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How Can What We Eat Affect Our Mood?

This Unexpected Thing Might Be Messing With Your Emotions

Have you ever heard your gut being referred to as your 'second brain'? Well, there's a reason for this.

Increased interest into gut health, and particularly the link between how our gut and brain interact has led to an influx of new research into the relationship between how what we eat and when we eat plays a role in how we actually feel. So, if you've ever eaten a particular food, or eaten a particular way and found your moods being affected, there's now research to prove that this isn't just all in your head — or your gut.

To find out more we spoke to Nicole Dynan, The Gut Health Dietitian, to learn if eating yourself into a bad mood is possible and if there's an optimal way to eat for benefiting our mental health.

How Are Our Gut and Moods Linked?

Our gut and brain are linked by the longest nerve in the body - the vagus nerve. The vagus nerve is bi-directional, meaning it sends signals from the gut to the brain and the brain to the gut. Feeling butterflies in your tummy when you are nervous or experiencing constipation or diarrhoea when you are anxious are good examples of how this works. In the same way, when your gut is not working well you may experience 'brain fog' or feel like you're in a bad mood. When your gut is working well your mood may be lifted.

Can You Eat Yourself Into a Bad Mood?

Absolutely! If you regularly eat junk food, then you're more likely to be feeding the bad bacteria in your gut. This may lead to anxiety and depression, poor immunity and even long term health problems. Avoiding processed and ultra-processed foods and focusing on improving your gut health will ultimately have a positive impact on your mental health and overall health.

Can Unhealthy Eating Patterns Cause Mood Swings?

Eating processed foods such as cakes, chips and lollies may make us feel good for a short time, but a lack of nutrients means they are broken down quickly in the body. This causes a spike in blood sugar levels, making us feel energised initially but leaving us feeling tired and sluggish shortly after. Carbohydrates include a wide range of foods which are digested into sugar (glucose), and these provide energy for the body (which may be why we want to reach for them when feeling tired). The best choices are slowly digested (low GI) carbs which provide long-lasting energy for the brain like wholegrain bread, fruit and low-fat dairy foods. If you don't have enough carbohydrates to keep your body fuelled with glucose, you can feel tired and irritable. We feel good when our diet provides regular amounts of good quality carbohydrates to keep blood glucose levels stable. Eating breakfast is a great way to kick start healthy eating each day and reduce the likelihood of 'sweet binges' later in the day.

What Research Is There to Explain How Diet May Influence Mental Health?

There is now good evidence to show that diet can influence our mental health, and most of us will have experienced the impact of food on our mood. Research has compared the 'western diet' to traditional diets like the Mediterranean diet and shown that the risk of depression is significantly lower in those who eat a more plant-based, traditional diet high in vegetables, fruit, whole grains, nuts and legumes, with some fish, fermented dairy and small portions of meat. These diets are also lacking ultra-processed foods, sugars and saturated fats which are typical of a western diet.

Are Their Particular Foods That Are Worse For Our Mental Health?

Junk, discretionary or sometimes foods are all names for processed and ultra-processed foods that provide little nutrition to our body. They feed the bad bacteria in our gut which may lead to a 'leaky' gut, where food particles leak through into our bloodstream causing inflammation in the body and potentially, poor mental health. Our five food groups, fruit, vegetables, whole grains, meat and alternatives and dairy alternatives, on the other hand, all help to provide nutrients to support our mental health. They promote a diverse range of good bacteria in the gut which makes good compounds to protect the gut wall and reduce inflammation.

Is Good Nutrition Just as Important to Mental Health as Exercise?

Regular exercise and good nutrition are both key to maintaining positive mental health and tend to be intrinsically linked. If you are habitually active, then you are likely to eat a more diverse range of fruits and vegetables. This is due to what is known as the transfer effect - in other words, how improvements in one area of life, such as exercising, can motivate you to change other aspects, such as eating.

Is There a Particular way of Eating That Is Most Beneficial For Our Mental Health?

Diet quality and variety are key when it comes to our mental health. Some foods contain nutrients that are good for health and mood, including B-vitamins, Omega 3, selenium, tryptophan, resistant starch and some antioxidants. Although be sure to remember that overall diet quality is the key, rather than individual foods. When it comes to overall diet quality, eating whole foods like fruit and veggies, whole grains, legumes, nuts, lean meat, seafood and fermented dairy foods means we're more likely to meet our needs for vitamins, minerals, antioxidants and fibre. These positively impact on our gut and brain health. Prebiotic rich foods (those containing fermentable fibres or compounds such as polyphenols that feed the gut bacteria) such as oats, lentils, asparagus, onion, garlic and extra virgin olive oil are also proving to be highly valuable in ensuring good gut health and mental health. That's why traditional diets, like those from the Mediterranean, Japan and Norway can be great for our mood, as they emphasize whole foods, are based on the five core food groups and have very little to no processed foods.

  • B vitamins, such as those found in whole grains, vegetables and lean meats help neuronal function and many processes in our brains. Pineapples are high in manganese and are a good source of vitamin B, C and folate. They have been positively linked to brain health.
  • Omega-3 is a healthy fat often linked with good mood and brain health. It's found in foods like oily fish and some nuts and seeds. Research suggests that omega-3 can reduce the symptoms of depression, as it may make it easier for serotonin, a chemical in our brain which can change our mood (often known as the happy hormone), to pass through our brain and to the cells which create happy feelings.
  • Selenium found in brazil nuts, meats, fish, seeds and wholemeal bread, can boost our levels of serotonin and help elevate a low mood.
  • Serotonin is made with an essential amino acid from the diet called tryptophan. Tryptophan can be found in foods like tofu, cottage cheese, eggs, chicken, salmon, red meat, chickpeas, almonds and peanuts. More tryptophan may get into the brain when carbohydrate-rich foods are eaten.
  • Resistant starch is a type of fibre that resists digestion and becomes available as food to our good gut bacteria. The bacteria turn it into short-chain fatty acids, which are the main source of energy for the cells lining our colon. They help to maintain the integrity of the intestinal wall and give us energy to feel good. Good sources of resistant starch include green bananas (and green banana flour), cooked and cooled potatoes, rice and pasta, legumes and oats. The cooking and cooling of starches makes the starch crystals become more resistant to digestion, nourishing the good bacteria - so try reheating those leftovers!
  • Cocoa powder is high in antioxidants, mainly flavonoids that may positively impact the brain. The darker the chocolate, the greater the percentage of cocoa and potentially, the greater the impact on your mood.

How Can You Use Food to Improve Your Moods and Mental Wellbeing?

Serotonin is a neurotransmitter that helps regulate sleep and appetite, mediate moods and inhibit pain. With other 90 percent of your serotonin produced in your gastrointestinal tract, it makes sense that your digestive system does more than just digest food, but also guides your emotions. Nourishing the good bacteria in the gut will help to protect the lining of your intestines and ensure they provide a strong barrier against toxins and 'bad' bacteria; they limit inflammation; they improve how well you absorb nutrients from your food, and they activate neural pathways that travel directly between the gut and the brain. Feeding them well will ensure they work optimally, resulting in a positive impact on your mood.

Image Source: Patrick Strattner / Getty
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