Nutrition Health Review

WINTER 2017

Nutrition Health Review provides consumers updates on the latest medical research, news, trends, and products in nutrition and healthy living.

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Winter 2017 • Volume 114 13 Being Out in Nature Can Help Clear Negative Thoughts R esearch shows that city living is associated with increased levels of mental illness, including depression. Exposure to nature, on the other hand, has been shown repeatedly to reduce stress and boost well-being. But no one has really been sure why. A group of researchers from Stanford University thought nature's positive effect on our well-being might have something to do with reducing rumination, or "a maladaptive pattern of self-referential thought that is associated with heightened risk for depression and other mental illnesses." In simpler terms, rumination is when you can't stop thinking about things that are really bothering you. Rumination seems to originate in the subgenual prefrontal cortex of our brains, which is the part of the brain that regulates negative emotions. In their study, published in Proceedings of the National Academy of Sciences, the Stanford scientists examined whether a nature walk could reduce rumination in 38 mentally healthy, city-dwelling people. Half of the study subjects took a 90-minute walk through grassland dotted with oak trees and shrubs, and the other half walked along a four-lane, traffic-logged street in Palo Alto. At the end of the study, the nature walkers showed decreases in rumination and in activity in their subgenual prefrontal cortices. The urban walkers showed no such improvements. The scientists believe nature reduces rumination by providing "positive distractions," similar to having a hobby or chatting with a friend. Natural environments are more restorative, the authors write, and thus confer greater psychological benefits. According to the authors, this effect should work with many types of natural landscapes, particularly those that engender "soft fascination," a "sense of belonging," and the "sense of being away." Source: Khanzan O. How walking in nature prevents depression. The Atlantic. June 30, 2015. Sunlight Stimulates Infection-fighting T Cells, According to New Study F or the first time, a study has reported the direct response of human cells upon exposure to sunlight, beyond the synthesis of vitamin D and production of melanin. Sunlight exerts important biological effects on human skin. In fact, sun exposure has been shown to play a role in a variety of health outcomes, including strengthening the immune system. While vitamin D has been shown to increase the expression of anti-microbial proteins, researchers have also wondered if there are additional components to sunlight that may improve the immune system. Researchers from Georgetown University Medical Center recently aimed to determine how blue light affects the immune system. They obtained T cells from both mouse cell cultures and human blood and exposed them to blue light, present in the sun's rays. T cells are a type of white blood cell responsible for identifying and destroying foreign invaders. The researchers tracked the molecular pathway activated from light. They found that when exposed to low levels of blue light (<300 mJ cm−2), T cells became more mobile. The authors provided insight on this finding: "We all know sunlight provides vitamin D, which is suggested to have an impact on immunity, among other things. But what we found is a completely separate role of sunlight on immunity. T cells, whether they are helper or killer, need to move to do their work, which is to get to the site of an infection and orchestrate a response. This study shows that sunlight directly activates key immune cells by increasing their movement." Sources: Phan, T. et al. Intrinsic Photosensitivity Enhances Motility of T Lymphocytes, Scientific Reports 2016; Sunlight offers surprise benefit—it energizes infection fighting T cells. Medical Express 2016. FAST FACT! Research shows that women who eat three or more 1/2 cup servings of strawberries or blueberries each week have a lower risk for heart attack. Source: High anthocyanin intake Is associated with a reduced risk of myocardial infarction in young and middle- aged women. Circulation 2013.

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