RESEARCH UPDATE: Mental Stress: Can Your Snack Make a Difference?
Mental stress is among the psychosocial factors thought to contribute to cardiovascular disease (CVD) risk. Heart rate variability (HRV), a measure of the fluctuation in time intervals between consecutive heartbeats, is an important indicator of the cardiovascular system’s response to stress and it is thought that lifestyle factors including physical activity and diet might impact HRV. Higher HRV represents greater adaptability of the heart in response to environmental and psychological challenges, while low HRV is linked to cardiovascular disease and sudden cardiac death. As part of a recent clinical trial, researchers at King’s College London measured HRV in participants undergoing a laboratory mental stress challenge and saw improvement in some measures of HRV in participants who had been replacing typical snacks with almonds over a six-week period. The study1 was funded by the Almond Board of California.
This new research finding was a secondary outcome measure of the ATTIS study, a 6-week randomized control, parallel-arm trial, where participants with above average cardiovascular disease risk consumed a daily snack of almonds or a calorie-matched control snack providing 20% of each participants’ estimated daily energy needs.
Participants in this study were British men and women, aged 30 to 70 years. Researchers measured their real-time heart rate (HR) and heart rate variability (HRV) at rest (lying down for 5-minute periods) and during a Stroop test (in which participants were asked to read colored words i.e. say “red” in a green font) to simulate a short period of mental stress. During acute mental stress, participants in the almond group showed greater cardiac resilience. This was demonstrated by better heart rate regulation compared to the control group, indicated by statistically significant differences in high frequency power, which specifically evaluates beat-to-beat intervals (a measure of HRV).
“This study shows that the simple dietary strategy of swapping almonds for typical snacks may bolster resilience to the adverse cardiovascular effects of mental stress by improving regulation of heart rate. We found that the stress-induced reduction in heart rate variability was lessened in the almond group compared to control following the dietary intervention, which indicates a cardiovascular health benefit. It is useful to think of having a higher HRV as the heart being able to switch gears faster in response to demands on the body, which means more cardiac resilience and flexibility during periods of stress. In the long term, this is beneficial for cardiovascular health,” said Dr. Wendy Hall, PhD, co-principal investigator and Reader in Nutritional Sciences at King’s College London. The researchers acknowledge that the mechanisms underlying this effect are still unknown and long-term studies are needed to understand this as well as the effects of almonds on HRV in at-risk populations.
“These results support our growing knowledge about almonds and heart health. And, they’re particularly timely given the heightened levels of stress many of us are experiencing right now, alongside increased snacking, from working at home,” said Dr. Sarah Berry, PhD, co-principal investigator.
Years of heart health research – including a systematic review and meta-analysis2 – support the inclusion of almonds in heart healthy eating plans.* Both ATTIS studies included measures that had never before been evaluated in clinical research trials investigating the impact of almonds. Although additional studies are needed to confirm these findings, the improvements in certain measures of HRV suggest that almonds may provide unexpected heart health benefits. Almonds provide 6 grams of plant protein, 4 grams of filling fiber and 15 essential nutrients - including 20% of the Daily Value for magnesium and 50% of daily needs for vitamin E - in every healthy handful. Click here to view the full study.
