Diet and Stress

This 2019 study analyzed whether healthy and/or unhealthy comfort eating could reduce stress, and whether the time period that the comfort eating took place could lead to greater stress relief. In order to induce stress, the 150 women in this experiment were faced with a socially evaluative stressor. Firstly, the participants underwent the Trier Social Stress Test in the lab before being randomly assigned to one of five conditions. The study adopted a between-subjects design, with food type (healthy or unhealthy) as the first independent variable, eating timing (during stress anticipation or after encountering the stressor) as the second, while the final condition as the control did not receive any food during the experiment. Finch et al. (2019) found that in comparison with the ‘no food’ control, neither the healthy nor unhealthy comfort eating reduced the reactivity of the psychophysiological stress inflicted upon the subjects. In addition, the participants’ reactivity or recovery did not vary by the type of comfort food consumed, suggesting that eating the healthier option of fruits and vegetables will alleviate stress as much as unhealthy foods do, while it improves diet quality and does not have the drawbacks of eating unhealthy foods like gaining extra fat deposits. [NPID: stress, comfort food, comfort eating, stress anticipation, eating timing, psychophysiological stress, fruit, vegetables, FV intake, diet quality, weight gain]

El Ansari et al. (2014) assessed the relationship between nutritional behavior with stress and depressive symptoms, by sex and university, using a sample of undergraduates (n = 3706) studying in one of England, Wales and Northern Ireland. The self-administered questionnaires included a 12-item food frequency questionnaire, Cohen's Perceived Stress Scale and modified Beck Depression Inventory. Variations in data such as in frequencies of food group consumption, depressive symptoms and perceived stress, arose by university and sex. Unhealthy eating of foods such as sweets, cookies, snacks, fast food, were associated with greater perceived stress in women, while it related to more depressive symptoms in both sexes. On the other hand, healthy foods such as fresh fruits, salads, cooked vegetables had a significantly negative relationship with both perceived stress and depressive symptoms in both sexes. Other associations identified include fish/seafood consumption with depressive symptoms (significantly negative among males only). The likes of lemonade/soft drinks, meat/sausage products, dairy/dairy products, and cereal/cereal products weren’t associated with either perceived stress or depressive symptoms. This study concluded that consumption of healthier foods might accompany interventions aimed at reducing depressive symptoms and stress among students. [NPID: stress, depression, England, Wales, Northern Ireland, sweers, cookies, snacks, fast food]

This 2013 study assessed whether chronic stress influences activation in reward, motivation and execution brain regions by performing functional magnetic resonance imaging (fMRI) on 30 women while they viewed pictures of high-calorie and low-calorie foods. On separate lab visits, food consumption from a snack food buffet in addition to circulating cortisol levels were examined. The study found exaggerated activity in the regions involving reward, motivation, and habitual decision-making upon viewing pictures of high calorie foods, while significant deactivation in frontal regions (BA10; BA46) linked to strategic planning and emotional control were seen in individuals with higher chronic stress. High chronic stress was related to the strengthening of the connectivity between the amygdala and the putamen based on data from the functional connectivity analysis, while low chronic stress was associated with greater connectivity between amygdala and the anterior cingulate and anterior prefrontal cortex (BA10). Moreover, lower cortisol levels and increased consumption of high calorie foods from the snack food buffet was reported in the high chronic stress group. On the basis of these findings, it appears that persistent stress exposure may influence the brain’s response to foods, increasing the chances for people with poor eating habits to gain weight and possibly becoming obese. [NPID: stress, chronic stress, reward, motivation, execution, fMRI, buffet, cortisol, strategic planning, emotional control, amygdala, putamen, anterior cingulate, prefrontal cortex, weight gain, obesity]

This 2016 article highlights the importance of tackling the problem of obesity and metabolic syndrome from early life, since obesity in infants can influence all body systems up to adulthood. Mocanu et al. (2016) believe in order to prevent obesity it is particularly important to understand the impact of stressors on weight status but the relationship between stress, eating behavior and obesity is not yet fully understood. There is evidence that stress causes disorders in the hypothalamic-pituitary-adrenal (HPA) axis - the system that regulates both stress and feeding responses. Although responses vary depending on type of stressors, chronic stress is associated with inducing HPA stimulation, excess glucocorticoids, insulin resistance, leading to retention of abdominal fat, accumulation of triglycerides, and inhibition of lipid transport. [NPID: stress, obesity, metabolic syndrome, HPA stimulation, glucocorticoids, insulin, insulin resistance, abdominal fat, triglycerides, lipid transport]

Since high levels of anxiety causes the release of sympathetic hormones that can decrease insulin secretion and even elevate cortisol and glucose levels, as well as possibly modulate the sensitivity of the insulin hormone, this 2019 review explored how stress and anxiety can affect type II diabetes by evaluating 3 research articles. The participants of the first article with non-insulin dependent diabetes were injected with saline or norephedrine, which saw norephedrine administration causing a decrease in glucose disposal and slower insulin secretion rate. The second article provided diabetic (type II) African-American adults with surveys focused on finding out whether stress, anxiety, and depression can influence lifestyle changes such as exercise and healthy dieting. Those subjects with higher stress levels were less likely to comply with their lifestyle regimes. The third article investigated brain activity (using an MRI) in 2 female sample groups (high and low chronic stress) as they viewed pictures of high-caloric foods. The responses in multiple brain structure activities were different between those with high chronic stress and those with low levels of chronic stress. This data could prove helpful for healthcare providers in managing patients with exacerbated type II diabetes resistant to medication and lifestyle changes. [NPID: stress, hormones, insulin, cortisol, glucose, diabetes, norephedrine, anxiety, depression]

This 2007 review analyzed human and animal literatures to determine how different types of psychological stress affects diet. Adam & Epel (2017) consider a theoretical model of reward-based stress eating, which highlights how cortisol and the reward circuitry are involved in the motivation of consuming high caloric foods and demonstrates potential neuroendocrine mediators in the relationship between stress and eating. The researchers then turn their attention to addiction literature which heavily link the brain reward circuitry with stress-induced food consumption. Since stress and eating palatable foods can induce the release of opioids, opioid secretion was proposed as one of the organism’s defense mechanisms providing protection from the detrimental effects of stress through reduced activity of the HPA axis. Repeated stimulation of these reward pathways and eating highly palatable foods may cause neurobiological adaptations promoting the compulsive nature of overeating, while cortisol may modulate the reward value of foods. Under chronic stress, glucocorticoids may have a role in increasing food intake and accumulation of visceral fat too. While scientists are working on elucidating these mechanisms, the widespread chronic stress may be currently exacerbating this obesity epidemic. [NPID: stress, animal, psychological stress, reward, neuroendocrine, opioids, cortisol, glucocorticoids, obesity]

The aim of this 2020 study was to analyze the eating habits of 378 undergraduate medical students (aged 19-26) and assess their relationship with sociodemographic, socioeconomic, and psychological factors. The students were in their second through to sixth academic year at King Abdulaziz University, Jeddah, Saudi Arabia when they were asked to complete self-administered questionnaires on sociodemographics, eating habits, and psychological aspects of their lives. Eating habit score was discovered to be much lower among students who were smokers, did not exercise regularly, lived alone, lived in rented accommodation, and whose parents had separated. Looking at the multivariate analysis results, many psychological factors such as living alone and stress, were linked with dietary patterns. Alzahrani et al. (2020) determined that socioeconomic and psychological circumstances significantly affected these medical students’ eating patterns, which were mostly poor and unhealthy. [NPID: stress, medical students, sociodemographic factors, socioeconomic factors, psychological factors, eating habits, loneliness]

For the purpose of expanding our knowledge of the effect of whole food diets on stress, Soltani et al. (2018) conducted this randomized controlled trial documenting the impact of a diet based on the Dietary Guidelines for Americans (DGA) on psychological and physiological stress. Overweight and obese women were randomly assigned to either a diet based on the 2010 DGA or a diet based on a Typical American Diet (TAD) for 8 weeks while their stress load was monitored using the Perceived Stress Scale and allostatic load. The changes in perceived stress and allostatic load were not significantly different between the two diet intervention groups after the 8 weeks, although inverse associations were found between 8-week stress difference and intervention-based improvements in diet quality - indicated by lower sodium and higher vegetable consumption. When these negative associations were statistically accounted for, perceived stress and allostatic load did appear to be higher in the DGA group (p<0.04). These findings suggest that improving on vegetable and sodium components of the diet mediated the impact of the diet intervention on psychological and physiological stress load, providing more reason to consider optimizing vegetables and reducing sodium consumption when aiming to improve mental health. [NPID: stress, psychological stress, physiological stress, TAD, Typical American Diet, Western-style diet, WS diet, allostatic load]

This 2020 paper systematically reviewed and conducted meta-analysis on literature to uncover the relationship between psychological stress and diet quality among women of reproductive age (18-49 years old). The 24 studies included in this review were conducted in various countries, and consisted of studies on diet quality (8) and on food intake and consumption frequency (16). The 6 cross-sectional and 2 longitudinal designed studies on diet quality yielded data on 3982 participants, and used various indices to measure diet quality, including Alternate Healthy Eating Index (n = 2), Healthy Eating Index (n = 2), Dietary Approach to Stop Hypertension (DASH) Diet Index (n = 2), Dietary Quality Index- Pregnancy (n = 2), and Dietary Guideline Adherence Index (n = 1). The majority of the studies used Cohen's perceived stress scale and no study measured biological stress response. Sensitivity analysis left only 5 studies (3471 participants) to be included in the meta-analysis, which revealed a significant negative association between stress and diet quality, albeit considerable heterogeneity between studies also. This paper found that stress was significantly related with unhealthy dietary patterns (high in fat, sweets, salt, and fast food and low in fruits, vegetables, fish, and unsaturated fats). Future studies investigating dietary patterns or quality are advised to include indices and factor analysis, as well as measure biological markers of stress and dietary patterns simultaneously. [NPID: stress, psychological stress, reproduction, diet quality]

Herhaus et al. (2020) decided to examine both cortisol reactivity and stress-induced eating in a sample with obesity because cortisol reactivity under stress can be used to predict stress-induced eating behaviors that influence body mass index (BMI),. The aim of the study was to analyze the impact of high and low cortisol reactivity on the participants’ food intake levels. Through the use of the Trier Social Stress Test (TSST), the 36 obese adults and the 36 healthy weight controls (matched for age and gender) were divided into two sub-groups: high cortisol reactors (HCR) and low cortisol reactors (LCR). The group of obese high cortisol reactors significantly greater amounts than the low cortisol reactors. This same subgroup was found to demonstrate less emotional coping strategy of cognitive reappraisal (the subjective interpretation to stimuli in the environment). In the healthy weight controls, however, there were no marked differences between high and low cortisol reactors. In conclusion, stress-related eating in people with obesity is predicted by the degree of their cortisol reactivity to stress. But the same did not apply for healthy weight individuals. It was also suggested that not practicing cognitive reappraisal in emotion regulation may be a sign of susceptibility to stress-induced eating among obese high cortisol reactors. [NPID: stress, cortisol, obesity, BMI, cognitive reappraisal, stress eating, emotion regulation]

Although the hippocampus becomes damaged by exposure to severe and prolonged stress, Rahman et al. (2016) comment that research is lacking on how the hippocampal structure changes after repeatedly experiencing stress, and what sort of behaviors are affected by these alterations. Analyses of behaviors appeared to show that spatial memory becomes impaired over the 10 days of stress. But the consequences are not fully apparent until the stress is removed. Among these same animals, the stressed displayed significantly lower hippocampal volumes as early as the third day, compared with those unstressed. The largest early reductions in hippocampal volumes were seen in the animals behaving the worst at the end of chronic stress. These results link smaller hippocampal volume with stress-induced memory impairments. In addition, hippocampal volumes may be used to identify those at early risk of developing cognitive dysfunction observed in stress-related psychiatric disorders. [NPID: stress, hippocampus, memory, cognitive dysfunction]

Pannicke et al. (2021) discuss the negative effects of wealthier food environments, which appear to encourage the consumption of energy-dense and low-nutrient foods and make it tough for people to maintain a healthy diet and weight. The diet-related targets set by individuals also may be affected by stress, affects, and intense food cravings. This study explored the interlinks between these variables by recording participants’ momentary states and retrospective eating episodes four times a day for 14 days. The 84 subjects (aged between 18 and 38) were mostly recruited from universities. Goal-congruent eating was not specifically predicted by any of the momentary measures of stress (experience of stress or stress coping), momentary affects or craving. But temporal effects showed that participants with higher anticipated stress coping ate a diet more consistent with their goals. It seemed that the more confident individuals were in coping with their upcoming obstacles, the more likely they were to follow their ideal diet plan. So, while most eating behavior interventions look mostly at hunger, craving, negative and positive affect, stress coping is often overlooked although it represents a novel target intervention with plenty of potential. [NPID: stress, wealthy, rich, affect, craving, coping mechanisms, craving]

The objective of this 2021 study was to investigate the relationship between fruit and vegetable intake and perceived stress in adults aged ≥25 years using the participants of the Australian Diabetes, Obesity and Lifestyle (AusDiab) Study. The secondary aim was to find associations between carotenoid levels in the blood, biomarkers of fruit and vegetable intake, and perceived stress. The food frequency questionnaires used to assess dietary intake were administered in 1999-2000 to 8689 individuals. It was found that subjects with the highest intake levels of fruits and vegetables had 10% lower Perceived Stress Questionnaire index values than individuals who ate the least number of fruits and vegetables. Similar interactions were observed when analyzing fruits and vegetables separately. Moreover, subgroup analyses revealed the link between higher fruit and vegetable consumption and lower perceived stress in middle-aged adults (45 to 65 years), which was not replicated in the younger (<45 years) and older participant subgroups (≥65 years). Higher fruit and vegetable intake was also significantly correlated with lower perceived stress in men and women (studied separately). Radavelli-Bagatini et al. also identified an inverse interaction between carotenoid concentration in the blood and perceived stress before (although this did not hold after adjustments were made to the analysis model). To summarize, increased consumption of fruits and vegetables was related to lower perceived stress in Australian adults, particularly in the middle-aged subgroup. [NPID: stress, FV intake, carotenoid levels, Australia]

This 2019 review describes the interaction between stress and dietary patterns at a molecular level and connects these factors to brain health and mental fitness. According to Morera et al., people in general prefer to eat high caloric and hyperpalatable foods under chronic stress conditions. The consequences of this interplay between psychosocial stress and dietary patterns can be detrimental. For example, it can influence the hippocampus of the brain to produce a greater neuroinflammatory response, resulting in memory deficits. The composition of the microbes living in the human gut can also be modified by stressful environments, which can ultimately influence behavior and brain health. Furthermore, these biological processes can predispose an individual to develop diseases such as diabetes, obesity, cardiovascular disease, and metabolic syndrome. The findings of this review could assist the development of novel therapeutic targets for chronic diseases. [NPID: stress, molecular level, chronic stress, hippocampus, inflammation, neuroinflammation, diabetes, cardiovascular disease, metabolic syndrome]

Chronic stress and oxidative stress as common factors of the pathogenesis of depression and alzheimer's disease: The role of antioxidants in prevention and treatment