Personal health also depends partially on the social structure of a person's life. The maintenance of strong social relationships, volunteering, and other social activities have been linked to positive mental health and also increased longevity. One American study among seniors over age 70, found that frequent volunteering was associated with reduced risk of dying compared with older persons who did not volunteer, regardless of physical health status. Another study from Singapore reported that volunteering retirees had significantly better cognitive performance scores, fewer depressive symptoms, and better mental well-being and life satisfaction than non-volunteering retirees.
In a study in JAMA Internal Medicine, researchers reported that people who ate the most sugar had a higher risk of death from heart disease, even if they weren’t overweight. Another study found that spending just three months on a sugar-heavy diet changed fat metabolism in healthy men, causing them to develop non-alcoholic fatty-liver disease, which boosts the risk of cardiovascular disease.
The Australian government announced in May 2008 that it proposes to increase the thresholds, to $100,000 for singles and $150,000 for families. These changes require legislative approval. A bill to change the law has been introduced but was not passed by the Senate. An amended version was passed on 16 October 2008. There have been criticisms that the changes will cause many people to drop their private health insurance, causing a further burden on the public hospital system, and a rise in premiums for those who stay with the private system. Other commentators believe the effect will be minimal.