Depression is a common condition. Approximately 1 in 4 people in the United Kingdom will experience a mental health problem each year. Depression is rated by the World Health Organisation as the leading cause of disease burden amongst high income countries. Of course, mood can fluctuate and an individual’s experience of their mood is unique and dependent on a variety of factors, including external factors (like the situation they are in or have been in) and internal factors such as physiological processes like fluctuations in hormones, neurotransmitters and nutrient availability. It is therefore clear that there is no single mechanism that can account for all the clinical variations in depression manifestation. 

Recent research has focused on modifiable factors to support overall brain health and mood, as well as ‘risk factors’ involved in the development of depression. ‘Nutritional psychiatry’ is an emerging area of research, which seeks to establish the role of nutrition in mental health conditions, and how specific nutrients may be applicable and supportive. 

Symptoms of Depression 

It is normal to have changes in mood, particularly in reaction to emotionally challenging events in our lives. Depression however, is typically characterised by feelings of worthlessness or guilt, poor concentration, loss of energy, fatigue, thoughts of suicide or preoccupation with death, loss or increase of appetite and weight, a disturbed sleep pattern, slowing down (both physically and mentally), or agitation (restlessness or anxiety). Symptoms can range in severity, but to be considered a clinical depression, these symptoms must occur most of the time for at least two weeks.

What Causes Depression?

There are many factors that can contribute to the development of depression. There might be biochemical or psychological issues that predispose an individual to depression. There might be a trigger such as a stressful event, major trauma, a bereavement, loss of a job, or break up of a relationship. If you are experiencing low mood you should see your doctor, who can rule out medical causes and discuss the best ways to support you. 

Integrative Support for Depression

It is important to consider nutrition with regards to depression, with regards to essential building blocks – macronutrients (carbohydrates, proteins and fats) and micronutrients (e.g vitamins and minerals) that the body requires to make neurotransmitters and hormones responsible for a balanced mood. Exercise is also very important because regular exercise can exert a positive effect on mood, especially if it is done outdoors in a green environment. Even a mindful walk in the park or a stroll by the river is thought to be beneficial.

It can be difficult to find the motivation, appetite or energy to eat when you feel depressed. Depression and loneliness have been identified as key risk factors for malnutrition, particularly amongst elderly populations. Furthermore, depressive symptoms are also associated with making unhealthy food choices such as food high in sugars and decreased variety and choice in the diet. One study found that poor nutritional choices, reduced day-to-day functioning and emotional changes all exacerbate each other, and can therefore become a vicious cycle (1). Receiving support from a doctor, and other healthcare professional, as well as a qualified psychologist, therapist and nutrition professional, may be supportive and helpful. 

Foods and Nutrients

Increase Essential Fats

Omega 3 fatty acids are essential fatty acids that the body needs for brain function and cell growth, because unlike some other substances, they cannot be manufactured within the human body. Therefore it is essential that they are taken through the diet. The richest dietary source of omega-3 fats are from oily fish such as salmon, sardines, mackerel, pilchards, herring, and trout. There are two key types of omega-3 fats, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA can also be taken in supplemental form. Research has shown that the more fish the population of a country eats, the lower their incidence of depression (2) (3)(4).  

Many studies have found a beneficial effect of increased intake of PUFAs (particularly EPA) on symptoms of depression. A recent study found that omega-3 PUFA supplementation showed beneficial effects in people with very severe depressive symptoms (5) A meta-analysis of 19 clinical trials looking at omega-3 PUFA intake in participants with depression and depressive symptoms demonstrated significant clinical improvements in mood following supplementation with EPA and DHA (6).  

More recent research into depression has indicated that there are alterations in the immune system with pro-inflammatory chemicals in both the plasma and cerebrospinal fluid in the body influencing the progression and severity of depressive disorders.  There is compelling evidence that omega-3 PUFAs, in particular EPA, suppress pro-inflammatory and promote anti-inflammatory pathways in the body (7)

Vegan sources of omega-3:

Seaweed and algae are important sources of omega-3 for people on a vegetarian or vegan diet, as they are one of the few plant groups that contain DHA and EPA. Chlorella and spirulina can be added to smoothies or mixed with water. Nori is a type of seaweed found in sushi.

Seeds contain a type of omega 3 polyunsaturated fatty acid called alpha linoleic acid (ALA). Flaxseeds and pumpkin seeds are great sources of ALA and can be ground and sprinkled into porridge or in soups and smoothies. The body is able to convert ALA into EPA and DHA, however it should be noted that this conversion process is not always efficient.  

Key Actions:

Eat fresh oily fish at least 2-3 times per week. The best sources are mackerel, seabass, oysters, herring/kipper, sardines, anchovies, salmon and trout. Supplementing with a high potency, ethical and sustainably sourced fish oil can also be beneficial, but always consult a doctor before starting a new supplement regimen. Vegetarian and vegan supplements containing plant marine algae can also provide EPA and DHA. 

Side effects

Very occasionally, when starting omega-3 fish oil supplementation, some people may experience slightly loose bowels or a fish aftertaste in the mouth after taking the supplement. 

Increase intake of B vitamins

There are eight different B Vitamins, which play a vital role in many processes in the body, including supporting enzymes to do their jobs, breaking down amino acids, transporting oxygen and nutrients around the body and releasing energy from carbohydrates. 

People with either low blood levels of the B-vitamin folate, or high blood levels of the amino acid homocysteine (a sign of inadequate B6, B12 or folic acid consumption and / or absorption) have been found to be more likely to experience low mood and depression (8). Furthermore, individuals who are B12 deficient (at risk groups include elderly, those on low-quality vegan diets, or those on medications to reduce stomach acid called Proton-Pump Inhibitors (PPIS) like omeprazole or lansoprazole. Taking folic acid on its own can mask the symptoms of B12 deficiency, but the underlying nerve damage caused by B12 deficiency anaemia can persist.

Consuming the full range of B vitamins is important for clearance of homocysteine (9). 

B vitamins also act as helpers in the formation of neurotransmitters related to the regulation of mood, including dopamine and serotonin. 

Deficiencies in one or a number of B vitamins is a risk factor for low mood. B vitamin supplementation may offer an alternative or additional treatment to standard care aimed at optimising mood via modulation of the neurotransmitter function and improving homocysteine levels. Low vitamin B12 and vitamin D levels and increased homocysteine levels have also been found to play a role in the development of depression in children and adolescents (10). 

A systematic review and meta-analysis (11) was undertaken to examine and quantify the effects of B vitamin supplementation on mood in both healthy and ‘at-risk’ of depression populations (those who had nutrient deficiencies or reporting low mood). Participants in the studies were supplemented with a complete B vitamin supplement every day for at least four weeks.  Eleven of the 18 studies reported a positive effect for B vitamins over a placebo for overall mood or a facet of mood. Of the eight studies in ‘at-risk’ cohorts, five found a significant benefit to mood. 

Food Sources of B Vitamins

Some good sources of B Vitamins are:

Whole grains 
Meat and poultry
Fish
Eggs and dairy products 
Legumes
​Seeds and nuts 
Dark green leafy vegetables

Supplementing with a good quality multivitamin containing B vitamins can also be helpful. Always consult with your doctor before beginning any new supplements. 

Side effects

It is important to take folic acid in addition to B12, as the nutrients work synergistically together and taking folic acid on its own can mask deficiency of Vitamin B12. Sublingual forms (placed under the tongue to dissolve into the bloodstream) are better absorbed, particularly in the elderly. 

Key Action:

Check your homocysteine: your homocysteine level is an indicator of your B vitamin needs. You can test your homocysteine levels (please contact us at info@foodforthebrain.org for a list of partners who provide homocysteine testing). B Vitamin supplementation may help to reduce homocysteine levels, but this should be done under the supervision of your doctor and a qualified registered nutrition practitioner or dietitian. 

Eat B vitamin rich whole foods:  whole grains, beans, nuts, seeds, fruits and vegetables. Folic acid is particularly rich in green vegetables, beans, lentils, nuts and seeds, while B12 is only found in animal foods – meat, fish, eggs and dairy produce. A good starting point is also to supplement a multivitamin providing optimal levels of B vitamins or as specific B vitamin complex.

Amino Acids and Serotonin 

Amino acids are considered the building blocks of proteins. Nine of the 20 amino acids are essential – meaning the body cannot make these and we must get them from our diet. These are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. We need tryptophan to make energy and the neurotransmitters serotonin and melatonin. Serotonin supports mood and melatonin helps us to sleep. In order to convert tryptophan to serotonin and melatonin we must also have adequate amounts of other nutritional cofactors including vitamin B6, magnesium, vitamin C, zinc, iron and folate. 

If we are under a lot of stress, either psychologically or physically tryptophan can be converted to quinolinic acid instead of serotonin. Quinolinic acid is a neurotoxin which has been found to correlate with increased depressive symptoms in some individuals . Studies have found a link between lower levels of tryptophan (and higher levels of quinolinic acid) in some groups of people with depression (12). 

Key Actions: 

Increase protein rich foods to increase amino acids 

Tryptophan can be found in many protein-rich foods such as meat, poultry (particularly turkey), fish, beans, eggs, lentils, nuts and seeds. Having a portion (e.g a handful) of protein with each meal is important for giving the body what it needs to carry out many vital functions in the body. Protein powders can be a convenient and easy to take source of amino acids. Look for protein powders that are free from artificial sweeteners. Artificial sweeteners like aspartame are found in many diet drinks and sugar-free sweets. Aspartame can block the formation of serotonin and cause headaches, poor sleep and low mood. 

In order for your body to get the most out of the tryptophan it gets it requires carbohydrates to help tryptophan get into the brain where it can be used. Eating a complex carbohydrate at the same time as protein can be helpful. 

Balance Blood Sugar Levels 

There is a direct link between mood and blood sugar balance. All carbohydrate foods are broken down into glucose and your brain runs on glucose. Sugar is made from sucralose which is glucose and fructose. Sugar breaks down very quickly in the body and we can experience sharp rises in the amount of glucose in the blood. The more uneven your blood sugar supply the more uneven your mood can be. With blood sugar ups and downs we can feel tired, irritable, experience dizziness, insomnia, excessive sweating (especially at night), poor concentration and forgetfulness, excessive thirst, low moods, digestive disturbances and blurred vision. 

Refined sugar and refined carbohydrates (meaning white bread, pasta, rice, sweets and most processed foods) are also linked with depression because eating lots of sugar also depletes levels of B vitamins. Several studies have found that a higher intake of higher glycemic index (GI) foods (higher refined sugar content) is associated with a higher risk of depression (13).  

Sugar also diverts the supply of another nutrient involved in mood – chromium. This mineral is vital for keeping your blood sugar level stable because it is involved in the modulation of insulin, which clears glucose from the blood.

Key Actions:

Balance your plate

The best way to keep your blood sugar level more stable is to eat what is called a low Glycemic Load (GL) diet , which means avoiding refined sugar and refined carbohydrates, and instead following a varied diet including green leafy vegetables, whole grains, nuts, seeds, and berries. Including sources of protein, for example lean meats, fish, chicken, nuts and seeds, and essential fats, such as those found in oily fish, walnuts and avocados, with each meal may help to balance blood sugar, whilst keeping you feeling fuller for longer. 

Increase intake of chromium

Chromium is vital for keeping your blood sugar level stable because it is required for the functioning of insulin, which clears glucose from the blood. Good food sources of chromium include broccoli, turkey, liver, whole grains, seafood and green beans. Chromium can also be taken in a supplement form called chromium picolinate, although this should be done under the supervision of a doctor, particularly if diabetes medications are being taken (i.e metformin). 

Magnesium 

Magnesium plays an essential role in a wide-range of processes in the body, right down to the cellular level, and magnesium deficiency is linked in the development of various systemic diseases, including depression and anxiety. After zinc, magnesium is the second most commonly deficient mineral. Chronic stress and high amounts of sugar also deplete magnesium levels in the body. A higher intake of dietary magnesium seems to be associated with lower depression symptoms. One study found patients with major depression experienced an improvement in their symptoms after being subjected to 125 to 300mg of magnesium with each meal and at bedtime (14).  The daily recommended intake of magnesium for adults is 300mg a day for men (19 to 64 years) and 270mg a day for women (19 to 64 years).

Key Actions 

Increase magnesium-rich foods 

Foods high in magnesium include almonds, bananas, black beans, broccoli, brown rice, cashews, flaxseed, green leafy vegetables (spinach), nuts, oatmeal, seeds (pumpkin, sesame, sunflowers) soybeans, sweet corn, tofu, and whole grains. Magnesium supplements can be added alongside food sources, and Magnesium can also be administered via Epsom bath salts and Magnesium sprays. 

Side effects: higher dosages of Magnesium (400mg>) may cause diarrhoea. 

Vitamin D

Known as the ‘sunshine vitamin’, around 90% of our vitamin D is synthesised in our skin by the action of sunlight. Vitamin D deficiency is increasingly being recognised as a common problem around the globe and may be implicated in depression, particularly if you feel worse in winter.

You are most at risk for vitamin D deficiency if you are elderly (since your ability to make it in the skin reduces with age), dark-skinned (you require up to 6 times more sunshine than a light-skinned person to make the same amount of vitamin D), overweight (your vitamin D stores may be tucked away within your fat tissue), or you tend to shy away from the sun – covering up and using sun-block. 

Key Action:

Get your vitamin D levels tested: ask your GP or qualified nutrition practitioner for a vitamin D test.

Get sensible sunshine exposure: Get some sensible sun exposure, without sun-block, but do not allow yourself to become sunburned. 

Foods and Inflammation

Some foods are associated with mood problems. For example, in a huge population study, Coeliac Disease (a severe intolerance to gluten – the protein found in wheat, rye and barley) was associated with an 80% increased risk for depression. It is thought that Coeliac Disease is vastly underdiagnosed in the UK. Some symptoms of Coeliac Disease are fluctuating digestive symptoms including diarrhoea, constipation or bloating, and otherwise unexplained anaemia. A doctor can test for Coeliac disease, but it is important to continue consuming gluten until after the test, as otherwise this may impact results. However, it should be noted that it is possible to have mood symptoms relating to gluten consumption, even without a diagnosis of Coeliac Disease, as some individuals are very sensitive to gluten. Therefore a gluten elimination diet may still be appropriate. In all instances, a gluten elimination diet should be conducted under the supervision of a qualified nutrition practitioner. 

Side effects? None, if changes are made with professional guidance. Dramatic changes to diets without professional supervision may cause nutrient deficiencies, especially over the longer term.

Key Action:

Try an elimination diet: you may suspect some foods which may or may not be one of the usual suspects – are gluten (wheat, rye, barley), wheat, dairy (all types – cow, sheep, goat, milk, cheese, cream etc), soya, yeast and eggs. If this is the case, you could try an exclusion of the food or foods for a brief trial period under the supervision of a qualified nutrition practitioner.

Get a food intolerance test: alternatively, you could undertake an IgG ELISA blood test to determine whether you have raised antibody levels to specific foods in your blood which is a good indication. Either way, do not make dramatic changes to your diet or cut out whole food groups without professional guidance to ensure your diet remains healthy and balanced – this is especially important for the elderly, individuals who have chronic illnesses and for children.

Researched by: Dr Emma Weymouth, PhD (Psychology), Nutritional Therapist

Date Published: October 2021

Due for Review: October 2022

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