Australian researchers mull over dietary guideline improvements

Researchers from Australia, Finland and the U.K. sought to improve dietary guidelines by taking age and sex into account. Their report on a new Dietary Guidelines Index (DGI) was published in the journal Nutrition Research.

• The researchers believe that measuring diet quality over time is important due to its impact on health.
• To their knowledge, a DGI with consistent scoring across childhood/adolescence (youth) and adulthood has not been validated.
• The researchers hypothesized that a DGI that reflects age- and sex-specific guidelines could be a valid measure of diet quality in youth and adulthood.
• They based the DGI on the 2013 Australian Dietary Guidelines to reflect the current understanding of diet quality. The DGI comprises nine indicators with a maximum score of 100 points.
• The researchers calculated DGI scores for participants of the Australian Childhood Determinants of Adult Health study, which included a 24-hour food record during youth (ages 10-15 years) and a 127-item food frequency questionnaire during adulthood (ages 26-36 years).
• They also evaluated construct validity (distribution of scores, principal components analysis, correlation with nutrient density of intakes) and criterion validity (linear regression with population characteristics).
• The researchers reported that the DGI scores they calculated were multi-dimensional in underlying structure and normally distributed.
• They found a significant association between a lower DGI among youth and smoking, lower academic achievement and lower socioeconomic status.
• DGI scores were also negatively correlated with energy, sugar and fat, but were positively correlated with fiber, protein and micronutrients.
• Among adults, low DGI scores were associated with low education, low self-reported health, high waist circumference, insulin resistance and high total and low-density lipoprotein serum cholesterol.

The researchers believe that their proposed DGI is an appropriate measure of diet quality in youth and adulthood because higher scores reflect nutrient-dense, instead of energy-dense, intake and discriminate between population characteristics in a manner consistent with literature.

Journal Reference:

Wilson JE, Blizzard L, Gall SL, Magnussen CG, Oddy WH, Dwyer T, Venn AJ, Smith KJ. AN AGE- AND SEX-SPECIFIC DIETARY GUIDELINES INDEX IS A VALID MEASURE OF DIET QUALITY IN AN AUSTRALIAN COHORT DURING YOUTH AND ADULTHOOD. Nutrition Research. May 2019;65:43–53. DOI: 10.1016/j.nutres.2019.01.007