News briefs

Benefits of healthy diet greater for those at high genetic risk of obesity

US research published in the BMJ has shown that the benefits of sticking to a healthy diet to prevent long term weight gain are greater in people at high genetic risk for obesity than in those with lower risk. The researchers analysed data from two large studies of US health professionals – 8828 women in the Nurses’ Health Study and 5218 men from the Health Professionals Follow-up Study from 1986 to 2006. Genetic risk score was calculated on the basis of 77 gene variants known to influence body mass index. Changes in body mass index and weight were calculated every 4 years. Changes in dietary patterns were also assessed every 4 years with three diet quality scores: the Alternate Healthy Eating Index 2010 (AHEI-2010), Dietary Approach to Stop Hypertension (DASH), and Alternate Mediterranean Diet (AMED). These diets are all rich in fruit and vegetables, nuts and whole grains, and low in salt, sugary drinks, alcohol and red and processed meats. After 20 years’ follow-up, the researchers found that improving adherence to the AHEI-2010 and DASH was associated with decreases in body mass index and body weight, and that the effect was more prominent in people at high genetic risk for obesity than those with low genetic risk. In addition, they noted that “the genetic risk of weight gain is attenuated by improving adherence to these healthy dietary patterns”. No clear interaction pattern was found for AMED. The authors pointed out that this was an observational study, so no firm conclusions could be drawn about cause and effect. Nevertheless, they said that their findings “highlight the importance of improving adherence to a healthy diet in the prevention of weight gain, particularly in people genetically predisposed to obesity”.

http://www.bmj.com/content/360/bmj.j5644

http://www.bmj.com/content/360/bmj.k7

Genetic risk could guide prostate screening

A new score for predicting a man’s genetic risk of developing aggressive prostate cancer could help guide decisions about who to screen and when, according to research published in the BMJ. The researchers used data from an international study collaboration (the PRACTICAL consortium) to develop and test a genetic tool for predicting age of onset of aggressive prostate cancer and to guide decisions about who to screen and at what age. They analysed more than 200 000 gene variants (single nucleotide polymorphisms, or SNPs) in 31 747 men of European ancestry with and without prostate cancer, and identified 54 SNPs associated with increased risk of prostate cancer. These polymorphisms were incorporated into a survival analysis to estimate their effects on age at diagnosis of aggressive prostate cancer in the form of a hazard score. To validate the final model, it was applied to data from an independent clinical trial of 6411 men. The hazard score was a highly significant predictor of age at diagnosis of aggressive cancer; men in the top 2% of the score had an almost three-fold greater risk for aggressive prostate cancer than men with average risk. The researchers commented that the score is representative of a man’s fixed genetic risk, so “it can be calculated once, long before onset of prostate cancer, and substantially inform the decision of whether he should undergo screening”. They acknowledged some study limitations, and could not rule out the possibility that other, unmeasured factors may have influenced their results. Nevertheless, they said these results “add to existing data as further evidence that genetic features can predict risk of prostate cancer”.

http://www.bmj.com/content/360/bmj.j5757