Previous studies had suggested that vitamin E might improve the immune system. In animal studies vitamin E seemed to protect against various infections.

Harri Hemila and Jaakko Kaprio, of the University of Helsinki, Helsinki, Finland, studied whether vitamin E supplementation might decrease the risk of tuberculosis. They analyzed the data of the randomized trial (Alpha-Tocopherol Beta-Carotene Cancer Prevention Study) which was conducted in Finland between 1985-1993 and included male smokers aged 50-69 years. There were 174 cases of tuberculosis in 29,023 participants during the 6-year supplementation of 50 mg/day vitamin E.

The effect of vitamin E on tuberculosis risk was modified by the intake of vitamin C in diet. Vitamin E had no effect on participants who had dietary vitamin C intake less than 90 mg/day. Unexpectedly, vitamin E supplementation increased tuberculosis risk by 72% in those who had dietary vitamin C intake over 90 mg/day. The most dramatic increase in tuberculosis risk by vitamin E was restricted to a one-year period after the initiation of supplementation.

The US nutritional recommendations, issued by the prestigious Institute of Medicine, consider that vitamin E is safe in amounts up to 1000 mg/day. This new study suggests that in some population groups vitamin E supplementation may be harmful at a substantially lower dose, 50 mg/day.

The researchers concluded that the consumption of vitamin E supplements by the general population should be discouraged because there is evidence of harm for some people.

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The summit has brought together world experts across a range of areas, including academia, government, business, law, economics and urban planning to promote change.

According to Associate Professor of public health Ruth Colagiuri, from the University of Sydney, 4 million working days were lost each year in Australia due to obesity; she says fresh food needed to become more affordable and the sugar, fat and salt content of food reduced.

The three-day summit, Building a Healthy Future, was organised by the Oxford Health Alliance, a coalition of health and business groups including researchers from the University of Oxford, and will finalise recommendations for urgent action to be given to the Federal Government's 2020 summit in April.

Professor Anthony Capon, of the University of Sydney, has called for cities to be redesigned as "human habitats" if the dual crises of chronic disease and global warming is to be solved.

Professor Capon says jobs, services, schools and shops needed to be built close to where people live and public transport needed to be improved so that physical activity can be built back into people's lives.