Objective To review systematically the evidence for an effect of long chain and shorter chain omega 3 fatty acids on total mortality, cardiovascular events, and cancer. Data sources Electronic databases searched to February 2002; authors contacted and bibliographies of randomised controlled trials (RCTs) checked to locate studies. Review methods Review of RCTs of omega 3 intake for 3 6 months in adults (with or without risk factors for cardiovascular disease) with data on a relevant outcome. Cohort studies that estimated omega 3 intake and related this to clinical outcome during at least 6 months were also included. Application of inclusion criteria, data extraction, and quality assessments were performed independently in duplicate. Results Of 15 159 titles and abstracts assessed, 48 RCTs (36 913 participants) and 41 cohort studies were analysed. The trial results were inconsistent. The pooled estimate showed no strong evidence of reduced risk of total mortality (relative risk 0.87, 95% confidence interval 0.73 to 1.03) or combined cardiovascular events (0.95, 0.82 to 1.12) in participants taking additional omega 3 fats. The few studies at low risk of bias were more consistent, but they showed no effect of omega 3 on total mortality (0.98, 0.70 to 1.36) or cardiovascular events (1.09, 0.87 to 1.37). When data from the subgroup of studies of long chain omega 3 fats were analysed separately, total mortality (0.86, 0.70 to 1.04; 138 events) and cardiovascular events (0.93, 0.79 to 1.11) were not clearly reduced. Neither RCTs nor cohort studies suggested increased risk of cancer with a higher intake of omega 3 (trials: 1.07, 0.88 to 1.30; cohort studies: 1.02, 0.87 to 1.19), but clinically important harm could not be excluded. Conclusion Long chain and shorter chain omega 3 fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer.

Objective To assess the effectiveness of a primary care referral scheme on increasing physical activity at 1 year from referral. Design Two-group randomized controlled trial recruiting primary care referrals to a borough-based exercise scheme. Setting A local authority borough in the north-west of England. Participants 545 patients defined as sedentary by a primary care practitioner. Intervention Referral to a local-authority exercise referral scheme and written information compared with written information only. Main outcome measures Meeting physical activity target at 12 months following referral, with a secondary outcome measured at 6 months from referral. Results At 12 months, a non-significant increase of 5 per cent was observed in the intervention compared with control group, for participation in at least 90 minutes of moderate/vigorous activity per week (25.8 versus 20.4 per cent, OR 1.45, 0.84 to 2.50, p = 0.18). At 6 months, a 10 per cent treatment effect was observed which was significant (22.6 versus 13.6 per cent, OR 1.67, 1.08 to 2.60, p = 0.05). The intervention increased satisfaction with information but this did not influence adherence with physical activity. Conclusion Community-based physical activity referral schemes have some impact on reducing sedentary behaviour in the short-term, but which is unlikely to be sustained and lead to benefits in terms of health.

Several risk factors for the development of cataract have been identified. This review evaluates epidemiologic literature that has examined tobacco smoking as a risk factor for cataract formation using established causality criteria. Twenty-seven studies were included in this review. Evidence suggests that smoking has a 3-fold increase on the risk for incident nuclear cataract development. There was also evidence of dose response, temporal relationship, and reversibility of effect. There was limited evidence of an association between smoking and posterior subcapsular cataract, but little or no association with cortical cataract. Thus, the literature review indicated a strong association between smoking and the development of cataract, particularly nuclear cataract. The association fulfills the established criteria for causality. The association between smoking and other types of cataract is less distinct and requires further evaluation.

Many people take dietary supplements, but information on characteristics associated with their use is lacking. The relationship between lifestyle behaviours, morbidity and use of dietary supplements has not been examined and earlier studies have limited applicability to a general population. These issues were addressed in the current study. Information was obtained by postal questionnaire sent to a sample of the general population. The questionnaire was completed by 70·5% of the sample (15465 from a total sample of 21923), with at least one-third (35·5%) taking dietary supplements. In adjusted analyses, supplement users were more likely to be women, white, home-owners, non-smokers and physically active. Use of vitamin, mineral and/or antioxidant supplements was associated with eating more fruits and vegetables, and taking fish-oil supplements was associated with eating oil-rich fish. A history of CVD or risk factors for CVD reduced the risk of taking vitamins, minerals and/or antioxidants or fish-oil supplements. Those reporting musculoskeletal disorders such as arthritis were more likely to take fish-oil supplements For the first time, we have shown that dietary supplement use is related to different types of morbidity. In particular, people at risk of primary or secondary CVD seem less likely to use dietary supplements, despite possible benefits shown in clinical trials. Public health organisations need to develop guidelines for the public and health professionals regarding the uncontrolled use of dietary supplements in the community.

Area-based interventions offer the potential to increase physical activity for many sedentary people in countries such as the UK. Evidence on the effect of individual and area/neighbourhood influences on physical activity is in its infancy, and despite its value to policy makers a population focus is rarely used. Data from a population-based health and lifestyle survey of adults in northwest England were used to analyse associations between individual and neighbourhood perceptions and physical activity. The population effect of eliminating a risk factor was expressed as a likely effect on population levels of physical activity. Of the 15 461 responders, 21 923 (27.1%) were physically active. Neighbourhood perceptions of leisure facilities were associated with physical activity, but no association was found for sense of belonging, public transport or shopping facilities. People who felt safe in their neighbourhood were more likely to be physically active, but no associations were found for vandalism, assaults, muggings or experience of crime. The number of physically active people would increase by 3290 if feelings of “unsafe” during the day were removed, and by 11 237 if feelings of “unsafe” during the night were removed. An additional 8342 people would be physically active if everyone believed that they were “very well placed for leisure facilities”. Feeling safe had the potential largest effect on population levels of physical activity. Strategies to increase physical activity in the population need to consider the wider determinants of health-related behaviour, including fear of crime and safety.

Background Sedentary behaviour is a public health priority in many countries. Hundreds of community-based exercise referral schemes have been established in Europe and USA, to increase physical activity. Experimental evidence questions the effectiveness of these schemes. No previous evaluations have considered a population approach nor provide detailed information on the types of people accessing these schemes. This is of concern given increasing health inequalities in other areas of care. Our register-based study quantified the numbers and characteristics of patients referred and accessing a district-wide exercise referral scheme. The analysis considers the effectiveness of these schemes to a geographically defined population. Methods Data were collected prospectively from a patient register for referrals made to a district-wide exercise referral scheme in north-west England. Analysis examined referral rates and the influence of practitioner and patient characteristics on access to the scheme. Results Over 5 years, 6610 adults were referred from 125 general practices, with 60.8 per cent female and a mean age of 51.3 years (SD 12.6). This represents 4 per cent of the adult sedentary population in that district. The most common reason for referral was musculoskeletal or cardiovascular risk. Overall, 79 per cent attended at least the first appointment, with statistically significant predictors by age and reason for referral. Those referred for ‘fitness’ or ‘mental health’ were most likely to attend. Patients in the youngest and oldest age groups were least likely to attend. Patient’s sex and deprivation and the number of patients referred by each general practice did not influence attendance. Conclusions Primary-care patients seem to view the concept of exercise referral schemes positively but practitioners remain reluctant to refer many of their sedentary patients. There is doubt that exercise referral schemes like this will influence population levels of sedentary behaviour, when considered alongside their impact on physical activity in the longer term.