The “C” Word
HIGHER VITAMIN D LEVELS LINKED TO LOWER COLORECTAL CANCER RISK
Higher levels of vitamin D are associated with a lower risk of colorectal cancer, according to a recent analysis of study data.1 In a pooled analysis, individuals who were deficient in circulating 25(OH)D (<30 nmol/L) had a 31% higher colorectal cancer risk. The difference in risk was statistically significantly lower in women (19%) but not statistically significant in men (7%), the authors found.
The researchers pooled data from 17 cohorts, including 5,706 colorectal cancer case participants and 7,107 control participants with a wide range of circulating 25(OH)D levels. Participants with circulating 25(OH)D levels of 75 to <87.5 had a 19% lower colorectal cancer risk, and those with levels of 87.5 to <100 nmol/L had a 27% lower risk.
The researchers found that colorectal cancer risk did not continue to decline at 25 (OH)D levels of 100 nmol/L or greater and that adjusting for body mass index, physical activity, and other risk factors did not have a significant effect on these associations.
1. McCullough ML, Zoltick ES, Weinstein SJ, et al. Circulating vitamin D and colorectal cancer risk: an international pooling project of 17 cohorts. [published online ahead of print June 14, 2018]. J Natl Cancer Inst.
COMMON VIRAL SPECIES LINKED TO ALZHEIMER DISEASE
Postmortem examination of the brain tissue of individuals diagnosed with Alzheimer disease (AD) revealed increased levels of two types of human herpes virus, in a study recently published in Neuron.1 Researchers set out to map and compare the biological networks of two phenotypes associated with AD, referred to in the study as preclinical AD and clinical AD, from human postmortem brain tissue. Functional genomic analysis of network alterations in tissue from preclinical AD individuals revealed evidence of viral activity. The researchers then analyzed the viral activity in tissue from individuals with clinical AD and cognitively normal controls of four large, multi-omic (genomic, transcriptomic, and proteomic) datasets. The analysis included use of next generation sequencing data, which enabled direct examination of viral DNA and RNA sequences.
The results of this study provide evidence linking the activity of specific viral species, particularly human herpesvirus 6A and human herpesvirus 7, to AD. However, the study authors stated, “It is important to note that the findings reported in this study are not sufficient to definitively demonstrate that viral activity causally contributes to the onset or progression of AD.”
1. Readhead B, Haure-Mirande JV, Funk CC, et al. Multiscale analysis of independent Alzheimer’s cohorts finds disruption of molecular, genetic, and clinical networks by human herpesvirus. Neuron. 2018. 99(1):64-82.e7.
FREQUENT DINING OUT ASSOCIATED WITH HIGHER LEVELS OF TOXIC CHEMICALS
Frequent dining out can lead to higher levels of antiandrogenic phthalates, reproductive toxicants that may have additive effects on male development, according to a study published in Environment International.1 Researchers set out to compare cumulative phthalate exposure from dietary sources consumed at home and away from home.
To estimate cumulative phthalate exposure, the researchers calculated daily intake from metabolite concentrations in urinary spot samples for 10,253 participants using data from the National Health and Nutrition Examination Survey. The researchers found that phthalate levels were consistently higher in participants who dined out more frequently.
1. Varshavsky JR, Morello-Frosch R, Woodruff TJ, Zota AR. Dietary sources of cumulative phthalates exposure among the U.S. general population in NHANES 2005-2014. Environ Int. 2018;115:417-429.
Section Editor David S. Boyer, MD
• Clinical Professor of Ophthalmology at the University of Southern California Keck School of Medicine, Department of Ophthalmology, in Los Angeles, California
• Member of the Retina Today editorial advisory board