DNA Damage Protection from Supplemental Carotenoid Mixture Intake

Protection and repair of DNA may have considerable relevance to degenerative processes and ultimately to human health.1 Oxidative stress refers to the damage to cells and tissues caused by reactive oxygen species (ROS) created partly as a consequence of normal metabolism. This can cause DNA to become oxidized and possibly impair its ability to function normally.²

DNA damage assays, specifically the Comet assay (single-cell gel electrophoresis), detect DNA strand breaks and oxidized pyrimidines. A modification of the technique by Singh et al. has become known as the alkaline Comet assay.³

Oxidative stress is believed to occur when there is an imbalance in the biological oxidant-to-antioxidant systems that can result in oxidative damage to lipids, proteins, carbohydrates, and nucleic acids. Imbalances may be due to excessive oxidant generation from normal cellular energy production, decreases in antioxidant protection, or an inadequate cellular repair caused by oxidative damage. Prolonged oxidative stress can be caused by accumulative development of ROS such as free radicals and peroxides produced either metabolically, from exhaustive exercise, or via mere aging. Significant contributions to oxidative stress can occur from cigarette smoke; environmental pollutants; excess alcohol consumption; ionizing radiation; and bacterial, fungal, or viral infections that can cause irreparable damage ultimately leading to cell death.

Excessive oxidative stress has been implicated in many human diseases such as inflammation, senescence, hearing and sleep disorders, atherosclerosis, hypertension, asthma, cancers, acute lung injury, heart failure, and sleep apnea. Cancer and chronic inflammatory diseases themselves generate even more ROS.⁴ Cells typically have adequate defense barriers to neutralize ROS to protect against oxidation of macromolecules. Dietary antioxidants such as vitamins and plant nutrients such as carotenoids are thought to significantly contribute to the antioxidant defense system. These nutrients are predominantly found in fruits and vegetables.⁵

Duthie and her colleagues demonstrated that supplementation with vitamins C and E, and beta-carotene, for 20 weeks significantly reduced oxidative base damage in lymphocyte DNA in male smokers and nonsmokers.⁶

Providing a dietary supplement containing a mixture of antioxidants similar to those found in fruits and vegetables, such as vitamins C and E, and beta-carotene, Duthie et al., demonstrated a moderating effect on oxidized DNA damage in lymphocytes with the Comet assay in smoking and nonsmoking individuals.⁶ In vitro hydrogen peroxide challenges on lymphocytes from subjects supplemented with antioxidants decreased DNA damage about 25% and showed greater resistance to further oxidative damage.

Clinical research from the Jean Mayer USDA–Human Nutrition Research Center for Aging at Tufts University (Boston) demonstrated that commonly consumed carotenoids taken in dietary supplement form have protective and reparative effects on DNA damage.⁷ Notable beneficial effects were achieved at typical dietary intake levels from a combination of carotenoids consumed from a single dietary supplement. Taken daily over a period as short as two weeks, this supplement, which contained an equivalent mixture of each of three different, highly purified and formulated carotenoids, showed demonstrable protective qualities within a period of days that were consistent and progressively effective over time.

Subtle chemical differences, such as the polarity of certain carotenoids, can result in differences in the extent and manner in which each are incorporated into cells and tissues, and, ultimately, their effects on cellular physiology. Lutein, for instance, is more polar compared with beta-carotene, which is less polar than lycopene. Torbergsen and Collins also noted differences in the rate of rejoining (repair) of hydrogen peroxide–induced DNA strand breakage in lymphocytes among individuals supplemented with different carotenoids.⁸ DNA from individuals who were supplemented with beta-carotene and lycopene rejoined more quickly than DNA from those supplemented with lutein. The authors suggest a “carotenoid-specific” effect, since lutein supplementation resulted in significantly increased plasma levels. Lycopene did not, but nevertheless allowed lymphocytes to repair hydrogen peroxide–induced DNA strand breaks more quickly. The best explanation given for DNA protection appeared to be due to an antioxidant effect, since it was difficult to differentiate from antioxidant effects and DNA repair rates.

The recent Tufts study demonstrated a significant (p < 0.01) synergistic effect in reducing endogenous DNA damage as early as the 15th day when subjects consumed a daily supplement containing a mixture of 4 mg each of lutein, lycopene, and beta-carotene.⁷ By day 15, mixed-carotenoid supplementation raised the accumulative carotenoid plasma levels well within the 50th to 75th percentile range of NHANES for the same age, gender, and ethnic group as those individuals on study. When DNA was challenged in vitro with hydrogen peroxide, a stronger measure of actual DNA strand breakage, carotenoid supplementation demonstrated progressive reduction of damage throughout the study, culminating in a significant reduction (p < 0.05) at day 57.

Mixed-carotenoid supplementation in the Tufts study demonstrated a significant increasing resistance to in vitro oxidized DNA-damage challenges over a period of 57 days compared with unsupplemented controls. Additionally, endogenous DNA damage was significantly reduced 21% by day 15 and 36% by the 57th day for subjects receiving a mixed-carotenoid supplement.⁷

Individuals who could be expected to be responsive to carotenoid-mixture supplementation include individuals with poor nutritional status, including those consuming a typical American daily diet of one vegetable and fruit serving per day. Less than 23% of adults in the United States consume the targeted goal of five or more servings per day of fruits and vegetables (CDC, 2003). This appears to be a constant pattern, since 1989–1991 records indicate that only 29% of all adults met the goal of five vegetable or fruit servings per day.⁹ Individuals with high oxidative stress who are possible benefactors of carotenoid supplementation include those who are obese and characterized with Multimetabolic Syndrome as well as dieting teenagers who don’t consume sufficient fruits, vegetables, and grains.^10,11 Other potentially responsive consumer segments are those with high levels of oxidative stress resulting from radiation, environmental pollutants, or smoking; certain groups undergoing drug therapy for disease; people with suppressed immune systems; athletes; and the elderly.

DNA damage is known to result in base changes and mutation when cellular replication occurs. Because DNA damage is often characterized as an initiating event in carcinogenesis and other disease states, a significant lowering of DNA damage could rightly be associated with a lowering of the risk of mutation and cancer development. Smith et al. also noted increases in DNA-damaged lymphocytes in cancer cases with increased body mass index.¹² Accumulating DNA damage in cancerous tissue is presumed to be due to excessive ROS and a lack of DNA repair activity due to genetic deficiencies.

DNA damage and DNA adducts are found in greater abundance in diseased arteries and associated tissues⁷ and are also involved in the development of coronary artery disease (CAD). An imbalance in oxidant-to-antioxidant levels creates oxidative stress in patients with CAD.^13,14

Consumer awareness and understanding of the association between increased consumption of fruits and vegetables and improved health is well understood. However, food intake patterns more closely align to intake of tasteful foods that consumers prefer rather than foods of nutritional importance. Fortification and dietary supplementation is one strategy to facilitate adoption of more healthful nutritional ingredient intake patterns.

Herb Woolf has spent most of his professional career as an industrial scientist, holding positions such as U.S. director of new product research for Wessanen USA and executive director of the National Dairy Research Foundation. For the last 13 years, he has served as technical marketing manager for the Human Nutrition Group at BASF Corp. (Florham Park, NJ). For more information about BASF, visit www.human-nutrition.basf.com.

REFERENCES

1. SB Astley et al., “Evidence That Dietary Supplementation with Carotenoid-Rich Foods Modulates the DNA Damage: Repair Balance in Human Lymphocytes,” British Journal of Nutrition, vol. 91 (2004): 63–72.

2. AR Collins et al., “Serum Carotenoid and Oxidative DNA Damage in Human Lymphocytes,” Carcinogenesis, vol. 19 (1998): 2159–2162.

3. NP Singh et al., “A Simple Technique for Quantitation of Low Levels of DNA Damage in Individual Cells,” Experimental Cell Research, vol. 175 (1988): 184–191.

4. B Halliwell, “Oxygen and Nitrogen are Pro-Carcinogens.Damage to DNA by Reactive Oxygen, Chlorine and Nitrogen Species: Measurement, Mechanism and the Effects of Nutrition,” Mutation Research, vol. 15 (1999): 37–52.

5. S Loft and HE Poulsen, “Cancer Risk and Oxidative DNA Damage in Man,” Journal of Molecular Medicine, vol. 75 (1996): 67–68.

6. SJ Duthie et al., “Antioxidant Supplementation Decreases Oxidative DNA Damage in Human Lymphocytes,” Cancer Research, vol. 56 (1996): 1291–1295.

7. X Zhao et al., “Modification of Lymphocyte DNA Damage by Carotenoid Supplementation in Post-Menopausal Women,” American Journal of Clinical Nutrition, vol. 83 (2005): 163.

8. AC Torbergsen and AR Collins, “Recovery of Human Lymphocytes from Oxidative DNA Damage: The Apparent Enhancement of DNA Repair by Carotenoids Is Probably Simply an Antioxidant Effect,” European Journal of Nutrition, vol. 39 (2000): 80–85.

9. SM Krebs-Smith et al., “Fruit and Vegetable Intakes of Children and Adolescents in the United States,” Archives of Pediatrics & Adolescent Medicine, vol. 150, no. 1 (1996): 81–86.

10. D Molnar, T Decsi, and B Koletzko, “Reduced Antioxidant Status in Obese Children with Multimetabolic Syndrome,” International Journal of Obesity and Related Metabolic Disorders, vol. 28, no. 10 (2004): 1197–1202.

11. D. Neumark-Sztainer et al., “Weight-Control Behaviors among Adolescent Girls and Boys: Implications for Dietary Intake,” Journal of the American Dietetic Association, vol. 104, no. 6 (2004): 913–920.

12. TR Smith et al., “DNA Damage and Breast Cancer Risk,” Carcinogenesis, vol. 24 (2003): 883–889.

13. W Martinet et al., “Gene Expression Profiling of Apoptosis-Related Genes in Human Atherosclerosis: Upregulation of Death-Associated Protein Kinase,” Arteriosclerosis, Thrombosis, and Vascular Biology, vol. 22, no. 12 (2002): 2023–2029.

14. IS Young, “Measurement of Total Antioxidant Capacity,” Journal of Clinical Pathology, vol. 54, no. 5 (2001): 339.

This article is the first in a series of articles based on presentations given at the 2006 World Nutra conference. For more information about World Nutra, visit www.worldnutra.com.