A new study from researchers at Indiana University School of Public Health-Bloomington has found that adding one ounce of walnuts (or one handful) to the diet of children and adults who do not normally eat nuts improves diet quality and intake of some under-consumed nutrients of public health importance.
Consistent evidence shows that walnuts as a snack or within a meal can provide good nutrition and be part of a healthy diet for life.
While nut consumption is already promoted in the Dietary Guidelines for Americans as part of a healthy dietary pattern, consumers are often not eating enough alongside whole grains, fruit and vegetables."
Dr. Krisha Thiagarajah, lead researcher on the study and Senior Lecturer of Nutrition at Indiana University School of Public Health-Bloomington
"Underconsumption of nutritious foods like walnuts as part of a balanced diet can result in nutrient inadequacies. When added in the diet, walnuts lead to small nutrition wins for the whole family," she adds.
For parents and guardians, ensuring children and adolescents are getting all the nutrients they need can be challenging. This is one of the few studies looking at the typical diet of both children and adults and simulating how the simple addition of walnuts to the diet could help achieve better nutritional status. Incorporating walnuts into snacks and meals may be an easy option for adults and children to consider as part of their diet.
Advanced statistical modeling techniques were used to see what would happen when one ounce of walnuts was added to the typical daily diet of nearly 8,000 Americans who do not currently eat nuts.
Participant health and dietary information were obtained from The National Health and Nutrition Examination Survey (NHANES), which is a nationally representative, cross-sectional survey of people living in the United States. Information was analyzed by age group (4–8 years, 9–13 years, 14–18 years, 19–50 years, 51–70 years, 71 years and older) and gender.
"We primarily wanted to see how adding a handful of walnuts to the typical U.S. diet could change intakes in nutrients of public health concern identified by the 2020–2025 U.S. Dietary Guidelines for Americans, including potassium, dietary fiber, and magnesium," explains Dr. Thiagarajah.
Researchers then evaluated diet quality with and without the added one ounce of walnuts using the 2015 Healthy Eating Index (HEI-2015).
Results at a glance
Adding one ounce of walnuts to the typical diets of Americans resulted in the following outcomes listed in Table 1.
Table 1. Summary of the nutrient impact of adding one ounce of walnuts to typical American diet
|Healthy Eating Index (e.g., Diet Quality)
- Significantly improved the diet quality for all ages and genders.
- Improvements were seen for the seafood and plant protein category (e.g., more seafood and plant protein), as well as the ratio of unsaturated to saturated fats (e.g., less saturated fat).
|Nutrients of Public Health Importance from the 2020 Dietary Guidelines for Americans
- Significantly improved fiber intake across all age and gender categories.
- Increased the percentage of adults above the recommended daily intake for potassium. A similar trend was observed among children and adolescents (4–18 years).
- Reduced the percentage of adults, children, and adolescents with intakes below the daily needs for magnesium and folate.
- Reductions in copper and zinc inadequacy for most age and gender groups.
"This was not an intervention or feeding study, but the modeling done as part of this research is highly important as it allows us to evaluate broad dietary implications for the general public which could have meaningful impacts to overall health," notes Dr. Thiagarajah.
Limitations of this study include the fact that self-reported 24-hour dietary recall data were used to conduct the modeling in this study and are subject to measurement error due to large day-to-day variations in food intake.
Additionally, this study can only be used to explain how adding walnuts to the diet of no-nut consumers may be impacted (n=7,757). No nut consumers tended to be younger, Hispanic or black, have an annual household income of less than $20,000.
While this modeling study demonstrates potential positive nutritional impact with walnut consumption, further observational studies or well-designed randomized clinical trials are needed to confirm these results.
A simple strategy such as adding one ounce of walnuts to a daily eating pattern can be a potential solution to improve diet quality for people of all ages. This modeling study clearly demonstrates that small dietary changes with nutrient-dense foods like walnuts may have significant benefits on nutrient intake and diet quality.
Spence, L.A., et al. (2023) Adding Walnuts to the Usual Diet Can Improve Diet Quality in the United States: Diet Modeling Study Based on NHANES 2015–2018. Nutrients. doi.org/10.3390/nu15020258.