In The News: December 2009

Studies published in a recent issue of JAMA reveal a decreased risk of Alzheimer’s disease and cognitive decline among individuals who report greater adherence to a Mediterranean diet.

In one study, Nikolaos Scarmeas, MD and his associates found that greater physical activity was associated with a lower risk of developing Alzheimer’s disease among 1,880 elderly men and women. When adherence to a Mediterranean diet was analyzed, those in the top third had experienced a 40% reduction compared to the lowest third.*

In a second study, greater adherence to a Mediterranean diet was associated with a reduction in cognitive decline.*

“The findings of Scarmeas, et al and Féart, et al fit into a larger and potentially optimistic view of prevention of late-life cognitive impairment through application, at least by midlife, of as many healthy behaviors as possible, including diet,” David S. Knopman, MD, concluded in an accompanying editorial.*

—Dayna Dye

Research conducted by Catherine Peterson and Mary Heffernan at the University of Missouri’s Department of Nutritional Sciences has correlated low vitamin D levels with an increase in a marker of inflammation.*

The study included 69 healthy women classified as being high or low in vitamin D based on ultraviolet-B exposure. Not surprisingly, mean serum 25-hydroxyvitamin D levels were significantly greater in those with increased sun exposure compared with those in the low D group. Dr. Peterson found that the inflammatory marker tumor necrosis factor-alpha averaged 0.79 picograms per milliliter (pg/mL) in the high vitamin D group and 1.22 pg/mL among those categorized as low in the vitamin. Higher serum 25-hydroxyvitamin D levels were also correlated with lower TNF-alpha levels.

The discovery could help explain the protective association found for vitamin D against inflammatory diseases such as heart disease and rheumatoid arthritis.

—Dayna Dye

A new study published online in Human Brain Mapping reports that elderly individuals who were obese or overweight had significantly less brain tissue than individuals of normal weight.1

The study, led by Paul Thompson, a University of California Los Angeles neuroscientist, reviewed the brain images of 94 people in their 70s who had participated in an earlier study looking at cardiovascular health and cognition. They were followed for five years, and it was discovered that clinically obese people had 8% less brain tissue, while simply overweight people had 4% less brain tissue compared to normal-weight humans.

“The brains of obese people looked 16 years older than their healthy counterparts, while those of overweight people looked 8 years older,” Thompson said. “This is the first study to show physical evidence in the brain that connects overweight and obesity and cognitive decline.”2

—Jon Finkel

A study funded by the British Heart Foundation charity and conducted by researchers at Imperial College London on mice has found evidence that a chemical in broccoli could protect arteries from clogging.*

In the report published in the journal Arteriosclerosis, Thrombosis and Vascular Biology, the research team found that a compound called sulforaphane, which occurs naturally in broccoli, had the ability to switch on a protective protein, called Nrf2, that is inactive in parts of the arteries that are vulnerable to clogging.

“What our study showed was that sulforaphane can protect those regions by switching on the Nrf2,” Paul Evans of the National Heart and Lung Institute at Imperial College said about the report.

While the research was conducted using purified sulforaphane, not actual broccoli, Evans said the next step is to test the effect of the chemical as it is found naturally in vegetables.

—Jon Finkel

An article published online in the American Journal of Clinical Nutrition revealed that vitamin C status has improved in the United States over the past decade, yet a significant incidence of deficiency still exists among smokers and individuals of low socioeconomic status.*

For their report, researchers at the Centers for Disease Control and Prevention in Atlanta compared data from the National Health and Nutrition Examination Survey (NHANES) III, conducted from 1988 to 1994, to data from NHANES 2003-2004. Overall, the presence of vitamin C deficiency among NHANES 2003-2004 participants was 7%, down from 12.4% among NHANES III participants. Smokers had levels that were one-third lower than nonsmokers, and had over three times as great a risk of deficiency. Vitamin C concentrations rose and deficiency declined with increased socioeconomic status.

“The vitamin C status of the US population appears to have substantially improved from 1988-1994 to 2003-2004,” the authors conclude.

—Dayna Dye

In a recent issue of the American Journal of Clinical Nutrition, researchers from the Linus Pauling Institute report that reducing dietary zinc is associated with increased breakage of peripheral blood cell DNA strands, while restoring zinc to normal levels reduces breakage. 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 current study, 9 men received zinc-depleted diets for 42 days. DNA strand breaks increased by an average of 57% by the end 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.

“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.

—Dayna Dye

A report published in the International Journal of Cancer describes research conducted at Oregon State University that reveals a potential role in cancer therapy for chlorophyllin, a water-soluble derivative of chlorophyll.*

Linus Pauling Institute’s Cancer Chemoprotection Program director Rod Dashwood and his associates tested the effect of chlorophyllin on cultured human colon cancer cells. They observed that the cells spent more time in their synthesis phase, resulting in a disruption in growth that led to cell death.

The researchers discovered that chlorophyllin reduces an enzyme needed for DNA synthesis known as ribonucleotide reductase. The enzyme is also targeted by the chemotherapy drug hydroxyurea. Comparison of chlorophyllin and hydroxyurea’s effects revealed a ten times greater benefit for chlorophyllin against colon cancer cells. The finding suggests a role for chlorophyllin in combination with conventional cancer treatment, which could enable the administration of a lower dose of potentially toxic chemotherapeutic drugs.

—Dayna Dye

Researchers from the University of Toronto report in the American Journal of Epidemiology that one out of seven young adults in a sample of the population were deficient in vitamin C, which was associated with increased waist circumference, body mass index, blood pressure, and C-reactive protein (CRP), a marker of inflammation.*

Dr. Ahmed El-Sohemy and his associates examined data from 979 participants in the Toronto Nutrigenomics and Health Study conducted between 2004 and 2008. Approximately one-third of the participants had suboptimal serum vitamin C levels, and 14% had levels that were deficient at less than 11 micromoles per liter.

“The implications of these findings underscore the importance of obtaining the RDA for dietary vitamin C in order to decrease the prevalence of serum ascorbic acid deficiency in young Canadians and to potentially decrease the risk of long-term adverse health effects,” the authors write.

—Jon Finkel

In the British Journal of Surgery, researchers report the benefits of supplementing with folic acid in patients with peripheral artery disease.*

In a double-blind trial, 133 peripheral artery disease patients were assigned to receive 400 micrograms folic acid, 400 micrograms

5-methyltetrahydrofolate (5-MTHF, an active form of folate) or a placebo daily for 16 weeks.

Red blood cell and plasma folate increased in participants who received folic acid and 5-MTHF, and homocysteine was reduced compared to those in the placebo group. Brachial artery pressure index was also significantly improved in both the folic acid and 5-MTHF groups.

Due to the similarity in benefits observed in this study for 5-MTHF and folic acid, the authors conclude that the data “suggest that 5-MTHF may be a safe and effective alternative to folic acid.”

—Dayna Dye

The results of a study published online in Circulation reveal a disturbingly low percentage of Americans who meet the standard criteria for being at low risk of cardiovascular disease.*

Researchers evaluated data from four health surveys of Americans conducted between 1971-1975, 1976-1980, 1988-1994 and 1999 to 2004. Factors that conferred a low risk of cardiovascular disease included not smoking, having a total cholesterol level of less than 200 mg/dL without using cholesterol reducing drugs, blood pressure lower than 120/80 mmHg in the absence of antihypertensive medication use, having a body mass index of less than 25 kg/m2, and never having been diagnosed with diabetes.

Among the findings was that only one in twelve Americans had a low cardiovascular disease risk profile from 1994 to 2004, down from over one in ten from 1988 to 1994, a trend that the researchers attribute to an increasing number of overweight and obese men and women.

—Dayna Dye