Adequate Zinc Intake Protects DNA

Life Extension Update Exclusive

August 28, 2009

Adequate zinc intake protects DNA

Vitamin C levels up, but low income groups and smokers still at risk of deficiency

Researchers from the Linus Pauling Institute at Oregon State University, Children’s Hospital Oakland Research Institute, and the University of California, Davis report in the August, 2009 issue of the American Journal of Clinical Nutrition that reducing dietary zinc is associated with increased breakage of peripheral blood cell DNA strands, while restoring zinc to normal levels reduces breakage. Zinc deficiency is estimated to affect 2 billion people worldwide, and is believed to elevate the risk of several chronic diseases, including cancer. The ability of zinc to increase DNA repair, in addition to its role as an antioxidant, may be responsible for its protective effect.

For the first 13 days of the current study, nine healthy men received a diet that contained 11 milligrams zinc per day to ensure adequate zinc status. The subjects then underwent a period of zinc depletion during which they received liquid diets containing 0.6 milligrams zinc for seven days, followed by a diet containing 4 milligrams zinc for 35 days. During the first 21 days of the low zinc diet, participants received 1.3 grams per day of phytate, which inhibits zinc absorption. On the 56th day of the study, the participants were switched back to the zinc replete diet provided at the beginning of the study, and continued on this diet for 18 days with the addition of supplemental zinc for the first 7 days of this period. Fasting blood samples drawn at the beginning and end of the study and at several intermediate points were analyzed for DNA damage, plasma zinc levels, and antioxidant status.

By the end of the period during which the subjects received zinc-depleted diets, DNA strand breaks increased by an average of 57 percent compared to the beginning of the period, indicating that six weeks of reduced zinc intake significantly increases DNA damage in peripheral blood cells. These increases proved to be reversible by restoring adequate zinc intake, since DNA strand breaks decreased by 39.9 percent by the end of the study. The researchers also observed a decline in DNA damage during the 13 day baseline zinc-adequate period, suggesting that the participants may have had DNA damage prior to enrollment. Plasma F2-isoprostanes, which indicate oxidative stress, and total antioxidant capacity did not vary significantly over the course of the study.

The study is the first, to the authors’ knowledge, to report DNA damage in human peripheral blood cells associated with zinc deficiency. “Overall, these data suggest that dietary zinc status affects DNA damage in peripheral blood cells and that adequate zinc status may be essential to maintain DNA integrity in humans,” the authors write. “Importantly, the alterations in DNA integrity occurred before significant changes in plasma zinc were detected.”

Printer Friendly Save as PDF Email this Page View Archive Subscribe Today
Health Concern

Colorectal cancer

Colorectal cancer develops through a process involving genetic change in the epithelial cells of the colon lining. The main factors that initiate colorectal cancer are consumption of cooked red meat (due to heterocyclic amines) (Gerhardsson de V et al 1991; Reddy S et al 1987), high intake of refined carbohydrates (Franceschi S et al 2001), poor vitamin and mineral intake, alcohol consumption, smoking, bile acids, fecal mutagens (DNA-damaging agents), fecal pH, and compromised detoxification enzymes (Winawer SJ et al 1992). An example of one important detoxification enzyme is N-acetyltransferase, which catalyzes the formation of DNA-damaging products from heterocyclic amines that form in cooked meats. Differences in the activity of this enzyme classify individuals as slow or fast acetylators. The level of red meat consumption in fast but not slow acetylators is associated with risk for colorectal cancer development (Welfare MR et al 1997).

In industrialized Western societies, both polyps and colon cancer occur more frequently due in part to diets low in fruits, vegetables, vegetable protein, and fiber (Satia-Aboutaj J et al 2003). Fecal mutagens are produced by certain diets such as those containing overcooked or burnt meat or fish. Increased intake of fiber, on the other hand, shortens the intestinal transit time, which in turn reduces the exposure of the colorectal lining to mutagens within the stool (Johansson G et al 1997).

Low folate intake, especially when combined with alcohol consumption and a low-protein diet, increases colorectal cancer risk (Kato I et al 1999). Dietary folate influences DNA methylation, synthesis, and repair. Abnormalities in these DNA processes enhance cancer development, particularly in rapidly growing tissues such as the colorectal mucosa (Lengauer C et al 1997; Feinberg AP et al 1983). Higher folate intake from either dietary sources or supplements may protect against the initiation of colorectal cancer (Giovannucci E 2002, 1998).

Low levels of selenium correlate with the presence of adenomas (benign tumors), whereas increased levels of selenium are associated with reduced risk of adenomas. Intervention trials have found a beneficial effect of selenium supplementation (Russo MW et al 1997).

Featured Products

Enhanced Life Extension Protein

add to cart

Scientists have begun to investigate the ability of certain biological components of whey protein to enhance immunity. Those include: lactoferrin, beta-lactoglobulin, alpha-lactalbumin, glycomacropeptide, and immunoglobulins. Years of scientific research have resulted in the development of a specially designed whey protein that can boost immune function, protect against free radical attack, and maintain lean muscle mass.

Life Extension® offers whey protein powders in four flavors that contain added lactoferrin. Life Extension uses a production method that produces a high quality whey protein isolate. Using a low temperature microfiltration technique, it is possible to produce a 98% undenatured whey protein isolate that acts as a powerful immune stimulant and retains all the important sub-fractions, such as lactoferrin, a strong antioxidant with immune-stimulating properties.

Super Omega-3 EPA/DHA with Sesame Lignans & Olive Fruit Extract

add to cart

Featured Video

An abundance of scientific research substantiates the wide-ranging health benefits of omega-3 fatty acids in fish oil and monounsaturated fatty acids-polyphenols in olive fruit. In fact, supportive but not conclusive evidence shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease.

The Super Omega-3 formula uses a patented EPA/DHA extraction process that results in one of the purest, most stable and easiest-to-tolerate fish oil extracts in the world. While most fish oil is distilled to decrease contaminants such as mercury and PCBs, the Pure+™ fish oil used in Super Omega-3 is produced with a patented method that purifies the oil with an intense distillation process to reduce pollutants to virtually undetectable levels. Super Omega-3 is certified to contain no detectable levels of mercury, arsenic, lead, cadmium, and other toxic metals by the International Fish Oil Standards (IFOS™).

News Archive

Life Extension Update

What's Hot

Life Extension magazine

If you have questions or comments concerning this issue or past issues of Life Extension Update, send them to or call 1-800-678-8989.

For longer life,

Dayna Dye
Editor, Life Extension Update
954 766 8433 extension 7716
Sign up for Life Extension Update

For copyright permission, please refer to Life Extension copyright policy