Asthma And The Role Of Carotenoids

Remember when you were a child and your mother told you to eat your vegetables? Mom was onto something: Vegetables and fruits, especially those brightly colored ones, are rich in substances called carotenoids. Carotenoids are important not only because they give your salads and fruits those wonderful colors, but also because they fight cancer and are potent antioxidants that can protect you against asthma. In fact, the reason why plants make carotenoids is to protect themselves from free radicals. So, whenever you hear the word "vegetable" or "fruit," a smile should come to your face and the word "good" should fall from your lips.

 

There are about 600 different carotenoids, but only fourteen of these fat-soluble compounds concern the well-being of humans, with most of the excitement over five in particular—alpha-carotene, beta-carotene, lycopene, lutein, and zeaxanthin. Besides being important for lung health, these carotenoids play important roles in preventing heart disease, cataracts, and macular degeneration. Asthmatics tend to get shortchanged when it comes to antioxidants, and studies have found that many asthmatics are deficient in beta-carotene. Even worse, decreased dietary beta-carotene may increase cancer risk and cardiovascular disease. Besides protecting our lungs from oxidative stress, carotenoids are essential for making vitamin A, which is needed for a healthy immune system. This is especially important for asthmatics considering that viral infections can cause asthma exacerbations.

 

That carotenoids play an important role in immune function is an accepted fact, but whether or not carotenoids enhance immune function independently or through vitamin A remains controversial. There is, however, evidence that dietary beta-carotene independently boosts immune function and protects against cancer. It's probably better to let the scientists sort this out while you just eat your vegetables. The important message is that carotenoids can help your asthma, in particular by protecting you against viral infections, which can make an asthmatic's life miserable.

 

One Israeli randomized, double-blind, placebo-controlled trial of thirty-eight patients with exercise-induced asthma (EIA) examined the effect of giving the subjects 64 mg of natural beta-carotene per day. The study found that 53 percent of the subjects who took beta-carotene "were protected against EIA." Another study from the same group examined the effect of supplementing with lycopene (30 mg daily) in twenty patients with EIA for one week. In the lycopene group, 55 percent of the patients were significantly protected against EIA, most probably through an antioxidative effect, according to the authors.

 

 

Alpha-carotene is abundant in carrots and leafy green vegetables. Most authorities recommend at least 6.5 mg of alpha-carotene a day. Drug interactions with bile-acid sequestrants and colestipol are reported, so talk to your doctor before supplementing with alpha-carotene if you're taking any of these medications.

 

 

Beta-carotene is found in broccoli, cantaloupe, carrots, pink grapefruit, sweet potatoes, and virtually all leafy green vegetables. While there are no official guidelines for carotenoid intake, the typical daily dose of 15 mg (or 25,000 IU) of natural beta-carotene a day is a good start.

 

I emphasize "natural" beta-carotene because studies have suggested that smokers (especially smokers who drink alcohol) who take synthetic beta-carotene may actually increase their risk of lung cancer. If you smoke, avoid synthetic beta-carotene supplements and stick with good old-fashioned fruits and vegetables. Another reason to avoid synthetic beta-carotene is that it does not pack the antioxidant punch found in the natural product.

 

If you decide to take additional beta-carotene, stick to naturally derived sources that come from Dunaliella salina algae. Don't go overboard with beta-carotene, since doses over 30 mg a day can turn your skin yellow-orange; this side effect is reversible by stopping supplementation. You should also take additional vitamin E, as prolonged beta-carotene supplementation may reduce vitamin E levels. As for drug interactions, beta-carotene can react with bile-acid sequestrants, cisplatin, colchicine, colestipol, cyclophosphamide, docetaxel, lansoprazole, methyltestosterone, mineral oil, neomycin, orlistat, paclitaxel, quinidine, and chemotherapy drugs. Check with your doctor before supplementing with beta-carotene if you're taking any of these medications.

 

 

To boost lycopene levels, eat plenty of apricots, carrots, green peppers, and tomatoes. Tomato paste and sauce are particularly rich sources of lycopene, a carotenoid antioxidant that appears to be more powerful than beta-carotene and is known to protect against a variety of diseases, including prostate cancer. There is also evidence that lycopene can protect against heart disease and boost immune function. Most authorities recommend at least 6.5 mg of lycopene per day. No drug interactions have been reported with lycopene.

 

 

Lutein-rich foods include corn, carrots, potatoes, spinach, lettuce, peas, egg yolks, tomatoes, and any leafy green vegetable. Typically, take at least 6 mg of lutein daily. No drug interactions have been reported with lutein.

 

 

Leafy green vegetables are particularly rich in zeaxanthin. Most authorities recommend 6 mg of zeaxanthin daily.

When shopping for fruits and vegetables, as a general rule remember that the more intense the color, the greater the concentration of carotenoids. A final word about cooking: Although carotenoids do not degrade with cooking, given the fact that cooking may destroy other vital nutrients, I recommend steaming your vegetables or eating them raw. Most authorities recommend, at a minimum, five to six fruit and vegetable servings daily.