For Colon and Vision Support
Lutein Can Help Prevent Colon Cancer
ne of the marquee messages from the investigation of carotenoids substances found in many fruits and vegetables that give them their red, orange, or yellow color is that their chemical properties offer cancer-protection benefits. A new study, examining how specific carotenoids protect against particular types and stages of colon cancer, has found lutein to have the greatest protective effect.1
An inverse relationship between lutein intake and colon cancer was found, meaning that the more lutein-containing foods consumed, the less the risk of colon cancer. This was especially true for those who were relatively young when their cancer was diagnosed.
The study in question was led by Martha Slattery of the Health Research Center in Salt Lake City, Utah, where scientists examined 1993 subjects (30 to 79 years) who had been diagnosed with colon cancer. Reports of the foods they had eaten for two years before their diagnosis were compared with those of a control group of 2410 healthy people, and the nutrient contents of the foods were tabulated from a database of the known constituents of various foods.
Of all the carotenoids investigated, only lutein and zeaxanthin showed a protective effect against colon cancer. Subjects who consumed the most lutein were 17% less likely to contract colon cancer than those who consumed the least amount. The risk reduction was even greater for diagnoses of colon cancer at a young age, with the odds dropping by 34%.
Oddly, however, even a high intake of lutein could not protect against colon cancer in subjects with a family history of the disease. According to Dr. Slattery, these patients might have genetic factors that override the beneficial effects of lutein intake.2
VICTORY FOR THE GREENS?
Although one carotenoid, beta-carotene, has been mired in controversy - it may not be a good idea to use it if you have been a heavy smoker3 - carotenoids in general have long been recognized for their antioxidant properties and have been associated with reduced levels of stomach cancer, prostate cancer, breast cancer, head and neck cancers, cardiovascular disease, age-related macular degeneration, and now colon cancer.4 Carotenoids are increasingly being studied because of their effects on the regulation of cell growth and the modulation of gene expression and, possibly, immune response.5 The principal benefits of lutein and zeaxanthin derive from their ability to scavenge free radicals, rendering them harmless. They are superb antioxidants, as are most other carotenoids. Other health benefits are thought to derive from lutein's and zeaxanthin's reactions with cell membranes in the colon, which are susceptible to carcinogenesis.
Is it possible to get enough carotenoids from food? Many people think so, especially the hardy advocates for "natural" living and things that are green, especially if they're "organic." Claiming victory following the Utah study is Colleen Doyle, a registered dietician and director of nutrition and physical activity at the American Cancer Society in Atlanta.6 According to Doyle, "We've said for a long time that substances in fruits and vegetables are very protective against cancer, colon cancer especially, but we didn't know what it was specifically that was protective. This gives some indication that it's the carotenoids."
That is true, but there is much evidence that it's difficult to eat enough fruits and vegetables to get all the carotenoids you need, and even if you could, it would be expensive. Tomatoes, for example, contain a carotenoid, lycopene, that has been shown to be beneficial for prostate cancer at a level of 30 mg/day. To obtain that much from fresh tomatoes, however, you'd have to eat up to 3 pounds of them daily, in part because lycopene in that form is poorly absorbed in the gut. Except in season, the cost of tomatoes runs in excess of $1/lb. Therefore, a month's supply would cost about $90.
At the going rate of lycopene, however, the equivalent monthly amount is $35. So taking lycopene in supplement form is not only more convenient - 3 pounds of tomatoes is quite a plateful - but far more economical. The same economic and convenience factors hold true for most carotenoids. If you want the benefits, you need to take supplements. "Green" advocates like to claim that the knowledge and use of carotenoids is their achievement, but the unsung praise, at least in part if not significantly, belongs to the scientists who battled the conventional wisdom, and still do.
A new study, examining how specific
carotenoids protect against particular
types and stages of colon cancer,
has found lutein to have the
greatest protective effect.
SEEING RED, ORANGE, AND YELLOW INSTEAD OF GREEN
Returning to lutein, another report contributes more evidence that this carotenoid can help prevent macular degeneration, a common, age-related cause of vision loss in which the macula, the part of the retina that distinguishes detail in the center of the field of vision, gradually breaks down.7 The macula is composed of, among other things, lutein and zeaxanthin (see Improve Your Vision - October 1998). The problem is that, as damage accumulates over the years, less lutein and zeaxanthin end up in the eye, and these antioxidants get used less efficiently. One study found that the macular pigment density, represented by lutein and zeaxanthin, declines directly with age.8
"Our study demonstrated that consumption of fruits and vegetables of various colors would increase dietary intake of lutein and zeaxanthin, and showed that the options are not limited to dark green leafy vegetables, which were previously recommended," write the authors, a team of researchers led by Dr. Olaf Sommerburg of the University of Heidelberg Medical School in Germany.
Prior research had suggested that a diet rich in dark green leafy vegetables could protect against macular degeneration, but yellow corn, orange peppers, red grapes, and other fruits and vegetables in that part of the color spectrum are better sources of lutein and zeaxanthin. Dr. Sommerburg reported that egg yolks contain some of the highest levels of these compounds. But eggs are not the best source of carotenoids, because they raise LDL (the bad cholesterol) levels.
It is hard to obtain enough lutein or zeaxanthin by eating greens. Nutrient supplementation, however, is convenient, inexpensive, and helps in preventing macular degeneration, colon cancer, and many other cancers. Adding carotenoid supplements to your life extension program seems like an intelligent choice.
- Slattery ML, Benson J, Curtin K, Ma KN, Schaeffer D, Potter JD. Carotenoids and colon cancer. Am J Clin Nutr 2000 Feb;71(2):575-82.
- Beaulieu M. Lutein the most potent carotenoid for colon cancer prevention. ReutersHealthcom 2000 Feb 3; http://www.reutershealth.com/frame_eline.html
- Woutersen RA, Wolterbeek AP, Appel MJ, van den Berg H, Goldbohm RA, Feron VJ. Safety evaluation of synthetic beta-carotene. Crit Rev Toxicol 1999 Nov;29(6):515-42.
- Cooper DA, Eldridge AL, Peters JC. Dietary carotenoids and certain cancers, heart disease, and age-related macular degeneration: a review of recent research. Nutr Rev 1999 Jul;57(7):201-14.
- Hughes DA. Effects of carotenoids on human immune function. Proc Nutr Soc 1999 Aug;58(3):713-8.
- Corn, orange peppers, help preserve vision. ReutersHealthcom 1998 Aug 6; http://www.reutershealth.com/frame_eline.html
- Sommerburg O, Keunen JE, Bird AC, van Kuijk FJ. Fruits and vegetables that are sources for lutein and zeaxanthin: the macular pigment in human eyes. Br J Ophthalmol 1998 Aug;82(8):907-10.
- Hammond BR Jr, Wooten BR, Snodderly DM. Density of the human crystalline lens is related to the macular pigment carotenoids, lutein and zeaxanthin. Optom Vis Sci 1997 Jul;74(7):499-504.