How Is Diet Quality Measured?

By Nikki Ford, Ph.D, Senior Director, Avocado Nutrition Center

What is diet quality, how is it measured and why?

You can help your patients assess their diet quality and/or compare them to their demographic group. Various indices exist for assessing diet quality, with the Healthy Eating Index (HEI) in the United States being a USDA tool that evaluates diet based on alignment with the Dietary Guidelines for Americans. The HEI-2020 and HEI-Toddlers-2020 utilize nationally representative survey data to calculate scores for different age groups.

On average, diet quality in the U.S. falls below the ideal score of 100 across all age groups, indicating non-alignment with the Dietary Guidelines. Notably, young children and adults over 60 exhibit relatively higher average?scores.

The HEI-Toddlers-2020 specifically addresses children aged 12-23 months, considering 13 components related to complementary foods and beverages. Saturated fats are uniquely considered for this age group, with no limit on saturated fat as long as it doesn’t displace energy needed for adequate food group intake.

Here are the HEI-2020 components and scoring standards.

Collecting dietary intake

As a health professional, you may be using diet assessment tools. Although numerous diet collection tools exist, the 24-hr dietary recall is the gold-standard measurement. Two widely used tools include the Automated Self-Administered 24-Hour Dietary Assessment Tool (ASA24) and the Nutrition Data System for Research (NDSR). It’s important to note that these tools may categorize foods differently. For instance, NDSR classifies avocados as a fruit, while ASA24, which uses the USDA Database, classifies avocados as a vegetable. This distinction can impact the Healthy Eating Index (HEI) calculation, particularly for avocado intake.

How does diet quality change when avocados are eaten?

In a 26-week clinical study2 involving 1008 adults with abdominal obesity, half of the participants received one avocado daily while maintaining their usual diets. This intervention resulted in a significant 4.74-point increase in Healthy Eating Index scores.

Although the study initially used NDSR to capture food intake, researchers adjusted the HEI-2015 calculation to align with the USDA’s classification of avocados as a vegetable. Avocado servings were included in the Total Vegetable HEI-2015 component and excluded from the HEI-2015 fruit components. Despite employing the most conservative estimate of diet quality, avocado supplementation led to increased self-reported vegetable intake, improved fatty acid ratio, and reduced sodium, refined grains, and added sugars. Notably, these changes were not correlated with shifts in cardiometabolic risk factors. The research, supported by the Avocado Nutrition Center, contributes to the growing body of evidence suggesting that avocados can be part of healthy dietary patterns and may naturally displace less healthy options.

References:

1. “Comparison of NDSR and the ASA24 for 24-hour Dietary Recall Collection.” University of Minnesota. https://www.ncc.umn.edu/wp-content/uploads/2015/12/Comparison-of-NDSR-vs-ASA24-for-Dietary-Recall-Collection.pdf
2. Petersen K. et al. “One avocado per day as part of usual intake improves diet quality: Exploratory results from a randomized controlled trial.” Current Developments in Nutrition. 2024.

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