Rather than focussing on individual dietary components, some researchers have studied the effects of entire diets on disease risk. As a result, a number of dietary assessment indices have been created in an attempt to better measure diet quality. Three commonly used diet indices include the Recommended Food Score (RFS), the Healthy Diet Score (HDS) and the Mediterranean diet score (MDS). The RFS is based on measurement of diet quality against foods consistent in dietary guidelines (lean meat, poultry and fish, whole grains, fruits and juices, low-fat dairy, and vegetables). In contrast, the MDS is based on measurements against how closely a diet resembles the traditional fish, vegetable and whole grain diet of the Mediterranean area. The HDS was adapted for use in the British population and originates from a diet inversely associated with all cause mortality (high fibre, fruit and vegetables with limited sugar, fat and cholesterol).
Researchers1 have investigated the effects of the HDS, RFS and MDS on the risk of all cause mortality in a group of 972 British subjects over 65 years of age. The data was collected from a 4 day diet record that was originally included in the British Diet and Nutritional Survey in 1994 and 1995, with a follow-up for mortality in 2008. The hazard risk for all cause mortality were adjusted for known confounding variables such as age, sex, energy intake, region, social class, smoking physical activity and body mass index, using Cox regression. Following adjustment, the MDS was significantly inversely associated with mortality (hazard ratio 0.78 between highest and lowest quartile). In addition, the RFS was significantly inversely associated with mortality (hazard ratio 0.67 between the highest versus the lowest quartile). However, the HDS showed no significant associations with mortality (hazard ratio 0.99 between highest and lowest quartiles).
These results suggest that the MDS and RFS can be useful predictors of all-cause mortality in healthy individuals over 65 years. The HDS has been shown previously to be inversely associated with all-cause mortality in populations from the Netherlands, Italy and Finland, but in this study no association was found. This may relate to the methodology employed, as previous studies used younger subjects and had longer follow-up periods. The explanation of the null findings in this study may also relate to the less varied diets of the British that in this case may not have included enough subjects eating healthy diets close to the HDS. The beneficial effects of the MDS support previous research in the nutritional literature that suggests a role for the Mediterranean diet in promoting health. Individual components of the diet that are known to confer disease protection include olives, whole grains, vegetables, fibre, red wine, diary, fish oils, fruits and herbs.
1McNaughton, S. A , Bates, C. J. and Mishra, G. D. 2012. Diet quality is associated with all-cause mortality in adults aged 65 years or older. Journal of Nutrition. 142: 320-325