Are vitamins relevant to cancer risks? A Mendelian randomization investigation.

OBJECTIVE: The relationship between vitamin intake and the occurrence of cancer is controversial. The aim of this study was to examine the genetic associations between vitamins D, E, and B12 and five cancers (i.e., colorectal cancer, breast cancer, prostate cancer, malignant melanoma, and squamous cell carcinoma). METHODS: This study started from genome-wide association data for three vitamins (N = 11 238) and five cancers (N = 373 316). The study analyzed their associations using Mendelian randomization (MR) methods. Additionally, survival analysis was performed using data from The Cancer Genome Atlas (TCGA) to further evaluate some MR results. RESULTS: MR analysis indicated that intake of vitamins D, E, and B12 is not relevant to the risk for the five cancers (PMR > Bonferroni-corrected P = 0.02). Some of the results were supported by epidemiological observations; some were further supported by survival analysis using TCGA data. CONCLUSION: There is no genetic evidence to support the association between intake of vitamins D, E, and B12 and the risk for colorectal, breast, and prostate cancers, malignant melanoma, and squamous cell carcinoma.

Decline in semen concentration of healthy Chinese adults: evidence from 9357 participants from 2010 to 2015.

The present study aims to analyze sperm concentration trends among young and healthy Chinese adults in Wuhan, Central China, from 2010 to 2015. Semen analysis data from 9357 participants were collected and analyzed using a general linear model and the Cochran-Armitage trend test. A significant decline was observed in sperm concentration (ß [standard deviation]: -1.53 [0.16]; P < 0.001). In addition, a decline in sperm density was observed by stratifying student versus nonstudent sperm donors and by analyzing the year of birth or birth year cohort of the participants. Furthermore, the percentage of participants with sperm densities of over 40 × 106 ml-1 significantly decreased with year. Notably, a dramatic decline in sperm density was recorded over the first 5 years of study. This research reported a decline in sperm concentration among young adults in Wuhan, Central China, in 2010-2015.