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Supplements

beta-carotene

What Is It?
Health Benefits
Forms

Recommended Intake

If You Get Too Little

If You Get Too Much
How to Take It
General Dosage Information
Guidelines for Use

General Interaction
Cautions

Evidence Based Rating Scale
References
 

What Is It?

Beta-carotene is probably the best known of the carotenoids, those red, orange, and yellow pigments that give color to many fruits and vegetables. The body converts beta-carotene into Vitamin A, a nutrient first identified in the 1930s and now recognized as vital to the growth and development of the human body.

As a potent immune-system booster and a powerful Antioxidant—it counters the effects of molecules called free-radicals that damage cells—beta-carotene plays an important role in human health.

Consuming plenty of fruits and vegetables is the best way to supply the body with beta-carotene. In addition, beta-carotene is now sold in supplement form.

Scientists have long hoped that supplements could provide concentrated sources of beta-carotene and thus provide increased protection against heart disease and even against certain cancers. But disappointing results from the well-publicized Harvard University Physicians' Health Study, in which more than 22,000 U.S. male physicians took 50 mg of beta-carotene every other day for nearly 13 years, showed no beneficial effects of increased intake of beta-carotene supplements in the prevention of major cardiovascular events or cancer. (1, 2) In fact, some large-scale studies indicate that single, high-dose beta-carotene supplements may actually do more harm than good--possibly increasing (rather than decreasing) the number of cell-damaging free-radicals in the body. Most of the beneficial effects of beta-carotene supplementation appear to occur when it is taken in combination with vitamin C, vitamin E, selenium, and zinc.

Until more information is available, it's probably wise to get beta-carotene in supplement form only as part of a mixed complex, along with other health-promoting carotenoids. Look for products that combine beta-carotene with other carotenes, such as alpha-carotene, lycopene, lutein, zeaxanthin, and cryptoxanthin.

Health Benefits

In addition to the numerous studies on beta-carotene's effectiveness for heart disease and cancer, researchers have also explored the nutrient's potential for treating chronic fatigue syndrome, Alzheimer's disease, fibromyalgia, male infertility, and psoriasis. However, few studies have demonstrated any beneficial effects in these conditions.  

Specifically, beta-carotene, when taken in a comprehensive antioxidant program, may help to:

Slow progression of age-related macular degeneration (AMD). Patients with advanced stages of this condition, which is characterized by the degeneration of the macula—the central, most light-sensitive portion of the retina—may benefit from supplementation with beta-carotene; however evidence is conflicting. The principal damage in macular degeneration is likely caused by free radicals. The scavenging properties of beta-carotene, when taken in combination with vitamin C, vitamin E and zinc, have been shown to reduce the risk for loss of vision and progression of AMD in patients with advanced stages of the condition. The Age-Related Eye Disease Study involving more than 3,600 patients with varying stages of AMD found that in patients with advanced AMD, taking 15 mg of beta-carotene combined with 500 mg of vitamin C, 400 IU of vitamin E and 80 mg of elemental zinc daily reduced the risk of loss of vision by 27% and of progression of AMD by 25%. (3, 4) But, the study was unable to conclude whether this combination is beneficial for those with less advanced stages of macular disease. And note that taking beta-carotene along with the other antioxidants, but without zinc, did not seem to have any effect on AMD. (3, 5) A 1994 multi-center Eye Disease Case-Control Study involving more than 800 participants found that increasing dietary intake of beta-carotene may decrease the risk of developing AMD by up to 43%. (6) However, conflicting evidence found that consuming above average amounts of beta-carotene was only efficacious in combination with nutrients like vitamin C, vitamin E and zinc, which helped to reduce risk by up to 35%. (7, 8)

Prevent recurrent bronchitis. When combined with flavonoids, beta-carotene acts as an antioxidant and also helps to combat viral infections and inflammation. The nutrient may help to heal damaged lung tissue and reduce inflammation in patients with chronic bronchitis, as well as to prevent recurrent episodes.  As part of the Alpha-Tocopherol Beta-Carotene Cancer Prevention study with more than 29,000 participants, high intake of dietary beta-carotene and vitamin E was associated with a low prevalence of chronic bronchitis.  However, taking beta-carotene supplements did not seem to offer the same protection. (9)

Reduce risk of asthma. Low levels of vitamin A have been associated with increased risk of asthma and wheezing in children. (10) And a 2006 study of 218 patients with asthma or COPD found that an imbalance in nutrients like beta-carotene, lycopene and vitamin C was associated with chronic airflow limitation and oxidative stress. (11) A 2010 study of 41 patients with stable, persistent asthma showed that those with airway hyper-responsiveness (AHR), uncontrolled asthma and severe asthma have impaired antioxidant defenses and reduced levels of beta-carotene and alpha-tocopherol. These patients are, therefore, more susceptible to the damaging effects of oxidative stress, indicating a potential role for antioxidant supplementation. (12) However, an earlier meta-analysis of 10 studies involving more than 13,000 subjects found no association between dietary intake of beta-carotene, vitamin C and vitamin E and the risk of asthma. (13)

Prevent certain cancers. Beta-carotene's antioxidant actions make it valuable in protecting against,  precancerous conditions affecting the breast By examining results from a cohort of 83,234 women who were participating in the Nurses' Health Study in 1980, researchers evaluated the association between dietary beta-carotene and breast cancer and found that eating a diet high in beta-carotene may reduce the risk of breast cancer in premenopausal women. This was found to be especially true for those at high risk due to family history or high alcohol intake. (14, 15)  

To provide anti-cancer actions, however, beta-carotene must be taken as part of an antioxidant supplement formula featuring other carotenoids, vitamins C and E, and selenium. In fact, large studies indicate that beta-carotene taken as a single supplement offers no cancer-protective actions at all. (2) 

To confuse matters, an increased risk for lung cancer has actually been linked to beta-carotene supplements in smokers. In one highly publicized study, researchers in Finland found that more cases of lung cancer developed in male smokers (including former smokers) who were taking high doses of the supplement, particularly those who smoked twenty cigarettes or more a day. (16, 17) However, beta-carotene intake from food did not seem to have the same adverse effect. 

Several factors were considered responsible for this finding. Smokers typically have low levels of vitamin C, for example, which when combined with an excess of beta-carotene creates an imbalance that may result in an increase (rather than decrease) in the formation of cell-damaging Free radicals. 

In treating cancer with chemotherapy or radiation--both of which can damage healthy cells as they attack cancer cells--beta-carotene taken with other carotenoids, such as lycopene, and antioxidants such as vitamins C and E, may help to protect the body. Preliminary evidence suggests that increasing dietary intake of beta-carotene appears to guard against adverse side effects in children undergoing chemotherapy for lymphoblastic leukemia. (18) 

Improve male fertility. Antioxidants are important in protecting fragile sperm from free radical damage, which can lead to abnormal sperm and low sperm counts. Preliminary evidence indicates that beta-carotene from food and from supplements can have positive effects on sperm quality. In a 2005 study of 97 healthy, non-smoking men a higher intake of beta-carotene from food and supplements was associated with improved sperm concentration. (19) More research is needed. 

Prevent lupus. Preliminary studies point to a possible connection between low blood levels of beta-carotene (along with low levels of vitamins A and E) and subsequent development of lupus, an autoimmune disorder. (20-21) However, it's still not clear whether the low nutrient levels contribute to the development of lupus or whether they're the result of existing lupus that has not yet been diagnosed.

Forms 

  • capsule
  • liquid
  • powder
  • tablet

 

Recommended Intake

No RDA has yet been established for beta-carotene, but about 10,000 IU of this nutrient fulfills the RDA for vitamin A.

If You Get Too Little

Symptoms of a beta-carotene deficiency mimic those of a vitamin A deficiency: dry skin, night blindness, susceptibility to infection. Such deficiencies are seldom seen, however, even in people who don't eat fruits or vegetables or take supplements, because so many other foods supply the nutrient.

If You Get Too Much

It is nearly impossible to overdose on beta-carotene because the body excretes what it doesn't need. However, ingesting high levels of beta-carotene from foods (such as carrot juice) or from supplements can cause the palms of the hands and the soles of the feet to turn orange. If this occurs, consult a doctor. In most cases, the coloration is harmless and will gradually fade upon reduction of beta-carotene intake.

How to Take It

Special tips: By far the best sources of beta-carotene are fresh fruits and vegetables. Excellent sources include carrots, cantaloupe, and myriad other yellow, orange, and red fruits and vegetables. Green vegetables are also a good source. Choose dark ones such as broccoli, romaine lettuce, and spinach; the darker color indicates higher beta-carotene content.

As for supplements, the most effective and economical way to take beta-carotene is as part of a formula containing other significant health-promoting carotenoids, such as alpha-carotene, lycopene, lutein, zeaxanthin, and cryptoxanthin. Many products supply these carotenoids in one pill.

General Dosage Information

While the amount of beta-carotene converted to vitamin A and absorbed by the body varies, the measurement generally used on food and supplement labels expresses vitamin A activity as international units (IU). Some sources measure vitamin A activity in retinol activity equivalents (RAE), reported as ug/day rather than as IU; one RAE is equivalent to 3.3 IU of vitamin A.

Most multivitamins offer vitamin A as beta-carotene, as large amounts of vitamin A in supplement form can be toxic. However, the body will convert only as much vitamin A from beta-carotene as it needs. That means beta-carotene is considered a safe source of vitamin A.

For age-related macular degeneration: 15 mg of beta-carotene, plus 500 mg of vitamin C, 400 IU of vitamin E, and 800 mg of zinc oxide has been used.

For bronchitis: 5,000 IU of vitamin A activity has been used.

For asthma: No dosage has been established. 10,000 IU of beta-carotene fulfills the RDA for vitamin A.

As part of a program to prevent cancer: Take one dose daily of a mixed carotenoid supplement that provides 25,000 IU of vitamin A activity. For those at a particularly increased risk for cancer or trying to minimize the effects of cancer treatment on healthy cells, consider increasing the dose to two mixed-carotenoid pills daily.

For male infertility: No dosage has been established. 10,000 IU of beta-carotene fulfills the RDA for vitamin A.

For lupus: No dosage has been established. 10,000 IU of beta-carotene fulfills the RDA for vitamin A.

Guidelines for Use

Take beta-carotene and all other carotenoid supplements with food.

General Interaction

There are no known drug or nutrient interactions associated with beta-carotene.

Cautions

Those who have a sluggish thyroid (hypothyroidism), liver or kidney disease, or an eating disorder, should consult a doctor before trying beta-carotene supplements, as the conditions can interfere with conversion of beta-carotene. 

Many experts caution smokers to avoid beta-carotene supplements. The supplements are even riskier for smokers who also drink significant amounts of alcohol. 

Ingesting high levels of beta-carotene from either foods or supplements may lead to orange discoloration of the palms of the hands and the soles of the feet. If this occurs, consult a doctor. In most cases, the coloration is harmless and will gradually fade if upon reduction of the intake of beta-carotene.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.

 

Condition

Rating

Explanation

 

Asthma

   

Preliminary evidence indicates potential efficacy of beta-carotene supplementation to improve airflow and oxidative stress in patients with severe asthma. However, a meta-analysis found no beneficial effect of dietary intake of the nutrient. (10-13)

Bronchitis  
Favorable patient evidence indicates beta-carotene is necessary for maintaining healthy lung tissue and reducing inflammation. A large-scale trial showed higher intake of dietary beta-carotene is associated with a low prevalence of chronic bronchitis. However, supplemental beta-carotene did not offer the same protection. (9)
Cancer prevention  
Preliminary studies indicate some efficacy in preventing breast cancer in premenopausal women when mixed with other anti-oxidants, but conflicting evidence exists regarding other types of cancer. Large-scale studies indicate no efficacy, and a large-scale study indicates an increased risk of developing lung cancer male smokers taking it as a single supplement. (14-18)
Date Published: 04/18/2005
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