Motivation and emotion/Book/2020/Nutrition and anxiety

Overview
Anxiety is highly prevalent around the world and conventional pharmacological treatments often have limited success (Aslam et al., 2018). Diet underpins the biological functions involved in anxiety (Jacka et al., 2010) and the International Society for Nutritional Psychiatry Research recommends that nutritional treatment should be used in mainstream practice (Kris-Etherton et al., 2020). Despite this, psychiatry lacks evidence based dietary prevention methods and treatments (Jacka et al., 2010). For example, a meta-analysis of randomised controlled trials showed that dietary interventions did not significantly improve anxiety (Firth et al., 2019). However, it is an emerging field and there is a lot of theory and research to support that nutrition can help anxiety.

Food and emotion theories and related research show a clear bidirectional relationship between anxiety and food. For example, anxiety can cause overeating or consumption of unhealthy foods, and eating can reduce anxiety temporarily (Canetti et al., 2002). Other research has shown that less than optimal nutrition is part of the pathology for anxiety (Kris-Etherton et al., 2020). It also shows that good nutrition can help to deal with anxiety, and that unhealthy Western foods can increase anxiety (Kris-Etherton et al., 2020). A challenge to implementing this is that anxiety has a complex aetiolology, and because of this it is difficult to gather strong evidence to support that diet as a single factor can help to reduce anxiety.

This chapter describes anxiety, looks at food and emotion theories and research, and considers the negative affect of Western diet patterns on anxiety. It also looks at micronutrients and dietary patterns that are helpful for anxiety, and the relationship between the gut, the brain, and anxiety.



Jack is in his mid-twenties and has suffered with generalised anxiety disorder since he left high school. He spends a lot of time worrying about different things that are out of his control. He has tried psychological therapy, and antidepressants, which has helped him manage it a bit, but it is expensive and the medication is causing him to gain weight, which is making him more feel more anxious about his health and appearance. Jack decides to speak to a dietitian about managing his diet to help with his mental health. He learns that nutrition is important for healthy brain function and that by limiting unhealthy food, and eating more nutritious foods, he can greatly reduce his anxiety. After several weeks of eating a whole food diet that was recommended to him, Jack's anxiety has greatly improved, and he decides to book an appointment with his GP to talk about getting off his medication.

Focus questions:
 * What is anxiety?
 * How can food and emotion theories and research help anxiety?
 * Which dietary patterns are unhelpful for anxiety?
 * Which dietary patterns and micronutrients are helpful for anxiety?
 * What is the relationship between the gut-brain axis and anxiety?

What is anxiety?


Anxiety is a common and unpleasant emotion that involves fear and dread about the future (Rieger, 2017). It also involves physical and behavioural alterations, such as activation of the HPA axis, the stress response system, and neurotransmitters (Steimer, 2002). When functioning correctly, it serves an adaptive function to help animals and humans survive in response to environmental threats (Rieger, 2017).

When anxiety becomes excessive and persistent, it can be considered a disorder and no longer adaptive (American Psychiatric Association, 2013). It is one of the most common types of mental disorders around the world and causes widespread suffering (Bateson & Brilot, 2011). According to an American study on 965 primary care patients, 19.5% had at least one anxiety disorder (Kroenke et al., 2007).

Conventional pharmaceutical interventions often have limited success at treating anxiety, are costly, and cause side effects in most people (Flynn & Chen, 2003). This is why finding healthier ways to help deal with anxiety is important. This chapter is aimed at helping people with all types of anxiety. 

Anxiety stops being adaptive and is considered a disorder when it becomes ____ and ____.
 * type=""}

- Widespread and adaptive + Persistent and excessive - Widespread and excessive - Adaptive and persistent

Food and emotion theories
Eating behaviours can change according to one's emotional state, such as anxiety (Canetti et al., 2002). Research has shown that people are more likely to consume healthy food when experiencing positive emotions and junk food when experiencing negative emotions (Canetti et al., 2002). Research has also established that negative emotions influence higher food intake (Canetti et al., 2002). Psychological theories attempt to explain the relationship between emotions and eating, as well as the psychological effects of overeating, dieting, and losing weight (Canetti et al., 2002). These theories are largely rooted in literature about obesity (Canetti et al., 2002). These theories and related research shows that food consumption can reduce anxiety while eating through physiological and learning processes, that anxiety can cause self control to run out when on a strict diet, and that anxiety can cause obese people to overeat unhealthy foods in secret.

Psychosomatic theories of obesity
The Kaplan and Kaplan theory of obesity (1957) and Bruch's theory (1973) suggest that eating may reduce anxiety and that people with obesity eat to lessen discomfort (Canetti et al., 2002). One explanation for this is that carbohydrate and protein consumption can influence the synthesis of neurotransmitters, particularly serotonin, which increases pleasant feelings and reduces anxiety. Elements of learning are also involved, as people associate eating with pleasure and reduced anxiety and learn to eat when anxious (Canetti et al., 2002).

The restraint hypothesis
The restraint hypothesis states that individuals who restrain themselves from eating will overeat in the presence of disinhibiting factors, such as anxiety, stress, the perception of overeating, or alcohol (Canetti et al., 2002). Research reviews have supported this and shown that those who chronically restrain their eating and think in an all-or-nothing way, are more likely to overeat after they have already eaten too much (Canetti et al., 2002). Research on highly emotional states, show that emotions, such as anxiety, can decrease a person's self-control to diet, and make them more likely to overeat. Other research has found that people who are unrestrained eaters ate less when experiencing high anxiety, while restrained eaters ate slightly more when experiencing high anxiety.

Emotional eating
A literature review on food and emotion theories and research by Ganley (1989), found that emotional eating is common in obese people, and most of the research showed a strong connection between eating and negative emotions (Canetti et al., 2002). Emotional eating was also likely to be done in secret, and consist of high energy or high carbohydrate food (Ganley, 1989). The studies consistently showed that emotional eating was preceded by negative emotions, such as anxiety.

 Norma tries to follow a strict diet of lean meats, whole grains, fruits, vegetables, nuts, and seeds. One day she feels anxious about the prospect of finding a new job and finds herself losing self control of her diet and pigging out on chocolate and chips in place of a healthy lunch until she feels sick. Because she already slipped, she gives up on her diet that day, and overeats again for dinner and dessert.



Case study 1.2 best describes:
 * type=""}

- The Kaplan and Kaplan psychosomatic theory of obesity - Bruch's theory - Emotional eating + The restraint hypothesis

Western dietary patterns and anxiety
Before the introduction of agriculture and farming, roughly 10,000 years ago, there was a scarcity of food (Cordain et al., 2020). Over time humans evolved to crave and store energy dense foods, such as fatty, sugary, or salty foods (Cordain et al., 2005). Now there is an over availability of processed and refined foods, and this has happened too quickly for our bodies to evolve new craving and storage mechanisms (Cordain et al., 2005). This discord between our biology and eating patterns is linked to many diseases (Cordain et al., 2005).



The World Health Organisation (2003) calls this modern Western change in diet, the “nutrition transition” and claims that the harmful shift includes a diet that is higher in energy density foods, saturated fats and sugar, and a decreased intake of fruits and vegetables, complex carbohydrates, and dietary fibre.

Examples of unhealthy Western foods that are unhelpful for anxiety include:


 * Beer
 * Cake
 * Candy
 * Chips
 * Chocolate milk
 * Donuts
 * Hamburgers
 * Meat pie s
 * Sausage s
 * White bread
 * Soft drink s

Studies from around the world show that the Western diet has negative affects on people's physical and mental health, and is associated with an increase in anxiety.

In Australia: A study of 1,046 women showed that a Western diet containing processed, fried, sugary, and refined foods, such as: meat pies, processed meats, pizza, chips, hamburgers, white bread, sugar, flavored milk, and beer was associated with increased prevalence of depression and anxiety disorders (Jacka et al., 2010).

In Norway: A study of 5,731 people showed that a diet high in unhealthy and processed foods was significantly related to increased anxiety (Jacka et al., 2011).

In Iran: This unhealthy dietary shift extends beyond strictly Western cultures. A cross-sectional study on 1,782 young Iranian adults showed that an increase in processed food consumption was significantly related to anxiety (Bakhtiyari et al., 2013).

 Limiting your intake of foods that are high in salt, sugar, or saturated fat can help with anxiety.

Micronutrients that are helpful for anxiety
Micronutrients are vitamins and minerals that your body needs to function (NHMRC, 2005). They are different from macronutrients, which are vital sources of energy (protein, carbohydrates, and fat; NHMRC, 2005). Rectifying nutritional deficiencies through the consumption of micronutrients plays a significant role in mental health and managing anxiety (Kris-Etherton et al., 2020).

Research shows that B vitamins (particularly B6 and B12), vitamin C, choline, folic acid, magnesium, long chain fatty acids (such as omega 3 and omega 6), and zinc are important for regulating stress responses and the production and metabolism of neurotransmitters, such as dopamine, serotonin, and norepinephrine (Kris-Etherton et al., 2020; Jacka, 2016). Which can in turn reduce the risk and severity of anxiety.

Table 1.

Food groups containing helpful micronutrients and examples of good sources (NHMRC, 2005).

PUFAs omega-3 and omega-6 fatty acids, which are mainly found in fish and seed oils, have been given a lot of attention in mental health research, particularly for their role in anxiety and depression (Larrieu & Layé, 2018). PUFAs are essential for the growth and function of the central nervous system and have been found to improve brain inflammation, and cell survival and production (Bazinet & Layé, 2014). Problems with PUFA transmission has been shown in anxiety. Research by Larrieu and Layé (2018) showed that low levels of omega 3 PUFA in the blood is a risk factor for anxiety and that supplementing PUFAs can be used as a prevention or treatment. Other research shows that patients with social anxiety disorders have lower levels of omega 3 PUFA than healthy controls (Lin, Huang, and Su, 2010). This highlights that PUFAs are very helpful for anxiety.
 * Polyunsaturated fatty acids (PUFAs)

In Australia: A large epidemiological study of 935 women analysed the amount of fish, omega 3 fatty acids, and omega 6 fatty acids consumed. The results showed that the only type of fatty acid significantly associated with anxiety disorders was a type of omega 3 fatty acid called DHA. Individuals who consumed a high amount were 50% less likely to have an anxiety disorder (Jacka et al, 2013).

Dietary patterns that are helpful for anxiety
While micronutrients are beneficial for anxiety, the overall quality of the diet is more important in mental health and there is a movement toward examining whole diets in nutritional psychiatry (Jacka, 2016). Worldwide epidemiological studies suggest high-quality dietary patterns, such as traditional, and Mediterranean diets can lessen the risk of anxiety (Kris-Etherton et al., 2020).

In Netherlands: A survey on 1,634 adults showed that an increased consumption of non refined grains and whole grains was linked to a lower levels of anxiety severity, while refined grains was linked to higher levels of anxiety (Gibson-Smith et al., 2019).

Mediterranean diet
The Mediterranean diet has been shown to reduce depression, risk of chronic disease, and anxiety (Jacka et al., 2017), and is related to lower levels of brain inflammation (Jacka et al., 2010). A randomised controlled trial in Australia, also called the 'SMILES' trial, measured the effect of dietary intervention on major depression, anxiety and mood. In this trial 31 individuals received dietary support for a Mediterranean diet model and 25 received social support for 12 weeks. Afterwards, the dietary support group showed significantly lower levels of anxiety than the control group (Jacka et al., 2017).

Table 2. Modified Mediterranean diet, based on the Australian Dietary guidelines and Dietary Guidelines for adults in Greece (Jacka et al., 2017).

Traditional diet
A traditional diet is one that has a historical lineage to cultivation practices of the land of a particular country (Kris-Etherton et al., 2020). A study of 1,046 Australian women aged 20 to 94 years found that a traditional dietary pattern containing fruit, vegetables, fish, meat, and whole grains, was linked to lower risk of anxiety, major depression, and dysthymia (Jacka et al., 2010). However, the authors noted that reverse causality (for example: having anxiety causes you to eat less healthy foods and eating unhealthy foods causes anxiety) could not be ruled out (Jacka et al., 2010).

Low FODMAP diet
A low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet refers to the chemical names of sugar that have difficulties being absorbed in the small intestine (Health Direct, n.d.). It can help treat anxiety in those with irritable bowel syndrome (IBS), which is common in people with anxiety disorders (Varjú et al., 2017; Kortlever et al., 2019; See section on gut-brain axis and anxiety below for more information). A study by Kortlever et al. (2019) on 111 IBS patients found that a low FODMAP diet was effective at significantly reducing IBS, anxiety, depression, and fatigue after six weeks and six months.

Table 3. Examples of foods to eat and avoid on a low FODMAP diet (Health Direct, n.d.)



The Modified Mediterranean Diet recommends the consumption of 3 tablespoons of olive oil per day
 * type=""}

+True - False



What does FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) refer to?

It is the chemical name for:
 * type=""}

- Hard to digest sugars found in your gut microbiota - Polyunsaturated fats found in fish - Fermentable neurotransmitters + Sugars that the small intestine has trouble absorbing

 Eating fish twice a week can help with anxiety.

Gut-brain-axis and anxiety
The relationship between the gut and the central nervous system, also known as the gut-brain-axis, has been a growing field of research in the last few years (Clapp et al., 2017). Microbial imbalance and gut inflammation has been attributed to causing anxiety, among other mental disorders (Clapp et al., 2017). A healthy gut has been shown to be associated with healthy central nervous system function (Clapp et al., 2017). One explanation of this is that neurotransmitters and hormones are sent via the gut-brain-axis (Clapp et al., 2017). The biopsychosocial model proposes a bidirectional relationship between stomach problems and an increased risk of anxiety or depression, where gut health influences psychological symptoms, and psychological symptoms influence gut health (Fond et al., 2014).

Gut microbiota
The term gut microbiota describes the microorganisms found in the gut (Clapp et al., 2017). Probiotics, which are found in fermented foods, have been shown to balance gut microbiota to a healthy level and for this reason could be a potential treatment for anxiety (Clapp et al., 2017). A systematic review by Yang et al. (2019) found that regulation of the intestinal microbiota by using probiotics and dietary changes were effective at treating anxiety symptoms in more than half of the 21 studies, and dietary changes as a treatment were found to be successful in 80% of studies. Additionally, the studies showed that effective regulation of the gut microbiota was successful at treating anxiety in 86% of cases (Yang et al., 2019). Other evidence suggests that regulating gut microbiota with probiotics can in turn regulate the HPA axis and help with anxiety (Clapp et al., 2017)

Fermented foods


Fermented foods contain functional organisms called probiotics, prebiotics and biogenics. These have the potential to change the gut-brain-axis, and through this, mental health (Aslam et al., 2018). However, the literature on how fermented foods in the treatment and prevention of anxiety in humans is limited and varied (Aslam et al., 2018).

Examples of fermented foods include (Aslam et al., 2018):


 * Cheese
 * Kimchi
 * Kombucha
 * Kefir
 * Miso
 * Sauerkraut
 * Sourdough bread
 * Soy sauce
 * Yoghurt

Research has shown that fermented foods can change gut permeability, stimulate gut immune cells, and have anti-inflammatory and brain modulatory effects that can alter pathways that are involved in anxiety (Aslam et al., 2018).

Irritable bowel syndrome
Irritable bowel syndrome (IBS) is a disorder of the gastrointestinal tract and is characterized by stomach pain, bloating, and irregular bowel movements (Fond et al., 2014). The prevalence of IBS is high and up to 60% of patients with IBS experience psychological problems, particularly anxiety and depression (Fond et al., 2014). Research shows that a dysfunctional gut-brain-axis plays a role in its aetiology (Fond et al., 2014).

A systematic review and meta-analysis by Fond et al. (2014) found that IBS-C (constipation) and -D (diarrhea) subtypes were significantly associated with anxiety. Other subtypes were found to be related to anxiety but contained fewer studies. Participants with IBS were found to have significantly higher rates of anxiety and depression than the control condition (Fond et al., 2014).



Which dietary pattern is unhelpful for anxiety?
 * type=""}

- Traditional diet - Mediterranean diet + Western diet - Low FODMAP diet



Eating fermented foods can help to regulate the gut microbiota.
 * type=""}

+True - False

 Eating fermented foods, such as kombucha, miso, kefir, and yoghurt can help with anxiety.

Conclusion
This chapter looked at using nutrition to help deal with anxiety using psychological theory and research. It found that anxiety is an emotion, and a physical and behavioural response to real or perceived threats. Because conventional methods to treat anxiety have limited success, finding new and healthy ways, such as modifying the diet, to help reduce it is important.



Food and emotion theories show that obese people eat to comfort themselves and reduce anxiety. This is unhelpful for anxiety because they may consume unhealthy foods in excess, and these unhealthy foods are associated with poorer health and increased anxiety, which can create a vicious cycle. The restraint hypothesis suggests that people who are overly strict with their diets are more likely to overeat or binge when anxious. This suggests that people should allow themselves to occasionally eat foods outside a healthy diet to stop them overeating of binging in future. Research also showed that emotional eating was linked to anxiety, and that emotional eaters were likely to consume unhealthy foods in secret. Being aware of emotional eating and planning with healthy snacks or distractors in advance could help. These theories and research demonstrate a clear bidirectional relationship between emotions and food.

The Western dietary patterns were found to be a common dietary shift toward unhealthy, processed, and refined foods, which people crave because of a discord between biology and food availability. Studies from around the world showed that these foods were significantly related to anxiety. Because of this, limiting the consumption of these foods can help with anxiety. Micronutrients were explored and found to be crucial building blocks for regulating emotions. Polyunsaturated fatty acids, that are largely found in fish, seeds, and nuts have, been shown to be particularly helpful for mood and anxiety. However, one large epidemiological study found that the only type of PUFA that helped to reduce anxiety was DHA.

Focusing on whole dietary patterns is more important than focusing on individual nutrients to help with anxiety. The Mediterranean diet and traditional diet were found to be particularly helpful for dealing with anxiety. The low FODMAP diet was also shown to be beneficial for anxiety in those with IBS, which is important because IBS is common in people with anxiety. A look into the gut-brain axis found that a healthy gut is important for the correct function of physical mechanisms that underlie anxiety. The research showed that probiotics, found in fermented foods, can regulate the gut microbiota, and can in turn reduce anxiety. Research also showed that regulating the gut microbiota can help with IBS symptoms.

In conclusion, using nutrition as an intervention to treat nutrition is an emerging field and more randomised controlled trials are needed for it to be implemented in primary health care. Nevertheless, this chapter found a lot of evidence to support that nutrition can help to deal with anxiety.

Key points:
 * Nutritional intervention in mental health is an emerging and promising field.
 * Using food as a coping mechanism for anxiety can turn into a vicious cycle, according to the Psychosomatic Theories of Obesity.
 * Allowing yourself to occasionally indulge can help reduce overeating and binging when feeling anxious, according to the Restraint Hypothesis.
 * Anxiety can lead to emotional eating of unhealthy foods in secret. Being aware of this and preparing with healthy snacks or distractors can help.
 * Anxiety and nutrition have a clear bidirectional relationship.
 * Limiting unhealthy, processed, and refined foods can help with anxiety.
 * Following the Mediterranean or traditional diet can help with anxiety.
 * If you experience IBS, the low FODMAP diet can help with anxiety.
 * Eating probiotics can help regulate the gut microbiota and manage anxiety.