Beta-carotene
Background
The name "carotene" was first coined in the early 19th Century by the scientist Wachenroder after he crystallized this compound from carrot roots. Beta-carotene is a member of the carotenoids, which are highly pigmented (red, orange, yellow), fat-soluble compounds naturally present in many fruits, grains, oil and vegetables (green plants, carrots, sweet potatoes, squash, spinach, apricots, and green peppers). Alpha, beta, and gamma carotene are considered provitamins because they can be converted to active vitamin A.
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 (a drying condition of the cornea of the eye), 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.
Synonyms
A-beta-carotene, alpha carotene, beta carotene, beta-cryptoxanthin, carotene, carotenoids, dry beta carotene, eyebright, gamma carotene, green leafy vegetables, palm oil, provitamin A, red palm oil, sunflower oil, synthetic all-trans beta-carotene, retinol.
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. 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. 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 shortness of breath 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) Beta-carotene has been used for PLE. Additional study is needed in this area. | 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. 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. | 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. 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 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 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;
F: Strong scientific evidence against this use.
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, bronchial asthma (exercise-induced bronchoconstriction symptoms in young athletes), bronchopulmonary dysplasia in premature infants, chronic atrophic gastritis, chronic myeloid leukemia, diabetes, Graves' disease, high cholesterol, HIV, improving lung function, iron deficiency prevention, low birth weight (prevention), multiple myeloma, nasal polyposis, nutrition supplementation (during alcohol rehabilitation ), sepsis, Streptococcal infections (group A), supratentorial glioblastoma, weight loss (HIV, post-partum).
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 6-8 milligrams 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. 1,800 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):
15-180 milligrams taken by mouth of supplemental beta-carotene has been studied for various indications.
Children (younger than 18 years):
There is insufficient available data to recommend high-dose oral (by mouth) supplementation in children.
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.
