New Study Bolsters Existing Evidence that Walnuts Support Well-Being for Gen Z

Food plays a big role in everyone’s identity, and those born between 1997-2012, commonly known as Gen Z, have been deemed the “foodie generation”. Gen Z is driven to a particular food by varied factors, but data suggests foods that support health and well-being by providing energy, managing weight, and fostering mental health are priorities.^1,2 Yet when it comes to choosing foods that support these needs, Gen Z, along with millennials and beyond, often overlook a convenient and important food group – tree nuts, including walnuts.

Walnuts and Well-being

Nuts, including walnuts, are nutrient dense and considered a key component of many recommended dietary patterns, including the Mediterranean and vegetarian diets. They are also recommended for daily consumption in India’s new dietary guidelines by National Institute of Nutrition, which highlight that nuts, such as walnuts, as an essential part of a healthy meal. New research further suggests people, especially Gen Z and millennials, should reconsider nuts, like walnuts.

California Walnuts

New Research Evaluates the Impact of Nuts on Weight Management for Gen Z and Millennials

In a recent observational study from Indiana University School of Public Health-Bloomington and funded by the California Walnut Commission, researchers observed that adolescents and young adults who consumed walnuts and other nuts had a lower prevalence for obesity when compared with those who consumed no nuts.⁴

Researchers analyzed data from the National Health and Nutrition Examination Survey (NHANES) which included more than 19,000 adolescents (12 – 19 years old) and young adults (20 – 39 years old) to understand the associations between consumption of walnuts and other nuts with measures of obesity including relative fat mass (RFM), a validated tool for estimating body fat percent and regional fat composition.

In particular, young women consuming only walnuts had a significantly lower prevalence of obesity when compared to non-nut consumers. However, this association was not found among young men, adolescent boys, or adolescent girls who consumed walnuts only. Researchers also observed that adolescent girls and young women who consumed walnuts only, or other nuts, had a significantly lower RFM compared to non-nuts consumers. Only young males in the walnut and other nut groups showed an inverse association with RFM compared to no nuts group, this was not found in adolescent boys.⁴

These results are promising suggesting that there may be an association between the consumption of nuts, especially walnuts with a lower prevalence of obesity and lower RFM within certain populations. However, cause and effect could not be determined, and additional research is needed to support these results. Additionally, the average nut consumption in this population group was low with 76% of adolescents and 69% of young adults reporting no daily nut consumption. Furthermore, when walnuts were consumed, adolescents only ate ~ 2g/day while young adults had ~ 4g/day, which is far below the recommended intake for nuts of 56 – 85g per week or 30g per day, respectively.³

“While additional research is needed, these results showed that food should not be judged based on calories alone. The addition of nuts, like walnuts, as a part of a healthy eating pattern may help lower the risk of obesity,” explains Dr. Carla Miller, PhD, RD, Professor of Nutrition at Indiana University School of Public Health-Bloomington. “Whether it is a handful as a snack or part of a meal, even in small amounts, nuts, including walnuts, can and should be a part of a nutritious diet to support well-being.”

Beyond Weight Management: Walnuts May Support Overall Physical and Mental Well-Being in Gen Z & Millennials

Teens and young adults crave food that supports both their physical health and mental health, with over 30% seeking emotional and mental health benefits.¹ Research suggests that daily walnut consumption could potentially support cognitive health and mental well-being in this unique population.

• Daily Walnut Consumption May Support Teens’ Focus and Attention – In a multi-school randomized controlled trial of 771 healthy teenagers ages 11 to 16, participants who consumed 30 grams of walnuts per day (1 handful) for six months had improved neuropsychological scores for attention, fluid intelligence (i.e. problem solving, quick reasoning skills) and ADHD symptoms, when compared to the group not eating walnuts.^6,* The positive results in this study were only seen in those teenagers who could better comply with eating more than 3 servings of walnuts per week. Only less than half of participants in the intervention group adhered to eating walnuts daily for 6 months, which might have impacted the data accuracy. No significant results were found for the primary outcomes of this study regarding neuropsychological function, indicating that the intervention did not work overall. However, this study does provide valuable insights and a basis for further clinical and epidemiological research on the effect of walnuts on brain development in adolescents.

• Walnuts May Improve Mental Health and General Well-Being in University Students – A novel study of 80 healthy university students ages 18 to 35, who ate 60g of walnuts a day for 16 weeks, compared to those who did not eat walnuts, prevented negative changes in self-reported mental health scores and scores of stress and depression during a stressful academic period. The group that ate walnuts experienced an increase in metabolic markers that protect against stress and a decrease in those that are linked with stress. While inconclusive, researchers found that the group who consumed walnuts also saw an improvement in sleep scores related to getting to sleep, sleep quality, awakening from sleep, and behavior following wakefulness by the end of the study period. ^7,*

• Snacking on Walnuts May Improve Metabolic Health in Young Adults – In a recent study of 84 young adults, ages 22 to 36, with at least one metabolic syndrome risk factor, researchers found that snacking on 30g of mixed unsalted tree nuts, including walnuts, twice daily, may improve metabolic health, when compared to carbohydrate-rich snacks. Researchers observed a reduction in waist circumference and lipid biomarkers in female participants who consumed tree nut snacks, when compared to those who consumed carbohydrate-rich snacks. Males who consumed tree nut snacks had decreased blood insulin levels, compared to those who consumed carbohydrate-rich snacks. Both males and females consuming tree nut snacks saw an effect on triglycerides and TG/HDL ratios with TG/HDL ratios reduced ~11% compared to those consuming carbohydrate-rich snacks.^8,*

These studies are not without limitations. While the findings cannot prove causality, they do shed light on how nuts, including walnuts, can be a part of a healthy diet that supports metabolic health and well-being. Additional research is needed to determine how these results apply to other populations.

*Research was funded by the California Walnut Commission

References:

1. International Food Information Council. 2024 Food & Health Survey. June 20, 2024. foodinsight.org/I 2024-food-health-survey/. Accessed July 22, 2024.

2. International Food Information Council. 2022 Food & Health Survey. 18 May 2022. foodinsight.org/2022-food-health-survey/. Accessed July 22, 2024.

3. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020. Available at DietaryGuidelines.gov.

4. Gletsu-Miller N, Henschel B, Tekwe C, Thiagarajah, K. A Cross-Sectional Study on the Association of Walnut Consumption with Obesity and Relative Fat Mass among United States Adolescents and Young Adults in NHANES (2003-2020). Curr Dev Nutr. 2024; 8(8): 104407.

5. U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, 2019. fdc.nal.usda.gov.

6. Pinar-Mart A, Gignac F, Fernndez-Barrs S, et al. Effect of Walnut Consumption on Neuropsychological Development in Healthy Adolescents: A Multi-school Randomized Controlled Trial. eclinicalmedicine. 2023;59:101954.

7. Herselman MF, et al. The effects of walnuts and academic stress on mental health, general well-being and the gut microbiota in a sample of university students: A randomised clinical trial. Nutrients. 2022;14:4776.

8. Sumislawski K, Widmer A, Suro RR, Robles ME, Lillegard K, Olson D, Koethe JR, Silver HJ. Consumption of Tree Nuts as Snacks Reduces Metabolic Syndrome Risk in Young Adults: A Randomized Trial. Nutrients. 2023;15(24):5051.