Dr Sarah Brewer November 08, 2018

The impact of diet on our physical health is understandable, but did you know that diet could also affect your mental health? There is increasing research to show the importance of essential nutrients for good mental function, and deficiencies are linked to some psychological disorders including depression and anxiety.

Top foods that affect our mood


Carbohydrates are key for preventing low blood sugar levels. Low blood sugar levels can make you feel tired, weak and confused and could affect your mood. There’s even a modern word for the irritability associated with low glucose levels – 'hangry' describes feeling both hungry and angry.

To help maintain stable blood sugar levels, eat regular starchy carbohydrate-based meals that include things like wholegrain bread, brown rice, wholemeal pasta or sweet potatoes. It’s also important to eat plenty of fruit, vegetables and dairy foods.

Carbohydrates that are classed as having a low Glycaemic Index (GI) are digested relatively slowly which helps maintain stable blood glucose levels, so aim to include the following in your diet:

  • Pulses and beans
  • Wholegrain cereals including oats and pasta
  • Fruit and vegetables
  • Dairy foods such as yoghurt

Top tip: avoid skipping meals such as breakfast – even a breakfast on the go is better than a missed meal.

Omega 3

Interestingly, populations which have a low intake of fish have higher rates of depression and low mood, and it is believed that the omega 3 in oily fish could help protect against low mood.1

To get the recommended intake of omega 3 eat two portions of fish per week, one of which is oily, such as salmon, mackerel, sardines or herring. Canned, smoked, fresh and frozen sources are perfectly fine too. A portion is about 140g (5 oz) of fresh fish or one small can of oily fish.

Women past childbearing age (or not intending to have children), men and boys can eat up to four portions of oily fish a week. Women who are pregnant or breastfeeding, or likely to become pregnant, can safely have up to two portions a week. This limitation is due to the deep-sea toxins that are potentially present in oily fish – this worry does not apply to fish oil supplements that are produced to a pharmaceutical standard known as GMP, which are checked for purity.

Alternative sources of omega 3

It’s worth bearing in mind there are two ‘chain lengths’ of omega 3 fatty acids: short chain and long chain. Short chain omega 3 fatty acids aren’t thought to benefit our mood as effectively as the long chain versions, DHA and EPA, found in oily fish.

If you don’t eat fish, eggs enriched with omega 3 are a good source of short-chain essential fatty acids. You can also get short chain omega 3 from:

  • Nuts and seeds such as walnuts, pumpkin seeds and linseeds, rapeseed and linseed oils fortified spreads;
  • Soya beans and soya products such as tofu, natto, tempeh and soya mock meats;
  • Soya milk and dairy alternatives;
  • Green leafy vegetables.
  • If you are unable to eat food sources of omega 3, supplements rich in long chain omega 3 fats may be useful.

The Mediterranean diet

Recent studies reveal a Mediterranean diet – rich in vegetables, fruit, fish, nuts, seeds, pulses and olive oil – helps to protect against depression. Two separate studies found those who ate a typical Mediterranean style diet were 30 per cent less likely to experience depressive symptoms, for example. It is thought the combined effects of a plant-based diet, plus anti-inflammatory omega 3 fatty acids (found in fish, nut and seeds), vitamin and mineral-rich fruit and vegetables, and the anti-inflammatory fatty acids and antioxidants from olive oil offer protection against depressive illnesses.

Supplements that could boost your mood

St John’s wort

St John’s Wort (Hypericum perforatum) is one of the best known herbs to support mental health. Research suggests that it works in a similar way to antidepressants, but with fewer side effects and is most effective in mild to moderate depression.2 It may be taken as capsules, tablets, tinctures or tea: just check the dose required on the packet you buy, as preparation strength varies. As with any herbal preparation, do discuss this option with your GP before taking St John’s Wort, especially if you are on any prescribed medication.


Several studies show that 5-HTP supplements have a positive effect on low mood and are better than placebo in treating depression, with benefits usually occurring within two weeks. One study, involving 60 people with a first episode of depression, compared the effects of 5-HTP against the prescribed antidepressant drug, fluoxetine, for eight weeks. Both groups showed a significant and nearly equal improvement in depression, starting from the second week of treatment and increasing over the eight weeks. By the end of the study, 73% of those taking 5-HTP and 80% taking fluoxetine felt significantly better.3

Vitamin B

Lack of B vitamins can also impact your mental health. In one study, over a quarter of severely depressed older women were found to have low levels of vitamin B12 (found in meat, eggs and dairy products). One of the most effective ways to take a vitamin B12 supplement is in the form of an easily absorbable spray. This allows absorption of B12 within the mouth, which overcomes the reduced absorption within the gut that occurs in later life.


Interesting studies have linked low levels of the mineral selenium with an increased risk of tiredness, depression and anxiety. Although selenium has not yet undergone clinical trials in people with depression, there is concern that low levels of selenium in UK soil have led to low intakes. The most recent National Diet and Nutrition Survey found that 36% of adults did not even meet the lower reference nutrient intake (LRNI) which is the amount needed to prevent deficiency diseases. A British study has shown healthy people given selenium supplements found their mood improved – although having levels that are too high can also increase the risk of depression, so a balanced intake is key. Good sources of selenium include Brazil nuts (just a couple a day will provide your recommended daily intake) eggs, meat, sunflower seeds, fish and brown rice.

CBD oil

Cannabidiol (CBD) helps to reduce muscle tension, restlessness and fatigue which can contribute to inactivity and low mood. A study involving people with social anxiety found that taking CBD supplements before a public speaking engagement reduced anxiety, muddled thoughts, social discomfort and anticipatory anxiety significantly more than placebo.4 CBD may also help with the anxiety that can occur when stopping smoking. If you’re looking to safeguard your mood, especially during winter when Seasonal Affective Disorder (SAD) can strike, try this mood boosting bundle.

1Giles GE, e. (2018). Omega-3 fatty acids influence mood in healthy and depressed individuals, PubMed - NCBI
2Linde K, e. (2018). St John's wort for major depression, PubMed - NCBI
3TC, B. (2018). 5-Hydroxytryptophan: a clinically-effective serotonin precursor, PubMed - NCBI
4Bergamaschi, M., Queiroz, R., Chagas, M., de Oliveira, D., De Martinis, B., Kapczinski, F., Quevedo, J., Roesler, R., Schröder, N., Nardi, A., Martín-Santos, R., Hallak, J., Zuardi, A. and Crippa, J. (2011). Cannabidiol Reduces the Anxiety Induced by Simulated Public Speaking in Treatment-Naïve Social Phobia Patients, Neuropsychopharmacology

Nothing beats a healthy, balanced diet to provide all the nutrients we need. But when this isn't possible, supplements can help. This article isn't intended to replace medical advice. Please consult your healthcare professional before trying supplements or herbal medicines.



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