Beware friends and family, obesity is catching
OBESITY is often described as an ‘‘ epidemic’’ — as the number of affected people continues to rise, it has been likened to a contagious disease. Now researchers have found that obesity may indeed be contagious, through social networks. Published this week in theNew EnglandJournalofMedicine , the study shows that when a person becomes obese, there is a dramatic increase in the chances that those around them will also become obese. Their close friends have a 57 per cent increased risk of obesity, their siblings have a 40 per cent increased risk and their spouse has a 37 per cent increased risk. The findings were based on 12,067 adults who took part in the Framingham Heart Study between 1971 and 2003. Participants underwent frequent medical assessments, and provided information about their family and friends. Researchers constructed a map of the genetic and social relationships in the group, and compared it to body mass index. The greatest effect was among friends rather than relatives, suggesting that a person becoming obese can influence what their friends consider to be an appropriate body size. NEnglJMed 2007;357:370-379 (Christakis NA, et al) BABIES younger than four weeks old are vulnerable to sudden death while in a seated position, warns a new study in the Archivesof DiseaseinChildhood . Researchers analysed every case of sudden unexpected death that occurred in babies up to 12 months of age in the Canadian Province of Quebec between 1991 and 2000. During this period 534 babies died and the cause of death was fully investigated in 508. Seventeen (3.3 per cent) of the 508 deaths had occurred in babies who were seated upright, usually in a car seat. Premature babies were not at greater risk compared to full-term infants. But those aged less than one month were almost four times as likely to die suddenly while seated as were older babies. There is no question that car safety seats must be used when travelling with infants, say the authors, but parents should avoid seating very young babies upright. ArchDisChild 2007;doi:10.1136/adc.2007.119180 (Cote A, et al) CHOLESTEROL levels should be kept low to prevent heart disease, but a new study in the JournaloftheAmericanCollegeof Cardiology has found a surprising link between low cholesterol and cancer. Many people take drugs called statins to lower their levels of low-density lipoprotein (LDL) cholesterol. The study examined all of the large clinical trials of statin therapy conducted prior to November 2005, involving 41,173 patients. They found one additional incident of cancer per 1000 patients with low LDL levels when compared to patients with higher LDL levels. The cancers were not of any single type or location, and the findings do not prove that statins cause cancer. But certain aspects of lowering LDL with statins remain controversial, say the authors, and merit further research. JAmCollCardiol 2007;50:409-418 (Alsheikh-Ali AA, et al) SUN exposure during childhood may lower the risk of developing multiple sclerosis (MS), according to research in the current issue of Neurology . The authors surveyed 79 pairs of identical twins with the same genetic risk for MS, where only one twin had MS. They were asked whether they or their twin spent more time outdoors during hot days, cold days, and summer, and which twin spent more time sun tanning, going to the beach and playing team sports as a child. Overall, the twin with MS spent less time in the sun as a child than the twin who did not have MS. Depending on the activity, the twin who spent more time outdoors had a 25 to 57 per cent reduced risk of developing MS. For example, the twin who spent more time sun-tanning had a 49 per cent lower risk of developing MS than their genetically identical sibling. Neurology 2007;69:381-388 (Islam T, et al) OLDER adults who cannot read and understand basic health information have a 52 per cent greater risk of death over a fiveyear period than those with adequate ‘‘ health literacy’’, according to a report in the ArchivesofInternalMedicine this week. At the start of the study in 1997, 3260 American patients aged 65 and older completed a test of health literacy involving two reading passages and four mathematical problems. Scores ranged from zero to 100, indicating inadequate (zero to 55), marginal (56 to 66) or adequate (67 to 100) health literacy. The National Death Index was then used to identify participants who died over the next five years. Overall, 64.2 per cent of participants had adequate health literacy, 11.2 per cent had marginal health literacy and 24.5 per cent had inadequate health literacy. A total of 815 people (25 per cent) died during the follow-up period, including 39.4 per cent of those with inadequate health literacy, 28.7 per cent of those with marginal health literacy and only 18.9 per cent of those whose health literacy was adequate. ArchInternMed 2007;167:1503-1509 (Baker DW, et al) GOATS could soon be used to protect people against nerve gas poisoning, with scientists finding a way to produce large amounts of the antidote in their milk. Nerve gas and some insecticides contain toxic organophosphates, which poison the nervous system. Humans can produce small amounts of an enzyme called butyrylcholinesterase that can bind to organophosphates and prevent their effects, but not enough to survive a nerve gas attack. Currently, the enzyme is produced by extracting it from human blood, but this process is slow and yields only small amounts. In the ProceedingsoftheNationalAcademy ofSciences this week, scientists describe a new method of production in which they inserted the gene for the human enzyme into goat embryos. The resulting female animals were all healthy, and produced large quantities of the antidote in their milk. When the antidote was purified from the milk and injected into guinea pigs, it remained active, showing that it is possible to produce enough antidote from goats for the treatment of exposure in people. ProcNatlAcadSciUSA 2007;doi:10.1073/ pnas.0702756104 (Huang YJ, et al) Want to know more? Items are referenced where possible. A reference such as ‘‘ 2007;35:18-25’’ means the source article was published on pages 18-25 in volume number 35 of the publication, in 2007. A doi number or website address is used for research published on a journal’s website.
Gas attack: Goat’s milk may be the antidote