers in these children, and nearly all bilateral blindness, occurred in those with vitamin A deficiency [ 35 ].
Because vitamin A is fat soluble, the body stores excess amounts, primarily in the liver, and these levels can accumulate. Although excess preformed vitamin A can have significant toxicity known as hypervitaminosis A , large amounts of beta-carotene and other provitamin A carotenoids are not associated with major adverse effects [ 36 ].
The manifestations of hypervitaminosis A depend on the size and rapidity of the excess intake. The symptoms of hypervitaminosis A following sudden, massive intakes of vitamin A, as with Arctic explorers who ate polar bear liver, are acute [ 37 ]. Chronic intakes of excess vitamin A lead to increased intracranial pressure pseudotumor cerebri , dizziness, nausea, headaches, skin irritation, pain in joints and bones, coma, and even death [ 2 , 4 , 5 ].
Although hypervitaminosis A can be due to excessive dietary intakes, the condition is usually a result of consuming too much preformed vitamin A from supplements or therapeutic retinoids [ 3 , 5 ]. When people consume too much vitamin A, their tissue levels take a long time to fall after they discontinue their intake, and the resulting liver damage is not always reversible. Observational studies have suggested an association between high intakes of preformed vitamin A more than 1, mcg daily—only slightly higher than the RDA , reduced bone mineral density, and increased fracture risk [ 1 , 4 , 38 ].
However, the results of studies on this risk have been mixed, so the safe retinol intake level for this association is unknown. Total intakes of preformed vitamin A that exceed the UL and some synthetic retinoids used as topical therapies such as isotretinoin and etretinate can cause congenital birth defects [ ]. These birth defects can include malformations of the eye, skull, lungs, and heart [ 4 ]. Women who might be pregnant should not take high doses of vitamin A supplements [ 2 ].
Unlike preformed vitamin A, beta-carotene is not known to be teratogenic or lead to reproductive toxicity [ 1 ]. The most significant effect of long-term, excess beta-carotene is carotenodermia, a harmless condition in which the skin becomes yellow-orange [ 1 , 23 ].
This condition can be reversed by discontinuing beta-carotene ingestion. Supplementation with beta-carotene, with or without retinyl palmitate, for 5—8 years has been associated with an increased risk of lung cancer and cardiovascular disease in current and former male and female smokers and in male current and former smokers occupationally exposed to asbestos [ 25 , 39 ]. In the ATBC study, beta-carotene supplements 20 mg daily were also associated with increased mortality, mainly due to lung cancer and ischemic heart disease [ 25 ].
The CARET study ended early, after the investigators found that daily beta-carotene 30 mg and retinyl palmitate 7, mcg RAE [25, IU] supplements increased the risk of lung cancer and cardiovascular disease mortality [ 39 ].
The FNB based these ULs on the amounts associated with an increased risk of liver abnormalities in men and women, teratogenic effects, and a range of toxic effects in infants and children. The FNB also considered levels of preformed vitamin A associated with decreased bone mineral density, but did not use these data as the basis for its ULs because the evidence was conflicting. The FNB advises against beta-carotene supplements for the general population, except as a provitamin A source to prevent vitamin A deficiency.
However, many dietary supplements such as multivitamins do not provide all of their vitamin A as retinol or its ester forms. For example, the vitamin A in some supplements consists partly or entirely of beta-carotene or other provitamin A carotenoids. In such cases, the percentage of retinol or retinyl ester in the supplement should be used to determine whether an individual's vitamin A intake exceeds the UL.
That amount is above the UL for children from birth to 8 years but below the UL for older children and adults. Vitamin A can interact with certain medications, and some medications can have an adverse effect on vitamin A levels. A few examples are provided below. Individuals taking these and other medications on a regular basis should discuss their vitamin A status with their healthcare providers.
The manufacturers of Alli and Xenical recommend encouraging patients on orlistat to take a multivitamin supplement containing vitamin A and beta-carotene, as well as other fat-soluble vitamins [ 41 , 42 ].
Several synthetic retinoids derived from vitamin A are used orally as prescription medicines. Retinoids can increase the risk of hypervitaminosis A when taken in combination with vitamin A supplements [ 40 ]. The federal government's Dietary Guidelines for Americans notes that "Because foods provide an array of nutrients and other components that have benefits for health, nutritional needs should be met primarily through foods.
In some cases, fortified foods and dietary supplements are useful when it is not possible otherwise to meet needs for one or more nutrients e. For more information about building a healthy dietary pattern, refer to the Dietary Guidelines for Americans and the U.
Department of Agriculture's MyPlate. This fact sheet by the Office of Dietary Supplements ODS provides information that should not take the place of medical advice. We encourage you to talk to your healthcare providers doctor, registered dietitian, pharmacist, etc. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis.
Antioxidant supplements for preventing gastrointestinal cancers. Cochrane Database Syst Rev. Nutr J. Prostate cancer and vegetable consumption. Mol Nutr Food Res. Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration. Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration. Emerging potentials for an antioxidant therapy as a new approach to the treatment of systemic sclerosis.
Carotenoids and the risk of developing lung cancer: a systematic review. Am J Clin Nutr. Antioxidant vitamins and cardiovascular disease: Dr Jekyll or Mr Hyde? Am J Public Health.
A double-blind placebo-controlled trial of antioxidant therapy in limited cutaneous systemic sclerosis. Clin Exp Rheumatol.
Hu G, Cassano PA. Am J Epidemiol. Can the Mediterranean diet prevent prostate cancer? Jeong NH, et al. Preoperative levels of plasma micronutrients are related to endometrial cancer risk. Acta Obstet Gynecol Scand. Modulation of lung molecular biomarkers by beta-carotene in the Physicians' Health Study.
Antioxidant vitamin supplementation for preventing and slowing the progression of age-related cataract. Beta carotene: from biochemistry to clinical trials. Carotenoids and vitamins C and E in the prevention of cardiovascular disease. Int J Vitam Nutr Res. Amount of fat in the diet affects bioavailability of lutein esters but not of alpha-carotene, beta-carotene, and vitamin E in humans.
Dietary carotenoid intake is associated with lower prevalence of metabolic syndrome in middle-aged and elderly men.
J Nutr. Sweetman, SC.
0コメント