In the News

Study Reveals New Role for Vitamin C in Skin Protection

Adverse Event Reporting Guidance for Supplements Finalized

N-acetylcysteine May Offer Relief to Trichotillomaniacs

Fish Oil During Pregnancy May Halt Pediatric Allergy

Study Reveals New Role for Vitamin C in Skin Protection

Researchers at the University of Leicester and Institute for Molecular and Cellular Biology in Portugal studied new protective properties of vitamin C in cells from the human skin, which could lead to better skin regeneration.

The work, by Tiago Duarte, Marcus S. Cooke, and G. Don Jones, found that a form of vitamin C helped to promote wound healing and helped protect the DNA damage of skin cells. Their findings have been published in the journal Free Radical Biology and Medicine.

Duarte, formerly of the University of Leicester and now at the Institute for Molecular and Cellular Biology in Portugal, wrote, “The exposure to solar ultraviolet radiation increases in summer, often resulting in a higher incidence of skin lesions. Ultraviolet radiation is also a genotoxic agent responsible for skin cancer, through the formation of free radicals and DNA damage.

“Our study analysed the effect of sustained exposure to a vitamin C derivative, ascorbic acid 2-phosphate (AA2P), in human dermal fibroblasts. We investigated which genes are activated by vitamin C in these cells, which are responsible for skin regeneration,” he continued. “The results demonstrated that vitamin C may improve wound healing by stimulating quiescent fibroblasts to divide and by promoting their migration into the wounded area. Vitamin C could also protect the skin by increasing the capacity of fibroblasts to repair potentially mutagenic DNA lesions.”

This new evidence suggests that, in addition to “mopping up” free radicals, vitamin C can help remove any DNA damage once they get past the cell’s defenses. The study has the potential to lead to advances in the prevention and treatment of skin lesions specifically, as well as to contribute in the fight against cancer.

Ascorbic Acid, Sugar Found to Increase Absorbability of Catechins in Green Tea

An animal study conducted at Purdue University, West Lafayette, Indiana, has shown that adding ascorbic acid and sugar to green tea can help the body absorb helpful compounds and demonstrates the effectiveness of a model that could reduce the number of animals needed for these types of studies.

Mario Ferruzzi, associate professor of food science and nutrition, adapted a digestion model with human intestinal cells to show that adding ascorbic acid to green tea would increase the absorbability of catechins found in the tea. Catechins, a class of polyphenols common in tea, cocoa, and grape, are antioxidants thought to fight heart disease, stroke, cancer, diabetes, and other health problems.

Ferruzzi, Elsa Janle, a Purdue associate research professor of foods and nutrition, and Catrina Peters, a Purdue graduate student in nutrition, were able to demonstrate that adding ascorbic acid, sucrose, or both increases by as much as 3 times the amount of catechins that can be absorbed into the bloodstream. The results of the in vivo study compared well with those predicted by the in vitro model.

The model charts how the digestive stability, solubility, and absorption of polyphenols change based on modifications to a beverage's formula. It will not be exact in terms of measurements, but when compared to the in vivo test in rats, the model’s predictions matched directionally to the in vivo study and were relatively close proportionately.

Ferruzzi said testing with the model could allow researchers to predict how a new product formula might change the product’s properties, reducing the number of animals needed for testing to only products that showed desired characteristics in the model. The model also can be adapted to simulate the digestive characteristics of other animals or humans as originally intended.

Antioxidants Not Associated With Increased Melanoma Risk

Antioxidant supplements do not appear to be associated with an increased risk of melanoma, according to a report in the August issue of Archives of Dermatology.

A randomized trial of antioxidants for cancer prevention found that daily supplementation with nutritionally appropriate doses of vitamins C and E, beta-carotene, selenium, and zinc appeared to increase the risk of melanoma in women 4-fold. Because an estimated 48% to 55% of US adults use vitamin or mineral supplements regularly, the potential harmful effects of these nutrients is alarming, the study’s authors note.

Maryam M. Asgari, MD, MPH, of Kaiser Permanente Northern California, Oakland, and colleagues examined the association between antioxidants and melanoma among 69 671 women and men who were participating in the Vitamins and Lifestyle (VITAL) study, designed to examine supplement use and cancer risk. At the beginning of the study, between 2000 and 2002, participants completed a 24-page questionnaire about lifestyle factors, health history, diet, supplement use, and other cancer risk factors.

Intake of multivitamins and supplements during the previous 10 years, including selenium and beta-carotene, was not associated with melanoma risk in either women or men. The researchers also examined the risk of melanoma associated with long-term use of supplemental beta-carotene and selenium at doses comparable to the previous study and found no association.

Mediterranean-type Diet, Increased Physical Activity Associated With Reduced Risk of Alzheimer’s Disease

Elderly individuals who consumed fruits, vegetables, legumes, cereal, and fish and limited red meat and poultry and who were physically active had an associated lower risk of Alzheimer’s disease (AD), according to a study in the August issue of JAMA. In a second study, higher adherence to a Mediterranean diet was associated with slower cognitive decline but was not associated with a decreased risk of dementia.

Research regarding the effect physical activity can have on the risk of AD or dementia has shown mixed results, as has the effect of dietary habits. Their combined association has not been investigated.

Nikolaos Scarmeas, MD, of Columbia University Medical Center, New York, and colleagues examined the association between physical activity and risk of AD and the effect of physical activity and adherence to a Mediterranean-type diet on AD risk. The study included 2 groups that consisted of 1880 community-dwelling elderly residents of Manhattan without dementia at the start of the study, for whom both diet and physical activity information was available. Standardized neurological and neuropsychological measures were administered approximately every 1.5 years from 1992 through 2006.

The participants received measurements of their adherence to a Mediterranean-type diet (scale of 0-9; categorized as low, middle, or high) and their physical activity (sum of weekly participation in various physical activities, weighted by the type of physical activity [light, moderate, vigorous]; categorized into no physical activity, some, or much, also low or high), separately and combined. A higher score for diet was obtained with higher consumption of fruits, vegetables, legumes, cereals, and fish; lower consumption of meat and dairy products; a higher ratio of monounsaturated fats to saturated fats and mild-to-moderate alcohol consumption.

Individuals were followed up for an average of 5.4 years, during which a total of 282 developed AD. In considering only physical activity, the researchers found that more physical activity was associated with lower risk for developing AD. Report of some physical activity was associated with a 29% to 41% lower risk of developing AD compared with physically inactive participants, and report of much physical activity was associated with a 37% to 50% lower risk of developing AD.

When considered simultaneously, both physical activity and Mediterranean diet adherence were significantly associated with AD incidence. According to the researchers, “Belonging to the middle diet adherence tertile was associated with a 2% to 14% risk reduction, while belonging to the highest diet adherence tertile was associated with a 32% to 40% reduced risk. Similarly, compared with individuals with no physical activity, individuals reporting some physical activity had a 25% to 38% lower risk for AD, while individuals reporting much physical activity had a 33% to 48% lower risk for AD.”

The authors added, “Compared with individuals with low physical activity plus low adherence to a diet (absolute AD risk, 19%), high physical activity plus high diet adherence was associated with a 35% to 44% relative risk reduction (absolute AD risk, 12%). . . . Absolute AD risks declined from 21% in the group with no physical activity plus low diet adherence to 9% in the group with much physical activity plus high diet adherence.”