The June 21, 2006 issue of the Journal of the National Cancer Institute reported the finding of Rajesh Agarwal, PhD and his colleagues at the University of Colorado Health Sciences Center in Denver that the compound silibinin, derived from milk thistle, helps prevent the growth and development of lung tumors in mice.

Dr Agarwal's team injected 75 mice with urethane to induce lung tumors, and injected a control group with saline. The animals injected with urethane were provided with normal diets for two weeks, after which they were given diets containing 0.033 percent, 0.1 percent, 0.33 percent, 1 percent, or no silibinin. Ten mice from each group were examined 20 weeks following injection, when lung tumors in this model are in their early stage, while the remainder were examined after 29 weeks.

It was found that mice injected with urethane who received any of the silibinin-containing diets had fewer and smaller tumors than those who received unsupplemented diets at both stages of examination. At 20 weeks, the mean number of larger tumors was reduced by 93 percent among those who received 1 percent silibinin compared to injected mice given the control diet. A significant reduction in tumor size was also observed among the mice examined after 29 weeks, with a 50-83 percent reduction compared to untreated mice. Additionally, silibinin was associated with a reduction in tumor microvessel density of 89 percent compared to the tumors of mice who did not receive the compound, indicating an inhibitory effect on angiogenesis.

"Although the mechanisms by which silibinin interferes with lung tumor growth in preclinical models remains to be explored," the authors note, "these results raise the possibility that silibinin may have chemopreventive activity against lung tumor growth and progression in humans."

A report published in the June 2, 2006 issue of Science revealed the discovery that checkpoint proteins, which prevent the division of defective cells that can lead to cancer, are also involved in limiting life span. The finding reveals an important link between cancer and the increased risk of the disease that occurs with aging.

A research team led by Professor Gordon Lithgow, who started the project at the University of Manchester and completed it at the Buck Institute in California, genetically programmed the roundworm C. elegans to lack checkpoint proteins, which resulted in a 15 to 30 percent increase in the animal's life span.

"We have discovered that proteins that prevent cancer in humans by ensuring that cells don't divide if they are damaged also determine lifespan in the nematode worm," Dr Lithgow stated. "Our research has shown that these 'checkpoint proteins' – thought only to operate in cells that divide – function in cells that no longer divide as well. The fact that they appear to have dual functions opens a new way to study the connection between aging and cancer. If we look at checkpoint proteins as a gear, we have known for a long time that they drive the cancer engine; now we know that they also drive the longevity engine. This discovery has exciting potential as an area of inquiry into potential cellular links between aging and cancer."

Dr Dale Bredesen, who is the Buck Institute's Scientific Director, added, "If we're smart about it, we might be able to design strategies where you could keep checkpoint proteins active in dividing cells and stop them working in cells that no longer divide, such as brain cells. Increasing the survival of brain cells or 'neurons' could provide a new avenue of treatment for neurodegenerative diseases like Alzheimer's."

A review by Yale University researchers published in the May, 2006 issue of the Journal of the American College of Surgeons concluded that green tea consumption may be the explanation of the "Asian paradox." Similar to the French paradox, which refers to the hypothesis that red wine protects the French from the adverse cardiovascular effects of a fatty diet, green tea may protect Asians from the adverse effects of smoking. Many people in Asia are smokers, yet there is a lower incidence of cardiovascular disease and cancer than in many countries in which fewer people smoke.

Professor and Chief of Vascular Surgery at Yale's Department of Surgery Bauer Sumpio, MD, and colleagues reviewed over 100 experimental and clinical studies concerning green tea to arrive at their conclusion. He noted that the average 1.2 liters of green tea consumed each day by many Asians provides the antioxidant epigallocatechin gallate (EGCG), which may reduce low density lipoprotein (LDL) oxidation, lower platelet aggregation, regulate lipids, and promote proliferation and migration of smooth muscle cells, which are all factors involved in reducing cardiovascular disease. The compound has also been demonstrated to prevent the growth of some tumors.

Dr Sumpio stated, "We do not yet have a full explanation for the 'Asian paradox,' which refers to the very low incidence of both heart disease and cancer in Asia, even though consumption of cigarettes is greater than in most other countries. But we now have some theories."
"More studies are necessary to fully elucidate and better understand green tea's method of action, particularly at the cellular level," Dr Sumpio concluded. "The evidence is strong that green tea consumption is a useful dietary habit to lower the risk for, as well as treat, a number of chronic diseases. Certainly, however, smoking cessation is the best way to prevent cardiovascular disease and cancer."

In a report published in the May 31, 2006 issue of the Journal of Agricultural and Food Chemistry, Shela Gorinstein and her colleagues in Israel and Poland revealed that a lower dose of a garlic extract appears to be more effective than higher doses to lower cholesterol and help protect against excessive blood clotting. Garlic extract has been found to be helpful for several conditions, but the odor it imparts to its users has made taking higher doses undesirable for some people.

Dr Gorinstein's team fed rats diets containing 1 percent cholesterol to four groups of rats. Three groups also received a commercial garlic extract equal to 500, 750 and 1000 milligrams raw garlic per kilogram body weight. A control group was provided with a diet to which cholesterol and garlic were not added. The polyphenols and antioxidant potential of the extract were evaluated prior to its administration. Plasma lipids, fibrinogen (involved in blood clotting), clotting time, and antioxidant capacity were measured before and after the four week treatment period.

At the end of the study, all of the rats on the diets to which cholesterol was added experienced a decrease in plasma antioxidant activities, yet the decrease among rats who received the 500 mg/kg garlic-enhanced diets was not considered significant compared to the control group. Only the rats who received 500 mg experienced a significantly reduced rise in plasma lipids. The same group also showed a significant decrease in plasma fibrinogen and an increase in clotting time.

The amount of fresh garlic that a human would need to consume to be equivalent to the 500 milligram dosage is 1.25 ounces per day for a 150 pound person, which would be supplied by eating about 12 cloves. The authors concluded that "commercial garlic could be a valuable component of atherosclerosis-preventing diets only in optimal doses."