Diet And Depression: Is There A Link?

The BMC Medicine journal has just released a groundbreaking study that finally links diet to mental health¹

""We've known for some time that there is a clear association between the quality of people’s diets and their risk for depression[...]However, this is the first randomised controlled trial to directly test whether improving diet quality can actually treat clinical depression" - Professor Jacka

Known as the ‘SMILES’ trial (which stands for Supporting the Modification of lifestyle In Lowered Emotional States), researchers split 56 patients with moderate to severe depression into groups that received either dietary changes advised by a clinical dietician or social support from trained personnel to discuss neutral topics or play games. After 12 weeks, symptoms of depression had significantly improved in the group recommended dietary changes compared to the social support group. This suggests that dietary changes may be an effective and accessible treatment approach to help manage depression, with the added benefit of being better for your physical health too.

 This offers a lot of hope to those affected by mental health issues.  

So, what kind of nutrients are important for mental health? 

B vitamins 

B vitamins, particularly B1, B2, B3, B9 (folate/folic acid) and B12 are really key to mental health. Research has suggested that these B vitamins can help sustain your response to antidepressants and reduce the risk of relapse of clinical depression². Other researchers have suggested that there may be an interaction between the immune system, inflammation, B vitamins and depression, such that certain B vitamins can help to improve symptoms of depression³.  

Where can I get B vitamins from? 

Whole grains, meat, eggs, fish, nuts and beans.

Vitamin D 

Low levels of vitamin D have been linked with depression⁴, and for patients suffering from psychosis, they are more likely to display symptoms of depression if their vitamin D levels are low⁵. The exact role of vitamin D in mental health issues isn’t well defined, but it is thought to be involved in neurodevelopment, protection from injury and inflammation, as well as involved in making biochemical messengers in the brain called neurotransmitters⁶. Additionally, vitamin D also has a role in immunity and receptors for this sunshine vitamin can also be found in the brain, suggesting it must have some action there⁷.  

Where can I get vitamin D from? 

We primarily make vitamin D through exposure of our skin (with no sunscreen) in the sunlight. In northern hemispheres, we’re often not outside for long enough, nor do we have sufficient exposure to the sun, which is why supplementation is key. 

Antioxidants

Antioxidants help to protect our cells and other structures from free radical damage⁸. Free radicals steal electrons from other compounds which in turn makes them unstable and steal electrons from elsewhere. This means there’s a chain of events that results in damaged biochemical structures that can no longer do their job. Think of it as a form of biological rusting and ageing. The brain is thought to be particularly vulnerable to free radical damage and can contribute to mental illness including depression, bipolar disorder and schizophrenia⁹. Some research has found that antioxidants like vitamin C and E can help with stress-related mental health issues such as anxiety.¹⁰  

Where can I get antioxidants from? 

There is a huge variety of antioxidants and, luckily, a wide range of foods that contain them. Find out more about antioxidants, why we need them and where you can get them from here. 

Omega 3 

Far from just being good for your heart health, omega 3 fatty acids are also good for your brain too. Studies have found higher levels fish consumption can result in a reduction of anxiety and depression in a two-year follow-up¹¹ and intake of EPA (a type of omega 3) has been found to be more effective at helping to alleviate psychological distress and depressive symptoms than a placebo during menopause¹². The exact mechanism by which omega 3 helps isn’t clear cut, but it is thought that it is involved with neurotransmitters (chemical messengers used to communicate between brain cells), turning into other useful chemicals in the brain, may help signals pass through neurons (brain cells)¹³. In fact, the brain is made up of 60% fat, as brain cells are covered in fatty insulation, making it quicker for signals to go through brain cells. It is also thought that omega 3s help preserve this insulation. 

Where can I get omega-3 fats from? 

Oily fish (i.e. salmon, mackerel, sardines), seeds (i.e. chia, flax seeds), eggs, and nuts (i.e. walnuts). It’s important to go for good quality sources, as quality affects the omega-3 content of these foods. If you don't eat oily fish frequently, it is highly recommended to take a daily omega 3 supplement. 

Zinc  

Zinc is essential for many functions including growth, immunity and helps to reduce inflammation and oxidative stress in our bodies. In fact, zinc is integral to almost 3,000 proteins and without zinc, our ability to repair the normal wear and tear on our DNA would be compromised. Initial studies have found that zinc supplementation improves certain symptoms of depression¹⁴ and in a review of available literature, researchers have found that zinc can improve the effectiveness of antidepressants and may even help those who experience depression that hasn’t been successfully treated through conventional methods.¹⁵ 

Where can I get zinc from? 

Whole grains, oysters, beans and nuts as well as pumpkin seeds. 

Magnesium 

Magnesium is another mineral key for mental health. A study of over 5000 subjects found that magnesium intake resulted in lower scores on scale measurement of depression¹⁶, and other reviews of research have found that magnesium intake can be useful to combat anxiety.¹⁷ Double win! 

Where can I get magnesium from? 

Spinach, almonds, dark chocolate, pumpkin seeds, and black beans.

Protein 

Last but by no means least, protein is also important for mental wellbeing, in particular, the amino acid (building block of protein) tryptophan is required to make serotonin, the neurotransmitter involved in emotional wellbeing. 

Where can I get tryptophan from? 

Turkey, chicken, pineapple, cheese, soy, sea green (i.e. seaweed, spirulina) are all great sources of tryptophan. You can also try a protein powder that has the full 20 amino acids including tryptophan and add that to your morning smoothies/daily routine.  

When to get help

If you are struggling to cope and think you may have depression, it is very important to seek professional help from your GP. Many people wait a long time before seeking help for depression, but it's best not to delay. The sooner you see a doctor, the sooner you can be on the way to recovery. 

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