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Beta Carotene

Beta-carotene is a member of the carotenoids, which are highly pigmented, fat-soluble compounds present in many fruits, grains, oil and vegetables (green plants, carrots, sweet potatoes, squash, spinach, apricots, and green peppers).

The carotenes possess antioxidant properties. Vitamin A serves several biological functions including involvement in the synthesis of certain glycoproteins. Vitamin A deficiency leads to abnormal bone development, disorders of the reproductive system, xerophthalmia, and ultimately death.

Commercially available beta-carotene is produced synthetically or from palm oil, algae, or fungi. Beta-carotene is converted to retinol, which is essential for vision and is subsequently converted to retinoic acid, which is used for processes involving growth and cell differentiation.

Beta-carotene in doses of 20mg daily for 5-8 years has been associated with an increased risk of lung and prostate cancer and increased total mortality in people who smoke cigarettes, and in people with a history of high-level asbestos exposure. Beta-carotene 20-30mg daily in smokers may also increase cardiovascular mortality by 12% to 26%. Therefore, smokers and people with a history of asbestos exposure should not use beta-carotene supplements. These adverse effects do not appear to occur in people who eat foods high in beta-carotene content.

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Evidence
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence Grade*
Erythropoietic protoporphyria
Erythropoietic protoporphyria is a rare inherited genetic disorder of porphyrin-heme metabolism which has skin and systemic manifestations, including photosensitivity (painful skin sensitivity to sunlight), as well as gallstones and liver dysfunction. It is usually recognized during childhood. The over-the-counter synthetic beta-carotene product Lumitene is FDA approved for photoprotection in this disease. Effects may take 4-6 weeks to occur. Antihistamines may also be used to reduce symptoms. A

Carotenoid deficiency
Although consumption of provitamin A carotenoids (alpha-carotene, beta-carotene, and beta-cryptoxanthin) can prevent vitamin A deficiency, no overt deficiency symptoms have been identified in people consuming low-carotenoid diets if they consume adequate vitamin A. Recommendations by the National Cancer Institute, American Cancer Society, and American Heart Association to consume a variety of fruits and vegetables daily are aimed, in part, at increasing intakes of carotenoid-rich vegetables. After reviewing the published scientific research, the Food and Nutrition Board of the Institute of Medicine (IOM) concluded that the existing evidence in 2000 was insufficient to establish a recommended dietary allowance (RDA) or adequate intake (AI) for carotenoids. C

Cataract prevention
Study results of beta-carotene supplementation for cataract prevention are conflicting. Further well-designed clinical trials are needed before a conclusion can be drawn. C

Chemotherapy toxicity
Observational research suggests that greater dietary intake of beta-carotene may lower the incidence of adverse effects in children undergoing chemotherapy for lymphoblastic leukemia. However, in theory high-dose antioxidants may interfere with the activity of some chemotherapy drugs or radiation therapy. Therefore, individuals undergoing cancer treatment should speak with their oncologist if they are taking or considering the use of high dose antioxidants. Additional evidence is needed in this area before a clear conclusion can be drawn. C

Chronic obstructive pulmonary disease (COPD)
The prevalence of bronchitis and dyspnea in male smokers with chronic obstructive pulmonary disorder (COPD) seems to be lower in those patients who consume a diet containing high amounts of beta-carotene. However, beta-carotene supplements have not been proven to benefit COPD and may actually increase cancer rates in smokers. C

Cystic fibrosis
Individuals with cystic fibrosis may be deficient in beta-carotene and vitamin E, and it has been suggested that they may be more susceptible to oxidative damage. Theoretically, these patients may benefit from beta-carotene supplementation. Further research is needed before a conclusion can be drawn. C

Exercise-induced asthma prevention
Based on preliminary evidence, taking a mixture of beta-carotene isomers orally may prevent exercise-induced asthma. However, because synthetic beta-carotene has not been well tested for this indication, the difference between the activities of the two supplements cannot be deduced. Further research is needed before a recommendation can be made. C

Immune system enhancement
Preliminary research of beta-carotene for immune system maintenance or stimulation shows mixed results. Further research is needed before a conclusion can be drawn. C

Macular degeneration
Taking beta-carotene and other antioxidants has been proposed to help prevent or delay progression of age-related macular degeneration. However, other dietary carotenoids such as lycopene, lutein, and zeaxanthin may provide greater protection from radiation and oxidative damage in the retina than beta-carotene. Further research is needed before a conclusion can be drawn. C

Oral leukoplakia
Taking beta-carotene orally seems to induce remission in patients with oral leukoplakia. Further research is needed to confirm these results. C

Osteoarthritis
Beta-carotene supplementation does not appear to prevent osteoarthritis, but it might slow progression of the disease. Well-designed clinical trials are needed before a conclusion can be drawn. C

Polymorphous light eruption (PLE)
75 to 180mg of beta-carotene (the equivalent of 125,000 to 300,000 Units of vitamin A activity) a day has been used for PLE. C

Pregnancy-related complications
All-trans beta-carotene (synthetic beta-carotene) taken weekly before, during, and after pregnancy may reduce pregnancy-related mortality, night blindness, post partum diarrhea and fever. Synthetic beta-carotene has not been proven to reduce fetal and early infant mortality. Doses of 2400 micrograms of beta-carotene (red palm oil) has been reported to significantly improve maternal and neonatal vitamin A status and reduce the prevalence of maternal anemia. A regular intake of a micronutrient supplement at a nutritional dose may be sufficient to improve micronutrient status of apparently healthy pregnant women and could prevent low birth weight of newborn. However, further research is necessary to consolidate the evidence in this area before a clear recommendation can be made. C

UV-induced erythema prevention/sunburn
A combination of antioxidants may help protect the skin against irradiation. Long-term supplementation with beta-carotene may reduce UV-induced erythema, and appears to modestly reduce the risk of sunburn in individuals who are sensitive to sun exposure. However, beta-carotene is unlikely to have much effect on sunburn risk in most people. Some study results conflict. Taking beta-carotene orally can reduce photosensitivity in patients with erythropoietic protoporphyria (EPP), a genetic disorder resulting in defective porphyrin metabolism. It does not seem to reduce the incidence of solar keratoses or skin cancers associated with sun exposure. C

Abdominal aortic aneurysm (AAA) prevention
Long-term supplementation with alpha-tocopherol or beta-carotene has been shown not to have a protective or preventive effect in male smokers with large AAAs. D

Alzheimer's disease
Intake of dietary or supplemental beta-carotene has been shown not to have any effect on Alzheimer's disease risk. D

Angioplasty
There is some concern that when antioxidant vitamins, including beta-carotene, are used together they might have harmful effects in patients after angioplasty. A combination of beta-carotene 30,000 IU, vitamin C 500mg, and vitamin E 700 IU daily started 30 days before angioplasty, and continued for 6 months thereafter, seems to prevent beneficial vascular remodeling in patients after angioplasty by promoting fibrosis at the site of angioplastic intervention. Additional research is needed to determine the effect of beta-carotene specifically. Supplements containing these vitamins should be avoided immediately before and following angioplasty without the recommendation of a qualified healthcare professional. D

Birthmark/mole (dysplastic nevi) prevention
Beta-carotene has been shown not to reduce the development of new moles in patients with numerous atypical moles. D

Cancer
While diets high in fruits and vegetables rich in beta-carotene have been shown to potentially reduce the incidence of certain cancers, results from randomized controlled trials with oral supplements do not support this claim. There is some concern that beta-carotene metabolites with pharmacological activity can accumulate and potentially have cancer causing (carcinogenic) effects. A higher, statistically significant incidence of lung cancer in male smokers who took beta-carotene supplements has been discovered. Beta-carotene/vitamin A supplements may have an adverse effect on the incidence of lung cancer and on the risk of death in smokers and asbestos exposed people or in those who ingest significant amounts of alcohol. In addition, high-dose antioxidants theoretically may interfere with the activity of some chemotherapy drugs or radiation therapy. Therefore, individuals undergoing cancer treatment should speak with their oncologist if they are taking or considering the use of high dose antioxidants. Beta-carotene in the amounts normally found in food does not appear to have this adverse effect. D

Cardiovascular disease
Although several observational epidemiological studies suggest that diets high in fruits and vegetables containing beta-carotene appear to reduce the risk of cardiovascular disease, most randomized controlled trials with oral supplements of beta-carotene have not supported these claims. A Science Advisory from the American Heart Association states that the evidence does not justify use of antioxidants such as beta-carotene for reducing the risk of cardiovascular disease. D

Helicobacter pylori bacteria eradication
Infection with Helicobacter pylori bacteria in the gut can lead to gastric ulcers. Dietary supplementation with beta-carotene has not been found to be effective for this indication. D

Mortality reduction
Patients given beta-carotene supplements show no reduction in relative mortality rates from all causes based on most available data. D

Postoperative tissue injury prevention
Study results conclude that peri-operative supplementation with antioxidant micronutrients has limited effects on strength and physical function following major elective surgery. D

Stroke
Taking all-trans beta-carotene (synthetic beta-carotene) orally, 20mg daily for a median of six years, has been reported to have no effect on the overall incidence of stroke in male smokers. Additionally, there is some evidence that beta-carotene actually increases the risk of intracerebral hemorrhage by 62% in patients who also drink alcohol. D

Key to grades
A Strong scientific evidence for this use
B Good scientific evidence for this use
C Unclear scientific evidence for this use
D Fair scientific evidence against this use (it may not work)
F Strong scientific evidence against this use (it likely does not work)

Grading rationale

Uses based on tradition or theory
The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Acute respiratory infections, anemia, angina pectoris, asbestosis, benign breast disease, bone marrow transplantation, cell-to-cell communication, cervical cancer, chronic atrophic gastritis, chronic myeloid leukemia, colorectal cancer, diabetes, esophageal cancer, exercise-induced bronchoconstriction symptoms in young athletes, Graves' disease, group A streptococcal infections, high cholesterol, HIV, improving lung function, improving micronutrient status during alcohol rehabilitation, iron deficiency prevention, multiple myeloma, nasal polyposis, night vision, post-partum weight management, reduction of bronchopulmonary dysplasia without increasing mortality or neurodevelopmental impairment in extremely low birth weight infants, low birth weight prevention, sepsis, supratentorial glioblastoma, weight loss in HIV patients.

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Dosing
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
General:

Formulations : Beta-carotene supplements are available in both oil matrix gelatin capsules and water-miscible forms. Some clinical trials have used water-miscible beta-carotene (10%) beadlets. The water miscible form seems to produce a significantly higher response in plasma beta-carotene (approximately 47% to 50%) than oil matrix gelatin capsules. Oral dosage is available in capsules (U.S. and Canada), tablets (U.S. and Canada), and chewable tablets (Canada).

Dietary intake : Consuming 5 servings of fruit and vegetables daily provides 6-8mg of beta-carotene. Beta-carotene requires some dietary fat for absorption, but supplemental beta-carotene is similarly absorbed when taken with high-fat or low-fat meals. 1800 micrograms of beta-carotene has been reported to maintain adequate vitamin A levels.

Consensus recommendations : The American Heart Association recommends obtaining antioxidants, including beta-carotene, from a diet high in fruits, vegetables and whole grains rather than through supplements, until more information is available from randomized clinical trials. Similar statements have been released by the American Cancer Society, the World Cancer Research Institute in association with the American Institute for Cancer Research, and the World Health Organization's International Agency for Research on Cancer. The Institute of Medicine has reviewed beta-carotene, but has not make recommendations for daily intake, citing lack of sufficient evidence. Routine use of beta-carotene supplements is not considered necessary in the general population.

Adults (18 years and older):

Oral:

Erythropoietic protoporphyria (EPP) : Taking beta-carotene orally can reduce photosensitivity in patients with EPP, a genetic disorder resulting in defective porphyrin metabolism. In adults, 120-300 mg/day orally in divided doses has been used to maintain a blood carotene level between 4-6mcg/ml. Dosage may be adjusted based on age. Effects may take 4-6 weeks to occur. Treatment should be under medical supervision.

Age-related macular degeneration (AMD) : Beta-carotene 15mg plus vitamin C 500mg, zinc oxide 80mg, and vitamin E 400IU has been given daily for AMD.

Antioxidant : Clinical significance is unknown. Various dosing regimens have been suggested, often in combination with other antioxidants. For example, consumption of 2mg beta-carotene/100ml, 40mg alphatocopherol/100ml, 1mg zinc/100ml, 0.1mg copper/100ml and 10mcg selenium/100ml over 4 weeks has been reported to increase antioxidant activity in the body. In well-nourished healthy elderly individuals, supplementation with relatively low levels of beta-carotene (8.2mg) or lycopene (13.3mg) does not appear to affect cell-mediated immunity.

Gastric cancer prevention : 15-30mg daily has been used in people at high risk, although this has not been proven effective.

Maternal anemia :2400 micrograms of beta-carotene (red palm oil) has been used to improve maternal and neonatal vitamin A status and reduce the prevalence of maternal anemia.

Oral leukoplakia : 60mg daily for 6 months has been used.

Polymorphous light eruption : 75 to 180mg of beta-carotene (the equivalent of 125,000 to 300,000 Units of vitamin A activity) daily has been used.

Prostate cancer prevention : In men with blood carotene levels below 153.25 ng/mL, 50mg every other day has been suggested to reduce the risk of developing prostate cancer. However, some studies have reported an increased risk of other types of cancers with beta-carotene supplementation.

Sunburn prevention : In sun-sensitive individuals, beta-carotene 25mg orally daily has been used.

Children (younger than 18 years):

Oral:

General : There is insufficient available data to recommend high-dose oral supplementation in children.

Photosensitivity (erythropoietic protoporphyria (EPP)/polymorphous light eruption) :30 to 150mg of beta-carotene daily, taken orally in divided doses (the equivalent of 50,000 to 250,000 Units of vitamin A activity) may be used. Dosage may be adjusted based on age. For ages 1 to 4, the daily dose may be 60-90mg; for ages 5 to 8 years, 90-120mg; for ages 9 to 12 years, 120-150mg; for ages 13 to 16 years, 150-180mg; for age 16 and older, 180mg. If adequate photoprotection is not provided by theses doses, beta-carotene may be increased by 30-60mg per day for children under 16 years old, and up to a total of 300mg daily for people older than 16 years-old. Effects may take 4-6 weeks to occur. Treatment should be under medical supervision.

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Safety
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
Allergies

People who are sensitive to beta-carotene, vitamin A or any other ingredients in beta-carotene products should avoid supplemental use.

Side Effects and Warnings

Likely safe : When beta-carotene is consumed in amounts found naturally in foods, or when consumed in oral supplement doses of 15mg/day or less in people with good general health, when used orally and appropriately. Beta-carotene is likely safe in children, when used orally in amounts commonly found in foods. Beta-carotene is likely safe in pregnant and lactating women, when used orally and appropriately in amounts commonly found in foods.

Possibly safe :When used orally as a dietary supplement. Doses up to 300mg daily have been used with apparent safety for conditions such as erythropoietic protoporphyria. However, doses as low as 20mg daily have been associated with increased risk of lung and prostate cancer in adults who smoke. Although there is no evidence of significant adverse effects of beta-carotene in nonsmokers, the mechanism for cancer promotion is unknown. If beta-carotene supplements are used, it may be advisable to limit daily consumption to 7mg per day until more is known about its long-term toxicity. In children, when used orally as a dietary supplement, high doses (greater than 60mg daily) have been used with apparent safety for conditions such as erythropoietic protoporphyria. Supplemental beta-carotene in children should be limited to specific medical indications. There is insufficient reliable information available about the safety of large doses of beta-carotene in pregnancy and lactation.

Possibly unsafe :When used orally in people who smoke or have a history of asbestos exposure. Supplemental beta-carotene 20mg daily for 5-8 years seems to increase the risk of lung cancer, prostate cancer, intracerebral hemorrhage, and cardiovascular and total mortality in people who smoke cigarettes or have a history of high-level exposure to asbestos. Beta-carotene from foods does not seem to have this effect. Plasma concentration of beta-carotene below 0.25 µmole/L has also been associated with an increased risk of cancer. Eating disorders, kidney disorders, and liver diseases may cause high blood levels of beta-carotene, which may increase the risk of side effects.

Carcinogenic : Beta-carotene in doses of 20mg daily for 5-8 years has been associated with an increased risk of lung and prostate cancer and increased total mortality in people who smoke cigarettes, and in people with a history of high-level asbestos exposure. Smokers and people with a history of asbestos exposure should not use beta-carotene supplements. These adverse effects do not seem to occur in people who eat foods high in beta-carotene content.

Cardiovascular : In people who smoke, beta-carotene 20 to 30mg daily may increase cardiovascular mortality by 12% to 26%. In men who smoke and have had a prior myocardial infarction (MI), the risk of fatal coronary heart disease increases by as much as 43% with beta-carotene 20mg daily. There is some evidence that beta-carotene in combination with selenium, vitamin C and vitamin E might lower high-density lipoprotein 2 (HDL2) cholesterol levels. HDL levels are protective so this is considered to be a negative effect.

Dermatologic :Reversible yellowing of palms, hands, or soles of feet and to a lesser extent the face (called carotenoderma) can occur with high doses of beta-carotene.

Gastrointestinal : Loose stools and diarrhea have been reported.

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