SCIENTIFIC UPDATES
By Reed Mangels, Ph.D., R.D.
HOW MUCH BETA-CAROTENE DID YOU EAT TODAY?
Beta-carotene. What is it? If you answered, "Isn't that something from carrots that helps with night vision?" you would be close. Beta-carotene is a substance found in plants which our bodies convert to retinol (vitamin A). Vitamin A is essential for vision. Retinol is also found in foods but only in those from animals; so beta-carotene is an important source of vitamin A for many vegetarians.
In addition to its role as a vitamin A precursor, beta-carotene also functions as an anti-oxidant, protecting us from harmful oxidizing agents such as those found in cigarette smoke and pollution. Beta-carotene and other related substances (called carotenoids) have been proposed as a protective component in fruits and vegetables, which may explain why people who eat lots of fruits and vegetables have lower rates of many kinds of cancer. Alpha-carotene, lutein, and lycopene are among the other carotenoids which are found most commonly in our diets. Up until now, it was almost impossible to find out how much of these carotenoids someone ate. Tables with the amounts of alpha-carotene, lutein, and lycopene in foods simply did not exist.
Quantifying dietary carotenoids is an important step in evaluating their role in protection against disease. When I worked at the U.S. Department of Agriculture (USDA), one of my projects, in collaboration with other scientists at USDA and the National Cancer Institute, was to develop tables of carotenoids in foods. We also examined what the major sources of carotenoids are for women age 19 to 50 years. Their major source of alpha-carotene and beta-carotene was carrots; of lycopene was tomatoes; and of lutein was spinach and collard, turnip, or mustard greens. Table 1 will let you determine what are your major sources of these carotenoids.
At this point, scientists are not able to recommend how much of each carotenoid you need. However, if you look at Table 1 below, you will see many fruits and vegetables which provide substantial amounts of a variety of carotenoids. By choosing these foods as a regular part of your diet, you will not only get carotenoids, but also other nutrients found in fruits and vegetables.
Table 1. Important Sources of Carotenoids
| Beta-carotene | |
| 1/2 cup sweet potato | 7744 mcg* |
| 1/2 cup cooked carrots | 7154 mcg |
| 1 medium raw carrot | 5688 mcg |
| 1/2 cup cooked spinach | 5225 mcg |
| 1 cup cantaloupe chunks | 4800 mcg |
| 1/2 cup mashed pumpkin | 3782 mcg |
| 1/2 cup cooked kale | 3055 mcg |
| 1/2 cup mashed winter squash | 2448 mcg |
| 1 cup raw spinach | 2296 mcg |
| Alpha-carotene | |
| 1/2 cup mashed pumpkin | 4636 mcg |
| 1/2 cup cooked carrots | 2701 mcg |
| 1 medium raw carrot | 2592 mcg |
| Lycopene | |
| 1/2 cup tomato juice | 10,296 mcg |
| 1/2 cup tomato sauce | 7686 mcg |
| 1 cup watermelon chunks | 6560 mcg |
| 1/2 pink grapefruit | 4135 mcg |
| 1 medium tomato | 3813 mcg |
| 1/4 cup tomato paste | 2795 mcg |
| 1/2 guava | 2430 mcg |
| Lutein | |
| 1/2 cup cooked kale | 14,235 mcg |
| 1/2 cup cooked collard greens | 13,855 mcg |
| 1/2 cup cooked spinach | 11,970 mcg |
| 1/2 cup cooked Swiss chard | 9680 mcg |
| 1/2 cup cooked mustard greens | 7425 mcg |
| 1 cup chopped red pepper | 6800 mcg |
| 1 cup raw spinach | 5712 mcg |
| 1/2 cup cooked beet greens | 5544 mcg |
| 1/2 cup cooked okra | 5440 mcg |
| 1 cup romaine lettuce | 3192 mcg |
*mcg = microgram (1/1,000,000th of a gram)
For more information see: Mangels AR, Holden JM, Beecher GR, Forman MR, Lanza E: Carotenoid content of fruits and vegetables: An evaluation of analytic data. J Am Diet Assoc 93:284-296, 1993; and Chug-Ahuja JK, Holden JM, Forman MR, Mangels AR, Beecher GR, Lanza E: The development and application of a carotenoid database for fruits, vegetables, and selected multicomponent foods. J Am Diet Assoc 93:318-323, 1993.
