Research Update

February 11, 2008

Citrus Juice Preserves Tea Antioxidants

Source: RJ Green et al., “Common Tea Formulations Modulate In Vitro Digestive Recovery of Green Tea Catechins,” Molecular Nutrition and Food Research, vol. 51, no. 9 (September 2007): 1152–1162.

Antioxidants in green tea known as catechins remain stable after digestion longer when they are accompanied by citrus juice or vitamin C, according to new research from Purdue University (West Lafayette, IN).

In a study published in Molecular Nutrition and Food Research, Purdue University assistant professor of food science Mario Ferruzzi, PhD, used a simulated model of gastric and small intestinal digestion to explore the effects of juices, creamers, and other products on tea.

Ferruzzi found that while citrus juice produced a fivefold boost in the quantity of recovered catechins, vitamin C produced an even greater response-sixfold and thirteenfold increases in the two most abundant catechins, epigallocatechin and epigallocatechin gallate, respectively. Lemon juice appeared to be the most effective citrus additive, preserving about 80% of the catechins, but orange, lime, and grapefruit juices also had stabilizing effects.

Ferruzzi is currently working on an in vivo study to replicate the results in animals.

Sunlight, Vitamin D Links to Endometrial Cancer Studied

Source: SB Mohr et al., “Is Ultraviolet B Irradiance Inversely Associated with Incidence Rates of Endometrial Cancer: An Ecological Study of 107 Countries,” Preventive Medicine, vol. 45, no. 5 (November 2007): 327–331.

Women who live in latitudes that expose them to sunlight may have a lower risk of developing endometrial cancer than other women, according to University of California at San Diego (UCSD) researchers.
Using data gathered from the World Health Organization’s (Geneva) Globocan cancer database, the researchers studied endometrial cancer incidence rates in 107 countries, taking into account factors such as latitude and exposure to sunlight. Ultraviolet B rays in sunlight help trigger the production of vitamin D3 in the body. Some research suggests that vitamin D3 may have a protective effect against certain cancers.

“In general, endometrial cancer incidence was highest at the highest latitudes in both hemispheres,” according to UCSD professor Cedric Garland, DPh. “Even after controlling for known variables such as cloud cover, meat intake, weight, skin pigmentation, and others, the association remained strong.”

Garland added that the study was the first to depict an association between high serum vitamin D levels and reduced risk of endometrial cancer. “Previous epidemiological studies have focused on estrogen levels-either natural or through hormone replacement therapy-which play the major role in development of the disease, and on fat intake, which plays a smaller role,” Garland said. “Since most women cannot control their natural levels of estrogen, and very low levels of fat intake are not acceptable to most American women, this article provides evidence that vitamin D adequacy should be considered as part of a comprehensive program for prevention of this cancer.”

Beta-Carotene May Help Protect Memory

Source: F Grodstein et al., “A Randomized Trial of Beta-Carotene Supplementation and Cognitive Function in Men: The Physicians Health Study II,” Archives of Internal Medicine, vol. 167, no. 20 (November 12, 2007): 2184–2190.

Long-term use of beta-carotene may help delay memory problems and cognitive decline in some individuals, according to new research published in the Archives of Internal Medicine.

Researchers from Brigham & Women’s Hospital and Harvard Medical School (Boston) examined participants from two arms of the Physicians Health Study II. In the first arm, 4052 men took either a placebo or 50 mg of beta-carotene every other day for 18 years. In the second arm, 1904 men took the placebo or beta-carotene every other day for 1 year. At the end of each arm, the researchers interviewed the participants to assess their overall cognitive abilities and verbal memory.

There was no detectable difference in test scores between the treatment and placebo groups in the short-term arm, but the researchers did find significant differences in the long-term arm.

“In this generally healthy population, the extent of protection conferred by long-term treatment appeared modest,” wrote the authors. “Nonetheless, studies have established that very modest differences in cognition, especially verbal memory, predict substantial differences in eventual risk of dementia. Thus, the public health impact of long-term beta-carotene use could be large.”

In an accompanying editorial, however, University of California at San Francisco researcher Kristine Yaffe, MD, cautioned that antioxidant supplements may not be beneficial and warned that high-dose antioxidant supplements “may have adverse health consequences including mortality.”

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