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New Study Finds that Eating Almonds May Help Improve the Heart and Nervous System’s Responses to Mental Stress


Handful of Almonds
UK study shows improved heart rate variability in response to mental stress for participants eating almonds in place of typical snacks.

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 mental stress challenge and saw improved measures of HRV in participants who had been replacing  typical snacks with almonds over a six-week period.  The study[1] was funded by the Almond Board of California.

This new research finding was part 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. 

In this study, researchers measured participants’ 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 short period of mental stress.

During acute mental stress, participants in the almond group showed 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 (together with Dr. Sarah Berry, PhD) and Reader in Nutritional Sciences at King’s College London.  

The research suggests that eating almonds in place of typical snacks may diminish the drop in HRV that occurs during mental stress, thereby improving cardiac function.  This dietary strategy has the potential to increase cardiovascular resilience to mental stress, along with other heart health benefits of consuming almonds such as lowering LDL-cholesterol and improving the function of blood vessels. 

“These results are particularly timely given the heightened levels of stress many of us are experiencing, alongside increased snacking, from working at home.,” said Dr Sarah Berry, PhD, King’s College London.

Speaking about the study, Regional Head-Dietetics, Max Healthcare – Delhi, Ritika Samaddar commented, ““The results of this study are favourable, especially for a country like India where mental stress and cardiovascular diseases (CVD) are big areas of concern. The results of this new study showcase how regular almond consumption helped improve heart rate variability in response to mental stress for participants eating almonds in place of typical snacks. Therefore, I strongly recommend replacing calorie high junk food with almonds, which are a healthier and wholesome snacking option. In the long run, this simple change will also aid in a person’s overall heart health.”

This new study was part of the ATTIS trial. A recently published paper from ATTIS also examined the role of almond eating on LDL-cholesterol levels and endothelium-dependent vasodialation (measured through flow meditated dilation, or FMD), which is a predictor of cardiovascular disease risk

Commenting on the results of the study, Sheela Krishnaswamy, Nutrition and Wellness Consultant commented, “The results of this study are very promising, and relevant especially now when several Indians are experiencing high levels of stress due to the current pandemic. This research suggests that revising one’s dietary strategy to include almonds can increase cardiovascular resilience to mental stress in addition to reducing LDL-cholesterol and improving endothelial function of the blood vessels (as shown in other studies) – thereby improving cardiac risk factors.  Simply by replacing unwholesome snacks with almonds, people who are suffering from CVD or are at risk, can make a healthy difference to their lives.” 

Years of heart health research – including a systematic review and meta-analysis[2] – 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 including almonds. Although additional studies are needed to confirm these findings, the improvements in HRV and FMD suggest that almonds provide heart health benefits in a variety of ways.  Almonds provide fiber (12.5 / 3.5 g per 100g / 28g serving) and 15 essential nutrients including (per 100g / 28g serving): magnesium (270 / 76 mg), potassium (733 / 205 mg), and vitamin E (25.6 / 7.2 mg).

Speaking about the results of the study, Madhuri Ruia, Pilates Expert, and Diet & Nutrition Consultant, said, “It’s interesting to note the results of this study given the current situation and how it’s been taking a toll on everyone’s lifestyle and routine. For years now, I have been recommending almonds as a healthy snack – and the results of this study corroborate that. Besides heart health, daily almond consumption has a plethora of benefits associated with them across skin health, weight, and diabetes management as well. So I strongly suggest all Indians add a handful of almonds to their diet every day, as this will aid in better holistic health.”

Study at a Glance:

The Study

  • This randomized, controlled parallel dietary intervention study investigated the effects of almond consumption on cardiometabolic risk factors in adults with above average risk of CVD. The study looked at the impact of almonds vs. a control food designed to provide the same number of calories and carbohydrate/fat/protein composition to match average snack intakes in an adult UK population.
  • Adults 30-70 years old (n=51 in almond group, n=56 in control group) consumed 20% of their calorie requirements as whole roasted almonds or a control food for 6 weeks.  Cardiometabolic risk factors were measured, including endothelial function (flow-mediated dilation), heart rate variability, liver fat, insulin resistance, blood cholesterol and triglycerides, and body composition.
  • Prior to beginning the study, a separate 3-week trial was conducted to ensure that the control food had a neutral effect on lipids, blood pressure and body weight/composition.
  • Participants had their heart rate (HR) and heart rate variability (HRV) measured in 5-minute periods at resting and during mental stress. 
  • Real-time HRV was measured before (resting) and during a Stroop test (mental stress) while participants were in a supine position by using an ambulatory/ECG monitor.  The 5-min stress test was performed 15 minutes after recording resting HRV values.
  • The HRV parameters including high frequency (HF) and low frequency (LF) power and the LF/HF ratio were measured using a chest-worn heart rate monitor and specialized analytical software. 


  • There were no changes in body weight and total energy intakes of both the almond group and the control group did not differ, but the almond group had improved diet quality (high fiber, favorable ratio of unsaturated fats to saturated fats, increased magnesium, potassium, vitamin E and riboflavin; and decreased total carbohydrate, starch, free sugars and sodium).
  • During mental stress (Stroop test), HF power was higher following almond treatment by 124 ms2 (95% CI 11, 237), relative to control.  The LF/HF ratio was lower by -1.0 (95% CI -1.9, -0.1) relative to control.  No differences were found in other indices during mental stress.
  • In the resting state, there were no significant differences between treatment groups in the change in HRV indices following intervention.

Study Limitations:

Limitations of the study were the fact that there were some differences between groups in cardiometabolic disease risk factors at baseline.  Also, the participants were free-living, and although almond compliance was confirmed, it is possible there is potential for some inaccuracies in their reported food intake.  Finally, more research is required because the mechanism for the increase in HRV are unknown.


This study provides new research findings about how almonds can be part of heart healthy diet, affecting risk factors including the body’s response to mental stress.  Eating almonds in place of typical snacks can diminish the drop in HRV that occurs during mental stress, thereby improving cardiac function.  This dietary strategy has the potential to increase cardiovascular resilience to mental stress, along with other heart health benefits of consuming almonds such as lowering LDL-cholesterol and improving the function of blood vessels.

1 Vita Dikariyanto, Leanne Smith, Philip J Chowienczyk, Sarah E  Berry, Wendy L Hall. Snacking on whole almonds for six weeks increases heart rate variability during mental stress in healthy adults: a randomized controlled trial. Nutrients 2020, 12(6), 1828;

2 Musa-Veloso K, Paulionis L, Poon T, Lee HL. The effects of almond consumption on fasting blood lipid

levels: a systematic review and meta-analysis of randomised controlled trials.  Journal of Nutritional Science 2016; 5(e34):1-15.