The Link Between Diet and Mental Health

Mental health has become something that people are encouraged to talk about, and you can see that from the number of stories in the news. Reading around, mental ill-health seems to be a broad term covering common associations such as depression, Alzheimer’s, dementia, ADHD, and eating disorders, but also includes anxiety disorders and persistent unhappiness or pessimism. In contrast, mental good health is characterized, amongst other things, by happiness and optimism.

So, why am I writing about mental health? Isn’t that outside the scope of what we do? Not really. Our mission is to help our clients look and feel better. A lot of them come to us feeling down about themselves. Some have lost their ‘mojo’; others are unhappy about how they look; some suffer from anxiety or even depression. We get tears, we get pessimism, we get emotional outpourings, we get a low mood. Although the causes of mental health issues are varied and complex, there is no doubt that lifestyle factors can have an influence. If we can give our clients exercise and nutrition advice to help them feel physically better and give them more energy, perhaps we can also use the nutrition and lifestyle advice to improve their mood and their outlook. After all, there’s more to feeling better than just having more energy. Feeling better about yourself can be far more energising than any physical improvement.

So, it was with this in mind that I wanted to explore the way in which diet can impact your mental health. I am not claiming to be an expert in diet and mental health. Far from it. I have simply used my academic background to trawl the news and scientific literature for the key facts and serve them up in a way that is concise, relevant, and useful for our clients.

Three publications, in particular, provide a comprehensive round-up of the effect of food on mental health:

Feeding minds: This is an excellently written, well-researched, and comprehensive round-up of all the information relating to food and mental health, with lots of references in each section. You could just read this and it would tell you almost everything but…. it is rather long, being almost 70 pages.
Food for thought: Another nice summary but this time just 18 pages.
The effects of food on brain function: A scientific look at the way food affects our brains and the way they function.

In this article, if I make a statement without a citation, then you can assume the information is taken from one of these articles.

So, with the intro done, let’s have a look at some of the key points that link diet and mental health.

Associations between quality of diet and mental health

Here are some key general points about diet and mental health:

• There is a very close association between physical health and mental health. The two tend to go hand in hand. Maintain a diet that keeps you physically healthy and you are more likely to have good mental health. The reverse is also true.
• The first point should be no surprise. After all, the brain is an organ too and needs a good supply of proteins, healthy fats, carbohydrates, vitamins and minerals to function properly.
• Good nutrition has been correlated with academic success
• Processed foods have been linked to poorer mental health. A diet that is high in processed foods, sugar and saturated fat is more likely to lead to poor mental health.
• The government’s Eatwell guidelines still offer the best and simplest advice for healthy eating, both for physical health and mental health.
• Poor mental health is particularly associated with deficiencies in certain vitamins and minerals. For example:
• Depression can be improved by addressing deficiencies in vitamins B1, B2, B3, B6, and C and in folates, magnesium, zinc and selenium.
• Improvements in ADHD have been addressed through increases in zinc, magnesium, and iron.
• Dementia outcomes can be improved by lowering the fat content and increasing the vitamin and mineral content of the diet.

For a great summary of the effects of different vitamin and mineral deficiencies, take a look at the table on page 7 of the Food for Thought reference Table 1 (about halfway down) in the link on the effects of food on brain function.

For an interesting look at different neurotransmitters and the various foods to avoid or consume for optimal neurotransmitter functioning, take a look at the table on page 40 of the Feeding Minds article.

Fruit and vegetables

The first specific topic on the subject of diet and mental health is fruit and vegetables. Fruit and veg came up time and again during my reading as something that protects against mental health issues, much more than I had anticipated. It is the vitamins and minerals that fruit and veg provide that are largely responsible for improved mental health. Vitamins and minerals help:

• Essential Fatty Acids (EFAs) get assimilated into brain cells.
• The conversion of amino acids into neurotransmitters.
• Support healthy neurotransmitter activity
• The conversion of carbohydrates into glucose, the brain’s fuel.
• Protect the brain from oxidants, which have been shown to negatively impact mood and mental health

You can see that a lack of vitamins and minerals is going to lead to both short- and long-term issues with the brain and, consequently, mental health. That means suitably high fruit and vegetable consumption should be a lifelong lifestyle habit to ensure optimal mental health and longevity.

Here are some facts regarding fruit and vegetables:

• A lack of fruit and vegetables in the diet has been identified as a behavioural risk factor.
• Fruit and vegetables have been observed to improve self-worth and self-efficacy, helping overweight patients improve their weight loss and mental health.
• One paper states in its conclusions that “fruit and vegetable consumption was the health-related behaviour most consistently associated with mental well-being in both sexes”
• Another paper highlights a connection between antioxidants and optimism.
• There are lots of papers on this topic but worthy of mention is a paper which concludes “Eating fruit and vegetables may promote emotional wellbeing among healthy young adults”, and another which states “happiness and mental health rise in an approximately dose-response way with the number of daily portions of fruit and vegetables. Well-being peaks at approximately 7 portions per day.”

So, can you just take a multivitamin-mineral supplement to protect you against mental health issues? I wouldn’t recommend it. There are thousands of phytonutrients in the huge variety of fruit and vegetables out there. They provide many benefits over and above vitamins and minerals, as well as lots of fibre, carbohydrate,s and some protein. Get your fruit a veg and keep it varied.

If you need some inspiration to help you get in the habit of eating more veg, then take a look at our article here.

Essential Fatty Acids (EFAs)

EFAs were another prevalent topic that came up when looking at the link between diet and mental health. This one surprised me a little, probably because I haven’t looked into it for a while. Even though a large study has concluded that omega 3 intake has little or no effect on heart health, that’s still the benefit that lots of people associate with omega 3s. In reality, if you search for the benefits of omega 3, you’ll see a lot more references to brain health and mental wellness.

That makes sense when you consider this interesting fact: 60% of the dry weight of the brain is fat and a good deal of that fat is composed of omega 3 and omega 6 fatty acids in equal amounts. These essential fatty acids play an important role in the structure of brain cells and ensure the smooth transmission of signals.

Saturated fats make cell membranes less flexible and will have a negative effect on brain function. Trans fats are worse because they take the space that would otherwise be taken by essential fatty acids, preventing the brain from functioning optimally. Look out for hydrogenated or partially hydrogenated vegetable oil and avoid it!

In terms of impacts of EFAs:

• A high intake of EFAs and a low intake of saturated fat has been shown to slow memory loss and other cognitive functions.
• Unequal omega 3 and omega 6 intake has been associated with depression and with concentration and memory problems.
• Increased intake of EFAs has been shown to help in the management of the bipolar disorder.
• Increased intake of EFAs can help with cognitive impairment in middle age.

The government’s recommendation is that people should have at least two portions of fish a week including one of oily fish such as salmon. It’s likely you’re already getting enough omega 6, but if you’re in doubt, take a look at the Wikipedia entry for Omega-6.

Wholefoods and low GI carbs

Foods that go through minimal processing tend to contain lots of fibre and take longer for the body to break down. This slows the uptake of nutrients and the rise in blood sugar. These foods are said to be low on the Glycaemic Index (GI). In contrast, highly processed foods are often high GI and will raise blood sugar quickly. These high GI foods will often result in low blood sugar a short while later and that can negatively impact the functioning of the brain and mental wellbeing.

You may have heard the expression ‘hangry’. This describes the person who is experiencing the anger that often accompanies hunger. Hunger can be ravenous when your blood sugar is low, especially one that follows a high GI feed. This is just one example of the way in which choice of carbohydrate – or extent of food processing – can affect mental health. In fact, the impact of processed food on mental health is much more far-reaching and impactful.

The problem with fast-digesting carbohydrates is that they can become addictive. The serotonin released when we ingest refined carbohydrates gives rise to a ‘feel good. When that wears off and a low mood accompanies the resulting low blood sugar, it’s easy to reach for the next refined food meal and start the whole process again. Only more refined carbohydrates will keep the blues at bay. This behaviour will lead to overeating and, in the long run, it can lead to obesity and depression. This paper discusses this phenomenon.

Don’t ditch the carbs!

Now, before you think to yourself that a low carb diet might be the way to go, take note of the following. The government’s recommendation is that over 50% of your calorie intake should come from carbohydrate. One of the very good reasons for this is that carbohydrate is the brain’s preferred fuel. Unlike other organs, the brain is not a fat burner, it’s a carb burner. Getting a good supply of the right carbs will help your brain function well and help you feel good. Get your carbs but get them from low GI sources.

The effects of a high intake of high GI or refined foods seem to be more than just a transient impact associated with blood sugar. Here are some examples of papers on the topic:

• One paper found that higher GI diets are more likely to be associated with depression.
• Another paper states that high consumption of processed food was associated with increased odds of depression.
• The authors of a further study suggest that their results “strengthen the hypothesis that dietary glycemic index may play a role in the pathogenesis or progression of mental illnesses such as generalized anxiety disorder”
• Even papers from 50 years ago identify the link between low blood sugar caused by high GI foods and mental illness.
• Here’s a nice relatable account of low blood sugar and its effect on mood.
• It’s been noted that hungry children are more badly behaved. They could be hungry because they haven’t had breakfast or they’ve made poor choices that have resulted in low blood sugar and ravenous hunger.

The bottom line here is… eat unrefined food. Choose wholefood, wholegrain, wholewheat, eat fruit and vegetables, get some protein with each feed to delay hunger. Look up and learn the GI of your food choices. Make these changes a permanent adjustment to your diet.

The paper cited at the start on brain function gives a scientific explanation of what happens to your brain when you eat!

Calorie intake

Here’s the tangible link between diet and mental health: eating too much is likely to be bad for your mental health. Let’s look at two examples.

In one study the authors conclude “Obesity was found to increase the risk of depression. In addition, depression was found to be predictive of developing obesity.” In other words, the causal direction goes both ways. Being obese is likely to make you depressed. Being depressed is likely to make you overeat.

There is growing evidence that excess calorie intake may increase oxidative damage to the brain and accelerate cognitive decline. Conversely, a slight caloric restriction may reduce oxidative damage and improve longevity.

The bottom line here is, putting on a lot of weight is bad for your health, bad for your brain and bad for your soul. Do everything you can to avoid it. Avoid too many calorie dense, nutrient poor foods and exercise regularly. Make these lifestyle choices.

Risk factors

Here are some things to look out for – and minimize – in your current lifestyle:

• Energy-dense, nutrient-poor foods. These are generally refined processed foods. These include breakfast cereals, most bread, white potato flesh, pastries, biscuits, sweets, cakes, refined white grains, sugary drinks, and processed foods with high-fat content.
• Trans fats and excess saturated fat. Go for energy sparse, nutrient-dense food…. lots of fruit and veg to get your micronutrients.
• Poor physical health. Poor mental health is likely to go hand in hand. To avoid this, eat healthy food in the right quantities and exercise regularly.
• Overconsumption of stimulants – foods that give you a temporary high followed by a low. These include caffeine, sugar, and chocolate.
• Alcohol. Alcohol is a depressant. It might help you ‘relax’ but it will disrupt your sleep and leave you on a downer.
  Poor sleep. This will lower your mood and reduce your energy levels. Poor sleep could come from poor health, alcohol consumption, or caffeine.

The bottom line here… well, have you noticed how I keep repeating myself? It’s more or less the same as in each of the previous sections. Do the opposite of the things listed above as risk factors!

The Wrap-up

The recommendations for minimizing your risk of poor mental health are pretty much the same as those for attaining good physical health. In fact, the Eatwell guidelines issued by the government are the same for both physical and mental health.

So, as a summary of this article, here are your top 8 nutrition strategies for good mental health, with 3 extra lifestyle must-dos thrown in:

1. Eat healthy food that is nutrient-dense.
2. Manage calorie intake.
3. Avoid trans fats and excess saturated fat.
4. Get your essential fatty acids with the right balance of omega 3 and 6.
5. Eat plenty of fruit and veg.
6. Get plenty of low GI carbohydrates.
7. Stay within the recommended alcohol intake.
8. Avoid excess caffeine and sugar.

… and 3 lifestyle must-dos:

• Exercise.
• Get enough sleep.
• Stay hydrated.

You’ll see a lot of similarities between this list and the recommendations in our recent Healthy Eating Week article.

So, there you have it, the link between diet and mental health. However, please note: just as eating a healthy diet and exercising doesn’t guarantee you will be free of physical illness, so the above recommendations won’t guarantee you will be free of mental health issues. But, if you want to give yourself the best chance and virtually eliminate diet and lifestyle as a source of mental health issues, then the best thing you can do is … all of the above!

Cover image courtesy of Total Shape.