Toll like receptors in Chronic Lymphocytic Leukaemia

Literature Review “THE RELATIONSHIP BETWEEN STRESS, MENTAL HEALTH, WELLBEING AND FOOD

INTAKE/HABITS.”

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Table of contents:

• Introduction

• Search Results

• Gaps in the Literature

• Conclusion

• References

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Introduction

Stress refers to a state of emotional strain, in which the perceived or real demands of a situation or stimulus the body’s perceived or real capacity to manage it (Dweck, Jenkins & Nolan,2014).Stress can be physical, psychological or social in nature ( Shalev & Belsky, 2016).Stress is both beneficial for survival in allowing the body to flee quickly from a dangerous situation, and potentially deadly, leading to chronic disease (van Strien Roelofs & Weerth, 2013).Evidence suggests that nearly 500.000 individuals within the UK suffer from chronic work – related stress, depression or anxiety, or about 1,510 people for every 100,000 workers (Health and Safety Executive,HSE,2016).Stress also accounts for more than one third of all work – related injuries or illnesses within the UK (HSE,2016).The impacts of stress on health are multitudinous, and have substantial and immeasurable effects on society at large (Katterman et al.,2014).Stress produces long-term physiological changes that affect mental wellbeing (Stagl et al.,2015).Most notably, stress leads to the production of cortisol, which suppresses the immune system and contributes to insomnia, depression and low affect (van Strien et al.,2013).The purpose of this paper is to review literature pertaining to the relationship between stress, mental wellbeing and food intake/habits. An attempt was made to include the most important literature based on this results of this review and the large number pf papers that have been published on this topic. A search of the PubMed database was performed using the following keywords: stress, mental health; wellbeing and food intake/habits. A combination of data sources was included and studies that were published within peer reviewed academic journals. Literature most relevant to the study topic will be hand selected from the search results and critically reviewed in a chronological format.

Search Results

A search of the above terms revealed a total of seven studies within the PubMed database that contained all items. No studies contained all three items within the titles and abstract of studies. Additional searches were performed seeking to link all three terms in titles and abstracts of studies, yielding no additional items. Of the seven studies located in the search, just four directly pertained to the research question being addressed and were hand- selected from the list of seven. The results of the search are presented in Table 1 below:

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Table 1. Search results

Table 2 shows the four included in this review that directly pertained to the relationship between stress, mental wellbeing and food intake, and also contained primary data. The sample populations, intervention /design, comparators and outcomes are included. Benton & Donohoe (1999) conducted a review, seeking to evaluate the causes of emotional eating, which they found was related to endorphin release. Epel et al. (2001) performed an experimental design with 59 pre- menopausal women, comparing changes in eating behaviors with the presence of cortisol. Wallis & Hetherington (2004) also used an experimental design to assess the causes of food intake habits with 38 female university students, seeking to determine the role of ego- threat on emotional eating. Finally, Polivy & Herman (2005) performed the most extensive review to date on this topic, evaluating literature published from 1994 to 2004 that identified factors underpinning emotional eating. Results of these studies and their relevance to previous research are discussed in the following paragraphs.

Search Query Items found

1 Search -Stress and Mental wellbeing & food

intake

7

2 Search- Stress/Title/Abstract and mental wellbeing (Title/Abstract) and

Food intake (Title/Abstract) Schema

all.

0

3 Search- Stress/Title/Abstract and mental wellbeing (Title/Abstract) and

Food intake (Title/Abstract)

0

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Table 2. Studies included in review

Study Population Intervention/Design Comparator Outcome

Benton & Donohoe (1999)

N/A Review N/A Emotional eating is likely

caused by endorphin

release

Epel et al. (2001)

59 health pre- menopausal

women between 30

and 45

Repeated measures experimental design

Baseline scores Women with high reactivity

to cortisol consumed

large amounts of calories

when exposed to stress and consumed

sweeter foods

Wallis & Hetherington (2004)

38 female university

students from the UK

Mixed factorial and experimental design

Neutral (control)

Ego treat resulted in 23 percent more eating, while

emotional eating was

associated with more intake

only after ego threat in

comparison to controls.

Polivy & Herman (2004)

Unidentified number of

studies conducted over

previous 10 years (1994-

2004)

Literature Review N/A Strong support for physical stress on emotional

eating, particularly with

fatty and sugary foods.

Many correlates were

identified.

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Two of the studies included in this review adopted experimental designs and two adopted literature reviews. Irrespective of the design, studies assessing the relationship between stress, mental wellbeing and food intake were conducted with a high degree of rigour and the use of controls and bias risk reduction techniques serves as an advantage of those studies included in this review. However, eating behaviours were commonly measured through self-report and did not actually include dietary monitoring (Polivy & Herman,2005). Though these studies do offer insight into hypothetical eating behaviours, long-term intervention studies are needed to track actual food consumption to determine the impacts of stress and related biomarkers (e.g. cortisol) on food consumption behaviours.

Research showed that individuals consumed more food when exposed to different types of stress (Epel et al., 2001).This finding supports previous studies related to the effects of stress on copying styles (Bennet, Greene & Schwartz- Barcott,2013;Raspopow et al.,2013).Individuals who perceive a threat as greater than their individual capacity to manage it, will engage in coping that reduces the severity of the stressor (Raspopow et al., 2013).For example, one study showed that women consumed more food when they experienced threats to their ego (Wallis & Hetherington,2004).Another study showed that women with higher reactivity to cortisol were more likely to engage in emotional eating (Epel et a., 2001).These findings are fairly consistent with biopsychosocial and psychological manifestation of stress symptoms. Results show that stress, either physical based on the production of cortisol in a cognitively demanding task, or psychological or emotional based on the threat to the ego, increase the desire or likelihood to seek stimulation and comfort trough food. The reasons for this behaviour are not fully understood and are likely multidimensional in nature.

One possibility for this finding is that some of foods stimulate the production of neurochemicals like serotonin and dopamine, which offer immediate chemical relief from the effects of stress (Bennett et al.,2013).Another possible explanation is that some individuals have developed conditioned responses to associate food with comfort, and their parasympathetic nervous system initiate a relaxation response when near food (Bongers et al.,2015).This effect is also potentially evolutionary in nature (Bongers et al.,2015)

Benton and Donohoe (1999) offered a seminal review in which they speculated about the effect of nutrients on affect. Like many authors, these concluded that many foods stimulate the release of endorphins, which drives emotional eating in the event of environmental stress ( Zenk et al., 2013; Jaaskelainen et al.,2014) These authors also speculated that nutrients deficiency drives emotional eating based on cravings for distinct nutrients that body is lacking. Therefore, diets that promote restrained eating can be detrimental to wellbeing and eventually to health because of their promotion of on – again or off-again eating habits (Zenk et al., 2013). These fluctuations increase the likelihood of temporary nutrient deficiencies and carvings for certain foods,

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particularly fats and sugars (Benton & Donhoe 1999). Therefore, consistency and stability in the diet appears to be critical for general wellbeing.

Epel et al., (2001) studied the role of cortisol in stimulating emotion based eating, performing an experimental design that exposed women to cognitive and emotional stress and assessed attitudes towards eating. These authors found that women were more likely to engage in emotional eating when they demonstrated a high reactivity to cortisol, suggesting that this chemical has a distinct effect on mood and wellbeing. In particular, women craved sweet foods when exposed to stress and having high cortisol reactivity. This finding offers support for the effect of glucose in elevating mood based on its rapid metabolism and dissemination into the bloodstream. This emotionally based consumption of sweet foods is a potential contributor to diabetes and these findings help illustrate the psychological drivers of this disease (Jȁȁskelainen et al., 2014)

Wallis and Hetherington (2004) performed a novel experiment to assess the effects of stress on food intake. These authors conceived an experiment involving the Stroop task, which assesses performance under cognitively demanding conditions. Participants in this study were allocated to one of four experimental conditions based on the presence of ego – threat and/or cognitive demand. Results showed that emotional eating was significantly increased after cognitively demanding tasks, but only if they were threatening to the ego. This condition created an emotional response that may have initiated an emotion based copying style. Previous research has shown that emotion based copying occurs when perceived demands of a situation exceed one’s perceived resources (Jaaskelainen et al.,2014). In those participants who experienced threats to their egos, emotional alleviation was seen as the only viable solution. Findings from this study also reflect the heightened impact of stress on emotional eating in individuals which low restraint and low problem based copying (i.e. eating), and particularly relates to women based on the all-female sample. However, the generalisability of the findings is limited based on this exclusivity to one population demographic.

The impact of stress on eating and wellbeing has been made fairly clear, though the direction of this relationship has remained the subject of debate. One study in this review investigated this effect (Polivy & Herman,2005). Though these authors adopted a literature review design, a large number of studies included in their design found support for physical environmental stressors on emotional eating. This effect was particularly strong for fatty and sugar foods. Cravings for fatty foods may be related to the production of neurochemicals in the stomach. Additional factors that were identified as correlates of stress-based eating habits, mood and focus of attention (Polivy & Herrman,2005). These findings reflect the complex and multidimensional nature of stress effects on mental wellbeing and food intake. However, each of these effects support copying research and the theory of problem versus ‘emotion based copying (Jȁȁskelainen et al., 2014). Evidence from Polivy and Herman’s (2005) review suggest that this emotion

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based copying behaviour is underpinned by a biological desire or need for glucose and fat-induced serotonin release. This biological contribution to eating behaviours is important for dieticians and nutritionists, as well as helping individuals to reduce shame or guilt associated with this copying behaviour. Research included in the current review showed that shame and guilt are common drivers, as well as effects, of emotional eating (Polivy & Herman,2005). However, these findings also illustrate that care needs to be taken to promote a more problem based copying style and to promote eating habits that provide sustainable energy throughout the diet and less fluctuation of glucose and fat – induced neurochemical production to prevent obesity, diabetes and other diet- related diseases. This relationship between mental health and eating behaviours is clearly bi directional and efforts are needed at both ends to promote healthy eating and mood regulation (Polivy & Herman ,2005)

Gaps in the Literature

Results from this study offer support for the impact of nutrients on mood and the relationship between stress mental wellbeing and food intake. However, some gaps in the literature exist that warrant further consideration. Perhaps most importantly, intervention research is needed based on the knowledge that stress adversely impacts mental health and wellbeing and stimulates unhealthy eating habits. The promotion of small, consistent meals that a prevent severe reductions in nutrients is recommended as a counter to diet – induced depression. Reducing stigmas associated with emotional eating are also important to modifying food intake habits, as they produce more stress and cortisol, leading to increased tendency for emotional eating. Interventions are needed that target these outcomes to promote long- term behavioural change.

Conclusion

The purpose of this review was to identify trends in the literature pertaining to the relationship between stress, mental wellbeing and food intake. A total of four

studies were located through a search of the PubMed database. Two of these studies were experimental in nature and the other two were reviews. All four

found support for the impact of environmental stress on emotional eating, though each offered novel proposed mechanisms driving this effect. It was clear from

this study that stress produces a biological, psychological and sociological response that facilitates increased food consumption, particularly in women,

individuals with high cortisol reactivity, those with mood disorders and those with genetic susceptibility to nutrient deficiencies or fluctuations in blood glucose

levels. This response may also be behavioural in nature based on a conditioned

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association between food consumption and positive mood, relaxation and affect. Future research is needed that explores interventions designed to promote mood stability, and it prevents reductions in individual’s nutrients be promoted to avoid

cravings. Behavioural modification may also be needed to eliminated paired associations, while targeting correlates to high stress and emotion based copying

(e.g., low self-esteem, depression) would be appropriate for many. For more details, refer to the References section.

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References

Bennet, J., Jreene, G. and Schwartz- Barcott, D., (2013). Perceptions of

emotional eating behaviour. A qualitative study of college students. Appetite,60,

pp.187-192

Benton, D. and Donohoe, R.R.T., (1999). The effects of nutrients oyn moody.

Public Health Nutrition, (23a), pp.403-409.

Bongers, P., van den Akker, K., Havermans, R. and Jansen, A., (2015).

Emotional eating and Pavlovian learning: Does negative mood facilitate

appetitive conditioning? Appetite,89, pp.226-236.

Dweck, J.S., Jenkins, S.M and Nolan, L.J., (2014). The role of emotional eating

and stress in the influence of short sleep on food consumption. Appetite,72,

pp.106-113.

Epel, E., Lapidus, R., McEwen, B. and Brownell, K., (2001). Stress may add bite

to appetite in women: a laboratory study of stress – induced cortisol and eating

behaviour. Psychoneurendocrinology,26(1), pp.37-49.

Health and Safety Executive (2016). Work related stress, anxiety and depression statistics in Great Britain 2016. [online] Available at: http://www.hse.gov.uk/statistics/causdis/stress/ .Accessed 3 Jan 2017

Jȁȁskelainen, A., Nevȁnpera, N., Remes, J., Rahkonen, F., Jarvelin, M. R and

Laitinen, J., (2014). Stress- related eating, obesity and associated behavioural

traits in adolescents: a prospective population-based cohort study. BMC Public

Health,14 (1), p.1.DOI: 10.1186/1471-2458-14-321.

Katterman, S.N., Kleinman, B.M., Hood, M.M., Nackers, L.M and Corica, J.A.,

(2014). Mindfulness mediation as an intervention for binge eating, emotional

eating, and weight loss: A systematic review. Eating Behaviors,15(2), pp.197-

204.

Polivy, J. and Herman, C.P., (2005). Mental health and eating behaviours: a bi-

directional relation. Canadian Journal of Public Health, S3. pp. S43-S46.

Raspopow, K., Matheson, K., Abizaid, A. and Anisman, H., (2013). Unsupportive social interactions influence emotional eating behaviours. The role of copying styles as mediators. Appettite,62, pp.143-149

Shaley, I. And Belsky, J., (2016). Early-life stress and reproductive cost: A two- hit development model of accelerated aging? Medical Hypthesis,90, pp.41-47.

Stagl, J.M., Bouchard, L.C., Lechner, S.C., Blomberg, B.B., Gudenfauf, L.M., Jutagir, D.R., Gluck, S., Derhagopian, R.P., Carver, C.S. and Antoni, M.H.,

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(2015). Long – term psychological benefits of cognitive- behavioural stress management for women with breast cancer: 11-year follow- up of a randomized controlled trial. Cancer,12l (11), pp.1873-1881.

van Strien, T., Roelofs, K and de Weerth, C., (2013). Cortisol reactivity and distress-induced emotional eating. Psychoneuroendicrinology,38 (5), pp.667-684.

Wallis, D.J. and Hetherington, M.M., (2004). Stress and eating: the effects of ego- threat and cognitive demand on food intake in restrained and emotional eaters. Appetite,43(1), pp.39-46.

Zenk, S.N., Schulz, A.J., Izumi, B.T., Mentz, G., Israel, B. A. and Lockett, M., (2013). Neighbourhood food environment role in modifying psychosocial stress- diet relationships. Appetite,65, pp.170 – 177.