Two linked studies, by Fowler and Christakis, and Cohen-Cole and Fletcher, discuss the transmission of health related factors through social networks.
That behaviours may spread over time from one person to another through their immediate and more distant social contacts. Social epidemiology has established the relevance of social connectedness for health, and social network transmission may be one mechanism through which both beneficial and adverse effects are mediated.”
The article by Fowler and Christakis investigated the social transmission of happiness. Happiness is related to several aspects of well being, including better work performance, greater job satisfaction, good family relationships, and a more satisfying social life,” but what has it got to do with health and nutrition?
Measures of happiness, cheerfulness, and related constructs were associated prospectively with reduced mortality, both in initially healthy people and in those with established illnesses. These effects were independent of initial health status, age, demographic factors, and risk factors, and not affected by anxiety and depression. These results indicate that happiness is beneficial over and above the absence of misery.
The pathways through which happiness might influence future health are not well established, Evidence relating happiness to health behaviours such as smoking, physical activity, and diet is mixed. More consistent findings have emerged from studies that look at biological outcomes. Happiness has been associated with lower cortisol output over the day, attenuated inflammatory responses, and patterns of heart rate variability indicative of healthy cardiac autonomic control. These associations are independent of socio-economic characteristics and negative affective states. One possibility is that frontal and limbic brain mechanisms that regulate neuroendocrine and autonomic function play a role. Happiness is also related to greater social connectedness and stronger ratings of social support.
Infectious disease epidemiologists have long studied how social networks affect the transmission of infectious agents.
Fowler and Christakis suggest that behaviours and psychological states relevant to health may also be transmitted from person to person.
Social bonds, especially friendship bonds, are often established between similar people sharing common personal attributes and the environments in which they live and work. These characteristics have been shown to be related to health outcomes and psychological states.
Fowler and Christakis use data from the Framingham Heart Study to investigate whether happiness in the “ego” (a key person in the study) is affected by the happiness of “alters” (people connected to the ego), Mutual friends may be more similar to one another than non-mutual friends or alter perceived friends (when the alter thinks of the ego as a friend but this is not reciprocated). Although the results seem to show slightly stronger associations for nearby friends than for nearby alter perceived friends, these two estimates may not really be all that different.
An intriguing finding is that the happiness of next door neighbours is more strongly associated with the happiness of the ego than it is for neighbours in the same block.
The important aspect of this for nutrition is that communal eating, a dying mode of food ingesition may be of great health importance.
Steptoe and Diez Roux 2009 Happiness, health and social networks BMJ vol 38 pp 1-2
Fowler and Christakis 2009 Dynamic spread of happiness in a large social network: longitudinal analysis of the Framingham Heart Study social network BMJ vol 338, pp 23-34
Cohen-Cole and Fletcher 2008 detecting implausible social network effects in acne, height and headaches. Longitudinal analysis BMJ vol 337
- Martin Eastwood