Diet Liberalisation in Older Australians Decreases Frailty without Increasing the Risk of Developing Chronic Disease.
BACKGROUND
Successful ageing relies on the prevention of frailty and chronic disease, many of which have a strong link with diet. Despite evidence suggesting diet is important in the management of frailty, there is little evidence investigating the impact of a liberal diet on the prevention of frailty and development of chronic diseases in the elderly.


OBJECTIVE
To determine the impact of a liberal diet on the development of frailty and whether this affects the incidence of obesity, diabetes, hypertension and hyperlipidaemia.


METHODS
Secondary data analysis of the Australian Longitudinal Study of Ageing, 1992 to 2000.


METHODS
Random selection of older adults from the South Australian electoral roll.


METHODS
1298 older Australians (629 women, 669 men), mean age 77 years.


METHODS
A validated food frequency questionnaire was used to measure the dietary exposure; liberal diet defined as: energy >10% estimated requirements; sodium >1600mg; total fat >35% energy; saturated fat >10%; refined sugar >10%; fibre <38g males and <28g females. Frailty was determined using the Fried phenotype in combination with Cesari's biological definition of frailty. Chronic disease outcomes were measured by medication usage and obesity defined as BMI >30kg/m². Binary logistic regression was performed using participants free of chronic disease at baseline to determine the impact of each dietary exposure independently, and combined, on the development of frailty and the incidence of chronic disease over the subsequent eight years.


RESULTS
Incidence of frailty after 8 years of follow up was 14%. The incidence of diabetes after 8 years of follow up was 5.3%, hypertension 39%, hyperlipidaemia 15% and obesity 6%. A liberal energy intake adjusted for age and sex, significantly reduced the risk of developing frailty eight years post baseline (OR 0.48, 95% CI 0.30, 0.77). After adjustment for age, sex and body weight, a liberal saturated fat intake (>10% of energy) increased the risk of hyperlipidaemia (OR 2.11, 95% CI 1.27, 3.54). A liberal intake of sodium, total fat, refined sugar and fibre did not increase the risk of diabetes, hypertension, hyperlipidaemia or obesity.


CONCLUSIONS
This study suggests that a liberal intake of energy may decrease the risk of developing frailty in the elderly without increasing the risk of developing obesity, diabetes, hypertension or hyperlipidaemia. Caution should remain however in the prescription of diets high in saturated fat as the link established with hyperlipidaemia in young adults appears to be consistent in the elderly. Further research is required to explore the optimal sources of energy for a liberalised diet and the effect of a liberalised diet on other diet related health conditions.
Associate Prof. Michelle Miller, Department of Nutrition and Dietetics, Flinders University, GPO Box 2100, Adelaide, South Australia, 5001, Phone: 61 8 8204-5328, Fax: 61 8 8204-6406, Email: michelle.miller@flinders.edu.au.
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Baulderstone
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Yaxley
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Luszcz
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Miller