“Improved prediction of chronological age from DNA methylation limits it as a biomarker of ageing”, Zhang et al 2018

DNA methylation is associated with age. The deviation of age predicted from DNA methylation from actual age has been proposed as a biomarker for ageing. However, a better prediction of chronological age implies less opportunity for biological age. Here we used 13,661 samples in the age range of 2 to 104 years from 14 cohorts measured on Illumina HumanMethylation450/EPIC arrays to perform prediction analyses using Elastic Net and Best Linear Unbiased Prediction. We show that increasing the sample size achieves a smaller prediction error and higher correlations in test datasets. Our predictors achieved prediction errors of about 4.5 years across cohorts, in contrast to >7 years for the widely-used Horvath and Hannum predictors. We demonstrate that smaller prediction errors provide a limit to how much variation in biological ageing can be captured by methylation and provide evidence that age predictors from small samples are prone to confounding by cell composition.


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Viewpoint: A Contributory Role of Shell Ginger (Alpinia zerumbet) for Human Longevity in Okinawa, Japan?

The longevity of the population in the Okinawa Islands of Japan has been ascribed to genetic factors and the traditional Okinawa cuisine, which is low in calories and high in plant content. This diet includes shell ginger (Alpinia zerumbet (Pers.) B.L. Burtt & R.M. Sm) of the ginger family (Zingiberaceae). Due to its local popularity, Alpinia zerumbet has become the subject of a good deal of study at the University of the Ryukyus in Okinawa. Personal local experience and review of the literature now suggest that culinary shell ginger may contribute to longevity among the population in Okinawa. This is supported by its abundant phytochemical content, with antioxidant and anti-obesity properties. The major bioactive phytochemicals are dihydro-5,6-dehydrokawain (DDK; 80?410 mg g?1 fresh weight), 5,6-dehydrokawain (DK; ?100 mg g?1), and essential oils, phenols, phenolic acids, and fatty acids (?150 mg g?1 each). Further, Alpinia zerumbet extends the lifespan in animals by 22.6%. In conclusion, culinary shell ginger may significantly contribute to human longevity in Okinawa.


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