Depression is rated by the World Health Organisation as the leading cause of disease burden amongst high income countries. Depression is 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), agitation (restlessness or anxiety).
There are many factors that can contribute to the development of depression such as psychological issues or biochemical imbalances, and triggers such as major stress or trauma.
There are also a number of nutritional imbalances that can make you prone to depression, which are explored further down.
What is Depression?
In Britain, 1 in 20, or around 3 million people, are diagnosed with depression. Unipolar Depression is rated by the World Health Organization as the leading cause of disease burden amongst high-income countries.
There are 2 major classifications of depression: typical and atypical. Typical depression tends to feature loss of weight, appetite and difficulty sleeping whereas atypical depression tends to include weight gain, increased appetite and excessive sleepiness and/or sleeping.
Are You Depressed?
Depression is diagnosed on the basis of symptoms in a questionnaire test, the most common being the Hamilton Rating Scale of Depression, or HRS for short. This contains questions about your mood, guilt feelings, suicidal thoughts, insomnia, agitation, anxiety, physical problems, sex drive, and so on. Depending on your test score on these questions, you will be diagnosed with either “mild,” “moderate,” or “severe” depression.
What Causes Depression?
There are many factors that can contribute to the development of depression. There might be underlying biochemical or psychological issues that predispose an individual to depression. There might be a trigger such as a stressful event, a bereavement, loss of a job, or break up of a relationship. If you are suffering with a low mood, whether you consider that it is depression or not, you should see your GP who can rule out medical causes, recommend counselling, cognitive behavioural therapy and psychotherapy, and assess your medication. Exercise is also very important and there’s lots of evidence that regular exercise boosts mood, especially if you’re able to exercise outdoors in a green environment. Even a walk in the park or a stroll by the river is thought to be beneficial.
Nutrition and Depression: What Works?
Increase your omega-3 fats
Omega-3 fats are called essential fats, because unlike some other substances, they can’t be manufactured within the human body, and therefore it is essential that you take them in through your diet. The richest dietary source is from oily fish such as salmon, sardines, mackerel, pilchards, herring, trout and fresh but not tinned tuna. Surveys have shown that the more fish the population of a country eats the lower is their incidence of depression. There are two key types of omega-3 fats, EPA and DHA and the evidence suggests that it’s the EPA which seems to be the most potent natural anti-depressant.
There are been a number of studies demonstrating the benefit of omega 3 in depression. A trial led by Dr Andrew Stoll from Harvard Medical School, published in the Archives of General Psychiatry, gave 40 depressed patients either omega 3 supplements versus placebo and found a highly significant improvement. The next, published in the American Journal of Psychiatry, tested the effects of giving twenty people suffering from severe depression, who were already on anti-depressants but still depressed, a highly concentrated form of omega 3 fat, called ethyl-EPA versus a placebo. By the third week the depressed patients were showing major improvement in their mood, while those on placebo were not. A recent pooling of trials (a meta-analysis) which looked at all good quality trials of omega-3 fats and mood disorders concluded that omega-3 fats reduced depressive symptoms by an average of 53% and that there was as correlation between dose and depressive symptom improvement, meaning that higher dose omega-3 was more effective than a lower dose. Of those that measured the Hamilton Rating Scale, including one ‘open’ trial, not involving placebos, the average improvement in depression was approximately double that shown by anti-depressant drugs, without the side-effects. This may be because omega 3s help to build the brain’s neuronal (brain cell) connections as well as the receptor sites for neurotransmitters; therefore, the more omega-3s in your blood, the more serotonin you are likely to make and the more responsive you become to its effects.
Where’s the evidence? Search our evidence database for a list of scientific studies on omega 3 and depression.
Side effects? Very occasionally, when starting omega-3 fish oil supplementation, some people can get slightly loose bowels or fish-tasting burps, but this is quite rare. Supplementing fish oils also reduces risk for heart disease, reduces arthritic pain and may improve memory and concentration.
Eat fish at least twice a week, seeds on most days and supplementing omega 3 fish oils. Look for a supplement that contains EPA, DHA and GLA.
The best fish for EPA, the type of omega 3 fat that’s been most thoroughly researched are: mackerel (1,400mg per 100g/3oz), herring/kipper (1,000mg), sardines (1,000mg), fresh (not tinned) tuna (900mg), anchovy (900mg), salmon(800mg), trout (500mg). Tuna, being high in mercury is best eaten not more than twice a month.
The best seeds are flax seeds and pumpkin seeds. Flax seeds are so small they are best ground and sprinkled on cereal. Alternatively, use flax seed oil, for example in salad dressings. While technically providing omega 3 only about 5% of the type of omega 3 (alpha linolenic acid) in these seeds is converted in your body into EPA.
Increase your intake of B vitamins
People with either low blood levels of the B-vitamin folic acid, or high blood levels of the amino acid homocysteine (a sign that you are not getting enough B6, B12 or folic acid), are both more likely to be depressed and less likely to get a positive result from anti-depressant drugs. In a study comparing the effects of giving an SSRI with either a placebo or with folic acid, 61% of patients improved on the placebo combination but 93% improved with the addition of folic acid. But how does folic acid itself, a cheap vitamin with no side-effects, compare to anti-depressants?
Three trials involving 247 people address this question. Two involving 151 people assessed the use of folic acid in addition to other treatment, and found that adding folic acid reduced HRS scores on average by a further 2.65 points. That’s not as good as the results with 5-HTP (discussed below) but as good, if not better than antidepressants. These studies also show that more patients treated with folate experienced a reduction in their HRS score of greater than 50% after ten weeks compared to those on anti-depressants.
Having a high level of homocysteine, a toxic amino acid found in the blood, doubles the odds of a woman developing depression. The ideal level is below 7, and certainly below 10. The average level is 10-11. Depression risk doubles with levels above 15. The higher your level the more likely folic acid will work for you.
Folic acid is one of seven nutrients – the others being B2, B6, B12, zinc, magnesium and TMG – that help normalise homocysteine. Deficiency in vitamin B3, B6, folic acid, zinc and magnesium have all been linked to depression. Having a low homocysteine means your brain is good at ‘methylating’ which is the process by which the brain keeps it’s chemistry in balance. So it makes sense to both eat wholefoods, fruits, vegetables, nuts and seeds, high in these nutrients and supplementing a multivitamin.
Side effects? There are none, except lower risk for heart disease, strokes, Alzheimer’s and improved energy and concentration. However, if you are B12 deficient (most likely if you are elderly, vegan, or are on medication to reduce stomach acid), taking folic acid on its own can mask the B12 deficiency symptoms, but the underlying nerve damage caused by B12 deficiency anaemia can persist. So, don’t take folic acid without also supplementing vitamin B12 (sub-lingual forms are better absorbed, particularly in the elderly).
Check your homocysteine: your homocysteine level is an indicator of your B vitamin needs. You can be tested through your GP or using a home test kit. If your level is above 9mmol/l take a combined ‘homocysteine’ supplement of B2, B6, B12, folic acid, zinc, and TMG, providing at least 400mcg of folic acid, 250mcg of B12 and 20mg of B6. If your homocysteine score is above 15mmol/l double this amount.
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, which means 25mg-50mg of B1, B2, B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine) and at least 100mcg of folic acid and 10mcg of B12 and biotin.
Boost your serotonin with amino acids
Serotonin is made in the body and brain from an amino acid called tryptophan. Tryptophan is then converted into another amino acid called 5-Hydroxy Tryptophan (5-HTP), which in turn is converted into the neurotransmitter serotonin. Tryptophan can be found in the diet; it’s in many protein rich foods such as meat, fish, beans and eggs. 5-HTP is found in high levels in the African Griffonia bean, but this bean is not a common feature of most people’s diet. Just not getting enough tryptophan is likely to make you depressed; people fed food deficient in tryptophan became rapidly depressed within hours.
Both tryptophan and 5-HTP have been shown to have an antidepressant effect in clinical trials, although 5HTP is more effective – 27 studies, involving 990 people to date, most of which proved effective. . So how do they compare with anti-depressants? In play-off studies between 5-HTP and SSRI antidepressants, 5-HTP generally comes out slightly better. One double-blind trial headed by Dr. Poldinger at the Basel University of Psychiatry gave 34 depressed volunteers either the SSRI fluvoxamine (Luvox) or 300 mg of 5-HTP. At the end of the six weeks, both groups of patients had had a significant improvement in their depression. However, those taking 5-HTP had a slightly greater improvement, compared to those on the SSRI, in each of the four criteria assessed—depression, anxiety, insomnia, and physical symptoms—as well as their own self-assessment, although this improvement was not statistically significant.
Since anti-depressant drugs, in some sensitive people, can induce an overload of serotonin called ‘serotonin syndrome’ characterised by feeling hot, high blood pressure, twitching, cramping, dizziness and disorientation, some concern has been expressed about the possibility of increased risk of serotonin syndrome with the combination of 5-HTP and an SSRI drug. The balance of evidence suggests that there is little to no risk, however, if you wish to take 5-HTP or tryptophan alongside a serotonergic drug (SSRI or tricyclic antidepressant that boosts serotonin levels), you should first consult your prescribing doctor.
Exercise, sunlight and reducing your stress level also tend to promote serotonin.
Side-effects? Some people experience mild gastrointestinal disturbance on 5-HTP, which usually stops within a few days. Since there are serotonin receptors in the gut, which don’t normally expect to get the real thing so easily, they can overreact if the amount is too high, resulting in transient nausea. If so, just lower the dose or take it with food.
Supplement 5-HTP or tryptophan: Most of the effective studies used 300mg of 5-HTP, however we ideally recommend testing if you are low in serotonin with a platelet serotonin test and starting with 100mg, or 50mg twice a day. If 5-HTP is not available, you could supplement the amino acid tryptophan in amounts of 500mg – 2g per day – again, we would suggest starting at the lower end. Tryptophan is best absorbed either on an empty stomach or, ideally, with a carbohydrate snack such as a piece of fruit or an oatcake. 5-HTP is well-absorbed with or without food. Also, make sure you eat enough protein from beans, lentils, nuts, seeds, fish, eggs and meat, which are all high in tryptophan. Do not take 5-HTP or tryptophan if you are currently taking an anti-depressant without your doctor’s permission.
Balance your blood sugar
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. The more uneven your blood sugar supply the more uneven your mood. In fact, poor blood sugar balance is often the single-biggest factor in mood disorders.
Eating lots of sugar is going to give you sudden peaks and troughs in the amount of glucose in your blood; symptoms that this is going on include fatigue, irritability, dizziness, insomnia, excessive sweating (especially at night), poor concentration and forgetfulness, excessive thirst, depression and crying spells, digestive disturbances and blurred vision. Since the brain depends on an even supply of glucose it is no surprise to find that sugar has been implicated in aggressive behaviour, anxiety, and depression, and fatigue .
Lots of refined sugar and refined carbohydrates (meaning white bread, pasta, rice and most processed foods,) is also linked with depression because these foods not only supply very little in the way of nutrients but they also use up the mood enhancing B vitamins; turning each teaspoon of sugar into energy needs B vitamins. In fact, a study of 3,456 middle-aged civil servants, published in British Journal of Psychiatry found that those who had a diet which contained a lot of processed foods had a 58% increased risk for depression, whereas those whose diet could be described as containing more whole foods had a 26% reduced risk for depression.
Sugar also diverts the supply of another nutrient involved in mood – chromium. This mineral is vital for keeping your blood sugar level stable because insulin, which clears glucose from the blood, can’t work properly without it. There is more on chromium below.
The best way to keep your blood sugar level even is to eat what is called a low Glycemic Load (GL) diet and avoid, as much as you can, refined sugar and refined foods, eating instead whole foods, fruits, vegetables, and regular meals. Caffeine also has a direct effect on your blood sugar and your mood and is best kept to a minimum, as is alcohol.
Where’s the evidence? Search our evidence database for a list of scientific studies on sugar, caffeine and depression.
Eat a diet that will stabilise your blood sugar (known as the Low GL diet): this means eating low GL carbohydrates, as well as combining your low GL carbohydrates with protein in a ratio of 1:1.
Eat at regular intervals: including snacks that include low GL carbohydrate and protein such as fresh fruit with a handful of nuts, oatcakes with humous or celery and cottage cheese.
Sweet Foods: only eat sweet foods as a very occasional treat and only after a meal or healthy snack
Up your intake of chromium
This mineral is vital for keeping your blood sugar level stable because insulin, which clears glucose from the blood, can’t work properly without it. In fact it turns out that just supplying proper levels of chromium to people with atypical depression can make a big difference.
If you answer yes to a five or more of these questions and you might be suffering from atypical depression.
- Do you crave sweets or other carbohydrates?
- Do you tend to gain weight?
- Are you tired for no obvious reason?
- Do your arms or legs feel heavy?
- Do you tend to feel sleepy or groggy much of the time?
- Are your feelings easily hurt by the rejection of others?
- Did your depression begin before the age of 30?
It is called atypical because in ‘classic’ depression people lose their appetite, don’t eat enough, lose weight and can’t sleep whereas with atypical, the opposite is generally true. Atypical depression affects anywhere from 25 to 42 percent of the depressed population, and an even higher percentage among depressed women so it’s extremely common rather than being ‘atypical’. A chance discovery by Dr Malcolm McLeod, clinical professor of psychiatry at the University of North Carolina, suggested that people who suffer with ‘atypical’ depression might benefit from chromium supplementation.
In a small double-blind study McLeod gave ten patients suffering from atypical depression chromium supplements of 600mcg a-day and five others a placebo for eight weeks. The results were dramatic. Seven out of ten taking the supplements showed a big improvement, versus none on the placebo. Their Hamilton Rating Score for depression dropped by an unheard of 83%; from 29 – major depression – to 5 – not depressed. A larger trial at Cornell University with 113 patients has confirmed the finding. After eight weeks 65% of those on chromium had had a major improvement, compared to 33% on placebos.
Side effects? None, except more energy and better weight control. Chromium, if taken in the evening, can increase energy and hence interfere with sleep.
Supplement chromium: If you suffer from ‘atypical depression’ (see above) studies show that 600mcg of chromium a day is effective. Supplements generally come in 200mcg pills. Take two with breakfast and one with lunch. If this works, after a month reduce to one with breakfast and one with lunch. If this works, reduce to one with breakfast after a further month. Don’t take chromium in the evening as it can be stimulating.
Adopt a low GL diet: In addition to supplementing chromium, you should adopt the low GL Diet style of eating as outlined above.
Bring on the sunshine
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. Of course, you should never risk your skin health by getting sun-burned.
Get your vitamin D levels tested: ask your GP or nutritional therapist for a vitamin D test. If your level is below 75 nmol/litre, supplement 2,000 iu per day for 12 weeks, and then get a retest.
Get sensible sunshine exposure: Get some sensible sun exposure, without sun-block, but don’t risk your skin health by allowing yourself to get sunburned!
Bad mood foods
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. Your GP can test for it, and should test you if you have fluctuating digestive symptoms including diarrhoea, constipation or bloating, and especially if you have unexplained anaemia. In fact, you can have mood symptoms relating to gluten, even without Coeliac Disease.
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.
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.
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, don’t 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 frail and for children.
Fobbester, D et al., Optimum Nutrition UK survey, October 2004. Available from www.ion.ac.uk
G.Brown et al., Social support, self-esteem and depression. Psychol Med. 1986 Nov;16(4):813-31.
Hibbeln JR. ‘Fish consumption and major depression’. Lancet, vol 351(9110), pp. 1213 (1998)
M. Peet and R, Stokes, Omega 3 Fatty Acids in the Treatment of Psychiatric Disorders Drugs, vol 65(8), pp. 1051-9 (2005)
S Kraguljac NV, Montori VM, Pavuluri M, Chai HS, Wilson BS, Unal SS (2009) Efficacy of omega-3 Fatty acids in mood disorders – a systematic review and metaanalysis. Psychopharmacology Bulletin 42(3):39-54
Coppen & Bailey J. Affective Disorders 2000; 60: 121-130
M. J. Taylor et al., Folate for depressive disorders. The Cochrane Database of Systematic Reviews 2003 Issue 2. Art. No.: CD003390. DOI: 10.1002/14651858.CD003390.
I. Bjelland et al. Folate, Vitamin B12, Homocysteine, and the MTHFR 677CT Polymorphism in Anxiety and Depression: The Hordaland Homocysteine Study, Arch Gen Psychiatry, vol 60, pp. 618-26 (2003)
E. Turner, Serotoninalacarte: Supplementation with the serotonin precursor 5-hydroxytryptophan.’ Pharmacology&Therapeutics (2005) [article in press].
W. Poldinger et al. A functional-dimensional approach to depression: serotonin deficiency and target syndrome in a comparison of 5-hydroxytryptophan and fluvoxamine, Psychopathology vol 24(2), pp. 53-81 (1991)
Associate editor: K.A. Neve ‘Serotonin a la carte: Supplementation with the serotonin precursor 5-hydroxytryptophan’ ErickH. Turner a,c,d,*, Jennifer M. Loftis a,b,c, AaronD. Blackwell a,b,e Pharmacology & Therapeutics(2005) www.elsevier.com/locate/pharmthera
D. Benton et al, ‘Mild hypoglycaemia and questionnaire measures of aggression’, Biol Psychol, vol 14(1-2), pp. 129-35 (1982)
A. Roy et al, Monoamines, glucose metabolism, aggression toward self and others, Int J Neurosci, vol 41(3-4), pp. 261-4 (1988)
A. G. Schauss, Diet, Crime and Delinquency, Parker House (1980)
M. Virkkunen, ‘Reactive hypoglycaemic tendency among arsonists’, Acta Psychiatr Scand, vol 69(5), 1984, pp. 445-52
M. Virkkunen and S. Narvanen, ‘Tryptophan and serotonin levels during the glucose tolerance test among habitually violent and impulsive offenders’, Neuropsychobiology, vol 17(1-2), 1987, pp. 19-23
J. Yaryura-Tobias and F. Neziroglu F, ‘Violent behaviour, Brain dysrythmia and glucose dysfunction. A new syndrome’, J Ortho Psych, vol 4, pp. 182-5 (1975)
M. Bruce and M. Lader, ‘Caffeine abstention and the management of anxiety disorders’, Psychol Med, vol 19, pp. 211-14 (1989)
L. Christensen, ‘Psychological distress and diet – effects of sucrose and caffeine’, J Appl Nutr, vol 40(1), pp. 44-50 (1988)
L. Christensen, ‘Psychological distress and diet’ Ibid.
Akbaraly TN et al., (2009) Dietary pattern and depressive symptoms in middle age. Brit J Psychiatry. 195:408-413
Lifting Depression – The Chromium Connection by Dr Malcolm McLeod (Basic Health Publications):
J. R. Davidson et al, Effectiveness of chromium in atypical depression: a placebo-controlled trial, Biol Psychiatry, vol 53(3), pp. 261-4 (2003)
Docherty, J et al, ‘A Double-Blind, Placebo-Controlled, Exploratory Trial of Chromium Picolinate in Atypical Depression’. Journal of Psychiatric Practice. Vol 11(5), pp. 302-314, (2005)
Lansdowne AT, Provost SC. (1998) Vitamin D3 enhances mood in healthy subjects during winter. Psychopharmacology (Berl). 135:319–323
Golden RN et al., (2005) The efficacy of light therapy in the treatment of mood disorders: a review and meta-analysis of the evidence. Am J Psychiatry 162:656-62
Pearce SHS , Cheetham TD (2010) Diagnosis and management of vitamin D deficiency, BMJ 340:142-147
G.W. Lambert et al., ‘Effect of sunlight and season on serotonin turnover in the brain’, Lancet, 2002;360(9348):1840-2
C.Wilkins et al.,’ Vitamin D deficiency is associated with low mood and worse cognitive performance in older adults.’ The American Journal of Geriatric Psychiatry, 2006;14(12):1032-40;
A.Nanri et al., ‘Association between serum 25-hydroxyvitamin D and depressive symptoms in Japanese: analysis by survey season’, European Journal of Clinical Nutrition, 2009 Dec;63(12):1444-7: R. Jorde et al., ‘Effects of vitamin D supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial’, Archives of General p
Psychiatry, 2008 May;65(5):508-12.
Ludvigsson JF et al., (2007) Coeliac disease and risk of mood disorders-a general population-based cohort study. J Affect Disord. 99:117-26
Ford RP. (2009) The gluten syndrome: a neurological disease. Med Hypotheses.73(3):438-40