Your brain is a powerhouse, is always “on and needs a constant supply of energy.” It takes care of your thoughts and movements, breathing and heartbeat, and senses — it works hard 24/7, even while you’re asleep. This means your brain requires a constant supply of fuel. That “fuel” comes from the foods you eat — and what’s in that fuel makes all the difference. What you eat directly affects the structure and function of your brain and, ultimately, your mood.

Just as there is no magic pill to prevent cognitive decline, no single food can ensure a sharp brain as you age. Nutritionists emphasise that the most essential strategy is to follow a healthy dietary pattern that includes a lot of fruits, vegetables, legumes, and whole grains. Try to get protein from plant sources and fish, and choose healthy fats, such as olive oil or canola, rather than saturated fats. Green, leafy vegetables, Fatty fish which are abundant sources of omega-3 fatty acids, Berries, and Walnuts, which are high in a type of omega-3 fatty acid called alpha-linolenic acid (ALA), are highly recommended for a healthy brain. 

Junk food can negatively impact the brain in many ways, including: 

1. Mental health. Junk food can contribute to depression, anxiety, and poor memory. The high sugar content in junk food can cause mood swings and irritability. 
2. Cognitive decline
   Junk food can accelerate neurodegenerative diseases and lead to cognitive decline. 
3. Brain chemistry. Junk food can change the brain’s chemical composition, making the body more dependent on it. 
4. Nutrient deficiencies. Junk food lacks essential nutrients that are important for brain health and function. 
5. Dementia. A study found that a 10% increase in ultra-processed food consumption was associated with a 25% higher risk of dementia. 
6. Obesity. Overeating junk food can lead to obesity, which can impair the brain’s response to nutrients. Obesity affects all the organs in the body, including the brain.
7. Digestive issues. Poor digestive health can negatively impact mood and hormones in the brain, affecting hunger and weight balance. 

Your gut detects the brain. Serotonin is a neurotransmitter that helps regulate sleep and appetite, mediate moods, and inhibit pain. Since about 95% of your serotonin is produced in your gastrointestinal tract, and your gastrointestinal tract is lined with a hundred million nerve cells, or neurons. The function of these neurons — and the production of neurotransmitters like serotonin — is highly influenced by the billions of “good” bacteria that make up your intestinal microbiome. These bacteria play an essential role in your health. They protect the lining of your intestines and provide a substantial barrier against toxins and “bad” bacteria; They improve how well you absorb nutrients from your food; and they activate neural pathways that travel directly between the gut and the brain.

Studies have compared “traditional” diets, like the Mediterranean diet and the traditional Japanese diet, to a typical “Western” diet and have shown that the risk of depression is 25% to 35% lower in those who eat a traditional diet. Scientists account for this difference because these traditional diets tend to be high in vegetables, fruits, unprocessed grains, and fish and seafood, and to contain only modest amounts of lean meats and dairy. They are also void of processed and refined foods and sugars, staples of the “Western” dietary pattern. In addition, many of these unprocessed foods are fermented and act as natural probiotics.

Nutritional psychiatrists state that anxiety and depression can seriously undermine mental health and quality of life globally. The consumption of junk foods, including ultra-processed foods, fast foods, unhealthy snacks, and sugar-sweetened beverages, has been linked to mental ill health.

There is also evidence that brain-derived neurotrophic factor (BDNF) may be reduced by consumption of a high fat diet. BDNF is associated with supporting existing neurons and the production of new neurons and is implicated in the pathogenesis of depressive disorder. A reduction in BDNF impairs synaptic and cognitive function and neuronal growth, contributing to the development of psychological disorders