How to eat well for mental health and immune

Key Highlights

• Our diet affects our physical health via the immune system, and our mental health via the enteric nervous system (ENS)

• What we consume decides whether our gut grows good bacteria or bad bacteria

• Good bacteria promote immunity and good health, whereas bad bacteria can lead to immunity-related problems like immunodeficiency, autoimmune disorders, inflammation, and mental health problems like depression.

• Eating whole foods, plant-based diet, probiotic-rich foods, prebiotic-rich foods can enhance our immunity

• Consuming processed food, junk food, food laden with added sugars and salt can all harm the immune system in various ways

• Cooking techniques like steaming and stir-frying best help to retain the food’s nutritive value

• Practice eating a healthy, balanced diet comprising of fresh, locally-produced foods. Accompany it with a habit of drinking lots of water and getting a fitful sleep

Your diet not only influences your energy levels but also your mood and overall immunity. So, it would be safe to say mental health & immunity share a deep connection. The health of our immune systems is complex and relies on many factors, not on the intake of one specific food or nutrient.

A diet limited in variety and nutrients can negatively affect the immune system. In addition, a diet high in red meat and refined sugar can upset the balance of healthy intestinal bacteria, contributing to chronic inflammation of the gut and reduced immunity.

Nutritionists suggest that instead of eating the same meals every day, you must eat a variety of foods to get all the nutrients that strengthen your brain. To boost your mood and improve your memory and concentration you need to nourish your body with a healthy mix of carbohydrates, proteins, and minerals.

Did you know?

• The human gut is known as the ‘largest immune organ’ that is responsible for 50-70% of our immune response.

• 25-33% of people suffering from chronic ailments are at risk for becoming a victim of depression.

• Obesity, a factor common for enhancing immunosuppression and mental health problems like depression, is increasingly burdening children in Southeast Asia. According to the WHO, around 6.6 million children below the age of 5 in SE Asia, are overweight.

• Traditional cuisine like Japanese and Mediterranean cuisine lower the risk of depression by 25-35% due to their unprocessed food content.

• Awareness about the importance of probiotic foods for immunity enhancement is growing the world over, especially after the Covid-19 pandemic. According to Allied Market Research studies, the global probiotics market is projected to reach $73.9 billion by 2030.

Our mental health, the food we consume, and our immune health share an interesting correlation with each other. Let us see how:

Why would mental health also affect our immune system?

Our mental health and our immune system share a yin n’ yang relationship. Each is dependent on the other for its wellness. We get sick when our immunity is negatively affected. A warm body, sniffling nose, aching muscles or upset tummy do not exactly put anyone is a good mood.

People suffering from chronic ailments and/or undergoing extensive treatments are at a higher risk of slipping into depression. The constant pain or discomfort, humungous changes in lifestyle, lack of unhindered mobility, and anxiety about the future makes a person suffering from chronic illnesses more vulnerable to depression. Chronic illnesses are a by-product of heavily compromised immune systems.

Some studies say that low mood and depression elevate the levels of a neuropeptide called central corticotropin-releasing hormone (CRH) in the central nervous system. This elevation leads to lowering of innate and cellular immune responses.

The effects of the hormone cortisol on the hypothalamus-pituitary-adrenal (HPA) axis are common knowledge. Cortisol is produced due to excessive and chronic stress, and leads to suppression of our immune system, which in turns causes health problems.

Interestingly, a compromised immune system also has a negative impact on one’s mental health. Certain infections have been seen to cause mood disorders and psychotic disorders.

Cytokines – which are actually good proteins that help the body’s immune and inflammatory response – when they become proinflammatory cytokines, they lead to increased stress, anxiety, and depression.

How does nutrition affect mental health?

Considering the impact that mental health has on immunity (and, vice versa), it is important to maintain a good mental health to preserve one’s immunity. Among several factors affecting mental health, an important one is ‘nutrition’.

Usually we associate a health, nutritious diet with maintaining physical health. But a proper nutrition also has a positive effect on one’s mental health and wellbeing.

70% of our immunity stems from our gut and our gut health is closely correlated to the functioning of our brain (and vice versa). How so? Well, it’s because our brain and gastrointestinal system share a close relation.

Researchers are increasingly focussing on this ‘second brain’ or ‘little brain’ called the enteric nervous system (ENS), which plays a big role in digestion of food and release of enzymes and communicates directly with the main brain.

Hence, consumption of wrong foods that lead to temporary problems like gas or bloating, to bigger ones like chronic diarrhoea and Irritable Bowel Disease cause disturbance in the gastrointestinal system, which is conveyed to the main brain via the central nervous system, thus causing mood and behavioural changes.

On the flip side, this communication also leads to a nutritive diet helping you feel calm and peaceful, whereas an unhealthy diet making you feel stressed or tired. When the consumption of an unhealthy diet continues for long, it alters the gut’s microbiome environment such that the body’s immune system loses its ability to fight infections and control inflammation effectively.

How can what we eat help modify our immune responses?

Our gastrointestinal tract hosts millions of bacteria that affect the production and working of neurotransmitters like serotonin and dopamine.

‘Good bacteria’ acquired from non-processed foods, whole foods, antioxidant-rich foods and fermented foods has a positive effect on the neurotransmitter response, which in turn elevates your mood and energy levels. What’s more, they also help in controlling inflammation, erect a strong resistance towards toxins, and improve the gut’s capacity to absorb nutrients from food.

On the other hand, ‘bad bacteria’ acquired from processed foods, junk foods, sugar-heavy foods results in dysbiosis i.e., an imbalance in the gut microbiome. Dysbiosis can lead to a disruption in our immune responses, thus causing inflammation, obesity, insulin resistance, and cancer among other problems.

Excessive consumption of refined sugars has been seen to lead to mood disorders, especially depression.

Immune system-booster foods

To put it in a nutshell, immune system booster foods are those that are rich in nutrients, especially vitamin C, vitamin D, Vitamin E (all of which are immune boosting vitamins), iron, zinc, selenium, and proteins, as they help in the growth and protection of immune cells.

On the other hand, excessively processed foods and foods that are high in sugars and red meat can hamper the immune system to cause immunosuppression and inflammation of the gut.

Let us take a close look at which are these groups and types of immune system booster foods that one should consume for immune and mental health:

Benefits of whole foods

Fresh fruits, vegetables and unprocessed grains are a very good source of immunity due to the immunity-boosting beta carotene, vitamin E and vitamin C that they contain. Most fruits and vegetables are laden with antioxidants, which also helps enhance immunity by lowering oxidative stress.

• Carrots, broccoli, spinach, bell peppers, tomato are all good sources of beta carotene, which is a great antioxidant that can lower inflammation and increase the disease-fighting ability of the body.

• Lemons, oranges, red peppers, cauliflower are al rich in vitamin C, whereas spinach, broccoli, almonds, peanuts, pumpkins are all rich in vitamin E. Both these vitamins can enhance the body’s immunity by destroying free radicals that increase the risk of chronic diseases and inflammation.

• Spinach, mushroom, egg yolk and some types of fish like tuna are rich in vitamin D which reduces the growth of proinflammatory compounds and thus prevents viral infections. Vitamin D also helps reduce the risk of chronic diseases like hepatitis and cardiovascular diseases.

• Chickpeas, poultry, whole grains, cashews, almonds are all good sources of zinc, which is called ‘nutrition for white blood cells’ and thus increases the body’s baseline immunity.

• Foods rich in omega-3 such as walnuts, salmon, and sardines can enhance the body’s immune function to the optimum.

The benefits of a plant-based diet

A plant-based diet comprises of non-processed or minimally processed vegetables, fruits, legumes, herbs, spices, beans, and seeds. It is often suggested for reducing/ preventing inflammation which is stoked due to unhealthy foods that cause obesity, diabetes, and inflammation of internal organs, among others.

• A plant-based diet is rich in antioxidants, minerals, and vitamins that fortify the body against infections and inflammation. It also helps maintain your weight and prevent obesity, thus also helping boost your immune system in that way.

• Some people also like to go a step ahead and follow a raw-food plant-based diet, which is rich in fibre. Consuming the food raw, without cooking, helps retain the maximum micronutrients.

Fibre reduces the risk of cancer, high cholesterol, and inflammation by improving the gut health through better absorption of nutrients. However, it cannot be followed by elderly people, young kids, pregnant women, and those with an already-suppressed immune system.

Hence, it is better to follow a simple plant-based diet wherein 2/3rd portions of your plate can be made up for plant-based foods.

• Spinach is a powerhouse of several immunity-boosting elements like vitamin C, vitamin D, and beta carotene.

• Cruciferous vegetables like cauliflower, broccoli, and kale are rich in folate, beta carotene, and vitamins C, E, K, but more so they’re loaded with  sulforaphane, a phytochemical that enhances the body’s immunity by several notches.

• Papayas are available all year long, and are rich in folate (an ace cell-rebuilder), potassium, vitamin B, and the enzyme papain that has superior anti-inflammatory properties.

• 2-3 cloves of garlic a day can help fight infections better. Garlic has antimicrobial and anti-viral properties due to its sulfuric compounds like allicin.

• Similarly, ginger, which contains gingerol, is a good anti-inflammatory food and antioxidant.

• Turmeric, which is rich in beta carotene, potassium, fibre and 300 such natural components, gets its very helpful anti-inflammatory properties from the chemical curcumin.

Benefits of probiotics and prebiotics

The importance of probiotics has been understood and accepted from several centuries, in culinary cultures around the world. From the Greek yoghurt to the Indian curds, and from the Indonesian tempeh to the Vietnamese nuoc-mam, the importance of these ‘living microorganisms’ in maintaining the delicate gut microbiome balance to preserve immunity, prevent ailments like autoimmune problems, allergies, obesity, and cancer, has been advocated for long.

• Probiotics stimulate the natural enzymes and digestive juices such that the digestive system functions properly. When this happens, the gut microbiome can perform its immunological and metabolic duties in a proper way, thus enhancing overall immunity and mental health (due to the ENS system described above).

• Probiotics are available as supplements, but are best consumed via fermented foods, for optimum benefit. You can get ample probiotics by consuming foods like yoghurt/curd, soft cheese like Gouda, sourdough bread, kimchi, kombucha, miso, and pickles.

• Probiotics can accord several health benefits such as lowering the bad ‘LDL’ cholesterol and blood pressure, keeping one away from depression, treat diarrhoea, reduce the intensity of inflammatory responses to treat rashes, allergies and eczema, and lowering weight by preventing the absorption of dietary fat in the gut.

As for prebiotics, they are fibre-rich foods that boost the growth of the good bacteria already present in the gut, which allows the production of nutrients for the colon cells, thus aiding a healthy digestive system.

Some good prebiotics include:

• Garlic: It has antioxidant and anti-inflammatory properties; helps in controlling lipids; and keeps the bad bacteria from growing inside the gut

• Onion: It has effective antibiotic properties; helps break down the fats in the gut; and enhances nitric oxide production in cells to boost immunity

• Asparagus: It has inulin that enhances the overall digestive health. It also contains lots of fibre and antioxidants along with several anti-inflammatory properties.

• Banana: Apart from being loaded with minerals, vitamins and fibre, bananas (especially, raw bananas) have a lot of resistant starch which contains prebiotic properties.

• Apples, barley, cocoa, and flaxseeds also are known to behold several prebiotic benefits that promote immunity.

How to cook for best immunity

Equally important, and yet often overlooked, are the techniques of cooking and their effect on nutrition and immunity.

For instance, even if the raw material is healthy, if the dish cooked using them is deep fried or charred, the nutrition value goes way down, and instead it leads to build up of bad cholesterol and inflammatory issues.

• Eating raw food, while healthy, is not advisable for everyone and cannot be done every time. Hence, a balance is needed between eating raw food and cooking it to retain its nutrition content. The golden rules are to use minimum water, reduce the cooking time, and lower the surface area of food exposed to heat.

• Instead of opting for deep frying, go for shallow frying or stir frying, which uses minimal oil and less heat. Air fryer is a good option as well.

• Steaming helps retain the colour, texture, and nutrition of the foods best. Just be sure not to over-steam foods like cauliflower and cabbage as they lose their anti-cancer glucosinolates due to over-steaming.

• Instead of direct pressure cooking which causes a loss of vitamins due to excessive heat exposure, try cooking in a preheated pressure cooker or boiling water.

What not to eat

There are certain types of foods that can have a marring effect on your immunity and subsequently, mental wellbeing.

• Foods like candy, cake and sugary beverages that are high in added sugar can increase the risk of inflammation due to production of inflammatory proteins like TNF and CRP, which weaken the immune system.

• Excessively salty foods like chips and frozen foods can increase the risk of contracting autoimmune diseases and can trigger tissue inflammation.

• Fried foods such as potato chips, fried chicken, pakoras etc are loaded with advanced glycation end products (AGEs), which affect the gut bacteria negatively, harm the body’s antioxidant mechanism, and trigger inflammation.

• Processed meats are not just high in AGEs but also in saturated fats, which mar the immune system heavily by promoting systemic inflammation.

• High refined carbs like white bread and baked goods made of refined flour can increase the production of free radicals and proinflammatory proteins like CRP.

• Fast food is rich in phthalates and can disrupt the working of the endocrine system, as well as, the gut microbiome balance.

Conclusion

To a large extent, your mental health & immunity depends on what you eat. Hence, be aware about what you consume, how much you consume, and when you consume.

The Japanese have taught us several ways of mindful nutrition.

• They avoid eating while walking; they eat a variety of foods in a meal which comprises of fermented foods, foods low in calories, seasonal vegetables, and foods that are easy to digest.

• More importantly, they practice the ancient concept of hara hachi bun me which advocates knowing when to stop eating. This helps prevent overeating and overloading the digestive system.

The ancient Indian food culture also advocates similar principles such as eating an early dinner (so as to prevent obesity and heart disease, get ample sleep which in turn boosts the T-cell functions for immunity, improving the digestive system function, and enhancing mental health), eating fresh and seasonal produce, eating herbs and spices that boost immunity, and avoiding stale or processed foods.

Mental health and immunity is closely linked. Hence, eating healthy, nutritious food goes a long way in promoting physical and mental wellness.

Follow a diet rich in fresh, seasonal, locally-available produce. Avoid processed, junk, and fried foods. Drink a lot of water to help the body flush out harmful toxins.

If you follow these simple golden rules, your health is bound to be bouncy for long!