Once considered just a potent source of vitamin A, beta-carotene has gained prominence as a disease-fighting substance. Today, experts think that beta-carotene, along with the related nutrients called carotenoids may protect against heart disease and cancer.
What it is
Beta-carotene is part of a larger team of nutrients known as carotenoids, which are the yellow-orange pigments found in fruits and vegetables. Because the body converts it to vitamin A, beta-carotene is sometimes called provitamin A. However, beta-carotene provides many additional benefits besides supplying the body with that vitamin.
What Does It Do
An immune system booster and powerful antioxidant, beta-carotene neutralizes the free radicals that can damage cells and promote disease. By acting directly on cells, it combats and may even reverse some disorders. It appears to be most effective when combined with other carotenoids.
• Acts as a preventive for cancer and heart disease.
• May reverse some precancerous conditions.
• Has cell-protecting properties that may aid in the treatment of a wide variety of ailments from Alzheimer's to male in fertility.
Beta-carotene is a celebrated soldier in the war on heart disease. Results from a survey of more than 300 doctors enrolled in the Harvard University Physicians' Health Study revealed that taking 50 mg (85,000 IU) of beta-carotene a day cut the risk of heart attack, stroke, and all cardiovascular deaths in half. Other studies have shown that it can prevent LDL ("bad") cholesterol from damaging the heart and coronary vessels. High levels of beta-carotene may also offer protection against cancers of the lung, digestive tract, bladder, breast, and prostate.
Acting as an antioxidant, beta-carotene has reversed some precancerous conditions, particularly those affecting the skin, mucous membranes, lungs, mouth, throat, stomach, colon, prostate, cervix, and uterus. Further, it has been shown to inhibit the growth of abnormal cells, strengthen the immune system, fortify cell membranes, and increase communication among cells.
One hint of concern did arise, however, about beta-carotene's cancer-fighting benefits. In the early 1990s, landmark studies in Finland and the United States found that male smokers taking beta-carotene supplements had an increased risk of lung cancer. Though some found the studies flawed, many experts caution smokers to maintain adequate beta-carotene levels through natural food sources, not supplements.
As an antioxidant, beta-carotene may be helpful for a wide range of additional ailments, including Alzheimer's disease, chronic fatigue syndrome, male infertility, fibromyalgia, psoriasis, and a number of vision disorders.
How Much You Need
There is no RDA for beta-carotene, although about 10,000 IU meets the RDA for vitamin A. Higher doses are needed, however, to provide the full antioxidant and immune-boosting effects.
If You Get Too Little: Signs of a beta-carotene deficiency are similar to those of inadequate vitamin A: poor night vision, dry skin, increased risk of infection, and the formation of precancerous cells. A deficiency may also increase your risk of cancer and heart disease. However, vitamin A deficiencies are rare: Even if you don't eat fruits and vegetables or take supplements, you can still meet your vitamin A needs with eggs, fortified milk, or other foods that supply it.
If You Get Too Much: It's almost impossible to get too much beta-carotene: The body discards what it doesn't process. If you ingest high levels (over 100,000 IU a day) your palms and soles may turn a harmless orange tone, which will disappear when you lower the dose.
How To Take It
Dosage: Beta-carotene is probably most effective when combined with other carotenoids in a mixed carotenoid formula. Most people benefit from 25,000 lU (15 mg) of mixed carotenoids a day. Those at high risk for cancer can take up to 50,000 lU (30 mg) twice a day.
Guidelines For Use: Take supplements with meals. No adverse effects have been noted in pregnant or nursing women taking up to 50,000 10 a day.
Carrots are a rich source of beta-carotene, as are other yellow, orange, and red fruits and vegetables, from sweet potatoes to cantaloupe. Green vegetables, such as broccoli, spinach, or lettuce, are also beneficial; the darker the green, the more beta-carotene they contain.
• Consult your physician before using beta-carotene if you have a sluggish thyroid (hypothyroidism), kidney or liver disease, or an eating disorder.
• Many experts recommend that smokers, particularly those who consume large amounts of alcohol, avoid beta-carotene supplements.
Purchase beta-carotene in combination with other carotenoids, such as lycopene, alpha-carotene, cryptoxanthin, zeaxanthin, and lutein. These combination formulas are an effective and economical way to boost your antioxidant levels.
Beta-carotene may help protect against many types of cancer, but in smokers, it may actually increase the risk of lung cancer. Recent studies show that this surprising effect seems strongest in men who smoke at least 20 cigarettes daily and increases further when alcohol intake is "above average." (Interestingly, former smokers do not appear to be at heightened risk.) One theory is that smokers generally have low vitamin C levels, and this imbalance causes beta-carotene to heighten, rather than decrease, free-radical formation.